Permian Brachiopods
of West Texas, II
G. ARTHUR COOPER
and
RICHARD E. GRANT
SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY • NUMBER 15
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S M I T H S O N I A N C O N T R I B U T I O N S TO P A L E O B I O L O G Y • N U M B E R 15
Permian Brachiopods
of West Texas, II
G. Arthur Cooper
and Richard E. Grant
SMITHSONIAN INSTITUTION PRESS
City of Washington
1974
ABSTRACT
Cooper, G. Arthur, and Richard E. Grant. Permian Brachipods of West Texas, II.
Smithsonian Contributions to Paleobiology, number 15, pages 233-793, figure 40,
plates 24-191, 1974.—The second of a six-part monograph on brachiopods from
the reference area for the North American Permian in mountain ranges of West
Texas and adjacent New Mexico, this volume presents a historical resume of
the ordinal classification of the Brachiopoda, definitions of morphological terms,
techniques of measuring specimens, and remarks on the naming of species. The
major part of the work consists of descriptions and illustrations of genera and
species in the inarticulate superfamilies Discinacea and Craniacea and the
articulate superfamilies Eichwaldiacea, Orthotetacea, Derbyiacea, and Lyttoniacea.
Permian Brachiopods of West Texas, I. Smithsonian Contributions to Paleobiology, number 14,
231 pages, 39 figures, 23 plates, issued 29 December 1972.
OFFICIAL PUBLICATION DATE is handstamped in a limited number of initial copies and is recorded
in the Institution's annual report, Smithsonian Year. SI PRESS NUMBER 4787. SERIES
COVER DESIGN: The trilobite Phacops rana Green.
Library of Congress Cataloging in Publication Data
Cooper, Gustav Arthur, 1902-
Permian brachiopods of West Texas.
(Smithsonian contributions to paleobiology, no. 14-15)
Includes bibliographies.
1. Brachiopoda, Fossil. 2. Paleontology—Permian. 3. Paleontology—Texas. I. Grant, Richard E.,
joint author. II. Title. III. Series: Smithsonian Institution. Smithsonian contributions to
paleobiology, no. 14-15.
QE701.S56 no. 14, etc. [QE796] 560'.8s [564'.8'097649] 72-4218
For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402
Price $9.65 domestic postpaid or $9 GPO Bookstore
Contents
Page
Systematics 233
Historical 233
General Discussion 234
General Remarks on the Permian Fauna 234
Inarticulata 234
Articulata 235
Orthotetacea 235
Oldhaminidina 235
Chonetidina 235
Productidina 235
Rhynchonellida 237
Spiriferidina 237
Rhipidomellida 238
Rhynchoporacea 238
Spiriferinacea 238
Terebratulida 238
Terminology 239
Measurement of the Specimens 239
Note on the Naming of Species 239
Abbreviations 239
Class Inarticulata 240
Order Acrotretida 240
Suborder Acrotretidina 240
Superfamily Discinacea 240
Family Discinidae 240
Subfamily Orbiculoideinae 240
Genus Roemerella 240
Suborder Craniidina 241
Superfamily Craniacea 241
Family Craniidae 241
Genus Acanthocrania 241
Genus Lepidocrania 246
Genus Petrocrania 249
Class Articulata 251
Order Uncertain 251
Suborder Dictyonellidina 251
Superfamily Eichwaldiacea 251
Family Isogrammidae 251
Genus Isogramma 251
Order Strophomenida 255
Suborder Orthotetidina 255
Terminology of the Suborder Orthotetidina 257
Superfamily Orthotetacea 260
Family Orthotetidae 260
Family Schuchertellidae 260
Subfamily Pulsiinae 260
Subfamily Schuchertellinae 260
Genus Schuchertella 261
Genus Goniarina 262
Subfamily Hypopsiinae 272
Genus Hypopsia 272
iii
1 V SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
Page
Subfamily Diplaninae 274
Genus Diplanus 274
Subfamily Derbyoidinae 281
Genus Derbyoides 282
Superfamily Derbyiacea 285
Family Orthotetellidae 285
Genus Orthotetella 285
Family Derbyiidae 288
Subfamily Derbyiinae 288
Genus Derbyia 289
Genus Nothopindax 318
Subfamily Omboniinae 321
Genus Ombonia 321
Family Streptorhynchidae 326
Genus Streptorhynchus 326
Genus Chelononia 327
Genus Bothrostegium 830
Genus Tropidelasma 333
Family Meekellidae 349
Genus Meekella 350
Genus Niviconia 373
Genus Geyerella 376
Suborder Oldhaminidina 384
Superfamily Lyttoniacea 384
Family Poikilosakidae 388
Genus Poikilosakos 389
Genus Pseudoleptodus 392
Genus Choanodus 401
Genus Sceletonia 405
Family Lyttoniidae 407
Ecology of the Lyttoniidae 412
Genus Eolyttonia 414
Genus Petasmaia 429
Genus Loxophragmus 432
Genus Collemataria 433
Genus Leptodus 448
Genus Rigbyella 448
Genus Coscinophora 450
Literature Cited 457
FIGURE
40. Niviconia globosa (R.E. King) : Dorsal valve, showing cardinal process and its parts. 351
PLATES
24. Isogramma and Roemerella 459
25. Isogramma 461
26. Derbyoides and Isogramma 463
27. Lepidocrania and Acanlhocrania 465
28. Lepidocrania, Acanlhocrania, and Petrocrania 467
29. Lepidocrania 469
30. Niviconia, Derbyia, Tropidelasma, Diplanus, Acanlhocrania, and Lepidocrania 471
31. Hypopsia 473
32. Schuchertella and Hypopsia 475
NUMBER 15
Page
33. Schuchertella 477
34. Derbyoides 479
35. Ombonia and Derbyoides 481
36. Goniarina 483
37. Goniarina 485
38. Goniarina 487
39. Goniarina 489
40. Streptorhynchus and Goniarina 491
41. Goniarina 493
42. Goniarina, Strigirhynchia, and Dyoros (Dyoros) 495
43. Hypopsia, Derbyoides, and Goniarina 497
44. Diplanus 499
45. Diplanus 501
46. Diplanus 503
47. Diplanus 505
48. Diplanus 507
49. Diplanus 509
50. Diplanus 511
51. Tropidelasma 513
52. Tropidelasma 515
53. Tropidelasma 517
54. Tropidelasma 519
55. Tropidelasma 521
56. Tropidelasma 523
57. Tropidelasma 525
58. Tropidelasma 527
59. Tropidelasma 529
60. Tropidelasma 531
61. Tropidelasma 533
62. Derbyoides, Ombonia, Bothrostegium, and Dielasma 535
63. Bothrostegium 537
64. Derbyia 539
65. Derbyia 541
66. Derbyia 543
67. Derbyia 545
68. Derbyia 547
69. Derbyia and Meekella 549
70. Derbyia 551
71. Derbyia 553
72. Derbyia 555
73. Derbyia 557
74. Derbyia 559
75. Derbyia 561
76. Derbyia 563
77. Derbyia 565
78. Derbyia 567
79. Derbyia 569
80. Derbyia 571
81. Derbyia 573
82. Derbyia 575
83. Derbyia 577
84. Derbyia 579
85. Derbyia 581
86. Derbyia 583
87. Derbyia 585
88. Derbyia 587
89. Geyerella, Tropidelasma, Meekella, Derbyia, Collumatus and Teguliferina 589
90. Ombonia 591
VI SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
Page
91. Ombonia t-ga
92. Collumatus and Ombonia 595
93. Goniarina, Orthotetella, and Diplanus 597
94. Orthotetella and Goniarina 599
95. Chelononia and Orthotetella 601
96. Nothopindax 603
97. Nothopindax 605
98. Nothopindax 607
99. Meekella 609
100. Meekella 611
101. Meekella, Echinosteges, and Tropidelasma 613
102. Meekella 615
103. Meekella . . . . . . 617
104. Meekella 619
105. Meekella 621
106. Meekella 623
107. Meekella 625
108. Tropidelasma and Meekella 627
109. Niviconia 629
110. Niviconia 631
111. Meekella 633
112. Meekella 635
113. Meekella 637
114. Niviconia and Meekella 639
115. Meekella 641
116. Meekella 643
117. Meekella and Enteletes 645
118. Meekella, Bothrostegium, and Niviconia 647
119. Geyerella 649
120. Geyerella 651
121. Geyerella 653
122. Geyerella 655
123. Geyerella 657
124. Geyerella, Tropidelasma, and Meekella 659
125. Geyerella 661
126. Chelononia and Derbyoides 663
127. Pseudoleptodus and Poikilosakos 665
128. Pseudoleptodus 667
129. Pseudoleptodus, Coscinophora, and Collemataria 669
130. Pseudoleptodus 671
131. Pseudoleptodus 673
132. Pseudoleptodus and Poikilosakos 675
133. Collemataria, Choanodus, and Pseudoleptodus 677
134. Coscinophora and Choanodus 679
135. Choanodus 681
136. Choanodus 683
137. Choanodus and Loxophragmus 685
138. Sceletonia 687
139. Pseudoleptodus, Sceletonia, and Collemataria 689
140. Eolyttonia 691
141. Eolyttonia 693
142. Eolyttonia 695
143. Eolyttonia 697
144. Eolyttonia 699
145. Eolyttonia 701
146. Eolyttonia 703
147. Eolyttonia 705
148. Eolyttonia 7o7
NUMBER 15 Vll
Page
149. Eolyttonia 709
150. Eolyttonia 711
151. Eolyttonia 713
152. Eolyttonia and Loxophragmus 715
153. Eolyttonia 717
154. Eolyttonia, Collemataria, Liosotella, and Chonetinella 719
155. Eolyttonia and Poikilosakos 721
156. Eolyttonia <723
157. Eolyttonia and Collemataria 725
158. Eolyttonia 727
159. Eolyttonia 729
160. Eolyttonia 731
161. Eolyttonia 733
162. Eolyttonia and Choanodus 735
163. Petasmaia 737
164. Petasmaia 739
165. Petasmaia 741
166. Loxophragmus 743
167. Collemataria 745
168. Collemataria 747
169. Collemataria and Petasmaia 749
170. Collemataria 751
171. Collemataria 753
172. Collemataria 755
173. Collemataria 757
174. Collemataria 759
175. Collemataria 761
176. Collemataria 763
177. Collemataria 765
178. Collemataria 767
179. Collemataria 769
180. Collemataria and Eolyttonia 771
181. Collemataria 773
182. Rigbyella and Coscinophora 775
183. Coscinophora, Pseudoleptodus, Choanodus, Paranorella, and Collemataria 777
184. Coscinophora 779
185. Coscinophora 781
186. Coscinophora 783
187. Coscinophora 785
188. Coscinophora and Pseudoleptodus 787
189. Coscinophora and Pseudoleptodus 789
190. Coscinophora 791
191. Coscinophora, Eolyttonia, Leptodus, Collemataria, and Leptodus (type) 793

Permian Brachiopods
of West Texas, II
G. Arthur Cooper and Richard E. Grant
Systematics
HISTORICAL
Considering the richness of the fossil-bearing
Permian rocks of Texas, it is surprising that so
little work has been done in the past to make their
faunas known. Most of the effort placed on the
Permian of West Texas has been stratigraphic to
satisfy the needs of exploration for oil. The first
important fossil study is that of B. F. Shumard
(1858, 1859), who described the specimens collected,
by his brother G. G. Shumard on an expedition
under the direction of Captain John Pope to
find artesian water in the arid southwest. Shumard
recognized these specimens as Permian and helped
to establish the presence of rocks of this age in
North America.
Nothing more was done in the description of
brachiopods of this part of Texas until the collections
that were made by R. T. Hill, G. B. Richardson,
and G. H. Girty from various parts of West
Texas, including the Glass and Guadalupe Mountains,
were described in the now famous "Guadalupian
Fauna" of Girty (1909). This monograph
finally fixed the Permian age of these fossils beyond
debate. Girty continued this work in 1929 by describing
some fossils from the Hueco Group.
The Glass Mountains fauna was described by R.
E. King (1931), who described 185 species. Most
of them were compared with those of Girty and
Shumard but many new ones were included. This
G. Arthur Cooper and Richard E. Grant, Department of
Paleobiology, National Museum of Natural History, Smithsonian
Institution, Washington, D.C. 20560.
work was a great step forward and the faunal summary
contained in it is still valuable. The next
work containing information on brachiopods is that
of P. B. King (1948), the "Geology of the Southern
Guadalupe Mountains, Texas." This contains extensive
and valuable notes on the brachiopods by
Girty. Following this, the study "Permian Reef
Complex of the Guadalupe Mountains Region,
West Texas and New Mexico" by N. D. Newell and
party (1953) was issued. This work contains an
extensive compilation of brachiopods and one plate
illustrating some of the important species occurring
in that area, but it makes no new contribution to
knowledge of the brachiopods except for some details
of their stratigraphy.
Walter (1953) described a fauna from the Rustler
Formation of West Texas, which is the youngest
known Permian fauna in the area. Stehli (1954)
published an account of the "Lower Leonardian
Brachiopoda of the Sierra Diablo," describing new
genera and species and adding materially to knowledge
of Permian fossils. In shorter papers in 1955
and 1956, Stehli described interesting rhynchonellids
and oldhaminidinids from West Texas, chiefly
from the Delaware Basin but also from the Guadalupe
Mountains. Cooper and Stehli (1955) described
some new genera and species from the
Glass Mountains.
Muir-Wood and Cooper (1960), in their discussion
of the Productidina, described a number of
new genera and species from the Glass Mountains.
Grant (1965) described some of the Stenoscimataceans
from West Texas in a comprehensive study
of that group of brachiopods. In the same year
P. B. King (1965) published the "Geology of the
233
234 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
Sierra Diablo Region, Texas," which includes extensive
lists of brachiopods prepared by P. E. Cloud.
These monographs and smaller papers all proved
most helpful, but they cover only a small part of
the faunas ultimately collected by the present authors.
Termier, Termier, and Pajaud (1967) described
a new genus from the Glass Mountains
thought to be the root stock of the Thecideidina.
Cooper and Grant (1969) published 34 new genera
from West Texas as a preliminary note to the
present monograph.
GENERAL DISCUSSION
The variety and perfection of the fossils described
herein attest to the value of searching for
silicified specimens. Most of the genera can be illustrated
completely with good interior as well as
exterior details. The specimens thus contribute
importantly to the systematics of the Brachiopoda.
The major classification depends largely
upon family characters, chiefly those of the dorsal
interior. Generic characters are found among details
of the exterior and some features of the pedicle
valve interior. The practice is best exemplified
in the classification of the revived superfamily
Orthotetacea. This is divided into two major
groups based on the character of the cardinalia
whether with or without supporting plates. The
genera are based on aberrations of the pedicle valve
interior, i.e., on the presence or absence of dental
plates, on the character of the dental plates, and
also on the strength of the cardinalia. Geyerella
and Ombonia have similar ventral valve interiors,
but the cardinal process of the former is large and
ponderous, that of the latter short and delicate.
They also have different shapes, that of Geyerella
suggesting origin from Meekella but the other indicating
possible derivation from Derbyia.
We also continue to classify all of the punctate
genera as a related line. This is contrary to present
thought, which argues for the polphyletic origin of
punctae. It is our belief that punctae originated
from an impunctate stock, but, once developed,
lines parallel to those of impunctate stocks evolved.
The brachiopod, being a fairly primitive sessile
animal, did not have many lines of evolution
available; consequently, much repetition of form
took place among the various developing punctate
and impunctate lines. It is difficult to follow the
argument that the terebratulids were derived from
impunctate spirifers because the initial loop and
spire have the same form. The spire scarcely could
have had any other form in such minute shells.
It seems more reasonable to derive the terebratulids
from the punctate dalmanellids rather than from
any impunctate stock. The homeomorphy of the
punctate brachiopods seldom converged toward
developments of the pseudopunctate line.
GENERAL REMARKS ON THE PERMIAN FAUNA
The Permian fauna is one of the most interesting
in the geological column because it contains
culminating stocks that disappear at the end of
Paleozoic time. It also contains the transient stocks
that survived the Permian and gave rise to the
Triassic and later Mesozoic faunas. Unfortunately
the Glass Mountains and Guadalupe Mountains
do not contain very late Permian faunas. It is impossible,
therefore, to describe the culminating
forms accurately, although it is possible to detect
in some of the major groups elements that foreshadow
the Triassic.
INARTICULATA
Only one genus of chitinous inarticulates, Roemerella,
was found in all of the collecting. This
may be explained in two ways: the facies is wrong
and the method of collecting is not conducive to
preservation of the chitinous genera. No lingulids
were seen in any of the sediments. Normally these
would not be expected in the coarse lime sands of
most of the formations. But lingulids were not
seen in any of the dark mud rocks either, where
they would be expected. This might be because
of possible deep water deposition of the mud rocks
(since lingulids are commonly shallow water animals).
It is also possible that dissolution of blocks
in hydrochloric acid dissolved or destroyed any
specimens that might have been present. The one
specimen of inarticulate recovered from acid was
seen by accident and split out before it had been
completely destroyed. It is unusual for its large
size.
The few inarticulates occurring in abundance are
the cranias, which are difficult to recognize in piles
of debris and which are represented by brachial
valves only. Although we have searched carefully,
NUMBER 15 235
no pedicle valves were seen on corals or other
brachiopods. One would think that the broad surfaces
of the ventral side of the lyttoniids would be
ideal places of attachment for Crania, but no specimens
were seen there. The Permian was evidently
a poor time for the inarticulates because few of
them are recorded in faunas from other parts of
the world. Branson (1948) lists only six genera.
ARTICULATA
One great value of the Glass Mountains silicified
specimens is their reefy forms, often preserved in
growth position and with interior characters in perfection.
Important among these are the Orthotetacea,
which have been the subject of such speculation
as to how they lived.
ORTHOTETACEA.—Perhaps the heyday of the Orthotetacea
was in the Wolfcampian, when many
bioherms were composed substantially of their
shells. A greater variety of these brachiopods appears
in that time than any other. Then the schuchertellids
were diverse but on the wane, and
Derbyia, living on from the preceding period, flourished
in a variety of forms. Meekella, inherited
from the Pennsylvanian, became one of the commonest
brachiopods, and gigantic forms are preserved
in the Decie Ranch Member. They were
matched in size, but not abundance, by their external
homeomorph, Geyerella. The Orthotetacea
started to fall off in numbers and kinds after the
Wolfcamp (as defined herein). Geyerella and
Derbyia lingered into the upper Bell Canyon but
were rare. The Guadalupian is characterized more
particularly by Ombonia, but this genus is not
widely distributed in the United States. The Capitan
reef faunas have few specimens of Orthotetacea
other than Ombonia. One large Derbyia, known
from poor scraps, and Meekella occur with a small
Tropidelasma. In Asia a few other genera such as
Orthothetina occur, but the superfamily was on its
way out in the Late Permian.
OLDHAMINIDINA.—From humble beginnings in
the Pennsylvanian, this group blossoms into importance
in the Wolfcamp. The earliest form,
Poikilosakos, inherited from the Pennsylvanian, is
rare in the Permian, but its successor, Pseudoleptodus,
becomes fairly common and extends into the
Capitan and Bell Canyon formations. Large forms
occur in the late Word. Other related genera such
as Sceletonia and Choanodus are rare. Eolyttonia,
primitive but variable and the commonest form in
the Lower Permian, produced gigantic conical species
in the late Wolfcampian. It is displaced in the
late Leonard and Word by Collemataria, which
contributed importantly to bioherms in the Cathedral
Mountain Formation but lived in small clusters
in the Word. This genus persisted into the
Capitan and Bell Canyon formations but never attained
the abundance of earlier times; it is relatively
rare in the late Guadalupian. The evolution
of this group was directed to compressing the lobes
of the pedicle valve into septa and to elimination
of the conical form of the early genera, whereas
the evolution of the exterior of Poikilosakos was
directed toward the development of a conical form
and elevation above its host. Its interior however
was largely static.
CHONETIDINA.—Although the chonetids of the
Permian of West Texas are abundant in places and
occur in swarms in some formations, they do not
seem to have evolved conspicuously. The majority
of forms, which are smooth, developed a widely
extended outline in the late Leonardian and early
Guadalupian. In the upper Word of the Glass
Mountains, however, they tended to a more rectangular
or quadrate form. In the Bell Canyon
and Capitan formations they maintained their
transverse outline, but generally they were smaller
than those of the late Leonardian. The Neochonetes
stock became extinct in the Wolfcamp, but
costellate chonetids (Rugaria) of uncertain origin
appeared late in that time—but did not persist.
PRODUCTIDINA.—The productids are legion in the
Permian. They, more than any other brachiopod,
are likely to be found in any of the facies. The
Permian was also the time when the Strophalosiacea
had their greatest development. The Productacea
match those of the Mississippian (Visean) in variety
of form and adaptation and even exceed them in
diversity.
The Aulostegacea now are separated as a superfamily
distinct from the Strophalosiacea. They lack
the teeth and sockets that are retained by the
Strophalosiacea and, in addition, have developed
high interareas for more advantageous attachment
of the ventral beak to the substrate. The Strophalosiacea
in the Glass and Guadalupe Mountains
are represented mainly by small attached shells
236 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
that constitute important epifaunas in some parts
of the column, especially in the Word. The Aulostegacea,
on the other hand, are represented by
large and robust forms that contribute importantly
to bioherms. The earliest of these, Limbella, appears
in the Pennsylvanian, but it becomes abundant
in parts of the Wolfcamp. It probably gave
rise to Edriosteges, an abundant element in the
upper Cathedral Mountain and in the Road Canyon
Formation. Echinosteges is characteristic of
the Guadalupian, although it appears first in the
Road Canyon Formation. A variety of small Aulostegacea
such as Xenosteges, Scapharina, and
Cooperina are important members of the epifauna
that covers dead shells or the exterior of living
ones in the Guadalupian. Glyptosteges, Spyridiophora,
and Institella are highly sculptured shells,
leptaenoid in form and seemingly unlikely as attached
brachiopods, yet they are fixed by the beak
and anchored by spines that often are very long,
as in Institella. Chonosteges with its bizarre anterior
funnels—probably intake valves for feeding—
is the most highly specialized member of the
superfamily. The Aulostegacea become rare above
the Word.
Offshoots from the strophalosiid line, we believe,
are Teguliferina and Acritosia, which contrast
strongly with the richthofeniidae, which they resemble
superficially in the absence of vesicular tissue
in the apex of the pedicle valve, a strongly
oblique cone, and a strophalosiid type of cardinal
process. These appear in the Pennsylvanian, but
they increase in size, numbers, and kinds in the
Wolfcampian.
Although Tschemyschewia, an aberrant genus
with a strong ventral median septum and forked
cardinal process, obviously is related to Scacchinella,
the two genera in Europe are widely separated
in time. In the Glass Mountains, however,
they are contemporaries. Tschemyschewia is an
extremely rare shell, but it is known in the Skinner
Ranch and Road Canyon formations.
Scacchinella differs from Tschemyschewia chiefly
in the "reefy," strongly conical form of the pedicle
valve and the growth habit of cementation and
strengthening the hold by fastening with spines.
Scacchinella, as a contemporary of Tschemyschewia,
probably was not derived from it, but the
two may have had the same, but now unknown,
source. Scacchinella was inherited from the Pennsylvanian
when it was very rare, but it is abundant
in the Skinner Ranch, less so in earlier formations
and members.
The Productacea are numerous and important in
the Permian. Thirty-seven genera appear in the
Wolfcampian (Uddenites-bearing Shale Member),
which includes representatives of major families
except the Productellidae and Leioproductidae.
With this good beginning, a wide deployment of
genera and species resulted. The Overtoniidae
are represented by only three small and rare genera.
Fimbrinia does not survive the Wolfcampian, and
Rhytisia and Simplicarina are confined to the Road
Canyon Formation. The Marginiferidae are more
abundantly represented and include three subfamilies.
Hystriculina and Kozlowskia, holdovers from
the Pennsylvanian, generally are rare and do not
survive the Wolfcampian. Of the Costispiniferinae,
Echinauris is the most abundant and attains a large
size in the upper Word, but it does not extend
higher. Bothrionia, which is similar to the preceding,
is interesting for the development of an
anterior tubulation like that of Chonetella from
the Salt Range. Kutorginella and Thamnosia represent-
the third family (Retariinae); they evolved
large species that also are characterized by the development
of anterior tubes in the upper Word and
Capitan formations.
The Echinoconchidae are represented abundantly
in the Pennsylvanian, but not many flourished
in the Permian. Echinaria and Calliprotonia,
rare in the early Wolfcampian, did not survive into
the Lenox Hills Formation. The same is true of
Juresania, which is common in the late Pennsylvanian
and early Permian of the Midwest. Waagenoconcha
appears in the late Pennsylvanian (Cisco)
and occurs sparsely in the Permian into the upper
Word. Actually, there is some uncertainty about
the generic affinities of the North American Waagenoconcha.
Kochiproductus undoubtedly has a
Pennsylvanian ancestor, but it extends well into
the Permian. It is often represented by huge forms,
especially in the Arctic Permian. Several large
species occur in West Texas, but the genus becomes
extinct at the end of the Leonardian.
The Dictyoclostidae are well represented in the
Permian of West Texas by genera inherited from
the Pennsylvanian and by new ones that evolved
NUMBER 15 237
later. Dasysaria, a strongly convex and finely reticulate
genus, characterizes the Wolfcampian to which
it is confined. Reticulatia, common in the Pennsylvanian,
fails to survive the Wolfcampian.
Nudauris, Spinifrons, and Antiquatonia are uncommon
and mainly Wolfcampian types. Peniculauris
is a large dictyoclostid that takes over the place of
Reticulatia in the fauna and is characteristic of the
Skinner Ranch Formation through the Road Canyon,
after which it is unknown. Rugatia marks
the upper Cathedral Mountain and Road Canyon
formations, while Xestosia and Spinarella belong
in the Cathedral Mountain and Road Canyon formations
respectively. In West Texas the family
disappears at the end of the Road Canyon Formation.
Horridonia, best known in the Arctic, is a
rare element in that formation.
The Linoproductidae are represented by a variety
of unusual forms. Linoproductus and Cancrinella
are inherited from the Pennsylvanian, but generally
they are rare forms that persist to the top of the
Word. Cancrinella may have given rise to two
bizarre Late Wolfcampian forms: Liraria and Undellaria.
These are very rare, with very thin and
fragile shells. Grandaurispina is another relative
of Cancrinella that began in the Cathedral Mountain
Formation but extends to the end of the Word.
Megousia is one of the commonest of West Texas
linoproductids, originating high in the Skinner
Ranch and extending into the Capitan, where it is
very rare. Holotricharina is unusual in having two
kinds of spines on its pedicle valve. Siphonosia,
from the lower Cathedral Mountain, is unusual for
its convergence toward Proboscidella of the Old
World Visean.
The subfamily Striatiferinae is represented abundantly
in all reefy parts of the section and in a few
others as well. We have called one species in the
lower Neal Ranch Striatifera because it has a narrow
but well-formed hinge and is quite unlike
Compressoproductus, which is acuminate and without
a straight hinge.
Paucispiniferidae are among the commonest of
the West Texas productids. Liosotella and Paucispinifera
abound from the Road Canyon to the
top of the Word. They also appear in the Bell
Canyon and Capitan formations, where they are
the most frequent productids. Anemonaria, from
the lower Cathedral Mountain, is possibly the progenitor
of the line. Polymorpharia is a Word aberration
of Paucispinifera, having a bizarre form,
possibly the result of attachment.
The Richthofeniiacea, among the most typical of
Permian fossils, were abundant in the Leonardian.
They probably originated in the Pennsylvanian or
early Permian. Two stocks can be distinguished,
one with a strong median septum, the other without
a septum. The stocks show parallel development
from an aperture protected by spines to one
with a coscinidium. The latter group developed
a form, Collumatus, with a coscinidium but without
anchor spines. In late Guadalupe time two
genera lived simultaneously, one with a coscinidium,
the other without one, but neither genus was
common at that time.
RHYNCHONELLIDA.—The rhynchonellids are everywhere
and in great variety. They are remarkable
in having a completely smooth sulcate genus, Paranorella,
and a number of fine-lined forms such as
Lirellaria, and Ptilotorhynchus. The latter genus,
with its winged deltidial plates, suggests some genera
of the Mesozoic. The crura of many of the
genera are similar to modern forms as they have
typical falcifer crura. Development of an apical
chamber or "septalium" is rare in these rhynchonellids.
The median septum is evanescent; about as
many genera lack the septum as possess it. Nevertheless,
its presence or absence seems a valid means
of distinction. A number of genera such as Deltarina,
Fascicosta, and Divaricosta have divided or
intercalated costae, a rare condition among rhynchonellids.
Leiorhynchoidea scelesta is a huge form
for a Paleozoic rhynchonellid. A modern trend in
the Glass Mountains rhynchonellids is the tendency
toward smoothness or the development of fine lines
on the exterior. Amphipella, with its interior
pouches, is a remarkable development and a smooth
rhynchonellid as well.
SPIRIFERIDINA.—Except for the discovery of the
buccal plate in Neospirifer, this group shows little
evolution or advance over its predecessors. Aberrations
of form and ornament made possible the
recognition of Gypospirifer, Lepidospirifer, and
Cartorhium. The first genus characterized the
early Wolfcampian, while the second is diagnostic
of the Cathedral Mountain and upper Skinner
Ranch. The last extends from the Cathedral Mountain
into the Capitan. Spiriferella is first seen in
238 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
the Road Canyon Formation, where it is very rare.
It is common throughout the Word but rare again
in the Bell Canyon, where it is represented by a
small species. Eridmatus is inherited from the
Pennsylvanian, but it does not survive beyond the
Uddenites-bearing Shale Member. Eliva and Elivina
are confined to the Bell Canyon and Capitan
formations. Spiriferinaella is a rare wide-hinged
spiriferid hitherto improperly classified with the
Spiriferinidae, which appears in the Road Canyon
and extends to the upper Word.
Composita is legion, but no general trend of
evolution was detected. Two developments toward
gigantism appear, one toward the end of the Word
and the other in the Capitan. Rallacosta and Heteraria
are new types appearing in the Cathedral
Mountain and Bell Canyon formations. Astegosia
and Anomaloria, contemporaneous homeomorphs,
are common only in the upper Capitan Formation
and the Lamar Member. Neophricadothyris is common
in Wolfcamp and Leonard rocks but rare in
the Word. One of the surprises is discovery of
Nucleospira in the Permian, a genus hitherto
known to range from middle Silurian to the lower
middle Mississippian. Xenosaria is a new genus,
having the external form of Nucleospira but with
different cardinalia. Crurithyris occurs in all of the
formations, but Cleiothyridina, which is abundant
in the Eurasian Permian, is very rare in the West
Texas sequence. It is an inheritance from the
Pennsylvanian, but it did not flourish in the West
Texas Permian. Its species range from tiny to
small.
RHIPIDOMELLIDA.—The punctate rhipidomellids
occurring in the Permian are the final expression
of a line that originated in the early Ordovician.
The Permian Rhipidomellae are like the Pennsylvanian
ones in having a narrow hinge and small
interarea, and they suggest Perditocardinia. In a
few places in the Glass Mountains and Sierra Diablo,
Rhipidomella is abundant in the lower strata,
but it does not survive into the Road Canyon Formation.
Four genera of Enteletacea occur in the Glass
Mountains. The small Acosarina ranges from the
Neal Ranch Formation through the Road Canyon,
but the larger Orthotichia is characteristic of the
Wolfcamp only. Enteletes is common in the Wolfcamp,
in places abundant in the Cathedral Mountain
and Road Canyon, and extends to the lower
part of the Willis Ranch Member of the Word,
above which it disappears. An offshoot of Enteletes,
the sulcate genus Parenteletes is nowhere
common. It is inherited from the Pennsylvanian
and extends into the Lenox Hills Formation, where
it is rare. A single occurrence is known in the
Skinner Ranch Formation (Poplar Tank Member).
No evolutionary trends were detected in the enteletids
except for the development of huge Enteletes
in the Taylor Ranch Member of the Hess
Formation and in the lower part of the Word, after
which the genus disappears in the United States.
RHYNCHOPORACEA.—Rhynchopora is inherited
from the Pennsylvanian and is a rare shell. It occurs
in the Wolfcamp and extends to the top Word
in the Glass Mountains. It was not seen in the
Bell Canyon or Capitan formations in the Guadalupe
Mountains.
SPIRIFERINACEA.—Several new genera have been
recognized in the Spiriferinacea, which are fairly
common in the Glass Mountains but are abundant
in the Bell Canyon Formation. Reticulariina is
inherited from the Pennsylvanian, but Punctospirifer,
widely identified in Pennsylvanian rocks,
does not appear in the Permian of West Texas. It
appears in the Wolfcampian shale sequence in
north-central Texas but not in the limestone sections.
Crenispirifer, Spiriferellina, Paraspiriferina,
Altiplecus, and Reticulariina are long ranging and
appear in all parts of the column. Sarganostega is
confined to the Bell Canyon and Capitan. Metriolepis
is seen first in the Skinner Ranch Formation,
but it extends to the Lamar Member of the Bell
Canyon Formation. One member of this genus
exhibits a new type of deltidial cover. Arionthia
is rare.
Hustedia and Thedusia are narrow-hinged punctate
spiriferids that are very abundant in all parts
of the column. A tendency to gigantism appears in
the Skinner Ranch and Bone Spring formations
in H. hessensis, in the Word Formation with H.
pugilla and its varieties, and in the Bell Canyon
with H. rupinata. An interesting species appears
in the genus Thedusia, in which both valves are
slit from the anterior nearly to midvalve to foreshadow
the lobation of Pygope.
TEREBRATULIDA.—Dielasma and Beecheria are
inherited from the Pennsylvanian, the former to
NUMBER 15 239
exist throughout the range of the rocks treated
herein, but the latter not surviving the Wolfcampian.
Lowenstamia and Camarelasma are
small forms restricted to the Wolfcampian, and
Aneuthelasma is an amygdaloidal genus confined to
the Bell Canyon Formation. Plectelasma is characterized
by an anteriorly plicated front margin. It
is rare in the Skinner Ranch Formation and the
Appel Ranch Member of the Word, fairly common
in the Bell Canyon Formation, but rare in the
Capitan. Ectoposia has a loop suggesting those of
the short-looped terebratulids of the Jurassic.
Pseudo dielasma and its rare plicated offshoot
Pleurelasma are characteristic of the Word and Bell
Canyon formations. The former genus occurs in
swarms in the Willis Ranch Member of the Word
Formation, but Pleurelasma is very rare.
Terebratulids with a centronelliform loop—
Chondroma, Notothyris, and Timorina—are small
and generally very rare.
The long-looped brachiopods such as Heterelasma,
Cryptacanthia, Glossothyropsis, and Texarina
are rare, but each of these genera has been
discovered in sufficient abundance to illustrate the
full development of their loops. This is a significant
contribution to knowledge of the Terebratulida.
TERMINOLOGY
The terminology used in this monograph, unless
specifically defined under special groups such
as the Oldhaminida and Orthotetacea, is that proposed
by J. Allan Thomson (1927) and Schuchert
and Cooper (1932). We have used "pedicle and
brachial valve" to denote the two shells because
most of the manuscript was prepared when there
was uncertainty as to the orientation of the shell.
In general our terminology is in accord with that
proposed in the "Treatise" (1965) with the exception
of the term "socket ridge." Our view on this
is explained in detail in the discussion of the Spiriferida.
MEASUREMENT OF THE SPECIMENS
A note on the measurement of specimens illustrating
the species is important. The many measurements
are not entirely precise because the
specimens were too fragile to bear the pressure of
calipers. Some specimens were lost by breakage in
the attempt to measure them. Some measurements
could not be taken but had to be approximated
because of abundant spines or spine bases on the
surface. This was especially true of the longitudinal
surface measure of many of the productids, in
which numerous spines were well preserved.
An asterisk (*) after a measurement indicates
that the figure given is based on a half measurement,
that is, the width, hinge, or other lateral
measurement is based on the more complete or
well-preserved half of a specimen; the final figure,
thus, would be double the actual measurement.
This of course may not be the true measure of a
particular dimension because most specimens are
never exactly bisymmetrical.
NOTE ON THE NAMING OF SPECIES
This monograph contains a large number of
specimens that are described and illustrated without
receiving formal names. To the casual reader
this may suggest inconsistency since we have named
formally some species that are based on a few specimens
or only a single specimen. The explanation
is that some specimens are so distinctive that their
usefulness as a species is not jeopardized by their
rarity. A seemingly abnormal single specimen
would not be named in any case. The appellation
"species" has been used on some suites of specimens,
often including a supply that might be considered
sufficient to name a species. We have
refrained from naming some of these lots because
the specimens have indefinite or generalized characters
that make differentiation from other species
difficult. An example is Grandaurispina from locality
USNM 721u. This is the oldest species of
the genus, but the five specimens in the lot do not
crystallize the concept of the species. We believe it
important that such material, having a critical
meaning as the herald of a stock, an aberrant occurrence,
or a stratigraphic anomaly, should be
described and illustrated even though not named.
Every bit of evidence that can be brought to bear
on the biology and stratigraphy of these fossils
should be presented.
ABBREVIATIONS
Abbreviations (used with catalog numbers),
240 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
showing ownership of the specimens illustrated or
mentioned in the systematic part of this monograph,
are as follows:
AMNH = American Museum of Natural History
USNM —United States National Museum (collections in
the National Museum of Natural History, Smithsonian
Institution)
UT —University of Texas (Bureau of Economic Geology)
YPM —Yale Peabody Museum
USNM locality numbers for the Permian of West
Texas are in a 700 series. When cited in descriptions,
they will carry only the abbreviation
"USNM" except when they appear with the above
catalog numbers, in which case, both the terms
"locality" and "type" will be used, where necessary,
with the abbreviations to avoid confusion. For the
abbreviation of other visitations or names used
with locality numbers, see "Register of Localities"
in volume I of this monograph.
Class INARTICULATA Huxley, 1869
Order ACROTRETIDA Kuhn, 1949
Suborder ACROTRETIDINA Kuhn, 1949
Superfamily DISCINACEA Gray, 1840
Family DISCINIDAE Gray, 1840
Subfamily ORBICUI.OIDEINAE Schuchert and
Levene, 1929
The few specimens described below are the only
representatives of the hingeless brachiopods that
have a chitinous shell. No linguloids were found
in any part of the Permian of the Glass Mountains,
Guadalupe Mountains, or Sierra Diablo. In
some parts of the Paleozoic they are fairly common,
but they are rare in this part of the Permian. Two
reasons seem to explain this scarcity of chitinous
brachiopods. The first is the fact that most of the
residues on which this study is based were taken
from rocks deposited in turbulent near-shore environments,
from conglomerates, and from coarse
lime sands. The few fine-grained rocks in the sequence
studied have not produced any of these
shells, nor have the bituminous limestones, where
they might be expected to appear, as in parts of
the Road Canyon or Bell Canyon formations.
These bituminous limestones, also showing some
evidence of turbulence, may not have been a hospitable
environment for them.
Another possible reason for not finding any of
the linguloids is that the hydrochloric acid used in
dissolution dissolves or destroys chitinous or phosphatic
materials; consequently, if rare specimens
were present, they may have been lost.
In spite of these unfortunate circumstances, one
startlingly large chitinous brachiopod was found by
accident. In addition, the calcareous Inarticulata
(Craniacea) are found now and then and have left
an interesting record of their existence.
Genus Roemerella Hall and Clarke, 1890
Roemerella gigantissima, new species
PLATE 24: FIGURES 7, 8
Unusually large for genus, wider than long, shell
narrowing in posterior direction; anterior margin
rounded. Sides flattened or indented and narrowed
just posterior to midvalve, more broadly rounded
than posterior margin. Surface marked by narrowly
rounded concentric undulations separated by
rounded grooves of slightly greater width, and numbering
about 4 in 5 mm near margin.
Pedicle valve of variable convexity, posterior part
nearly flat but anterior part moderately concave.
Pedicle opening small, elliptical, and located just
posterior to apex, which forms most concave part.
Brachial valve poorly preserved but forming a
low cone with apex probably somewhat eccentric.
MEASUREMENTS (in mm).—Holotype (pedicle
valve): length about 61, maximum width (half
measure) 65, length of pedicle opening 10; paratype
(brachial valve): length 68.5, maximum width
68.5. height 6.5?
STRATIGRAPHIC OCCURRENCE.—Road Canyon Formation
(top).
LOCALITY.—USNM 703.
DIAGNOSIS.—Roemerella of gigantic size.
TYPES.—Holotype: USNM 151393a; paratype:
151393b.
COMPARISON.—This is the largest species of the
genus known and one of the largest orbiculoids yet
described.
DISCUSSION.—Two specimens are in the collection,
one representing each valve, but neither is
well preserved. The brachial valve is badly
NUMBER 15 241
crushed and part of it was lost, but enough can be
seen to establish that it was a low cone with the
apex probably eccentric. This specimen also shows
the flattening or emargination of the sides just posterior
to midvalve, indicating a definite posterior
narrowing of the shell to produce a more rounded
posterior and broadly rounded anterior—a feature
seen in both valves.
The pedicle valve is definitely flat to convex in
the posterior half but concave in the anterior portion
so that this part of the valve extends well into
the cavity of the brachial valve. Details of the
pedicle opening are too obscure to determine. It
is small for a shell of such gigantic proportions.
Suborder CRANIIDINA Waagen, 1885
Superfamily CRANIACEA Menke, 1828
Family CRANIIDAE Menke, 1828
These scalelike brachiopods generally have been
overlooked in the American Permian. Branson
(1948) reports only two species of Crania and the
dubious craniid Choniopora. We have seen several
craniids outside of the Glass Mountains, one occurring
in the early Permian of Kansas and another,
from Australia, attached to the large auslostegid
Taeniothaerus. The residues from numerous
localities in West Texas have yielded a variety of
craniids but none in abundance. The variety recovered
from the residues suggests that they were
widespread and probably common but that they
have been overlooked in ordinary collecting methods.
The craniids are difficult to detect in the residues
because some of them have no definite form. Some
of the platyceratid snails may be confused with
them. Fortunately examination of the concave side
of these scalelike objects usually reveals the nearly
central and marginal large muscles that separate
them from the cap-shaped snails. In some the
preservation has been so good that punctae are
readily visible and contain evidence that the shell
is a brachiopod.
In all of the enormous amount of siliceous residues
examined in the course of this study we found
only two craniids attached to their hosts. We have
not found a single pedicle valve, consequently all
of the species made herein are based on brachial
valves only. We have carefully searched the surfaces
of all corals, sponges, bryozoans, and any
other massive shells or objects recovered for these
elusive valves. It is odd that attached Poikilosakos
and numerous juvenile leptodids, richthofeniids,
and productids have been found, but craniid pedicle
valves failed to appear. The number of brachial
valves found is no smaller than that of other attached
forms that shed one valve on death.
The remarkable feature of the Permian craniids
from West Texas is the predominance of ornamented
shells. Acanthocrania, adorned by a mat of
fine spines, is the most abundant genus. The new
lamellose genus Lepidocrania is the next most
abundant genus, and the remaining two are very
rare.
Species of Craniidae are difficult to distinguish,
as in all attached brachiopods. Chief reliance is
placed on the ornament in the spiny and lamellose
forms. Another complicating factor in the
recognition of species is the fact that the ornament
of the host often is faithfully preserved on the exterior
of the brachial valve as it grows over the
surface of the host. The collection of Craniidae
described herein is actually not large, but it represents
a considerable span of the Permian and indicates
wide diversity in these peculiar forms. It is
anticipated that each new discovery of specimens
will tend to modify understanding of those described.
It is also anticipated that further discovery
will lead to a proliferation of species and possibly
of genera.
Orientation for measurements of valve length
from posterior to anterior depend upon a view of
the inside, where the muscle marks can be seen on
the posterior margin. Distortion of some shells
could lead measurements awry, but reference to the
muscles gives the correct orientation. The measure
of surface length helps to depict the convexity of
the shell, as it does in the productids. A flat shell
and a steeply conical one may have the same length,
but the surface measure will indicate the convexity.
Genus Acanthocrania J. S. Williams, 1943
Acanthocrania J. S. Williams, 1943:71.
This name was proposed for craniids having the
exterior covered by fine spines. The genus appears
to be abundant in the Ordovician (Cooper, 1956),
242 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
but it is not well known between that period and
the Mississippian from which Williams took his
type-species. It is poorly known in the Pennsylvanian,
but the etch residues from the West Texas
Permian has revealed it in numbers sufficient to lead
to the belief that it was widely distributed and
probably fairly abundant. The Permian specimens
show no evolutionary advance over the early Paleozoic
representatives. Evidently all of the craniids
were very conservative.
Acanthocrania alta, new species
PLATE 27: FIGURES 2, 3
Medium size for genus, subquadrate in outline,
high conical in profile. Posterior margin nearly
straight; anterior margin gently convex; sides
slightly curved; profile a misshapen cone with beak
about one-third of length from margin; posterior
slope long and precipitous; lateral slopes steep; anterior
slope steep, but not so strongly inclined as
others. Surface very irregular but covered with felt
of long, slender spines.
Interior with large thick anterior adductor scars.
Posterior scars smaller and marginal, widely separated.
MEASUREMENTS (in mm).—Holotype: length 6.7,
width 7.0. surface length 11.0, height 4.0.
STRATIGRAPHIC OCCURRENCE.—Skinner Ranch Formation
(Base).
LOCALITY.—USNM 720g.
DIAGNOSIS.—Strongly conical Acanthocrania.
TYPES.—Holotype: USNM 152571.
COMPARISON.—This species is most similar to A.
densispina, new species, although its spines are
finer but not so fine as those of A. minutispinosa,
new species. Its cone is differently proportioned,
the posterior side is more abrupt and steeper, and
the beak almost overhangs the posterior slope.
Acanthocrania conferta, new species
PLATE 27: FICURES 22-26
Medium size for genus; wider than long and with
subquadrangular outline; sides and anterior margin
rounded; posterior margin usually straight. Profile
conical, apex rounded and variable in position, usually
one-fourth to one-third length from posterior
margin; posterior slope short and steep; anterior
slope convex; lateral slopes moderately steep. Surface
not lamellose but covered by dense mat of
short, thin, stubby spines.
Brachial valve interior with small marginal diductor
scars but large crowded adductor scars.
Some specimens with small anteriorly located median
ridge.
MEASUREMENTS (in mm).—
surface
length midwidth length height
AMNH 512
151429a 8.6 10.6 12.0 3.7
151429b 7.4 8.0 9.5 2.5
USNM 732
151430a 6.7 6.3 7.5 3.0
151430b (holotype) 6.2 7.2 8.0 2.7
STRATIGRAPHIC OCCURRENCE.—Cherry Canyon
Formation (Getaway Member), Word Formation
(China Tank Member).
LOCALITIES.—Getaway: AMNH 512, USNM 730,
732; China Tank: USNM 706z.
DIAGNOSIS.—Nonlamellose Acanthocrania covered
with a dense mat of small spines.
TYPES.—Holotype: USNM 151430b; figured paratype:
151429a; unfigured paratypes: 151429b, c;
measured paratypes: 151429b, 151430a, b; unmeasured
paratypes: 151430c—f.
COMPARISON.—This species, in die density of the
spines on its surface, may be compared to A. densispina
and A. minutispinosa, but the spines are
stouter than in both of these and are shorter than
those of A. densispina. It is difficult to use size or
shape as specific characters in the craniaceans, but
A. conferta appears to have a generally lower cone
and larger shell. The species is rare, perhaps because
of the difficulty in detecting such misshapen
objects in piles of residue. As in the other species,
we have not seen a pedicle valve.
Acanthocrania densispina, new species
PLATE 27: FIGURES 12-18
Medium size for genus, rounded quadrangular in
outline with width slightly greater than length;
posterior margin straight; sides and anterior margin
rounded; profile conical, apex located about
one-third length from posterior margin; posterior
slope precipitous; anterior slope long and steep.
Surface coarsely lamellose and covered by dense
mat of short, delicate spines.
NUMBER 15 243
Brachial valve with adductor scars widely spaced
and small; anterior adductor scars large, closely
spaced. Marginal brim broad and well developed
in old specimens, less so in young.
MEASUREMENTS (in mm).—
SNM 702C
151434a
151434b
151434c
length
6.2
6.4
8.0
midwidth
7.0
8.2
8.0
surface
length
8.0
10.0
10.0
heigh
2.8
3.3
4.7
STRATIGRAPHIC OCCURRENCE.—Cathedral Mountain
Formation, Road Canyon Formation.
LOCALITIES.—Cathedral Mountain: USNM 702,
726x; Road Canyon: 702c, 703a, 719x, 720d, 72lj,
72 lz, 722e, 724c, 724j.
DIAGNOSIS.—Fairly high lamellose cones with a
dense mat of small spines.
TYPES.—Holotype: USNM 151434b; figured paratypes:
151434a, c; unfigured paratypes: 151343b,
d-j.
COMPARISON.—This species may be compared to
those that have closely packed spines like a felt
over the whole surface. Acanthocrania densispina
has long slender spines and, in this respect, differs
from A. conferta, which has short, stubby, stout
spines. On the other hand, it differs from A.
minutispinosa in which the spines are exceedingly
fine and often difficult to see.
Acanthocrania intermedia, new species
PLATE 27: FIGURES 4-10; PLATE 30: FIGURES 25-27
Medium size for genus, subquadrate in outline
with straight posterior margin and irregularly
rounded sides. Profile poorly formed, usually low,
misshapen cone, with apex from one-fourth to onethird
length from posterior margin. Posterior slope
short and steep. Anterior slope long but irregular,
from flattened to fairly steep. Lamellae with long,
delicate spines, about 3 per millimeter on anterior
slope.
Brachial valve interior with large crowded adductor
scars, moderately thickened and usually
darker than surrounding shell. Posterior scars
smaller and widely separated. Anterior marked
medially by low boss or short ridge.
MEASUREMENTS (in mm).—
surface
length midwidth length height
USNM 706c
151440a 9.0 9.9 11.0 4.3
151440c (holotype) 7.4 8.2 8.5 2.1
USNM 706
151442a 7.9 8.6 9.0 2.5
151442b 6.9 8.0 8.5 2.7
151442c 7.7 8.1 8.5 2.0
151442d 6.4 7.9 7.5 2.4
USNM 706e
151444 8.0 8.1 11.5 4.9
AMNH 506
151439 7.5 8.2 8.0 2.7
STRATIGRAPHIC OCCURRENCE.—Word Formation
(China Tank, Willis Ranch, and Appel Ranch
members).
LOCALITIES.—China Tank: USNM 706c; Willis
Ranch: AMNH 506, USNM 706, 706e, 723t,
724u; Appel Ranch: USNM 722t.
DIAGNOSIS.—Lamellose Acanthocrania covered
with distantly spaced, moderately strong spines.
TYPES.—Holotype: USNM 151440c; figured paratypes:
151440a, b, 151442a; measured paratypes:
151439, 151440a, 151442a-c, 151444.
COMPARISON.—This species, because of the more
scattered arrangement and fairly large size of
spines, need be compared only with those similarly
adorned: A. magna, L. sparsispinosa, and A.
regular is, all new species. It differs from the first
in having more numerous and much smaller spines;
it is distinguished from the second by its more numerous
and narrower lamellae and the more abundant
spines; it is separated from the last by its
stronger lamellae and generally less numerous
spines, although they are of about the same size in
the two species.
DISCUSSION.—This species is fairly common in
the Willis Ranch Member of the Word Formation.
It is usually a fairly low cone and the shape is
rather uniform for attached shells; however, considerable
variation can be detected in the height
of the cones. Those from the China Tank (USNM
706c) assigned to the species are higher than is
usual among the Willis Ranch specimens.
Acanthocrania magna, new species
PLATE 446: FICURES 1-4
Large for genus, subtrapezoidal in outline, pos244
SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
terior margin straight, sides broadly rounded, anterior
margin nearly straight. Profile forming
misshapen cone having short steep posterior side
and long anterior slope. Apex rounded and about
one-third of length from posterior margin. Surface
marked by strong concentric growth lines and short
stout spines. Interior with thickened muscle scars.
MEASUREMENTS (in mm).—Holotype: length 13.9,
maximum width 17.6, surface length 18.0, height
6.2.
STRATIGRAPHIC OCCURRENCE.—Cathedral Mountain
Formation.
LOCALITY.—USNM 726o.
DIAGNOSIS.—Large Acanthocrania with trapezoidal
outline and coarse spines.
TYPES.—Holotype: USNM 153908.
COMPARISON.—The only species approaching this
one in size is A. vasta, new species, but that is a
lower, more irregular cone, much differently
shaped, from the Cathedral Mountain species. It
also is much larger and has smaller spines.
Acanthocrania minutispinosa, new species
PLATE 28: FIGURE 44
Small for genus, subrectangular in outline with
sides and anterior margin gently rounded; posterior
margin straight. Profile conical with apex about
one-fifth the length from posterior margin. Apex
rounded. Posterior slope steep; sides steep and
anterior slope convex. Surface not lamellose, covered
by dense mat of minute spines, about 8 per
millimeter in alternate rows.
Interior unknown.
MEASUREMENT (in mm).—Holotype: length 5.0,
midwidth 4.0, surface length 7.0, height 3.4.
STRATIGRAPHIC OCCURRENCE.—Bell Canyon Formation
(Hegler and Pinery members).
LOCALITIES.—Hegler: AMNH 635; Pinery:
USNM 725h, 725n.
DIAGNOSIS.—Acanthocrania with short, minute,
matted spines.
TYPES.—Holotype: USNM 151447.
COMPARISON.—The abundance and extreme fineness
of the spines of this species distinguish it from
all others.
Acanthocrania platys, new species
PLATE 28: FIGURES 14-16
Large for genus, almost square in outline with
subparallel, slightly curved sides and nearly
straight and nearly parallel anterior and posterior
margins. Profile uneven, posterior depressed but
anterior somewhat swollen, shape not strongly
conical. Posterior slope short and moderately steep,
occupying about one-fifth of valve length. Beak
depressed, not prominent, protruding only slightly.
Median region somewhat swollen; anterior slope
steep. Surface marginally lamellose and covered
by very fine spines numbering 6 to 8 in a linear
millimeter.
Interior with moderately thickened and large anterior
adductors, but small marginal adductor scars.
MEASUREMENTS (in mm).—Holotype: length 10,
width 10, and height 4.
STRATIGRAPHIC OCCURRENCE.—Bone Spring Formation.
LOCALITY.—USNM 728f.
DIAGNOSIS.—Acanthocrania nearly square in outline
with short posterior slope and fine, somewhat
distant spines.
TYPES.—Holotype: USNM 151456.
COMPARISON.—This species in its square outline,
short posterior slope and flattened form is unlike
any of the other sparsely spinose species. It suggests
the specimen from USNM 705a noted under
Acanthocrania species, but that specimen has its
fine spines forming a close mat, not separated as
in A. platys.
Acanthocrania regularis, new species
PLATE 30: FIGURES 20-24
Medium size for genus, crudely subquadrate in
outline, sides and anterior margins rounded; posterior
margin rounded; profile crudely conical, posterior
slope steeper than anterior one, which is
slightly convex. Beak small, smooth, located about
one-fourth length from posterior margin. Surface
finely lamellose, lamellae bearing rows of fairly
large, stout spines.
Brachial valve interior with moderately large anterior
adductors but small marginal adductor scars.
Other details obscure.
NUMBER 15 245
MEASUREMENTS (in mm).—
length
152572a 5.6?
152572b 6.4
152572c (holotype) 6.6
midwidth
6.9
6.6
8.1
surface
length
6.2
7.6
9.0
height
3.0
2.6
3.7
STRATIGRAPHIC OCCURRENCE.—Bell Canyon Formation
(Rader Member).
LOCALITY.—USNM 725f.
DIAGNOSIS.—Finely lamellose Acanthocrania with
moderately large, fairly regular stout spines, moderately
crowded.
TYPES.—Holotype: USNM 152572c; figured paratypes:
152572a, b.
COMPARISON.—This species is distinguished from
A. intermedia—the spines of which are about the
same size as those of A. regularis—by their greater
abundance and fairly regular size. It differs from
L. sparsispinosa in having finer lamellae and much
more numerous but smaller spines. Abundance and
regularity of spines distinguishes A. regularis from
A. magna.
Acanthocrania vasta, new species
PLATE 30: FIGURES 13-18
Exceptionally large for genus, subrectangular in
outline, posterior line nearly straight, sides somewhat
rounded and anterior margin crudely parallel
to the posterior line. Profile usually low, poorly
shaped, spreading cone. Posterior slope variable,
not steep, forming about one-fifth of length; lateral
slopes irregular; anterior slopes deformed in all
specimens. Beak low, poorly defined. Surface covered
by mat of short, closely crowded, fine spines,
3 to 5 per linear millimeter.
Interior of brachial valve with small anterior adductor
scars, but large posterior scars along margin.
MEASUREMENTS (in mm).—Holotype: length 16.5,
width 18.2. height about 6.
STRATIGRAPHIC OCCURRENCE.—Bell Canyon Formation
(Hegler Member, Lamar Member).
LOCALITIES.—Hegler: USNM 731; Lamar: 738b.
DIAGNOSIS.—Large Acanthocrania with depressed
conical brachial valve having fine spines fairly
closely crowded.
TYPES.—Holotype: USNM 152573; unfigured
paratypes: 152573b-e.
COMPARISON.—This is the largest species of the
genus yet found in the Permian. Its low conical
form, large size, and moderately dense spinose surface
distinguish it from A. conferta, which forms a
higher cone and stouter spines more densely
crowded than those of A. vasta.
DISCUSSION.—This appears to be a variable species
because some specimens have the spines more
closely crowded than others, but they tend not to
be densely matted. Shape, as usual with these cemented
forms, cannot be relied on as a helpful
character.
Acanthocrania species
Specimens were found at various localities in
numbers too few to warrant specific names. They
are noted below along with the chief characters that
distinguish them.
LOCALITY USNM 701.—A small highly conical
specimen (USNM 151448), with diameter of 5 mm
and height of 2.8 mm, small crowded spines a feature
in strong contrast to the Wolfcampian Lepidocrania
sparsispinosa, new species.
LOCALITY USNM 701a3.—Several immature specimens
of the above (USNM 151449).
LOCALITY USNM 701k.—A specimen of 3 mm
diameter with characters of the two above (USNM
151450).
LOCALITY USNM 705a.—The single specimen
(USNM 151453) from this locality is a large depressed
cone with apex one-fourth the length from
the straight posterior margin. It is 10.0 mm long
and 10.6 mm wide and has a height of 2.6 mm.
The anterior slope is long and gentle. The surface
is covered by a mat of short stout spines, about
20? in a square millimeter on the anterior slope.
Inside, the muscle scars are moderately thickened.
LOCALITY USNM 72 Ig.—This is a small conical
form (USNM 151455) with strong lamellae and
crowded fine spines probably related to, if not the
same as, specimens from USNM 701 and 701a3.
LOCALITY USNM 728f.—A fairly large but considerably
misshapen brachial valve (151456) 11.2
mm long by 11 mm wide by 4.8 mm high with a
lamellose surface and fairly strong scattered spines.
The apex is about one-third the length from the
posterior. All margins are irregular, the specimen
evidently having been attached to a very irregular
surface. The apex of the cone is not elevated, making
for a very flat cone like that of A. platys from
246 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
the same locality. The different character of the
spines of these two prevents placing them together.
LOCALITY USNM 725n.—Three misshapen cones
(USNM 152574) with strongly lamellose exterior
bearing distant, knoblike spines or nodes.
LOCALITY USNM 726o (Plate 27: figure 11).—
Seven specimens (USNM 153046a-g) were taken
from the residues of the bioherm at this locality.
They are obviously young specimens, but they are
characterized by a dense mat of long but very delicate
spines. Type: Figured specimen USNM
153046a.
LOCALITY USNM 726x (Plate 27: figures
19-21).—Two specimens (USNM 153047a, b), a
large high cone and an immature specimen, have
low, stout spines. Figured specimen: USNM
153047a.
LOCALITY AMNH 500L.—A single well-formed
low cone (USNM 151460). 5 mm long by 6.5 mm
wide by 1.6 mm high, shows traces of thick spines.
These are not prominent, but they appear to be
sufficient to refer the specimen to Acanthocrania.
It is lamellose, and a few plications run obliquely
across the specimen from lower right to upper left,
probably superimposed from the host.
Lepidocrania, new genus
[Greek lepidos (scale) + crania]
Craniacea having the usual scabious habit and
resembling Crania but with the exterior strongly
lamellose or scaly, the scales or laminae bearing
scattered stout spines.
TYPE-SPECIES.—Lepidocrania tardispinosa, new
species.
COMPARISON.—This genus resembles Petrocrania
in its form and habit but differs in having strong
shingled lamellae. It also resembles Acanthocrania
in the presence of spines on the exterior. In Lepidocrania
the spines are few and scattered and are
often concealed by the lamellae. In the type-species
the spines are confined to the younger lamellae
around the shell margin. In typical Acanthocrania
the spines cover the shell in a dense mat, in some
cases lending a feltlike surface to the specimens.
DISCUSSION.—Lepidocrania appears to be a rare
genus. We have not seen specimens from other
geologic periods that can be referred here. This
may be a matter of preservation because the acid
treatment lends itself well to revealing the delicate
lamellae, whereas specimens taken from shale or
broken from limestone will have the lamellae torn
off in collecting or worn off in weathering. The
genus is uncommon in the Permian of West Texas,
but continued dissolution of limestone from many
localities should result in many more specimens and
species.
Lepidocrania sparsispinosa, new species
PLATE 28: FIGURES 1-13
Shell about medium size for genus, slightly wider
than long with rounded to quadrate or rectangular
outline. Profile variable but usually forming low
cone with eccentric apex; posterior slope somewhat
flattened and fairly steep; apex located onesixth
to one-third valve length from posterior.
Lateral slopes moderately steep. Anterior slope
fairly steep. Surface marked by distant overlapping
lamellae and few stout, scattered spines.
Brachial valve interior with widely spaced marginal
posterior adductor scars and with smaller,
often thickened crowded anterior adductor scars.
Pallial sinuses not determinable. Marginal rim
narrow and poorly formed.
MEASUREMENTS (in mm).—
width
surface
length height
7.5
5.0
8.0
6.5
5.2
9.6
8.5 3.2
6.0 2.0
8.5 1.7
length
USNM 721g
151438a
151438b
151402
USNM 701c
151401 (holotype) 7.5 6.5 8.5 3.2
STRATIGRAPHIC OCCURRENCE.—Neal Ranch Formation
(beds 4-12 of P. B. King).
LOCALITIES.—USNM 701, 701a3, 701c, 701d, 721g,
727e.
DIAGNOSIS.—Broadly and sparsely lamellose Lepidocrania
with a few large, scattered spines.
TYPES.—Holotype: USNM 151401; figured and
measured paratypes: 151402, 151438a, b.
COMPARISON.—This species is thinner-shelled and
has more distant lamellae than either L. sublamellosa,
new species, or L. tardispinosa, new species;
furthermore, it does not have the angularity of outline
and thick shell that distinguishes L. sublamellosa.
DISCUSSION.—Lepidocrania is rare in Wolfcampian
strata. Lepidocrania sparsispinosa is repreNUMBER
15 247
sented by a number of immature individuals that
are scaly and smooth, seldom with any trace of
spines, which are a more adult feature.
Lepidocrania sublamellosa, new species
PLVTE 29: FIGURES 20-40
Shell about medium size for genus and represented
only by brachial valve; outline variable but
generally quadrate, slightly wider than long and
with angles usually rounded; profile varying from
misshapen and rounded cone to broad and gently
convex; apex usually broadly rounded, blunt and
posteriorly situated about one-fourth to one-third
the valve length from the posterior margin; posterior
slope short and steep, forming flattened triangular
area. Anterior slope long and gentle;
lateral slopes steeper than anterior slope. Surface
marked by closely overlapping concentric layers,
last layer overhanging margin.
Brachial valve interior with thickened and flattened
marginal rim; adductor muscles occupying
the posterior, consisting of marginal small pair and
larger pair just anterior to them. Anterior pair
thickened and bosslike in many specimens. Pallial
marks obscure, branch at midvalve extending laterally
and sending trunk posteriorly and one anteriorly
on sides; anteromedian region marked by
low, short longitudinal boss or ridge.
MEASUREMENTS (in mm).—
USNM 706e
151406a (holotype)
151406b
151406c
151406d
151406e
151406f
length
8.8
8.9
8.2
8.0
8.4
6.6
midwidth
9.3
9.6
9.6
8.4
9.7
7.0
surface
measure
11.5
12.5
12.0
10.0
10.0
10.0
heigh
4.0
3.7
3.3
2.6
2.2
3.0
STRATIGRAPHIC OCCURRENCE.—Road Canyon Formation,
Cherry Canyon Formation (Getaway Member),
Word Formation (China Tank, Willis Ranch,
Appel Ranch members, and lens between the last
two).
LOCALITIES.—Road Canyon: USNM 732j; Getaway:
AMNH 519, USNM 728, 730, 732; China
Tank: USNM 706c; Willis Ranch: AMNH 505,
USNM 706, 706e; Lens: USNM 706b; Appel
Ranch: USNM 715i, 722t; Word: USNM 737b.
TYPES.—Holotype: USNM 151406a; measured
and figured paratypes: 151406b, c, e, f; measured
paratype: 151406d.
DIAGNOSIS.—Lepidocrania of medium size having
a stout, thick shell with a broad marginal flattened
rim and somewhat angulated outline.
COMPARISON.—The thick shell, broad margin,
and angulated outline separate this species from
L. sparsispinosa. These features, except the thick
shell but less prominent lamination, help to separate
it from L. tardispinosa, new species.
DISCUSSION.—A fairly large number of specimens
of this species were taken from USNM 706e; nevertheless,
it must be declared a rare form. The fact
that an enormous amount of material was dissolved
from this locality undoubtedly accounts for the
large number of specimens, rather than abundance
of occurrence.
Lepidocrania tardispinosa, new species
PLATE 27: FICURE 1; PLATE 29: FIGURES 1-19;
PLATE 30: FIGURE 19
Small to medium for genus, wider than long and
roughly quadrangular in outline; profile variable,
ranging from gently convex to narrowly and steeply
conical, depending on the host; apex pointed in
well-preserved specimens but generally rounded
and blunt, located about one-third length anterior
to posterior margin; posterior slope usually short
but steep to precipitous; anterior slope long and
gentle to steep; lateral slopes variable, usually
steeper than anterior, but less so than posterior
slope. Surface marked by numerous overlapping
concentric layers, crowded at margins. Stout, blunt
spires appearing on the youngest lamellae, but
usually not numerous. Youngest layers often
ragged. Margin thick and flattened in old shells.
Brachial valve interior with adductor muscle
scars lightly impressed, anterior scars larger,
stronger, and fairly well separated. Marginal rim
wide, flat, prominent.
MEASUREMENTS (in mm).—
JSNM 702c
151395a
" c
' g
' J
" n
length
5.2
3.4
4.0
3.7
5.0
midwidth
6.0
3.1
4.7
4.7
5.3
surface
length
6.5
5.5
5.0
4.0
5.7
height
1.9
2.4
1.6
1.3
1.6
248 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
surface
151395p
" q
" r
USNM 720d
151397a
USNM 706f
151427
USMN 721z
152582a (holotype)
152582b
152582c
USNM 724c
152583a
USNM 721u
152581
length
4.6
7.7
6.7
7.7
5.6
7.8
7.3
6.8
7.6
7.6
midwidth
4.9
8.1
7.3
8.8
6.2
9.2
7.1
7.6
7.9
6.6
length
6.0
10.0
7.0
10.0
7.0
9.0
9.5
9.5
11.0
8.5
height
2.2
3.6
1.8
3.6
1.8
3.1
3.9
3.5
4.1
4.6
STRATIGRAPHIC OCCURRENCE.—Cathedral Mountain
Formation, Road Canyon Formation.
LOCALITIES.—Cathedral Mountain: USNM 702,
702 (low), 72lo, 72lu, 727p; Road Canyon: 702c,
703c, 706f, 707e, 720d, 721j, 721s, 721y, 721z, 722e,
724c, 726d, 726x, 726z, 736x.
TYPES.—Holotype: USNM 152582a; figured paratypes:
151395a, j , o, 151427, 152581, 152482c,
152583; unfigured and measured paratypes:
151395c, g, n, p-r, 151397a, 151427, 152582b, c.
COMPARISON.—The thick shell, extremely scaly
exterior, and high misshapen cones distinguish this
species from L. sublamellosa, which is usually lower
and more angular in outline. Lepidocrania sparsispinosa
is separated readily by its smaller size
generally, wider lamellae, and the few stout, scattered
spines.
DISCUSSION.—The numerous specimens from
USNM 702c help to make the growth of this species
better known. The young are small, scaly,
and have a smooth surface. Each new lamella is
added under the preceding one as the shell enlarges.
Depending on the surface of the host, the
shells tend to spread out or become fairly high
cones. In most specimens, spines are a late development
and often are partially or wholly covered
by the lamellae.
Lepidocrania species
A number of specimens of this genus are represented
by too few or too poorly preserved specimens
to describe. These are annotated below.
LOCALITY USNM 703a1.—This is a fairly strongly
conical form (USNM 151416) with height of 3 mm,
length of 7.5 mm, and width of 8.6 mm. Apex
bluntly rounded, located one-third the length from
the posterior; posterior slope short and steep, lateral
and anterior slopes less steep.
Interior marked by large closely crowded anterior
diductor scars and small more widely separated
posterior ones; marginal rim narrow.
LOCALITY USNM 715v.—This is an eccentric:
cone (USNM 151454) with steep posterior slope
and convex anterior slope with length of 6.2 mm,
widwidth of 6.7 mm, and the height of 3.4 mm.
It is strongly wrinkled, strongly lamellose, and has
moderately long, distantly spaced spines. It is
probably related to the smaller specimen (151421b)
from USNM 728f listed below.
LOCALITIES USNM 728e, 728f (Plate 27: figures
27-29).—Two specimens each were found in residues
from these localities. All are misshapen cones,
three of them fairly large. All are lamellose, with
the lamellae crowded marginally. The best preserved
specimen is from USNM 728f and is quadrate
in outline, the posterior margin straight. The
apex is about one-fourth the valve length anterior
to the posterior margin, and it is well rounded
and low. The posterior slope is short and steep,
but the anterior slope is long and moderately convex.
On the inside the muscles are crowded closely,
the diductor scars small, the adductor scars large
and forming thickened callosities. The anteromedian
region is marked by a low ridge in this
specimen but not in the others. Measurements (in
mm) of this specimen (USNM 151421a): length 8.5,
midwidth 9.6, surface length 11.0, height 3.1. USNM
728e: 151410a, b; 728f: 151421a, b. Figured specimen:
USNM 151421a.
LOCALITY USNM 728h (Plate 27: figures 30,
31).—This is a small misshapen cone (USNM
151145), strongly lamellose, and strongly like a
small specimen from USNM 728f (151421b), but it
differs in having fairly strong spines scattered distantly
over the surface. Figured specimen: USNM
151445.
LOCALITY USNM 731-A.—Small flattened cone
(USNM 152585) with apex near the posterior margin
and somewhat squarish outline, with numerous,
very strong, overlapping lamellae, which bear spines
between them or on their edges. This is a very
NUMBER 15 249
distinctive form, but only one good specimen is
known.
LOCALITY USNM 731-B.—This lot consists of
several misshapen cones (USNM 152586) of various
sizes up to about 7 mm, but no two of them are
alike. They all have distantly scattered strong
spines and lamellae.
LOCALITY USNM 736.—A single, small, rounded,
low, eccentric cone (USNM 151423) with strong
lamellae and, sandwiched between the layers, a few
fairly long, stout, sharp spines. This may be related
to specimens of the Pinery and Hegler members
noted below.
LOCALITY AMNH 404.—This is a single specimen
(USNM 151459) having very distinctive ornament
but so distorted by unfavorable growth that
it is best not described specifically. It is 3.8 mm
long by 6.5 mm wide by 2.4 mm high. It is thus
somewhat unnaturally rolled up in the direction of
valve length. It is strongly lamellose, the lamellae
strongly overlapping the one below. The lamellae
bear distant, thick, and long spines on their posterior
side, which protrude between the overlapping
layers. This suggests affinities with the specimen
mentioned under USNM 731-A.
Genus Petrocrania Raymond, 1911
Craniella Oehlert, 1888:101.
Petrocrania Raymond, 1911:229.
Lissocrania J. S. Williams, 1943:71.
Several species and a few specifically unidentifiable
specimens are referred to Petrocrania because
they are devoid of spines and lamellae. Their chief
ornament is concentric growth lines and growth
wrinkles. A few of the specimens such as P. teretis,
new species, are almost smooth and suggest Williams's
genus Lissocrania. The type-species of this
genus, however, conforms very closely to Petrocrania,
as it has all of the characters of Lissocrania
and seems indistinguishable.
Petrocrania is identified from Middle Ordovician
rocks and extends well into the Permian, although
it is rare in this period. In the United States few
specimens have been reported, but it should be
looked for in all acid residues and those resulting
from sediment processing.
Like all craniids the exterior of Petrocrania has
a variable form, nearly completely smooth to somewhat
lamellose, but the degree of lamellation never
reaches that of Lepidocrania.
Petrocrania diabloensis, new species
PLATE 28: FIGURES 29-34; PLATE 745: FIGURES 29-34
Large, subcircular to somewhat quadrangular in
outline; widest anterior to midvalve; posterior margin
narrow and straight; sides well rounded; anterior
margin broadly rounded. Profile depressed,
broadly conical, apex off center and located about
one-third the length from posterior margin. Posterior
slope moderately steep; anterior and lateral
slopes gentle. Surface marginally lamellose, otherwise
without ornament.
Interior of brachial valve with small anterior
adductor impressions and rather small marginal
adductor scars. Anterior-median region marked
medially by a low, rounded ridge.
MEASUREMENTS (in mm).—Holotype: length 13.7,
maximum width 16.1, surface measure 15.0, height
4.0.
STRATIGRAPHIC OCCURRENCE.—Bone Spring Formation.
LOCALITY.—AMNH 625; USNM 728e.
DIAGNOSIS.—Large, poorly lamellose Petrocrania
forming a fairly symmetrical but depressed cone.
TYPES.—Holotype: USNM 154103; figured paratype:
USNM 152577.
COMPARISON.—This is the largest Petrocrania
found in West Texas. It is distinguished from all
other species described herein by this character and
its unusually symmetrical form.
Petrocrania exasperata, new species
PLATE 28: FIGURES 35-38
Shell thin, subcircular in outline, length and
width about equal. Sides rounded to irregular;
posterior margin nearly straight; anterior margin
broadly rounded. Profile an unequal cone, posterior
shorter than anterior side. Beak small, varying
from nearly posterior to about one-fifth of
length from posterior margin. Posterior slope steep.
Anterior and lateral slopes irregular, moderately
steep. Exterior lamellose but surface varying with
host.
Posterior adductor scars large; anterior adductor
scars smaller than posterior ones.
250 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
MEASUREMENTS (in mm).—
length
USNM 731
152578a (holotype) 10.3
152578b 9.6
152578c 8.6
maximum
width
11.8
8.7
9.0
surface
length
11.5
10.0
11.0
heigh,
4.2
4.6
3.5
STRATIGRAPHIC OCCURRENCE.—Bell Canyon Formation
(Hegler and Pinery members).
LOCALITY.—Hegler: USNM 731; Pinery: 725h,
736.
DIAGNOSIS.—Petrocrania of medium size with
beak near the posterior margin.
TYPES.—Holotype: USNM 152578a; measured
paratypes: 152578b, c.
COMPARISON.—This species is the next largest to
P. diabloensis, but its unsymmetrical form, the
strongly posterior position of the apex, and the less
spreading habit distinguish the two. Petrocrania
exasperata is larger and thinner shelled than L.
sublamellosa and has softly rounded outlines,
whereas L. sublamellosa is generally stronger angular,
especially at the posterior. No septum appears
in these Hegler specimens, and thus they are readily
distinguished from P. septifera.
Petrocrania septifera, new species
PLATE 28: FIGURES 39-43
Small, squarish in outline with subparallel sides
and subparallel anterior and posterior margins.
Sides gently rounded; anterior margin nearly
straight. Profile depressed conical; beak pointed,
located about one-third of length from posterior
margin; posterior slope short and moderately steep;
anterior slope long and gentle. Surface strongly
and regularly lamellose. Interior with large anterior
scars and anterior half divided by low septum
increasing in height anteriorly but not
reaching margin.
MEASUREMENTS (in mm).—Holotype: length 5.2,
width 6, height 2.0.
STRATIGRAPHIC OCCURRENCE.—Bell Canyon Formation
(Hegler and Pinery members).
LOCALITIES.—Hegler: USNM 731; Pinery: 725h.
DIAGNOSIS.—Flatly conical Petrocrania with lamellose
surface and a median septum in the
brachial valve.
TYPES.—Holotype: USNM 151422.
COMPARISON.—This species is distinguished from
all others in the Permian by the presence of a
median septum in the brachial valve.
Petrocrania teretis, new species
PLATE 28: FIGURES 17-25
Small, smooth, variable cones with rounded sides
and anterior; posterior side usually straight. Cones
varying from nearly flat to high and misshapen,
usually low; beak off center, from one-third to
two-fifths of length from posterior margin. Posterior
slope gentle; median region somewhat swollen and
having steeper sides than the long anterior slope.
Surface smooth except for slight irregularities inherited
from host. Anterior adductor scars larger
than posterior adductors which are marginal.
MEASUREMENTS (in mm).—
USNM 706b
151404a
151404b
151404c
USNM 706e
151405a (holotype)
151405a
151405c
length
6.9
6.4
6.4
7.7
6.8
5.1
width
8.5
7.7
7.3
8.7
7.4
5.8
surface
length
8.0
7.0
7.0
9.3
7.0
5.3
height
1.7
1.8
2.0
2.6
1.7
1.4
STRATIGRAPHIC OCCURRENCE.—Cherry Canyon
Formation (Getaway Member), Word Formation
(Willis Ranch Member and lens between that
member and the Appel Ranch Member).
LOCALITIES.—Getaway: AMNH 512; Willis
Ranch: USNM 706, 706e; Lens: USNM 706b.
DIAGNOSIS.—Small, subcircular, depressed conical
Petrocrania.
TYPES.—Holotype: USNM 151405a; figured paratypes:
151404a, c; unfigured paratype: 15404b;
measured paratypes: 151405b, c.
COMPARISON.—Differs from other described West
Texas Craniidae in its completely smooth exterior
surface.
DISCUSSION.—Most specimens of this species are
very smooth and may be shells somewhat waterworn
before silicification. They are smoother than
ustial with Petrocrania.
Petrocrania species
Specimens thought to be Petrocrania were found
NUMBER 15 251
at several localities listed below. They occur in
insufficient quantity or quality of preservation for
description. They are, therefore, only recorded
with any significant facts about them that might be
of use to the paleontologist or stratigrapher.
LOCALITY USNM 702un.—A small specimen
(USNM 151415) with a diameter of about 3 mm.
It is an eccentric cone with thick, flattened marginal
rim.
LOCALITY USNM 708u.—This lot consists of
four specimens (USNM 151417) that are small,
flatly convex, broadly lamellose cones, obviously,
immature, and not specifically definable. It is indeed
possible that they are the young of Lepidocrania.
LOCALITY USNM 714w.—This locality yielded
a small specimen (USNM 151418) forming a low
cone with an apex less than one-third the valve
length from the posterior margin and with rounded
sides and anterior. The posterior margin is truncated
and the posterior slope steep. The anterior
slope is long and somewhat convex; the lateral
slopes are short and steep. The exterior is not
strongly lamellose and the surface is plicated by
superposition of ornament details of the host.
On the interior, the posterior adductors are large
and distant, but the anterior adductors are closely
crowded. Pallial sinuses are not distinguishable.
LOCALITY USNM 721o.—This is a single small
specimen, 4 mm long by nearly 5 mm wide. Its
most striking feature is its wide posterior margin
and steep, short, posterior slope in an otherwise
very low cone (USNM 152575).
LOCALITY USNM 721u (Plate 28: figures
26-28).—Three small scabby, thin-shelled specimens
(USNM 152579a) were taken from this place.
Subcircular in outline, they form flat cones. The
exterior is smooth (without spines), but it has inconspicuous
growth lamellae and rounded bumps,
probably reflecting the host. The posterior margin
is slightly flattened, but the rest of the outline is
well curved. Inside, the posterior adductors are
large, but the anterior adductors are smaller but
fairly large. The largest specimen is 6 mm long
by 6.5 mm wide by about 1.5 mm high.
Three small scalelike specimens (USNM 152579)
(Plate 28: figures 26-28) nearly circular in outline;
one shows impressions of the host ornament.
Figured specimen: USNM 152579a.
LOCALITY USNM 722t.—A fairly high cone
(USNM 152580) with nearly central apex has such
uncertain exterior details that its generic affinities
are difficult to place.
LOCALITY USNM 725f.—This locality is represented
by three specimens (USNM 152576), two
of which are fairly high cones, but the other greatly
depressed. The largest specimen is 5.8 mm long by
5.2 mm wide. The beak is prominent but off center
about one-third the length anterior to the posterior
margin. The lateral and posterior slopes
are steep, but the anterior slope is moderate. The
exterior has a few undulations, but is devoid of
other ornament. The interior fails to show detail
sufficient to determine the muscle marks.
Class ARTICULATA Huxley, 1869
Order Uncertain
Suborder DICTYONELLIDINA Cooper, 1956
Superfamily EICHWALDIACEA Schuchert, 1893
Family ISOGRAMMIDAE Schuchert and
Levene, 1929
Genus Isogramma Meek and Worthen, 1870
Isogramma Meek and Worthen, 1870:36 Barrois, 1882:326.—
Chao, 1928:32 Paeckelmann, 1930:210.—Schmidt, Hermann,
1931:278-287 Aigner and Heritsch, 1931:306.—
Cooper, 1952:116.—King, R. E., 1931:64.
Aulacorhynchus Dittmar, 1872:2.
Aulacorhyna Strand, 1928:37.
Isogramma is a poorly known genus morphologically
and its geological distribution is not
clearly known. It ranges from Mississippian into
Permian, but its occurrence in the Permian was not
known until this century. Specimens are common
in many parts of the United States in the Pennsylvanian,
but it is not known in the Mississippian
except in Alaska (Dutro, 1955). In some Pennsylvanian
formations it is abundant, but good specimens
are difficult to obtain because the shell is
usually large, fragile, and is commonly found in
friable shales. Consequently, its presence is revealed
mainly by numerous fragments. It attains a
large size in some formations of the Pennsylvanian
and also in the Permian.
252 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
A few specimens have been obtained in the
Glass Mountains and in related areas in the Sierra
Diablo and Guadalupe Mountains. These indicate
a considerable size range and a stratigraphic
distribution from early Wolfcampian to Guadalupian
(Getaway). Most of these specimens are
fragments, but a few good brachial valves and a
fragment of a pedicle valve (USNM 152566) aid
considerably in understanding the genus.
Isogramma is unusual among the brachiopods for
its broad, flat valves, the nature of the pedicle attachment,
and the shell structure. The pedicle,
beak regions, and shell structure of Isogramma are
like those of Eichwaldia and Dictyonella of the
Ordovician and Silurian to which it is related. A
fourth genus is the aberrant Megapleuronia Cooper
(1952), structurally like Isogramma but strongly
plicated radially. These four genera are now placed
in two families, which are sufficiently closely related
to be united into a superfamily: the Eichwaldiacea
Schuchert (1893).
The pedicle valve of Isogramma is moderately
convex, has a short interarea, and a plate depressed
below the level of the exterior to which the pedicle
is attached (Schmidt, 1931, pi. 10: fig. 10). The
surface is marked by numerous crowded concentric
elevated lines. Inside the brachial valve the depressed
pedicle plate in some species forms a platform
that probably was the site of adductor attachment,
and the large diductor muscles are located
adjacent to its sides. Teeth have not been seen;
articulation was achieved by bearing of delthyrial
angles of the palintrope against the sides of the
cardinal process.
The brachial valve usually is moderately to
strongly concave and is marked medially by a
strong median septum, which, in the adult, is
united to the shaft of a large, trilobed cardinal
process. Laterally and anterolaterally sweeping
"brachial ridges" reminiscent of those in the Productidina
occur on each side of the cardinal process
and median septum. The adductor scars have
not yet been identified certainly.
The inner shell layer is perforated by closely
crowded pores of varying sizes (Schmidt, Hermann
1931:281), thus constituting one of the most significant
characters of the genus and superfamily. The
punctae are not visible on the exterior.
Isogramma concavum, new species
PLATE 25: FIGURES 16, 17
Small for genus, wider than long, width about
twice length. Hinge straight, narrower than shell
width. Sides narrowly rounded and anterior margin
broadly rounded. Profile deeply concave, greatest
concavity located in median region. Surface
marked by closely crowded concentric undulations,
about 7 or 8 in 5 mm at lateral margins.
Interior with strong median septum extending
for two-thirds the valve length; cardinal process
small with shaft moderately long; myophore narrowly
trilobed. Other details obscure.
MEASUREMENTS (in mm).—Holotype: length 28.6,
maximum width 62.8, hinge width 60.0?, height 7.0.
STRATIGRAPHIC OCCURRENCE.—Neal Ranch Formation
(bed 4).
LOCALITY.—USNM 727e.
DIAGNOSIS.—Small Isogramma with fairly strong
ornament and deeply concave brachial valve.
TYPES.—Holotype: USNM 153188.
COMPARISON.—Differs from other Permian species
in its deeply concave brachial valve.
Isogramma diabloense, new species
PLATE 25: FICURE 15; PLATE 26: FIGURES 5-15
Small, somewhat variable in outline, wider than
long with narrowly rounded sides and subnasute
anterior margin, general outline forming crude triangle
in well-formed shells. Pedicle valve known
from the beak region only. Brachial valve gently
concave and marked by crowded concentric lines,
about 5 in 1 mm at midvalve.
Pedicle valve with broad and short triangular
pedicle plate and short, curved interarea.
Brachial valve with slender, bladelike median
septum and long-shafted cardinal process with
moderately expanded, medianly grooved, triangular
myophore. Junction of shaft and median septum
open, or closed. Brachial ridges not clearly
defined.
MEASUREMENTS (in mm).—Holotype: length 14.4,
midwidth 27.9, hinge width 23.4.
STRATIGRAPHIC OCCURRENCE.—Bone Spring Formation.
LOCALITY.—USNM 725y.
DIAGNOSIS.—Small, fine-lined, nasute Isogramma,
with long-shafted cardinal process.
NUMBER 15 253
TYPES.—Holotype: USNM 151382b; figured
paratypes: USNM 151382a, c, d.
COMPARISON.—Of described species this is most
like /. pachti Dittmar from the Carboniferous of
Russia, but it is not so strongly concave on the
dorsal side, and the cardinal process has a much
longer shaft and narrower myophore. The cardinal
process and the fine ornament distinguish this species
from /. texanum Cooper.
DISCUSSION.—The brachial valves of this species
are well preserved, but only fragments of the posterior
beak region of the pedicle valve were taken.
These indicate a wide pedicle plate, not deeply inset
because it does not appear as a platform on the
inside. The exterior surface is marked by a median
triangular mark that expands anteriorly. This surface
is too vaguely marked to interpret. A short
interarea is present, but no teeth can be identified.
The brachial valve is well preserved in the region
of the cardinal process, but not elsewhere, because
the brachial ridges cannot be identified; however,
a curved line parallel to the posterior margin,
which appears to separate two layers of shell, may
be a trace of part of the brachial ridge. This line
forms half of a V on each side of the median septum
just anterior to the cardinal process. The
characteristic cavity where the cardinal process
shaft encloses the median septum is present on several
specimens and exhibits the usual layered structure.
One specimen shows the cardinal process
shaft and median septum continuous, suggesting
that this is the ultimate stage for these structures.
Isogramma lobatum, new species
PLATE 24: FIGURES 1-4: PLATE 25: FIGURES 3-10
Species known from two brachial valves; large
for genus, broadly subelliptical in outline; widest
at midwidth. Sides narrowly rounded; median
region sulcate, sulcus shallow, forming fold toward
ventral side with marginal lateral folds in opposite
direction. Exterior marked by fine concentric lines,
about 3 per mm at posterior margin midway toward
lateral margin.
Interior with strong, elevated median septum extending
nearly to anterior margin, enclosed by anterior
end of cardinal process shaft. Cardinal
process broad and spreading, triangular outline,
median lobe broad concave, lateral lobes narrow.
Brachial ridges (?) broad, extending laterally along
posterior margin for two-thirds distance to lateral
margin, then forming broad but narrow hook toward
anterior margin.
MEASUREMENTS (in mm).—Holotype: length 47.4,
midwidth 100.0, hinge width 72.4; paratype: length
41.9. midwidth 91.0, hinge width 81.4.
STATIGRAPHIC OCCURRENCE.—Cathedral Mountain
Formation (Institella beds).
LOCALITIES.—USNM 702, 702b, 72lu.
DIAGNOSIS.—Large Isogramma with lobate anterior.
TYPES.—Holotype: USNM 151384; figured paratype:
151383; figured specimens: 153187a, c-f.
COMPARISON.—This species is difficult to compare
with others because the pedicle valve is unknown.
No other species has the strong anterior
folding of / . lobatum.
DISCUSSION.—Although only two specimens of this
species are known, both of them show the dorsal
interior in a remarkably good state of preservation.
The cardinal process, brachial ridges, and
median septum are better than in any other American
specimens. The peculiar arrangement of the
enclosure of the posterior end of the median septum
by lateral growths from the cardinal process
are shown to perfection. The enclosure is formed
by at least three layers of shell. The cardinal process
is broad and spreading, strongly trilobed, with
the median lobe largest and fairly deeply concave.
The lateral lobes are smaller and bounded by lateral
notches that received the edge of the palintrope
of the pedicle valve. The articulation is formed
by the cardinal process.
The so-called brachial ridge is unlike that of the
Productidina in its position and general form. It
is much wider and is located considerably posterior
to that of the Productidina. It appears to contact
the posterior edge of the shell and then swings
anterolateral^ to form a broad loop. Its relationship
to the adductor muscles is not known because
none of the specimens shows any trace of these
muscles. Traces of subradial pallial marks appear
in the anterior part of the specimen.
Isogramma vidriense, new species
PLATE 25: FIGURES 13, 14
Isogramma millipunctata R. E. King (not Meek and
Worthen), 1931:65, pi. 10: fig. 8.
254 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
Small for genus, outline approximately semicircular,
hinge almost equal to shell width which is
about one-third length anterior to cardinal extremity.
Sides narrowly rounded; anterior margin
broadly rounded. Lateral profile gently convex;
anterior profile broadly convex, maximum convexity
at midvalve, lateral slopes long, flat and
gentle. Concentric lines crowded, 5 in 7 mm near
midvalve and gentle. Pedicle plate opening long
and narrow, forming angle of 18°.
MEASUREMENTS (in mm).—Holotype: length 19.5,
surface measure 24.0, maximum width 21.0, hinge
width 20.5, height 5.0?.
TYPE.—Holotype: YPM 10837; plaster casts:
USNM 151385.
STRATIGRAPHIC OCCURRENCE.—Gaptank Formation,
Neal Ranch Formation.
LOCALITY.—Gaptank: King 203; Neal Ranch:
USNM 727d.
DIAGNOSIS.—Small Isogramma with long narrow
pedicle plate having an apical angle less than 20°
COMPARISON.—This species is distinguished by
its small size and the long pedicle plate having an
apical angle of only 18°.
DISCUSSION.—Only one good specimen of this
species is known but its anterior margin is uncertain.
Fragments of Isogramma occur rarely in the
Neal Ranch Formation.
Isogramma species
Specifically unidentifiable fragments of Isogramma
were taken from the following localities:
AMNH 497.—A fragment of a large and thickshelled
species (USNM 151^392).
AMNH 503=USNM 703 (Plate 25: figures 11,
12).—This is an exceptionally well-preserved fragment
of the pedicle valve (figured specimen USNM
152566) preserving the beak region. It is the only
silicified specimen of this part of an Isogramma
taken from any of the residues. The exterior ornament
is poorly preserved, but the pedicle area is
well shown. This is a smooth area, depressed below
the level of the surface, that forms an angle of 24°
with the beak and expanding anteriorly. It is
marked medially by a finely impressed line and
transversely by fine horizontal lines. The apex of
the angle at the beak is covered by shell, but just
anterior to this smooth patch the median line is
deep and two short lateral impressed lines appear.
The interarea is short and wide and the delthyrium
is short and very wide, forming an obtuse angle
(about 112°). The interior region corresponding
to the angular smooth region forms two shallow
longitudinal troughs separated by a low ridge that
probably corresponds to the impressed line of the
exterior. The triangular area is bounded laterally
by a low fold. Near the center of the triangular
structure is a low longitudinal fold that divides
the two long troughs. This median fold is marked
centrally at about midvalve by a short impressed
gash. Outside the bounding trough are two
elongate areas interpreted as impressions of the
subflabellate diductor scars. Marks on each side of
the median fold are interpreted as part of the adductor
scars. Internally the palintrope has no supports
and no teeth were seen.
USNM 702k.—A fragment of a large specimen
(USNM 152567) approaches the size of /. renfrarum
Cooper from the Millsap Formation of northcentral
Texas. It measures 60 mm long and has a
half measure of about the same amount in width
(about 120 mm). No diagnostic features other than
its large size are evident.
USNM 702n.—A very poorly preserved fragment
of a brachial valve (USNM 152568).
USNM 705a.—A poorly preserved fragment of a
small individual (USNM 151386).
USNM 720e.—This is part of a small and thinshelled
pedicle valve (USNM 151387).
USNM 720g.—Three fragments of a thick-shelled
species were found at this locality (USNM 152569).
USNM 722-1 (Plate 24: figures 5, 6).—A small
brachial (USNM 152570) valve, 11.4 mm long and
15 mm wide, represents the genus at this place.
The ornament is of fine concentric lines as usual
and the valve is anteriorly concave. On the inside
the long shaft of the cardinal process is preserved,
but the myophore has been broken off. The shaft
reaches fully two-thirds the valve length from the
posterior. This valve represents either a young example
of a large species or a new species.
USNM 728 (Plate 25: figures 1, 2).—A fragment
of the pedicle valve preserves the pedicle plate on
the exterior, but it is not elevated on the interior.
A well-developed palintrope is present, but no
teeth appear at the delthyrial extremities as in the
specimens from AMNH 503. No details of the musculature
are revealed. Figured specimen: 151388.
NUMBER 15 255
USNM 728e.—Fragments of two specimens of
moderate size are present from this locality (USNM
151389).
Order STROPHOMENIDA Opik, 1934
Suborder ORTHOTETIDINA Waagen, 1884
Pedicle valve without functional pedicle and usually
cemented apically in the young or throughout
life; chilidium well developed in early members,
usually poorly developed or absent in later genera.
Cardinal process welded to brachiophores (=dentifers),
with or without erismata (see definitions
below); lophophore calcified in one late member;
shell substance pseudopunctate. Mississippian to
Triassic.
The number of genera and species in this suborder
reached its maximum in the Permian. Perhaps
nowhere in the world is the group so well
represented as in the Glass Mountains. The abundance
and preservation of these brachiopods exceed
even that of the brachiopods from the famous Sosio
Limestone of Sicily (Greco, 1938). Fourteen genera
are known from the lower part of the Glass Mountains
sequence, and the richest and most distinctive
assemblage of genera is in the Neal Ranch Formation
of the Wolfcamp Series. These brachiopods
were for a long time classified under the Orthotetacea
that embraced a number of related and
unrelated genera.
Williams (1953) was the first to classify the Orthotetacea
in detail when he proposed the superfamily,
two new families, and one new subfamily.
He also assigned here two already established
families. This arrangement was a great advance
over that of the past, but it did not last long, because
the next year Stehli (1954) published a revision
that threw out of the superfamily some of
the elements Williams had assigned to it and Stehli
added three new subfamilies. He removed the
family Scacchinellidae from the Orthotetacea because
of its numerous characters that relate it to
the Productidina (Strophalosiacea) rather than to
Orthotetacea.
Prior to Williams, Dunbar and Condra (1932)
and Campbell (1957) discussed the classification
and development of the orthotetaceans. The former
authors, following Girty, based their views of
subfamily Orthotetinae on the development of the
pedicle valve and the presence or absence of dental
plates or median septum. Three groups were recognized:
one with dental plates, one with a median
septum in the pedicle valve, and a third without
dental plates or septa. The cardinalia were given
secondary consideration, but they were used on a
generic basis to separate Derbyoides from Derbyia.
Dunbar and Condra derived their phylogeny from
the basic stock of Schellwienella, which they placed
in the Silurian.
Campbell (1957:42), having the advantage of the
prior work by Dunbar and Condra, Williams, and
Stehli, discussed the classification of the Orthotetacea.
He believes, as we do, that the production
and elaboration of dental plates and septa have
taken place independently in different stocks and a
classification based entirely on structures of the
pedicle valve is unnatural. Campbell recognized
the value of the cardinalia and produced a possible
phylogeny based on Schuchertella in the Devonian.
The classification by G. A. Thomas (1958) followed
Williams in the main, but the new subfamily
Derbyoidinae was added. Tinkering with the superfamily
continued when, in 1960, Muir-Wood
and Cooper removed the Gemmellaroiidae because
they discovered anchor spines on this unusual genus.
Later in the same year, Sokolskaja (in Osnovy,
1960) recognized in the superfamily three families
and six subfamilies, one of them, the Omboniinae,
proposed as new.
The classification proposed in the Treatise (Williams
et al., 1965) submerged Orthotetacea by application
of the rules of nomenclature in favor of
Davidsoniacea. This classification does not take
into consideration the different shell structure of
some of the families and subfamilies. A basic difference
exists between Davidsoniacea and Orthotetacea,
the first one impunctate and the latter
one pseudopunctate (or, rather, possessing taleolae).
The Silurian and Devonian genera of the
Davidsoniacea are without punctae or pseudopunctae.
these include the Davidsoniidae and Fardeniidae.
These also have different cardinalia from the
Orthotetacea. Their cardinalia are strongly orthoid
with well-defined brachiophores (= socket plates
of Williams = dentifers). The sockets are excavated
in the shell tissue and the teeth rest on the
sloping face of the brachiophore (=: dentifer). The
structure described is more at home among the
256 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
Orthacea. We, therefore, separate the Davidsoniacea
into a separate superfamily with two families,
the Davidsoniidae and the Fardeniidae. This
restores to the superfamily Orthotetacea (now credited
to Waagen because of priority) some pseudopunctate
forms, which characterize the Paleozoic
above the Devonian. Further revision as given below
is suggested by the types of cardinalia of the pseudopunctate
genera.
A successful classification must consider a multitude
of characters. This holds true for brachiopods
as well as other organisms, and the failure to do
so, with the resultant abortive classifications, is well
illustrated by the Orthotetacea in which most
family and subfamily arrangements have been
based on features of the external ornament or on
plates in the pedicle valve. The presence or absence
of costae, costellae, or plications on the outside,
in combination with presence or absence of
dental plates, have been considered of paramount
importance, to the near unanimous neglect of the
brachial valve cardinalia as foundations for classification.
Campbell (1957) recognized the importance of
the cardinalia in the derbyoid group. G. A. Thomas
(1958) developed this theme further and employed
it more broadly in classifying the Permian Orthotetacea
of Western Australia. This is consistent
with the views expressed by Ulrich and Cooper
(1936:331) and Cooper (1970) on the taxonomic
value of the cardinalia in the Triplesiacea and
other brachiopods. Our studies of the Permian
Orthotetidina of West Texas bring us to the conclusion
that the group is much more successfully
classified by basing the higher categories on brachial
cardinalia than on ornament and dental plates.
Two major groups can be identified by the
course of development of the lateral supporting
plates of the cardinal process and of other minor
features of the cardinalia. This major dichotomy
does not alter the presently recognized subfamilies,
but it aligns them differently and more consistently.
We consider the difference in cardinalia so important
that we are recognizing two superfamilies on
that basis: Orthotetacea Waagen, 1884, and Derbyiacea
Stehli, 1954. These are defined below and
our revised classification is given below:
Order STROPHOMENIDA Opik. 1934
Suborder STROPHOMENIDINA Opik, 1934
Superfamily DAVIDSONIACEA, W. King, 1850
Family DAVIDSONIIDAE W. King, 1850
Genus Davidsonia Bouchard, 1849
"Biconostrophia Havlicek, 1956
Prodavidsonia Havlicek, 1956
Family FARDENIIDAE Williams, 1965
Genus Fardenia Lamont, 1935
Gacella Williams, 1962
Chilidiopsis Boucot, 1959
Orthopleura Imbrie, 1959
Schuchertellopsis Maillieux, 1939
Hipparionyx Vanuxem, 1842
Xystostrophia Havlicek, 1965
Coolinia Bancroft, 1949
Iridistrophia Havlicek, 1965
Morinorhynchus Havlicek, 1965
Pseudostrophomena Roomusoks, 1963
Suborder OTHOTETIDINA Waagen, 1884 ,
Superfamily ORTHOTETACEA Waagen, 1884
Family ORTHOTETIDAE Waagen, 1884
Subfamily ORTHOTETINAE Waagen, 1884
Genus Orthotetes Fischer de Waldheim, 1829
Streptopomum Havlicek, 1967
Family SCHUCHERTELLIDAE Williams, 1953
Subfamily SCHUCHERTELLINAE Williams, 1953
Genus Schuchertella Girty, 1904
Goniarina Cooper and Grant, 1969
Aerostrophia Havlicek, 1965
Drahanostrophia Havlicek, 1967
Serratocrista Brunton, 1968
Subfamily HYPOPSIINAE, new subfamily
Genus Hypopsia, new genus
Subfamily DIPLANINAE, new subfamily
Genus Diplanus Stehli, 1954
Subfamily DERBYOIDINAE G. A. Thomas, 1958
Genus Derbyoides Dunbar and Condra, 1932
Tapajotia Dresser, 1954
Permorthotetes G. A. Thomas, 1958
Werriea Campbell, 1957
Brochocarina Brunton, 1968
Subfamily PULSIINAE, new subfamily
Genus Schellwienella I. Thomas, 1910
Pulsia Ivanov, 192*5
Superfamily DERBYIACEA Stehli, 1954
Family ORTHOTETELLIDAE, new family
Genus Orthotetella R. E. King, 1931
Family DERBYIIDAE Stehli, 1954
Subfamily DF.RBYIINAE Stehli, 1954
Genus Derbyia Waagen, 1884*
Nothopindax, new genus
Licharewiella Sokolskaya, 1960
Subfamily OMBONIINAF. Sokolskaya, 1960
Genus Ombonia Caneva, 1906
Family STREPTORHYNCHIDAE Stehli, 1954
*Grabauellina Licharew, 1934, Pseudoderbyia, Licharew,
1934, and Derbyaeconcha Licharew, 1934, are regarded as
probable synonyms of Derbyia.
NUMBER 15 257
Genus Aesopomum Havlicek, 1965
Streptorhynchus W. King, 1850
Kiangsiella Grabau and Chao, 1927
Arctitreta Whitfield, 1908 (— Grumantia
Ustritsky, 1963)
Bothrostegium, new genus
Tropidelasma Cooper and Grant, 1969
Chelononia, new genus
Family MEEKELLIDAE Stehli, 1954
Genus Meekella White and St. John, 1867
Niviconia, new genus
Geyerella Schellwien, 1899
Perigeyerella Wang, 1955
Sicelia Gortani and Merla, 1934
Orthothetina Schellwien, 1900
Hamletella Hayasaka, 1935
Family THECOSPIRIDAE Bittner, 1893
Genus Thecospira Zugmayer, 1880
DISCUSSION.—In many groups of brachiopods the
current classification is only an approximation of
the truth and many factors tend to qualify these
classifications. Thus it is with the Orthotetidina,
so complicated by a lack of knowledge of how the
animals developed. This lack and its resultant uncertainty
is shown in the classification in the proposal
of Orthotetellidae for the genus Orthotetella,
whose cardinalia are intermediate between the Derbyiidae
and the Derbyoidinae. Orthotetella has a
cardinal process that is in the stage of development
of the Derbyoidinae, but it also has well-defined
erismata that suggest relationship to the Derbyiidae.
A similar situation exists with Tropidelasma, but
it is not so clean-cut as with Orthotetella. Most
species and specimens have no erismata; the extensions
from the anterior margin of the dentifers
curve laterally to meet the side of the valve and
produce a posterior trough. Some specimens, however,
show traces of erismata, suggesting those of
the Meekellidae or Derbyiidae buried in the callus
that forms part of the sockets and cements the
cardinalia to the valve wall. Two new species referred
to Tropidelasma, T. rhamphodes and T. robertsi,
have clearly defined erismata, not buried in
callus but boldly exhibited as in the Derbyiidae.
In T. culmenatum Cooper and Grant (the type of
the genus) many of the young have clearly defined
erismata, but these plates may be aborted or buried
in the adult. Tropidelasma gregarium (Girty) has
well-defined erismata in some specimens, in others
they are clearly buried, but in still others, young
and old alike, they appear to be aborted. In the
later species such as T. gregarium most specimens
have the erismata aborted, the buttressing of the
socket taking place by addition of shell material
to the anterior edge of the dentifer, but instead of
depositing along the whole side, it extends directly
laterally to join the wall of the valve as a shelf,
producing the troughlike structure along the posterior
margin. We interpret this evolution as that
of a gradual elimination of the erismata from a
stock in which originally they were primary structures.
In other words, they are converging toward
the Schuchertellidae while maintaining an advanced
forked cardinal process.
Terminology of the Suborder Orthotetidina
Authors are not consistent in the definition of
terms and often the same name is used for different
structures. In order that the reader may know
clearly the terms we are using in our treatment of
the Orthotetidina, we list in this section our new
names, their definitions, and the morphological
terms that may cause confusion (see Figure 40).
Brachial process (or brachiophore). See Socket
plates, Socket ridge, and Dentifer.
Cardinal process. The cardinal process of the
Orthotetidina is variable and two major types may
be distinguished: the schuchertelloid or orthotetid
type and the derbyoid type. The former is more
primitive, whereas the latter develops into the most
complicated structure in the Derbyiacea, as illustrated
by Geyerella and Meekella. The orthotetacean
cardinal process, like that of the strophomenids,
has two lobes that are not strongly developed
in the orthotetids and schuchertellids, but that become
extravagant in the derbyias and meekellas.
The cardinal process of the schuchertellids generally
does not have a single shaft, but that of the
derbyoids has a prominent wide shaft terminating
in long divergent prongs that bear the myophore,
usually median slits on the prongs. Generally the
length of the cardinal process is determined by the
depth or thickness of trie pedicle valve but the
basic form of the process, whether orthotetacean or
derbyiacean, is not affected.
Chilidial boss. A vestigial form of the chilidum
is preserved in some late members of the Meekellidae;
it produces a monticulus in deep-shelled
species.
Chilidium. This structure is a variously developed
plate at the apex of the dorsal valve, some258
SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
what modified in form from the characteristic arch
over the notothyrium of strophomenoid brachiopods.
In the schuchertelloids the notothyrium is
reduced or has disappeared, but the chilidium is a
low arch, usually with a median trough at the
apex of the brachial valve. It normally is firmly
connected with the posterior part of the cardinal
process. The median trough in the chilidium often
scores the pseudodeltidium of the pedicle valve,
producing a groove along the crest of this plate.
The trace of the groove shows on the inside surface
of the pseudodeltidium as a low ridge. Young
Derbyia has this type of chilidium, and a groove
in the pseudodeltidium is a common feature; it
also shows in Bothrostegium. In the later development
of Derbyia many adults fail to show any
trace of a chilidium. In Meekella and other genera
with a strongly keeled cardinal process-shaft the
chilidium is reduced to a chilidial boss, a small
round plate at the apex closing the gap between
the monticulus and the dorsal apex.
Dental plates. In the Orthotetacea and Derbyiacea,
as in other brachiopods, it is important to
distinguish between primary and secondary plates.
Meekella and Geyerella have genuine primary dental
plates that are part of the shell in its earliest
stages (many minute specimens in the collection
can be identified as Geyerella or Meekella by their
separated dental plates or their spondylium). The
dental plates that form the minute spondylium of
Orthotetes are present in very early stages. This is
not true, however, of Derbyia, which often produces
an apical chamber simulating that of Orthotetes
in late stages of growth. The plates producing this
chamber in Derbyia are a feature of adult growth
and are secondary, often unequally developed or on
one side only, appearing individually rather than
as a specific characteristic. Secondary dental plates
are produced in some schuchertellids of the Mississippian
by adventitious growth from the dental
ridges to the valve floor. Some species of nonpseudopunctate
"schuchertellids'' in the lower Devonian
also exhibit this phenomenon. These have been
referred to Schellwienella, but that assignment certainly
is incorrect. The so called spondylium in
Permorthotetes appears to be a secondary structure
and the genus is a valid separation from Orthotetes,
but its relationship to Derbyoides has not
been established definitely. It thus is apparent that
the varying nature of dental plates must be determined
before generic assignments can be made with
confidence.
Dental ridges. These are the growth tracks of
the teeth, which show as ridges under the delthyrial
edges of the palintrope when dental plates are
absent. Depending on the size of the teeth, these
may be strong or weak.
Dentifer. This is a new name suggested for the
vestigial brachiophore that occurs in the Orthotetacea.
The name brachiophore was not a happy
selection because the structure probably never was
a support to the lophophore, as Williams (1953:9)
pointed out. Actually it probably served a dual
purpose in the orthids, where it was the sloping
face of the socket, forming the inner wall, and must
also have been associated with the lophophore, probably
its support. The brachiophore occupies essentially
the same position as the crural base of the
rhynchonellid, which extended as the cura into the
valve and determined the position of the body wall
where the lophophore is attached. The crus did
not support the lophophore either but did define its
position. The brachiophore probably served the
same purpose and was one of the supports of the body
wall; the mouth was located on the body well
between the ends of the brachiophores.
The brachiophore of orthaceans lies under the
edge of the notothyrium, and the edge of its free
extremity supported the tooth of the pedicle valve.
The brachiophore (called socket plate, later called
socket ridge—Treatise, page H 153—by Williams)
can be detected in the Strophomenida, where it
frequently forms a small rod under the notothyrial
edge and is associated with articulation. The same
rodlike structure occurs in the impunctate Davidsoniacea
and forms a more conspicuous element of
the cardinalia. Here it must have functioned in the
same manner as the orthid brachiophore. Unlike
the orthids, the brachiophore of the Davidsoniacea
tends to be buried under adventitious shell laid
down on its inside and anterior side, welding it
to the cardinal process and walling in the anterolateral
extremity of the socket to produce a cuplike
structure (socket plate, in part, of G. A. Thomas,
1958:9).
In the Orthotetacea, pseudopunctate homeomorphs
of the Davidsoniacea, the brachiophore is
still present, but it is much obscured by adventitious
NUMBER 15 259
shell, although usually it can be seen with little
difficulty. Later Orthotetaceans are characterized by
longer and forked cardinal processes. The more
primitive orthotetaceans are very similar to the
Davidsoniacea as can be seen in Schuchertella
(sensu stricto) and Derbyoides. In the Derbyiidae,
however, the cardinal process begins to lengthen
and bifurcate, and the brachiophore (i.e., dentifer)
appears as an oblique ridge on the long sloping
face of the erisma, which is welded to the cardinal
process shaft. In this group of brachiopods the
dentifer may (or may not) extend anteriorly to
the edge of the erisma and thus simulate a brachiophore
or crus.
In the Meekellidae the dentifer evolves into a
complicated combination of plates called the
promontorium (q.v.). Although the promontorium
may not once suggest the brachiophore or dentifer,
its development can be followed in various juvenile
stages from a simple ridge like the dentifer to the
complicated promontorium.
Erisma. This name is suggested for the plates
supporting the cardinal process and dentifer. These
are the socket plates of G. A. Thomas (1958:19,
figs. 6b, c), which are clearly extensions from his
socket ridge, which buttresses the socket plate. They
are not the same as the socket plates of the Schuchertellidae
(G. A. Thomas, 1958:18, fig. 5). Erismata
are present in the youngest stages of the Derbyiidae
and Meekellidae and thus are unlike the socket
plates of the Orthotetidae and Derbyoidinae, which
are secondary and achieve their greatest development
in large or old specimens. Erismata are conspicuous
in the Derbyoidinae, Streptorhynchidae
(except Tropidelasma), and Meekellidae. They are
present in Orthotetella, but they are anomalous in
supporting a retarded cardinal process without
shaft and bifurcated myophore. Perhaps the largest
development of the erismata is in Ombonia.
Some of the schuchertellids develop secondary
erismata and thus come to mimic the interior of
the Derbyiidae. To prove this, the student must
seek young specimens to determine the primitive
condition of the cardinalia.
The opposite condition has been detected in one
species, Tropidelasma gregarium (Girty), in which
the erisma is partially or in some specimens wholly
eliminated by deposition of adventitious shell.
Enough specimens show the erisma clearly to make
certain the identification of the species.
Fulcral plates. These are small curved plates
located at the proximal end of the socket, defining
small cavities into which the teeth are inserted.
They are not universally present in the Orthotetacea
but are very well developed in Meekellidae to
add to the complexity of their cardinalia. These
are definite and separate plates and are not simply
excavations in adventitious shell.
Gusset. The plate uniting the dentifer to the
cardinal process shaft.
Keel. The angular edge of the posterior side
of the cardinal process shaft in the Meekellidae.
Monticulus. The small, longitudinal, narrowly
rounded fold on the median part of the pseudodeltidium
in the Derbyiacea such as Tropidelasma,
Meekella, and Geyerella. This usually appears on
shells having elongated palintropes in which the
pseudodeltidium is initially convex but becomes
flat in adult stages. The monticulus is the growth
track of the identation at the distal edge of the
pseudodeltidium produced by a fold accommodating
the keel or the chilidial boss.
Myophore slits. Deep longitudinal slits on the
distal end of the prongs of the cardinal process.
These are usually internally crenulated and evidently
were the site of diductor muscle attachment.
Perideltidium. A narrowly triangular region on
the interarea outside the pseudodeltidium but not
reaching the posterolateral margins, which is ornamented
differently from the remainder of the
interarea and is separated from it by a more or
less distinct line. The perideltidium commonly is
ornamented by longitudinal lines as well as the
usual concentric growth lines that parallel the
hinge margin. It normally is well developed on
Derbyia, but it was not observed on all of the
Orthotetidina treated herein.
Promontorium. This is a structure variously
developed in the Meekellidae and best seen in
Niviconia globosa (R. E. King). It is located on
the laterally sloping face of the cardinal process
and is a development from the dentifer (socket
ridge of authors) combined with the gusset, which
is concave in N. globosa. It forms a more or less
horizontal shelf over the lateral interior of the
valve. In Meekella the proximal end of the promontorium
is thickened and forms the inner edge
260 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
of the socket opposite and above the fulcral plate.
Septa. A variety of septa appear in the Orthotetidina,
but the median septum of the pedicle
valve has perhaps most significance. Septa may be
primary or secondary. The septum of Derbyia, for
example, appears in minute specimens and is taken
to be a primary structure. The so-called septum of
Derbyoides appears to be secondary (euseptoidum
of Fredericks 1927b:2), appearing only in adults,
fairly strongly in some, but not present in the
young. This is probably true also of Permorthotetes,
but we have not seen young specimens to substantiate
the point. A distinction, but a difficult one, may
be made between septa and ridges. We call a septum
the strong distinct vertical plate of Derbyia, but we
would term the secondary structure illustrated in
Permorthotetes and Derbyoides a median ridge because
it is low and more in the nature of a myophragm.
We would also call the median ridge
appearing in the brachial valve of Tropidelasma
and some other genera a myophragm rather than a
median septum.
Socket plates. As presently employed in Orthotetidina
by G. A. Thomas (1958:9), the term socket
plates seem to us to refer to two types of plates.
For one of these we have coined the term erisma
to be applied to the widely divergent plates of
Derbyiidae and Meekellidae that support the cardinal
process and form an arch posterior to the
adductor field. These appear to be primary structures
because they occur in the very young. They
are not the same structure to which Thomas has
applied the term socket plates in the Schuchertellidae.
These schuchertellid plates are secondary and
are deposited on the inside of the dentifer (socket
ridge of Williams) and the anterior side of the
socket to form a cuplike socket wall, which is the
most conspicuous mark of the Schuchertellidae and
Orthotetidae.
Neither of the examples above accord with
Williams' first use of the term socket plate or his
later modification called socket ridge, nor are they
like the socket ridges of the Rhynchonellida, Spiriferida,
and Terebratulida to which we would
restrict the term. These terms refer to the brachiophore
of Schuchert and Cooper to which we apply
the name dentifer to be used in the Orthotetacea.
Socket ridge. Originally called socket plates by
Williams (1953c:9), they were later referred to as
socket ridges (Treatise, page H153). Williams
pointed out that these structures, which were called
brachiophores by Schuchert and Cooper, actually
are not lophophore supports but are more concerned
with the articulation. Although socket plates
or socket ridges aptly define these plates, the terms
conflict with the socket ridge of the cardinalia of
the Rhynchonellida, Spiriferida, and Terebratulida,
which are not the same structures. If there is an
homology, the brachiophore is the crural base of the
Rhynchonellida and Terebratulida, but that is not
a socket ridge (see Thomson 1927:85). In order to
avoid confusion, we prefer to use the new term
dentifer, which implies the function as well as
identifies the plate in the Orthotetacea.
Spondylium. The union of the primary dental
plates with a median septum produces a spondylium.
It is important to distinguish between a
primary spondylium such as that of Orthotetes,
Ombonia, and Geyerella from that of Derbyia and
Permorthotetes, which, when present, is a secondary
structure.
Superfamily ORTHOTETACEA Waagen, 1884
Orthotetidina without erismata.
Family ORTHOTETIDAE Waagen, 1884
Orthotetacea having well-developed dental ridges,
a median septum with short spondylium, and, in
some genera, short apical plates or false apical
plates forming a small chamber.
Family SCHUCHERTELLIDAE Williams, 1953
Early progressive Orthotetacea having cuplike
sockets, well-formed chilidium and variable delthyrial
chamber.
PULSIINAE, new subfamily
Schuchertellidae with dental plates. Subfamily
based on Pulsia Ivanov, 1925, from the Carboniferous.
Subfamily SCHUCHERTELLINAE Williams,
1953
Schuchertellidae without dental plates, sponNUMBER
15 261
dylium, or median septum in the pedicle valve and
with recurved cuplike secondary plates forming
the sockets in the brachial valve.
Genera in the Glass Mountains: Schuchertella
and Goniarina.
Genus Schuchertella Girty, 1904
Schuchertella Girty, 1904:734.-Weller, 1914:53.
Ranging from small to large, usually biconvex,
pedicle valve having greater depth; hinge wide,
variable; interarea variable, usually prominent;
anterior commissure variable; pseudodeltidium
strongly convex; perideltidial area well developed.
Surface usually finely costellate.
Pedicle valve interior without dental plates but
with strongly developed dental ridges. Muscle field
roundly flabellate; with large diductor scars and
enclosed adductors; myophragm usually not strongly
developed.
Brachial valve interior with short bilobed cardinal
process and prominent chilidium; myophore
lobes with wide furrows; brachiophores (=dentifers)
appearing as flat blades surrounded by shell tissue
to form cuplike sockets, and forming sloping inner
face of socket. Adductor field large, subcircular,
usually deeply impressed, divided medially by a
poorly developed median ridge. Pallial marks seldom
visible.
TYPE-SPECIES.—Streptorhynchus lens White (1862:
28).
DISCUSSION.—Three features are of prime importance
in the understanding of Schuchertella, which
has given its name to an important family of brachiopods:
(1) the shells are pseudopunctate and thus
distinguished from most Devonian forms bearing
this name; (2) dental plates are absent; and (3)
the dentifers are vestigial, surrounded by callus
(socket plates), and do not have anterolateral extensions,
a considerable distinction from some
later genera.
Schuchertella has been identified in Permian
rocks by Stehli (1954:298). These and Pennsylvanian
forms like them (Streptorhynchus affine
Girty) are placed by us in a new genus Goniarina
because of differences in both valves and a difference
of exterior shape. One Permian species, however,
Schuchertella subvexa, new species, cannot be assigned
to Goniarina and is placed in Schuchertella
in spite of some differences from the type-species.
Schuchertella subvexa is more conical than usual
with typical Schuchertella and the interarea is
longer than usual, but the interior of the pedicle
valve has no dental plates, and no median ridge or
myophragm is developed. This valve seems to be
assignable only to Schuchertella. The brachial valve
is not entirely typical of Schuchertella, but it is
sufficiently like it to warrant the use of the name,
at least until more material can be found. The
cardinal process, however, has unusual features.
The cardinal process has characters that make it
transitional between Schuchertella and Derbyia.
The chilidium is bilobed as in Derbyia, but
this seems not to have affected the pseudodeltidium.
The dentifer is not clearly visible in any of the
specimens. The myophore is schuchertellid in its
brevity and wide myophore slits, but the lateral
plates that buttress it are widely divergent, thin,
and bear an oblique ridge about halfway toward
their distal extremity, the similar-appearing ridge
in Derbyia and other genera. The muscle marks
are clearly impressed.
Schuchertella? subvexa, new species
PLATE 32: FIGURES 1-5; PLATE FIGURES 1-26
About average size for genus; biconvex to planoconvex
to shallowly or moderately conical, normally
not distorted; outline transversely semielliptical
to semicircular; hinge normally forming
widest part of shell, but slightly narrower than
midwidth in some specimens; commissure rectimarginate
to gently sulcate; costellae moderately
high, crests rounded, weakly to strongly crenulate
by intersection with fine concentric ornamentation,
added anteriorly by insertion, averaging about 14
in 5 mm on pedicle valve, 16 in 5 on brachial
valve, younger costellae normally weaker, intertroughs
slightly narrower than costellae; growth
lines weak, nearly uniformly spaced.
Pedicle valve flatly semiconical, apex pointed or
blunt; lateral profile gently convex to concave;
anterior profile broadly and flatly convex; interarea
normally flat to slightly concave or convex,
commonly apsacline, asymmetrical; pseudodeltidium
completely arched, dorsally expanding;
perideltidial area obscure, its limits normally
nearer edge of interarea than midline.
262 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
Brachial valve flat to slightly convex, with very
narrow interarea, commonly disappearing before
reaching hinge ends; anteromedian region of adults
sulcate, sulcus wide and shallow; cardinal extremities
flattened.
Pedicle valve interior with small teeth extending
apically as dental ridges and meeting at apex; no
median septum. Valve floor with rather deep striations
becoming deeper near margins.
Brachial valve interior with short, straight, bilobed
cardinal process projecting posteriorly from
beneath thick childium; lobes widely longitudinally
grooved; dentifers rudimentary, imbedded in thick
callus continuous with sides of cardinal process;
dentifers widely diverging and projecting into body
chamber, laterally fused to shell wall by short, thin
callus, bounding wide sockets. Muscle area short,
occupying between one-fourth and one-third valve
length, weakly delimited, may be bisected by low
rounded median ridge; muscle marks faintly impressed
longitudinal striae and ridges. Floor of valve
moderately deeply striated, striae becoming deeper
near margins.
MEASUREMENTS
152589a
152589b
152589c
152589d
152589e
152589f
152589g
152589h
152589i
152589J
(holotype)
(in mm).—
brachial
valve
length
4.0
6.5
7.5
11.2
13.1
17.3
5.7
25.0
p
?
midwidth
5.8
6.6
9.7
11.2
15.7
18.2
22.8
26.0
21.0
14.0
hinge
width
5.3
5.8
8.6
11.0
16.2
19.0
23.0
22.0
21.0
9.4
thickness
3.3
5.0
3.5?
6.0
5.3
6.0
10.9
7.6
?
?
length
interarea
2.2
3.7
3.2
6.4
6.4
8.0
10.9
11.3
?
?
brachial
valve
length
4.0
5.2
6.9
?
?
?
?
?
14.7
12.0
STRATIGRAPHIC OCCURRENCE.—Neal Ranch Formation
(upper 15 feet of bed 2 = the Gray Limestone
of King).
LOCALITY.—USNM 701.
DIAGNOSIS.—Moderately large Schuchertella with
long interarea and delicate cardinalia.
TYPES.—Holotype: USNM 152589h; figured paratypes:
152589b, e, f, g, i, j , k; measured paratypes:
152589a-g, i, j ; unfigured paratypes: 152589a, c, d,
1-v.
COMPARISON.—This is the only species in the
Glass Mountains referred to Schuchertella. It is
characterized by its wide hinge, shallow and conical
pedicle valve with long apsacline interarea, strong
external costellae, and internal striae. It differs from
Goniarina pyelodes, new species, which also occurs
in the Neal Ranch Formation, in its larger size,
stronger costellation, more flatly conical and anteriorly
expanding or spreading pedicle valve, and
proportionately thinner shell and narrower brachial
interarea. These features also distinguish it from
Goniarina futilis, new species, from the Leonard of
the Glass Mountains. It differs from Goniarina
permiana (Stehli) from the lower Bone Spring of
the Sierra Diablo and lower Skinner Ranch of the
Glass Mountains in its flatter, less cup-shaped
pedicle valve, larger average size, posteriorly projecting
interarea, stronger costellation, and lack
of an anteromedian node in the brachial muscle
area.
DISCUSSION.—Schuchertella subvexa, a rare species,
probably grew attached to some foreign
object by the tip of its pedicle beak. Attachment
marks on most specimens are small, not deeply
impressed, and are near the apex. The shell may be
slightly distorted, normally by twisting or by asymmetrical
growth, but the amount of distortion is
not sufficient to suggest that it lived in closely
crowded clusters.
Genus Goniarina Cooper and Grant, 1969
Schuchertella Dunbar and Condra (not Girty), 1932:117.—
Stehli, 1954:298.
Streptorhynchus Dunbar and Condra (not W. King), 1932:
121.
Goniarina Cooper and Grant, 1969:2.
Small, semiconical, with long interarea; generally
attached by part of pedicle valve when young but
NUMBER 15 263
living free in adult stage. Valves unequal; brachial
valve flat to slightly convex, pedicle valve deep.
Anterior commissure rectimarginate. Perideltidal
area developed. Surface costellae, costellae narrow
and rounded, commonly with strong fila. Pseudopunctate.
Pedicle valve interior with deep delthyrial cavity
and long teeth; no dental plates; muscles lightly
impressed.
Brachial valve interior with cardinal process
bilobed, lobes medially grooved and separated by
thin median septum, and all fused into a thick
curved plate covered by arched chilidium; dentifers
long, laterally compressed and distally pointed.
Adductor field subcircular, usually surrounded by
thickened rim and medially divided by short, often
club-shaped ridge extending anterior to muscle field
margin.
TYPE-SPECIES.—Goniarina pyelodes Cooper and
Grant (1969:2, pi. 4: figs. 26-30).
DIAGNOSIS.—Schuchertella-like but having median
ridge of brachial valve anterior to adductor
muscles.
COMPARISON.—Goniarina differs from Schuchertella
in its external form and minor details of the
interior; it has some features of Schuchertella and
some Streptorhynchus, but it is sufficiently different
from both to be separated as a new genus. Externally
Goniarina suggests Streptorhynchus in the
attached habit and the elongated interarea. This
is usually not so long as in the longest of the
streptorhynchids, but it is generally longer than
in most schuchertellids. Furthermore, the cardinal
process of the brachial valve of Goniarina is unlike
the elongated forked structure of Streptorhynchus
with its erismata.
Typical Schuchertella is generally biconvex, the
pedicle valve typically deeper but not strongly
conical. Goniarina is more conical than Schuchertella
and has an elongated and usually flat interarea.
The pseudodeltidium in both genera is strongly
arched and the dental plates are undeveloped. The
muscle scars of Goniarina are so lightly impressed
that they cannot be revealed except by the trace of
a broad myophragm, which can be seen in some
specimens. The cardinal processes of the two genera
are similar, both having the lobes welded into a
solid structure. In Goniarina a small median septum
divides the lobes. Unlike Schuchertella, this
new genus has extremely long, slender and flattened
dentifers, unusual for the Orthotetacea. The
sockets are large. An important difference between
the two genera is the presence of an irregular myophragm
or ridge that arises between the adductors
and extends anterior to the raised periphery of the
muscle scar to about midvalve. This type of structure
is not seen in Schuchertella, in which the myophore,
when present, is a broad rounded ridge
extending from just anterior to the cardinal process
to the anterior end of the adductor field; it is not
extended anteriorly out of the adductor field.
The shape of the shells, the elongated palintrope
of the pedicle valve, and the elongated, nonenclosed
dentifers without erismata separate Goniarina from
Derbyoides.
DISCUSSION.—The pedicle valve of Goniarina
does not offer any unusual characters calling for
discussion. The brachial valve, on the other hand,
contains the important generic characters. The
dentifers are longer than in Schuchertella and
allied genera, and they are not enclosed to form
cuplike structures as in Derbyoides. The elongate
character of these plates persists throughout the
life of the animal. In the very young they are long
and slender, but, as in the adults, they are buttressed
from below by adventitious shell.
The median ridge anterior to the adductor scars
is variable, ranging from a slender ridge to a clubshaped
structure with its thickened end extending
free into the mantle cavity. Many brachial valves
have the margin of the adductor field thickened.
The thickenings take the form of radial ridges and,
in some examples, of thick projections forming
serrated rims. This genus is strongly pseudopunctate
and some of the taleolae are arranged along
the hinge in a horizontal row, suggesting a crude
form of dentition for articulation of the valves.
This genus is generally rare and insignificant except
at one or two places. Schuchertella pratteni
(McChesney) and Streptorhynchus affine Girty are
placed in this genus, thus extending its range into
the Pennsylvanian. In the Permian it is fairly common
at one place in the Sierra Diablo, where it
occurs at the base of the Bone Spring Formation.
In the Glass Mountains it is found in the Wolfcamp
and throughout the Leonard.
The species of Goniarina are variable in size and
shape. Some are like the type G. permiana (Stehli),
264 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
strongly conical with deep pedicle valves. Two or
more species in the Glass Mountains are unlike
these and are somewhat more like the type-species of
Schuchertella, S. lens (White). The shells are shallow
and unequally biconvex, the pedicle valve generally
being deeper and somewhat broadly semiconical.
These species, as evidenced by the few good
specimens and fragments of others, attained fairlylarge
size, rivaling some of the flatter derbyias or
Derbyoides. These species have proved so rare that
not much is known about them. It was thought at
first that these large forms might be the adults of
the smaller forms, but the growth and resulting
shape of the shell are different. These aberrant
forms of Goniarina ultimately may form a separate
genus, but, as we view them now, they are only
larger and flatter forms of Goniarina.
Stehli (1954:298) depicted this genus as having
been attached to shells or to solid objects by the
apex. Several specimens in the national collection
remain attached by a portion of the ventral surface
rather than by the apex. Furthermore, none of the
pedicle valves show scarred apexes, but many of
them have flattened areas on which the costellae
that were the areas of attachment are not developed.
It seems most likely that the majority lived
loose on the sea-floor after having been ripped
from their original moorings.
Goniarina appeli, new species
PLATE 42: FIGURES 1-5
Small for genus, outline subrectangular, hinge
widest and extended into minute ears. Sides and
anterior broadly rounded, profile hemipyramidal.
Interarea of pedicle valve strongly apsacline.
Pseudodeltidium strongly arched; anterior commissure
slightly folded ventrally. Surface marked by
costellae of uneven size, about 3 per mm at front
margin.
Pedicle valve with small rounded beak; anterior
slope long and moderately steep; median region
slightly swollen. Brachial valve nearly flat in lateral
profile but slightly concave in anterior profile.
Shallow sulcus originating just posterior to midvalve
and extending to anterior margin.
MEASUREMENTS (in mm).—Holotype: length 7.6,
brachial valve length 6.7, hinge width 10.7, midwidth
10.6, thickness 5.3.
STRATIGRACHIC OCCURRENCE. — Hess Formation
(Taylor Ranch Member).
LOCALITY.—USNM 702d..
DIAGNOSIS.—Goniarina with strongly apsacline
pedicle valve interarea, flat brachial valve with
shallow median sulcus.
TYPES.—Holotype: USNM 150395.
COMPARISON.—This species is larger and has flatter
brachial valve.than G. futilis, new species, and
its median sulcus is deeper and wider. Goniarina
byelodes Cooper and Grant is similar to G. appeli
but has stronger ornament, less apsacline interarea
in the pedicle valve, and less sulcate brachial valve.
DISCUSSION.—This species is named in honor of
Mr. Carl Appel, owner of the Appel Ranch (Old
Word Ranch), who helped us in our work.
Goniarina diabloensis, new species
PLATE 39: FIGURES 1-8; PLATE 43: FIGURE 27
Large for genus, profile flatly conical, outline
subrectangular; hinge widest part; sides variable,
ranging from rounded to sloping medially; anterior
margin broadly rounded; anterior commissure not
consistently folded. Surface costellate, costellae increasing
by intercalation, crowded, about 7 in 5 mm
at front margin of adult.
Pedicle valve flatly triangular in lateral profile,
broadly and gently convex in anterior profile. Median
region distorted by attachment; lateral regions
slightly swollen. Interarea short, apsacline. Cardinal
extremities somewhat deflected.
Brachial valve usually somewhat distorted but
with gently convex lateral profile and broadly and
gently convex anterior profile. Umbonal region
slightly swollen; median region usually somewhat
depressed, flanks slightly convex to flattened or less
commonly concave on one side. Cardinal extremities
acute to rounded. Sulcus (when present) irregular;
present in anterior half.
Pedicle valve interior with stout teeth and welldefined
dental ridges. Myophragm small, apical.
Muscle region flabellate, lightly impressed.
Brachial valve interior with small cardinalia and
delicate dentifers; muscle field small with few thick
radial ridges; myophragm short and anteriorly
thickened in adults.
NUMBER 15 265
MEASUREMENTS (in mm).—
pedicle
valve
length
150390a 21.2
150390b (holotype) ?
brachial
valve
length
18.4?
16.3
maximum
width
31.7
28.7
hinge
width
29.7
28.7
interarea
length
6.4
0.8
thickness
6.3
2.9?
STRATIGRAPHIC OCCURRENCE.—Bone Spring Formation
(base).
LOCALITIES.—USNM 728f.
DIAGNOSIS.—Large shallow Goniarina with length
about 2/3 the maximum width.
TYPES.—Holotype: USNM 150390b; figured paratypes:
150390a, k; unfigured paratypes: 150390c-j;
measured paratype: 150390a.
COMPARISON.—This species differs from G. magniextensa,
new species, in having stronger and more
crowded costellae, a smaller and shorter myophragm
in the pedicle valve, a narrower shell, and a more
thickened adult interior.
DISCUSSION.—This is an extremely rare species,
having been found only at USNM 728f. A fragment
of a large Goniarina from USNM 728e may
belong to this "species, but it is not possible to be
sure. Only a few specimens have been taken, four
in the adult stage. The myophragm of the brachial
valve varies from a narrow ridge in these specimens
to a thickened club-shaped ridge in the largest
specimen. The pedicle valve myophragm is a short
and low ridge lodged in the apex. The pseudodeltidium
is thickened by callus and partially obscures
the dental ridges, especially that part of
them near the apex. The interiors are only slightly
thickened by callus.
Goniarina futilis, new species
PLATE 39: FIGURES 9-42
Small, piano- to biconvex, normally deeply conical,
some specimens twisted, bent, or compressed
in growth by contact with foreign objects; outline
transversely semiovate to subrectangular; hinge narrower
than midwidth, usually not articulate; commissure
regular or randomly irregular. Costellae
low, rounded, weakly crenulated, increasing anteriorly
by intercalation, younger costellae weaker;
costellae numbering between 14 and 22 in 5 mm
on pedicle valve and between 17 and 23 on brachial
valve; intertroughs shallow, rounded, about as wide
as costellae; growth lines moderately prominent on
pedicle valve, weak except near margins of brachial
valve.
Pedicle valve deeply conical, normally with large
preumbonal attachment scar; anterolateral profile
normally concave, rarely convex; interarea long,
flat, concave, or convex, commonly twisted or asymmetrical,
forming small obtuse angle with plane of
commissure; pseudodeltidium about one-third width
of interarea at hinge, broadly and completely
arched, without median groove or ridge; perideltidial
area obscurely marked, occupying about half
width of interarea.
Brachial valve slightly convex in lateral and anterior
profiles; interarea becoming slightly lower
near hinge ends. Sulcus poorly defined, sporadic in
occurrence. Ears slightly depressed.
Pedicle valve interior with teeth projecting forward
from edges of pseudodeltidial arch, converging
apically as dental ridges and meeting at apex; no
dental plates or septa. Muscle area in apex, shallowly
excavated, muscle marks obscure. Valve floor
moderately deeply striated, striae stronger near
margins.
Brachial valve interior with short bifid cardinal
process, each lobe projecting slightly posteriorly or
ventrally from beneath the arcuate chilidium and
each longitudinally grooved along posterior face;
dentifers long, bladelike, bounding shallow troughlike
socket and diverging into body chamber; sockets
moderately deep. Muscle area occupying about
half valve length, well impressed, anterior half bisected
by low, sharp-crested median ridge; muscle
marks bounded by longitudinal striae and broad
ridges. Valve floor deeply striate near edges, weakly
striate elsewhere.
266 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
M E A S U R E M E N T S
USNM 702
150393a
150393b
150393c
150393d
150393c
150393f
150393g
150393h
1503931
150393J
(in mm).—
pedicle
valve
length
1.6
1.8
2.7
2.5
3.4
3.9
4.7
5.0
4.7
4.9
brachial
valve
length
1.6
1.9
2.9
2.4
3.3
3.7
4.7
5.0
4.5
4.7
maximum
width
2.3
2.6
3.9
4.1
4.7
5.0
6.9
7.3
7.2
7.0
hinge
width
1.8
c.2.5
3.5
3.9
4.4
5.0
5.9
6.0
7.1
6.9
interarea
length
1.5
1.5
1.0
2.7
2.8
4.6
4.3
5.0
4.7
4.3
thickness
1.7
1.8
2.2
3.0
3.2
5.0
4.8
5.0
5.5
4.7
STRATIGRAPHIC OCCURRENCE.—Skinner Ranch
Formation, Cathedral Mountain Formation (Institella
Zone), Cathedral Mountain.
LOCALITIES.—Skinner Ranch: USNM 707a; Cathedral
Mountain: AMNH 500L, 500X, USNM
702, 702d, 702e, 703bs, 712o, 714w.
DIAGNOSIS.—Small Goniarina with proportionately
large and thick cardinalia.
TYPES.—Holotype: USNM 150393J; figured paratypes:
150393c, f-i; unfigured paratypes: 150393a,
b, d, e; measured paratypes: 150393a-i.
COMPARISON.—Goniarina futilis is distinguished
by its small size, deeply conical pedicle valve with
normally concave anterolateral profile, convex
brachial valve, nonauriculate hinge narrower than
midwidth, and well defined muscle area in the
brachial valve that is bisected by a low but narrow,
crested ridge only in the anterior half. It most
closely resembles G. pyelodes Cooper and Grant
from the Neal Ranch Formation, but differs in its
proportionately narrower hinge, concave anterior
profile, better defined muscle area with higher
median ridge that only occupies the anterior half.
It differs from G. permiana (Stehli) in its smaller
size, less auriculate hinge, weaker ornamentation,
concave anterolateral profile, and lack of any node
on the anterior end of the median ridge of the
brachial valve. This species bears little resemblance
to Schuchertella subvexa, which is much larger, less
deeply conical, more ornamented, thinner shelled,
with a weakly impressed brachial muscle area.
DISCUSSION.—Goniarina futilis grew attached to
some foreign object; many individuals attached
themselves to the shells of other brachiopods or to
other individuals of G. futilis. Many specimens in
the collection from USNM 702 are cemented together
in crowded clusters. Free individuals exhibit
large attachment scars anterior to the beak on the
pedicle valve, indicating that they too were fastened
to something during growth, and most of the individuals
are somewhat distorted by crowding.
Goniarina magniextensa, new species
PLATE 42: FICURES 20-26
Large for genus, width approximately twice
length; outline semicircular; sides rounded; hinge
wide, about equal to, or slightly less than, midwidth.
Anterior margin broadly rounded; anterior
commissure not folded. Surface costellate, costellae
of several sizes in several generations, 6 or 7 in
5 mm at front of large specimens.
Pedicle valve broadly and flatly conical with narrowly
triangular lateral profile; anterior profile
broadly and moderately convex. Interarea wide,
short, unsymmetrical in some specimens; median
and umbonal regions moderately inflated but flanks
flattened.
Brachial valve gently convex in lateral profile
and very broadly and gently convex in anterior
profile; median region flattened; sulcus not regularly
developed; posterolateral regions flattened.
Interarea greatly reduced.
Pedicle valve interior with low, thick median
ridge; muscle field irregularly developed. Teeth
small; dental ridges reduced and hidden by callus.
Brachial valve interior with small, delicate cardinalia,
equal in width to about one-sixth midwidth;
muscle field small; anteromedian myophragm
moderately elevated; chilidium short.
NUMBER 15 267
MEASUREMENTS
USNM 720e
150402a
150402b (holotype)
(in mm).—
pedicle
valve
length
19.6
?
brachial
valve
length
13.7
24.7
maximum
width
30.6
52.0
hinge
width
30.6
46.5
interarea
length
7.8
1.0
thickness
7.4
4.0?
STRATIGRAPHIC OCCURRENCE. — Skinner Ranch
Formation (Decie Ranch Member).
LOCALITIES.—USNM 705a, 720e.
DIAGNOSIS.—Wide Goniarina with length about
half the maximum width and with small, delicate
cardinalia. i\
TYPES.—Holotype: USNM 150202b; figured
paratypes: 150402a, g; unfigured paratypes:
150402c-f, h, i; measured paratype: 150402a.
COMPARISON.—Goniarina magniextensa is the
largest species of this genus yet found, best characterized
by its great width, which is about twice the
length. It differs from G. diabloensis, new species,
in this characteristic and in having less crowded
costellae, a larger and longer myophragm in the
brachial valve and less thickening of the adductor
region in the pedicle valve.
DISCUSSION.—The Decie Ranch Member in which
G. magniextensa is found is noteworthy for its
large number and variety of Orthotetidae. The
probably turbulent water furnished an ample supply
of food while the bioherms and shell clusters
common at this level supplied niches in which
these attached forms could maintain advantageous
positions. The irregularity of the exterior of these
shells, some distorted, others misshapen from living
in crowded places, all testify to the fact that they
must have spent a fair part of their life attached.
Goniarina permiana (Stehli)
PLATE 36: FIGURES 1-34; PLATE 37: FIGURES 1-27
Schuchertella permiana Stehli, 1954:298-299, pi. 17: figs.
19-23.
Small, piano- to biconvex, shallow to moderately
deeply conical, only slightly distorted; outline
transversely semiovate to subquadrate; hinge
slightly narrower to slightly wider than midwidth,
commonly auriculate; commissure without consistent
sinuosities. Costellae moderately strong,
rounded, increasing in number by intercalation,
weakly crenulated, numbering 12 to 14 in 5 mm
on pedicle valve, and 16 to 20 in 5 mm on brachial
valve; intertroughs shallow, narrow; growth lines
strong only near margins.
Pedicle valve with convex anterior profile. Interarea
moderately high, slightly concave to slightly
convex, occasionally twisted or bent; pseudodeltidium
broadly and completely arched, without
median ridge or groove; perideltidial area not visible
on most specimens, about half width of interarea
where visible.
Brachial valve nearly flat to slightly convex; interarea
short, tapering near hinge ends. Median
sulcus obscure, faintly developed on some specimens.
Pedicle valve interior with hinge teeth, converging
apically as dental ridges along inside of interarea
and meeting at apex. Muscle area at apex
shallowly excavated; diductor scars lobate, separated
by low median ridge. Valve floor weakly striated,
striae deeper near margin.
Brachial valve interior with short bifid cardinal
process covered at proximal end by thick arcuate
chilidium, each lobe of process longitudinally
grooved; dentifers often obscure, forming connection
between socket plates and sides of cardinal
process, elongate, bladelike, divergent, forming
shallow hinge sockets beneath edge of brachial interarea.
Muscle area rounded, occupying one-half
to one-third valve length, anteriorly bisected by low
median ridge with anterior node. Small rounded
node sporadically present at posterolateral corners
of muscle area, just below sockets; muscle marks
faint longitudinal striae. Floor of valve weakly
striated, striae stronger near margins.
268 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
MEASUREMENTS
USNM 728f
150405q
150405r
150405s
150405m
150405n
150405o
150405p
150405-1
150405k
150405a
150405b
150405c
150405d
150405e
150405f
150405g
150405h
150405i
150405j
150405t
(in mm).—
pedicle
valve
length
16.0
13.3
11.4
9.3
9.1
6.5
6.6
5.0
4.3
?
p
?
?
?
?
p
?
?
?
11.5
brachial
valve
length
11.6
9.0
8.2
7.7
7.S
5.7
5.6
4.1
3.9
12.5
11.7
11.0
9.4
9.2
9.8
8.7
7.4
5.7
4.5
8.4
maximum
width
20.0
14.0
12.8
13.0
12.0
9.2
8.4
6.3
5.2
19.2
17.3
16.4
15.1
14.1
15.0
12.8
9.4
9.5
6.9
12.5
hinge
width
16.3
12.8
11.2
10.6
11.7
7.1
8.7
5.7
4.7
14.6
16.4
14.0
16.5
13.6
13.3
11.0
11.3
9.2
6.8
12.6
interarea
length
7.0
9.5
6.0
3.8
4.4
3.5
4.2
3.0
2.6
1.1
1.4
1.1
0.7
1.0
1.2
1.1
0.6
?
?
7.4
thickness
7.6
9.6
5.9
4.4
4.6
3.6
4.1
3.0
2.5
flat
flat
flat
flat
flat
1.9
2.2
flat
flat
flat
9.1
STRATIGRAPHIC OCCURRENCE.—-Bone Spring Formation
(base).
LOCALITIES.—AMNH 625, 628, 629, 631, 696;
USNM 725c, 728e, 728f, 728h, 745.
DIAGNOSIS.—Medium sized, strongly conical Goniarina
with cardinalia width one-fourth the shell
width.
TYPES.—Figured hypotypes: USNM 150405a, q,
t, 153514a-m, 153515a-f, 153516; measured hypotypes:
150405a-t.
COMPARISON.—Goniarina permiana is characterized
by its rather large size, relatively strong costellation,
cup-shaped pedicle valve with convex anterior
profile, and flattish brachial valve with a
well-defined muscle area that is anteriorly bisected
by a low median ridge that terminates anteriorly in
a node. It differs from G. pyelodes, the type-species,
and G. futilis, new species, in its larger size, lower
interarea, and nodose brachial median ridge. It
differs from Schuchertella subvexa in its stronger
and thicker shell, weaker costellation, proportionately
narrower hinge, lower pedicle interarea,
which does not project so strongly backward, and
by its well-defined brachial muscle area with nodose
median ridge.
DISCUSSION.—Stehli (1954:299) discussed possible
mode of growth of G. permiana. Small attachment
scars and minimum of distortion of the shells indicate
that the species did not form closely crowded
clusters, but more probably "did not habitually
grow where there was excessive competition for
space . . . It is believed that the species may have
lived near the reefs, but not in the zones of strongest
wave action."
Goniarina pyelodes Cooper and Grant
PLATE 38: FIGURES 1-39
Goniarina pyelodes Cooper and Grant, 1969:2, pi. 4: figs.
26-30.
Shell small, biconvex, shallow to deeply conical,
normally slightly twisted or bent, but not usually
severely distorted; outline transversely semiovate to
subquadrate; hinge wide, slightly narrower than
maximum width of shell, normally slightly auriculate;
anterior commissure regular, without consistent
sinuosities. Fascicostellate, costellae low,
rounded, weakly crenulated on some shells, increasing
in number anteriorly by intercalation, younger
costellae weaker, between 15 and 22 on pedicle
valve in 5 mm, between 18 and 24 on the brachial
valve; intertroughs narrow, rounded; growth lines
faint to invisible except near margins.
NUMBER 15 269
Pedicle valve shallowly to deeply conical, normally
with attachment scar sharp or blunt near
apex; anterolateral profile normally convex, rarely
concave; interarea long, wide, nearly flat, asymmetrical
or twisted, meeting plane of commissure at
right or small obtuse angle; pseudodeltidium about
one-third as wide as interarea at hinge, broadly
and completely arched, without median groove or
ridge; perideltidial area obscurely marked, occupying
more than half width of interarea.
Brachial valve moderately convex; interarea very
low, becoming lower toward hinge ends.
Pedicle valve interior with hinge teeth extending
apically as convergent dental ridges, meeting at
apex of valve; no plates or septa. Muscle area not
visibly delimited; no muscle marks visible. Floor
of valve weakly striated, striae stronger near margins.
Brachial valve interior with very short, bifid
cardinal process, each lobe longitudinally grooved
and projecting slightly from beneath arcuate chilidium;
dentifers rudimentary, nearly buried in
callus, fused to sides of cardinal process, long,
divergent, troughlike, producing moderately deep
hinge sockets at attached end, free ends projecting
into body chamber, supported by adventitious shell.
Muscle area weakly impressed about half as long as
valve, bisected longitudinally by low median ridge;
muscle marks weak, consisting of longitudinal
troughs and ridges. Floor of valve weakly striated,
striae stronger near margins.
MEASUREMENTS
USNM 701k
150411a
150411b
150411c
150411d
150411e
15041If
15041lg (holotype)
15041lh
(in m m ) .—
pedicle
valve
length
30.
3.7
4.7
5.0
5.5
7.2
7.6
9.0
brachial
valve
length
2.0
3.3
4.0
4.3
5.2
5.3
5.9
?
maximum
width
2.9
4.4
5.8
6.0
7.5
7.8
8.4
10.4
hinge
width
2.6
3.4
5.0
5.3
6.6
6.9
7.1
9.1
interarea
length
1.6
1.3
2.5
3.0
2.0
2.5
4.3
5.5
thickness
2.5
1.8
3.5
3.9
2.9
4.0
5.6
5.0
STRATIGRAPHIC OCCURRENCE.—Neal Ranch Formation
(beds 9-14).
LOCALITIES.—USNM 701a3, 701k.
DIAGNOSIS.—Small, strongly fascicostellate Goniarina.
TYPES.—Holotype: USNM 15041 lg; figured paratypes:
15041 Id, f, i-n; unfigured paratypes; 150410,
15041 la-c, e, h; measured hypotypes: 15041 la-h.
COMPARISON.—Goniarina pyelodes is characterized
by its small average and maximum size, wide
and normally auriculate hinge, interarea that meets
the plane of commissure near a right angle, normally
convex anterolateral profile of the pedicle
valve, and low, weakly crenulate fasciculate costellae
that are relatively closely crowded. It differs
from Schuchertella subvexa, which also occurs in
the Neal Ranch Formation, primarily in its smaller
size, thicker shell wall, more strongly convex brachial
valve, auriculate hinge, and less posteriorly
projecting pedicle beak. Interiorly, its dentifers are
longer and more protruding, and its brachial muscle
area more definitely circumscribed. This species
differs from G. futilis, which also is small, but it is
shallower, with a more cup-shaped pedicle valve,
a convex rather than concave anterolateral profile,
a more frequently auriculate and proportionately
shorter hinge, and less strongly marked brachial
muscle area. Goniarina permiana (Stehli) is similar,
but it attains larger size, is more strongly ornamented,
and has a strong median node near the
anterior edge of the brachial muscle area.
DISCUSSION.—Goniarina pyelodes is not strongly
deformed by closely crowded growth, and the collection
contains no clusters, only individual shells.
The attachment scars on most shells are larger and
deeper than on Schuchertella subvexa and the
shells thicker, perhaps indicating that G. pyelodes
lived where currents were stronger and firmer attachment
was necessary. Goniarina futilis, on the
other hand, grew in clusters, with crowded conditions
producing more deformed shells.
270 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
Goniarina striata, new species
PLATE 40: FIGURES 2-25
Small, wider than long, pedicle valve subconical,
interarea long, ranging from procline to strongly
apsacline. Sides rounded; hinge wide, usually forming
obtuse cardinal extremities. Anterior margin
broadly rounded. Maximum width at midlength.
Anterior commissure without consistent folding.
Surface costellate, the costellae somewhat distant,
measuring 3 or 4 per mm on average specimens.
Brachial valve moderately convex in lateral profile,
forming triangular outline with palintrope.
Umbonal and median regions with marks of attachment.
Umbonal region moderately swollen;
anterior region flattened. Anterolateral slopes
steep. Interarea fairly long, pseudodeltidium moderately
arched.
Brachial valve variable in lateral profile from
flat to gently convex; cardinal extremities flattened;
median region slightly swollen; flanks flattened.
Pedicle valve interior without trace of muscle
impressions and without apical myophragm.
Brachial valve interior with broad and flat dentifers
strongly elevated and defining deep sockets.
Hinge with obscure teeth and sockets. Muscle area
small with fine radial lines along the anterior border.
Myophragm irregularly developed.
MEASUREMENTS
USNM 720d
150415a
150415b
150415c
150415d
150415e
150415f
USNM 721j
150417a
150417b
150417c
153550a (holotype)
(in mm).—
pedicle
valve
length
9.0
6.4
6.5
?
p
?
9.5
5.0
?
4.8
brachial
valve
length
5.8
4.1?
4.1
7.1
6.1
5.4
8.2
4.2
6.8
4.7
maximum
width
9.G
7.0
6.7
9.8
9.1
8.2
13.8
6.8
9.8
6.6
hinge
width
9.2
6.7
5.8
8.7
8.6
6.8
13.2
6.0
7.5
6.3
interarea
length
4.0
4.6
3.8
1.7
0.8
0.8
5.2
3.6
0.4
3.0
thickness
4.2
4.1
3.6
2.1?
1.2
?
4.8
3.4
?
3.0
STRATIGRAPHIC OCCURRENCE.—Road Canyon Formation.
LOCALITIES.—USNM 710u, 720d, 721j, 721z, 724b,
726e.
DIAGNOSIS.—Small, transverse, with broad-bladed
dentifers.
TYPES.—Holotype: USNM 153550a; figured paratypes:
150413, 150415c, e, 150417a, 153551a-d; unfigured
paratypes: 150415a, b, d, f; 150417a, c; measured
paratypes: 150415a-f, 150417a-c.
COMPARISON.—The specimens of this species are
variable and difficult to compare with other forms
also having considerable variability. This species
suggests the two small species: G. futilis and G.
pyelodes. It differs in having less regularly developed
costellae, more delicate cardinalia, and a more
modest development of the myophragm.
DISCUSSION.—The specimens of Goniarina striata,
like many others from USNM 720d are coated, inside
and out, by an amorphous material that may
have originally been an algal coating, now preserved
in siliceous form. Fortunately some of the
specimens were not completely covered and one
side or the other can be obtained fairly clean and
the structures seen. At USNM 721 j a few specimens
of Goniarina are generally larger but thinner
shelled. Their dimensions conform with those
from USNM 720d, but the interior details of the
brachial valves are not the same; however, the two
are tentatively given the same name.
Goniarina species
Several specimens of Goniarina of fairly large size
are not referable to any of the species described
above. These are represented mostly by brachial
valves and are noted below.
Goniarina SPECIES 1 (Plate 41: figures 18, 19).—
This is represented by several specimens, all but
one of them in a youthful or juvenile condition.
NUMBER 15 271
The one adult is a large brachial valve 15.1 mm
long, 27.4 mm at midwidth, which is the widest
part, the hinge 23.8 mm and the thickness 3.7 mm.
It is, thus, gently convex in both profiles and fairly
inflated in midvalve. The costellae are unequal
in size, larger ones setting off groups of smaller
ones, presenting an ornamentation like that of some
Mississippian species of Schellwienella. The cardinalia
are unusually narrow and the muscle region
longitudinally slightly elliptical. The myophragm
is slender, but an elevated ridge, not extending anterior
to the anterior margin of the muscle field,
bounds each side of the field just anterior to the
end of the dentifer. This valve has details not
seen in other of the large Goniarinas. This specimen
comes from USNM 708u at the base of the
Cathedral Mountain Formation.
Figured specimen: USNM 150420.
Goniarina SPECIES 2 (Plate 93: figures 1, 2).—
Two not fully grown brachial valves and one juvenile
pedicle valve. The brachial valves are like the
above in ornament, but the cardinalia are not narrowly
bowed; instead, they are spread out. The
specimens are from the Cathedral Mountain Formation
(Institella zone) at USNM 702b and 703b.
Figured specimen: USNM 150421a.
Goniarina SPECIES 3 (Plate 42: figures 9-14; Plate
42: figures 17-19).—The lot (USNM 150423) consists
of four fragmentary specimens, one part of a
pedicle valve, the other a nearly complete brachial
valve. The pedicle valve has a length of about 17
mm and a width of 26 mm. The interarea is short
and the pseudodeltidium flatly convex. The ornament
consists of thin costellae, the larger ones
setting off groups of one to three which are intercalated.
No details of the interior can be ascertained.
The brachial valve is about 18 mm long
and has a midwidth of 35.6 mm. The hinge is 33
mm wide. The shell is somewhat distorted, but
normally it would be nearly flat. The cardinalia
are wide and thick. The adductor field is small, but
its margin is considerably thickened laterally. The
myophragm rises to a crest anteriorly and is thick
and strong. The species is from the Road Canyon
Formation at USNM 722-1.
Figured specimens: USNM 153513a, b, 150423a.
Goniarina SPECIES 4.—A specimen with both
valves measuring 24 mm at the hinge and 17 mm
long is strongly apsacline and has a large convex
pseudodeltidium. The brachial valve is nearly flat.
The specimen is unsilicfied and comes from the
Uddenites-bearing Shale Member at USNM 701x.
Mentioned specimen: USNM 155126.
Goniarina SPECIES 5 (Plate 41: figures 1-17;
Plate 94: figure 19).—Reminiscent of G. magniextensa.
Two growth forms are included here, but
the extended form may not be characteristic of the
species because several other specimens are not
nearly as wide. The lot (USNM 152562) consists
of 12 specimens in various states of fragmentation
except for one perfect valve. Since three are immature
pedicle valves, no clear view of the species
can be obtained. In the best specimen, the brachial
valve is about 35 mm wide at the hinge but only
15 mm long. Another specimen (based on the half
measure) is 30 mm wide by 19 mm long. The
cardinalia of both specrmens are delicate and rather
narrow. The median ridge is moderately long and
well developed. The best' pedicle valve is 14 mm
wide by 11 mm long and is fairly long. The interarea
is flat with a slightly arched pseudodeltidium.
The exterior is ornamented by costellae
of two sizes, the stronger costellae separate groups
of 1, 2, or 3 finer costellae. Four of the larger
costellae appear in 5 mm at the anterior margin.
These specimens were recovered from the silty
limestone of the Cathedral Mountain Formation of
USNM 721u and may be related to, if not the same
as, Goniarina species 3.
Figured specimens: USNM 153549, 152562a-i.
Goniarina SPECIES 6 (Plate 43: figures 3-26).—
Several specimens indicate a species of large size,
but no adult pedicle valves have been taken. Three
immature pedicle valves have a prominent and
somewhat twisted umbonal region and long interarea
with strongly convex pseudodeltidium. The
brachial valves are almost flat with wide hinge but
narrower than maximum width, which is near midvalve.
The sides are rounded and the anterior
margin broadly curved. The largest specimen measures
24 mm in length by 40 mm at midvalve. The
specimens come from the Neal Ranch Formation
(bed 4) at USNM 727e.
Figured specimens: USNM 153541a-f.
Goniarina SPECIES 7 (Plate 42: figures 6-8; Plate
93: figure 3).—This is a medium-sized species represented
by 14 specimens (USNM 152564); only
one of them is adult and only two of them pedicle
272 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
valves. The largest specimen is nearly perfect and
is 18 mm wide by 12 mm long. The valve is subrectangular
in outline with the cardinal extremities
nearly a right angle. The cardinalia are short
and wide, fairly strongly bowed. The median ridge
is short and a callosity appears just anterior to the
brachiophores. The cardinalia, median ridge, and
callosities are thick and exaggerated in one of the
juveniles. The pedicle valve conforms in outline to
the brachial. The interarea is apsacline and fairly
long, but the pseudodeltidium is not strongly elevated.
This species is smaller and has a different outline
than Goniarina species 5 and G. magniextensa.
Good pedicle valves are needed to define all of the
above species, but they appear to be rare in adult
form. The specimens are from the Road Canyon
Formation at USNM 726x.
Figured specimen: USNM 153511a, 152564a.
HYPOPSIINAE, new subfamily
Schuchertellidae having a spondylium in young
forms, the spondylium becoming sessile in adult
and old individuals.
Hypopsia is at present the only genus known in
this subfamily.
Hypopsia, new genus
[Greek hypopsia (suspicion) ]
Biconvex or nearly planoconvex, shallow to
deeply conical; outline transversely semiovate to
subquadrate; hinge width nearly equal to midwidth.
Costellae moderately strong, rounded to
sharp, increasing anteriorly by intercalation, intertroiighs
shallow, rounded; growth lines covering
shell, producing light crenulation of costellae and
intertroughs, irregularly spaced stronger growth
lines more frequent near margins.
Pedicle valve shallow to deeply conical; lateral
profile gently convex to slightly concave, interarea
wide, high, convex, or concave; perideltidial area
lightly marked; pseudodeltidium completely but
gently arched.
Brachial valve moderately convex to nearly flat;
chilidium wide, arcuate; interarea definite but low,
tapering toward hinge ends.
Pedicle valve interior with strong teeth projecting
forward at sides of pseudodeltidium, extending
apically as convergent dental ridges along underside
of interarea, meeting at apex of valve, normally
buried in callus for most of length; strong
dental plates extending from each dental ridge,
meeting above floor of juvenile valves, forming
spondylium and median septum, meeting at floor
in larger individuals, and reaching floor without
meeting in largest specimens; above sequence preserved
in mature individuals, continuous from apex
to anterior end of spondylium. Muscle marks
within spondylium.
Brachial valve interior with very short, wide cardinal
process, two short lobes protruding from
cover of chilidium, each grooved along posterior
edge; prominent median ridge along underside of
process; sockets formed by long, divergent dentifers
and a proximal thickening; sockets reinforced by
shell deposited on their inner surfaces and anterior.
Muscle area in umbonal arch, occupying up to
half valve length.
TYPE-SPECIES.—Hypopsia versuta, new species.
DIAGNOSIS.—Schuchertellidae with spondylium.
COMPARISON.—Hypopsia is characterized by its
peculiar spondylium, which descends toward the
floor of the pedicle valve as the valve becomes
larger, which is progressively filled with shell material
at the posterior and which maintains the
spondylium floor at shallow depth. The wide but
short cardinal process is another distinctive feature,
necessitating a rather wide pseudodeltidial arch.
This genus combines features of several genera.
The cardinal process and completely arched pseudodeltidium
most closely resemble those of Schuchertella
or Derbyoides. The moderately deeply
conical pedicle valve is more characteristic of
Derbyia and Ombonia; however, it closely resembles
the shape of some Goniarina that occur in the
Glass Mountains Permian.
The spondylium is the most characteristic feature
of Hypopsia. In young specimens or near the apex
of an older one it is Y-shaped, as in Ombonia or
Geyerella, with a rather high median septum. A
section across the pedicle beak near the apex would
show this type of spondylium, and, being unplicated,
the shell might easily be mistaken for a representative
of some species of Ombonia. A section
farther from the pedicle beak, cutting the spondylium
near its middle, would produce a V- or UNUMBER
15 273
shaped cross section, and the specimen might be
erroneously assigned to a species of Sicelia. A section
that cut the spondylium near its anterior end
would show dental plates that intersect the floor of
the valve without meeting, as in Sicelia.
This genus is without analogue among the
Schuchertellidae. Its resemblance to Ombonia at
one stage of growth and to Sicelia at another is
superficial at best: neither of those genera has the
widely arched pseudodeltidium of Hypopsia, and
both have long, narrower cardinal processes more
characteristic of Meekella or Derbyia. In addition,
both Ombonia and Sicelia are typically more conical,
the hinge narrower, the perideltidium more
strongly marked, and the interarea more normally
concave than convex as in Hypopsia. The spondylium
of Hypopsia appears to be similar to that
of Orthotetella if the median septum were fully
developed and the chamber of the spondylium reduced
by filling at the apex.
The cardinal process is very small and laterally
spread like that of Schuchertella. The chilidium is
entire, rather than bilobed, as in many genera such
as Derbyia and Ombonia. This also accounts for
the fact that the pseudodeltidium neither bears a
monticulus nor does it have a groove.
Hypopsia versuta, new species
PLATE 31: FICURES 1-21; PLATE 32: FIGURES 6-19;
PLATE 43: FIGURE 1
Moderately large, biconvex, shallow to deeply
conical; shell wall thick; outline transversely semiovate
to subquadrate; hinge wide, about equal to
midwidth; anterior commissure rectimarginate to
weakly uniplicate. Costellae moderately strong,
rounded to rather sharp, weakly crenulate, closely
spaced and with narrow intertroughs, numbering
between 10 and 18 in 5 mm on pedicle valve, averaging
about 14, slightly more crowded on brachial
valve, averaging about 15 in 5 mm; growth lines
light, closely crowded, forming transverse crenulation
of costellae and intertroughs, stronger growth
laminae widely spaced over shell, more closely
spaced near margins.
Pedicle valve shallow to deeply conical; lateral
profile gently convex to gently concave, flexed in
some species; interarea wide, normally long, commonly
convex, rarely concave, slightly twisted or
otherwise asymmetrical in some specimens; perideltidial
area lightly marked, about half width of
interarea; pseudodeltidium moderately wide, completely
arched, without median ridge or groove.
Brachial valve flatly convex; interarea low, tapering
toward hinge ends; chilidium broad, arched to
conform to pseudodeltidium.
Pedicle valve interior with strong teeth extending
apically as convergent dental ridges, meeting
at apex of valve, normally buried for most of
length by material of spondylium; dental plates
strong, thick, extending from dental ridges to converge
toward valve floor, meeting above floor and
joining a median septum in juvenile valves and
near apex of mature valves, meeting at floor of
more mature valves and about midway in still older
valves, not meeting but intersecting floor at anterior
end of spondylium in largest valves; spondylium
shallow, progressively posteriorly filled by
shell material with growth, maintaining nearly
constant depth of spondylium. Floor of valve anterior
to muscle area weakly to moderately strongly
striated, striae stronger near margins.
Brachial valve interior with short, wide, bifid
cardinal process, each lobe projecting from beneath
chilidium and grooved longitudinally; median
ridge on underside of process prominent, but extending
into umbonal arch; dentifers divergent,
protuberant, fused with cardinal process to form
sides of shallow sockets. Muscle area in umbonal
arch, occupying one-third to nearly one-half valve
length; bilobed, with very low median ridge terminating
at anterior end in slight swelling; muscle
marks consisting of weak longitudinal striae in
muscle area. Floor of valve weakly striated, striae
stronger near margins.
274 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
MEASUREMENTS
152587e
152587d
152587c
152587b
152587a
152587f
152587g
152587h
152587i (holotype)
(in mm).—
pedicle
valve
length
20.3
21.8
30.0
24.9
39.3
p
?
7.8
12.0
brachial
valve
length
?
?
p
p
?
23.0
11.2
p
10.5
maximum
width
22.1
26.0
27.3
28.5
37.7
34.8
15.7
9.6
14.0
hinge
width
19.3
23.5
23.9
25.0
34.4
32.8
12.3
10.0
13.0
interarea
length
9.0
11.5
15.7
12.0+
17.9
?
?
5.8
10.0
thickness
7.6
10.0
13.5?
10.5
16.0
4.8
2.0
5.6
10.7
STRATIGRAPHIC OCCURRENCE.—Neal Ranch Formation
(upper 15 feet of Bed 2 of P. B. King).
LOCALITY.—USNM 701.
DIAGNOSIS.—Hypopsia with variable spondylium.
TYPES.—Holotype: USNM 152587i; figured paratypes:
152587a-f, j-n; measured paratypes:
I52587a-h; unfigured paratypes: 152587g, h, o-v.
COMPARISON.—This is the only known species of
the genus.
DISCUSSION.—The specimens of this species are
not well silicified, which is unfortunate when one
considers the unique characters of the genus. The
shell was extremely thick and gross and the silicification
is largely superficial. Any crack in the silicification,
therefore, let the acid attack the thick
secondary deposits of the interior. The result is
that some of the specimens are ragged, and in
others the interareas are badly preserved. This
species is very rare and has been taken from one
place only, although it has been sought elsewhere
in the mountains.
DIPLANINAE, new subfamily
Schuchertellidae having large interareas on both
valves, cardinal process with short shaft and bifurcated
myophore; dentifers nearly obsolete, seldom
visible; sockets cuplike.
The only genus in West Texas is Diplanus
Stehli.
This subfamily has been set apart from its fellows
in the Schuchertellidae because of the advanced
character of the cardinal process, which
shows a tendency toward that of the Derbyiidae in
the elongation of the shaft and the bifurcation of
the myophore. Unlike Orthotetella, which has a
conservative cardinal process, no erismata are developed.
The anterior end of the sockets in Diplanus
are closed by thick shell deposits that answer to
G. A. Thomas' definition of socket plates. These
are secondary deposits. Diplanus seems to be a
terminal genus because we have not seen any other
genera quite like it or which might have been derived
from it.
In the youngest brachial valves of Diplanus seen,
measuring about 2.5 mm in width, the cardinal
process is like that of Schuchertella, bilobed rather
than bifurcated, and the dentifer (brachiophore)
is a flat blade. As growth continues, the cardinal
process elongates and the dentifer is completely
covered laterally on both sides and is also added to
on its edge. It cannot be identified as a discrete
plate in the adult.
Genus Diplanus Stehli, 1954
Diplanus Stehli 1954:299.
Small with elongate conical valve and convex
brachial valve; hinge straight, usually without ears;
interareas on both valves, that of brachial valve
unusually well developed. Anterior commissure
usually not folded unless the valves are distorted.
Attachment surface usually large and frequently
occupying most of the ventral surface. Valves
costellate and lamellose, costellae narrow and elevated
and prolonged into small spines on some
lamellae.
Pedicle valve with broad interarea and strongly
arched prominent pseudodeltidium; perideltidial
area not observed. Teeth large and protruding;
dental ridges thick; delthyrial chamber narrow; no
septum or myophragm. Musculature obscure.
Brachial valve with broad interarea, wide chilidium
usually medially grooved. Cardinal process
NUMBER 15 275
at high angle to hinge, forked and elongated;
socket plates broad, anteriorly narrowly rounded
and occasionally with trace of dentifer process;
sockets deep, bounded laterally by a thick ridge;
adductor field broad and rounded; myophragm
rare.
TYPE-SPECIES.—Streptorhynchus lamellatum R.
E. King (1931:49, pi. 4: figs, la-c only).
DIAGNOSIS.—Schuchertellidae with a broad interarea
on the brachial valve.
COMPARISON.—Diplanus is obviously externally
similar to Streptorhynchus, from which it differs
in the strongly lamellose ornament and well-developed
interarea on the brachial valve.
Diplanus is a distinctive and easily recognized
brachiopod, but it is so variable that it is difficult to
identify species within it. The distinction between
species is not difficult in adult forms, but the young
with distortion resulting from attachment and
crowding and the variability of the ornament make
problems in recognition. The attachment surface
may be confined to the umbonal region, or it may
take a generous share of the ventral surface. The
positioning of the embryo after it has settled and
the nature of the attachment surface are factors in
determining the ultimate shape of the shell. Specimens
on broad, flat surfaces tend toward roundness
and flatness, but ones attached in confined
spaces may undergo considerable distortion.
The most important distinguishing feature of
this genus and the one that gives its name is the
interarea on each valve. The brachial interarea is
better developed in this genus than in other
schuchertellids. Another feature is the lamellate
character of the interareas. This is shown in most
of the Glass Mountains specimens, but it may be
an exaggeration owing to the silicification. Specimens
of Diplanus from the lower Bone Spring Formation
in the Sierra Diablo generally have the
interarea smooth. The lamellose character appears
on both valves and is shared by the chilidium as
well as by the interarea. The brachial valve interarea
is shorter than the pedicle valve interarea and
is variable. In large and old specimens, it is generally
prominent and is nearly plane to concave.
The chilidium is broad and rises above the interarea
increasingly toward the pedicle valve, where
it is inserted under the margin of the pseudodeltidium.
Medially the chilidium is marked by a
depression representing the positon of the gap between
the lobes of the cardinal process. Behind
the chilidium, between it and the umbo, is a groove
and abrupt change in direction of the interarea.
This portion represents the earliest part in the development
of the structure.
An odd feature of Diplanus is the lack of a perideltidial
area, a feature that is common in many
orthotetaceans. No trace of this structure can be
seen on the exterior in the best-preserved specimens,
nor can any trace be seen in decorticated
or damaged specimens. The feature seems not to
have been developed in this genus.
The ornament of Diplanus is very distinctive and
consists of costellae and strong lamellae. The shell
grows by increments inside the margin, leaving
the preceding shell layer overhanging the new shell.
This also leads to development of a ragged or
falsely spiny appearance. The shell is costellate,
the costellae alternating in size, the new ones being
intercalated at the anterior of the shell. Some
costellae are continued anteriorly slightly beyond
the margin of the shell and thus appear as interiorly
grooved processes. When slightly curved
away from the margin, they have the appearance of
blunt or truncated spines. No definite pattern of
intercalation of costellae was detected; in some
specimens new ribs appear as single costellae between
the larger ones; in others a pair of costellae
are intercalated. In some young specimens the
costellae remain nearly the same size until near
maturity. These small differences create a variety
of types living together, presumably all of the same
species. Another variable feature is the anterior
widening of the costellae, which produces another
variable element in the ornament. One large specimen
of D. catatonus from the Neal Ranch Formation
shows a large band of fine costellae at the
anterior, the intercalation having gradually eliminated
the coarser costellae.
The interior of the pedicle valve does not offer
any structural novelties, but it is noteworthy for
the large size of the teeth. These are thick and
long, somewhat crescentic in cross section, and inclined
with the convex surface toward the sides. The
palintrope and the pseudodeltidium form a shelf
over them. Some slight longitudinal striation is
visible in large specimens. The delthyrial chamber
commonly is thickened considerably, and the pos276
SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
terior ends of the dental ridges thus buried, but,
in spite of this thickening, well-defined muscle
marks were not differentiated, and a myophragm
appears not to have been developed.
Like most other structural features of this genus,
the cardinalia are variable in length, thickness, and
their angular relation to the hinge or plane of commissure.
The structures are welded into a solid
piece in which some of the parts are clearly visible
but others not. The myophore, unlike that of most
schuchertellids, consists of two elongate lobes
grooved distally on the posterior face. The lobes
in some specimens are short, but in others they extend
for a considerable distance into the opposite
valve. In some specimens the lobes are welded together
but in others, more rarely, the lobes are
separate but subparallel. Posteriorly the lobes are
further cemented by the chilidium that overlies
them and bears a median indentation corresponding
to the depression dividing the myophore lobes.
The inner wall of the socket is joined to the anterolateral
face of the myophore, descends obliquely
anteriad, and is abruptly curved to form
the deep socket. The socket is bounded on the
outside by a thick ridge, and the areas outside this
ridge are concave. The structure is reminiscent of
that of Derbyoides, Goniarina, and Tropidelasma.
At the anterolateral extremity of the socket wall
mentioned, a small nub appears in some of the
better preserved specimens. This is the only trace
of a brachiophore or dentifer seen in the genus.
These nubs are very small and must be regarded
as vestigial. Supporting plates surrounding the muscle
field do not appear in this genus because the
cardinalia are greatly confined. The muscle field is
not well preserved in any of the silicified specimens,
but a delicate, short myophragm anterior to
the cardinalia appears in well-preserved specimens.
This is a threadlike ridge that scarcely attains
midvalve.
Diplanus has been found in the Glass Mountains
in rocks ranging in age from Upper Pennsylvanian
(Gaptank) into Leonardian (Cathedral Mountain).
The species are similar, but they show at least one
consistent developmental trend that may be used
to distinguish them. This involves the width of
the pseudodeltidium relative to the total width of
hinge. In these attached forms, gross shape of the
shell is variable and, therefore, nearly useless for
distinction of species. Ornamentation is quite similar
among the species, with only subtle differences
that require large collections in order to be distinguished.
Useful and consistent group distinctions
have been determined only in features of the
pedicle interarea and pseudodeltidium. In general,
the narrowest pseudodeltidia are in Pennsylvanian
specimens, and the widest in Leonardian specimens.
To some extent, this is a function of width of hinge
relative to total width of shell, but this parameter
alone would not distinguish the Pennsylvanian
from the Leonardian species.
Stehli (1954:300) states his belief that Diplanus
is known only from West Texas; however, a species
belonging to this genus was described from the
Schwagerina limestone of the Sosio Valley in Sicily
under the name Canavaria sinuata Merla (1928:76,
pi. 2: figs. 5-7). Greco (1938:5, 14) referred "C"
sinuata to Streptorhynchus, considering it to be
generically distinct from the other two species that
made up "Canavaria" (later changed to Gemmellaria
Ruiz, 1933:20, then to Sicelia, Merla, 1934:
284). Both of these authors (Merla, 1928:77; Greco,
1938:14, 1942:137) emphasized in their descriptions
of "C." sinuata the unusual development of the
brachial valve interarea. Merla's photographs (pi.
1: figs. 5-7) do not show this feature clearly because
of the angle from which they were taken, but
Greco's photographs (1938, pi. 1: figs. 1-8; 1942,
pi. 13: figs. 1-3) illustrate it very well. Presence of
a well-developed brachial valve interarea, as well as
details of ornamentation that are visible in Greco's
photographs, leave little room for doubt that the
species should be Diplanus sinuatus (Merla). This
species was not the type-species of "Canavaria",
and it is not congeneric with species of Sicelia as
now constituted.
Diplanus apochordus, new species
PLATE 44: FIGURES 26-40
Large, irregularly conical, outline elongate oval,
brachial valve strongly convex, nearly conical in
large individuals, hinge line slightly narrower than
widest part. Pedicle interarea long, triangular, flat,
concave, convex or twisted, bisected by narrow
pseudodeltidium.
Brachial valve interarea long for genus, normally
concave and overhanging hinge. Shell thick, ornaNUMBER
15 277
mented by strong circum-umbonal laminations with
weak, distant radial costellae, ornament similar on
both valves.
Pedicle valve interior a deep cone, devoid of
septa; hinge teeth thick and bluntly conical, projecting
from underside of palintrope, continuing as
thick ridges along sides of delthyrial cavity.
Brachial valve interior deeply concave, with
strong bifid cardinal process supported by fusion
of dentifers to it; sockets deep, outlined by sides
of cardinal process and socket plates. Muscle field
occupying about one-third valve length, commonly
bisected by low myophragm.
MEASUREMENTS (in mm).—
pedicle
valve
length
150440a 19.5?
150440b (holotype) 20.6
150440c 11.5
brachial
valve
length
20.7
17.4
11.5
maximum
width
19.1
17.8
11.6
hinge
width
15.0
11.4
8.5
interarea
length
15.0
10.3
8.5
thickness
24.8
16.0
15.6
STRATIGRAPHIC OCCURRENCE.—Skinner Ranch
Formation (Decie Ranch Member).
LOCALITY.—USNM 707a.
DIAGNOSIS.—Large and elongate Diplanus with
highly arched umbonal region in the brachial
valve.
TYPES.—Holotype: USNM 150440b; figured
paratypes: 150440a, c; unfigured paratypes:
150440a, c; unfigured paratypes: 150440d-e; measured
paratypes: 150440a, c.
COMPARISON.—This species is distinguished from
all others in the Glass Mountains by its large size,
the elongated pedicle valve, and the strongly arched
umbonal region of the brachial valve.
DISCUSSION.—The strongly arched umbonal region
of the brachial valve of this species, especially
when seen in lateral profile, is very striking. No
other species is so constituted, but some specimens
of D. catatonus, new species, approach it in late
adulthood or in obese specimens. Usually these can
be readily distinguished because they are shorter
than the Decie Ranch specimens.
It might be suggested that the specimens of D.
apochordus represent obese forms, but this appears
not to be so because the species is represented by
a fair range in size. The smallest specimen shows
the strong swelling of the brachial valve umbo.
Diplanus catatonus, new species
PLATE 44: FIGURES 1-24; PLATE 45: FIGURES 1-21; PLATE 46:
FIGURES 1-24; PLATE 49: FIGURES 13-30; PLATE 50: FIGURE 46
Streptorhynchus lamellatum R. E. King (part), 1931:49,
pi. 4: fig. 3.
Shell conical, deep or shallow, regular or distorted,
normally with attachment near apex or
along anterior slope of pedicle valve; outline nearly
circular, or subquadrangular, widest near midline
of nearly flat to strongly convex brachial valve,
some shells slightly constricted on one or both
sides immediately anterior to hinge, producing
slight alation. Pedicle interarea long, broad, triangular,
flat, concave, convex, or twisted to left or
right, bisected from apex to narrow, outwardly
convex pseudodeltidium that occupies less than
one-third of total width of hinge and is narrower
than one side of interarea; hinge straight, invariably
narrower than maximum shell width.
Brachial valve interarea short, decreasing laterally,
flat or slightly concave, continuing plane of
pedicle interarea or overhanging, divided by
strongly laminated convex chilidium, slightly
wider than pseudodeltidium, produced by posterior
growth of cardinal process. Shell thick, with strong
circum-umbonal laminae; brachial valve with peculiar
square-ended and posteriorly dimpled umbo,
and ornamented by strong costae, added by intercalation,
more or less sharply discontinuous, being
broken at edge of each lamina, but continuing on
successive laminae, some slightly recurved at edges
of laminae, giving spiked appearance to valve. Costation
of pedicle valve similar, but normally
weaker, absent along surfaces where valve attached
or adjoined neighboring shells.
Pedicle valve interior deep or shallow irregular
cone, flat along hinge line, devoid of septa or plates.
Hinge teeth bluntly conical, projecting dorsally
from beneath palintrope forming supporting ridges
278 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
on underside of interarea that converge toward
beak, along sides of arched cavity beneath pseudodeltidium.
Brachial valve interior semicircular to subquadrangular
in outline, slightly alate on one side or
both; hinge line straight. Cardinal process large,
strong, supported by convergent and posteriorly
flexed dentifers fused to anterior side; process bifid,
and either or both of the two lobes may be bifid;
growth producing a posterior groove along length
of process. Hinge sockets deep, close against cardinal
process, outlined by sides of process and fused
dentifers. Muscle field roughly same shape as valve,
extending forward about one-third valve length
bisected by low median ridge in some specimens.
MEASUREMENTS
USNM 701d
150432a (holotype)
100432b
150432c
150432d
150432e
150432f
150432g
150432h
150432i
150432J
150432k
150432-1
(in mm).—
pedicle
valve
length
19.3
18.0
15.1
12.8
11.6
11.0
13.2
12.3
8.5
7.8
6.3
5.0
brachial
valve
length
16.3
16.4
12.2
11.2
11.0
9.6
8.0
8.9
7.3
6.5
4.5
4.0
maximum
width
17.3
15.0
16.3
13.4
12.0
10.7
9.3
8.0
8.0
6.8
5.0
4.3
hinge
width
15.7
11.0
15.9
9.8
8.0
8.6
7.8
5.8
6.7
5.7
3.4
3.8
interarea
length
11.6
11.8
9.2
5.8
5.6
10.5
8.4
7.3
5.0
3.0
2.2
1.9
thickness
19.8
18.0
12.3
10.0
12.0
14.9
12.9
10.0
7.8
4.6
3.5
3.2
STRATIGRAPHIC OCCURRENCE.—Neal Ranch Formation
(beds 2-14 of King), Cibolo Formation.
LOCALITIES.—Neal Ranch: USNM 701, 701a,
701a3, 701c, 701d, 701h, 701k, 701-1, 706x, 708y,
721g, 727d, 727e; Cibolo: 728-1.
DIAGNOSIS.—Large Diplanus with flattened umbonal
region and moderately strong costellae.
TYPES.—Holotype: USNM 150432a; figured paratypes:
150431a, 150432e, g, h, i, k, 150433a-c,
150434a-c, 153496a-u, 153500; measured paratypes:
150432 b - !.
COMPARISON.—Diplanus catatonus most nearly
resembles D. lamellatus (R. E. King). It differs
primarily in its relatively narrower pseudodeltidium
that occupies only about one-third of the
total hinge width. Other differences are less distinct:
the ornamentation of D. catatonus is normally
a little stronger than that of D. lamellatus,
and the hinge is wider. The outline of the brachial
valve is more transverse in typical D. catatonus
and more elongate in D. lamellatus, although there
are many specimens that cannot be distinguished
by this feature alone. The average size of D. catatonus
is greater, and so is the maximum size.
Strong costation and flattened umbonal region
distinguish D. catatonus from D. apochordus;
strong costation and strong lamellation distinguish
it from the Sicilian species D. sinuatus (Merla).
Diplanus catatonus normally is larger than D. redactus,
new species, and has a wider hinge relative
to total width of shell, but also a wider pseudodeltidium,
relative to total width of hinge. The pedicle
interarea of typical D. catatonus is much higher
and its apical angle smaller than in D. redactus,
although some specimens do resemble D. redactus
in this feature, inasmuch as it partly depends on
the shape of the object to which the shell is attached,
and, therefore, it is a highly variable feature.
DISCUSSION.—Diplanus catatonus lived attached
to some solid object, and its shape was influenced
by the shape of this object. Since the shell normally
was attached by a large part of the pedicle
valve, the shape and ornamentation of the valve are
highly variable and not reliable in distinguishing
species.
Diplanus lamellatus (R. E. King)
PLATE 47: FIGURES 1-42; PLATE 48: FIGURES 1-39; PLATE 49:
FIGURES 1-5; PLATE 49: FIGURES 6-12; PLATE 50: FIGURES 15-20
NUMBER 15 279
Streptorhynchus lamellatum R. E. King, 1931:49, pi. 4; fig. 1
[not figs. 2, 3].
Diplanus lamellatus (R. E. King) Stehli, 1954:300, pi. 17:
figs. 27-29.
Shell distorted cone; pedicle valve irregularly
conical, brachial valve lidlike, moderately convex;
outline transversely subelliptical to longitudinally
subquadrangular or trapezoidal, widest anterior to
midline of brachial valve. Hinge narrow, straight;
pedicle interarea long, narrow, convex, or twisted,
bisected by relatively wide pseudodeltidium occupying
well over one-third of total hinge width and
normally wider than either lateral part of interarea.
Brachial valve interarea low, divided by wide
convex chilidium that nearly obscures flat parts of
interarea. Brachial valve umbo posteriorly blunt,
with 2 dimples, 1 on each side of axis; brachial
valve ornamented by strong radial costae, only
slightly interrupted by somewhat weaker circumumbonal
lamellae. Ornamentation of pedicle valve
similar, but normally weaker and more variable
due to attachment of that valve to foreign objects.
Pedicle valve interior devoid of plates or septa,
hinge teeth projecting from beneath palintrope, extending
as converging ridges along sides of pseudodeltidial
cavity toward apex of valve. Muscle
area slightly depressed in some individuals, normally
indistinct, asymmetrical.
Brachial valve interior shallow, concave, with
strong, long bilobed cardinal process, each lobe of
which may be slightly bifid at end; line of division
between 2 halves of process produces a groove along
its posterior length. Dentifer strongly flexed and
fused to anterior side of cardinal process; hinge
sockets deep, formed by sides of cardinal process
and fused brachiophores. Muscle area indistinct,
slightly depressed, subdivided by low median ridge.
MEASUREMENTS (in
USNM 703bs
YPM 11399 (holotype)
USNM 150450a
150450b
150450c
150450d
150450e
150450f
150450g
150450h
150450i
USNM 702d
150446a
150446b
150462a
USNM 707a
150455a
150455b
150454a
AMNH 631
152588a
152588b
mm).—
pedicle
valve
length
11.8?
15.6
12.8
12.5
10.7
7.9
7.4
6.9
5.2
4.3
11.4
13.9
10.7
10.4
11.9
13.9
17.1
p
brachial
valve
length
9.7
9.7
9.6
9.6
6.2
7.5
6.0
6.7
4.2
3.8
10.0
10.2
9.8
10.4
10.5
10.7
P
10.5
maximum
width
12.5
14.0
10.3
10.0
8.0
8.3
6.1
6.0
5.0
4.8
11.0
12.5
9.7
12.3
13.1
11.5
13.1
12.8
hinge
width
9.7
9.0
6.8
6.7
5.3
5.2
4.4
4.3
3.6
4.0
8.6
8.9
7.3
8.7
9.0
8.4
8.7
10.6
interarea
length
6.0
7.0
5.0
5.0
6.0
4.5
4.3
3.7
2.8
2.0
5.8
8.5
7.2
5.3
7.0
12.3
8.3
?
thickness
9.2?
14.8
9.9
8.3
9.4
8.0
6.9
6.3
2.9
2.8
11.8
13.7
14.8
9.6
13.7
19.0
?
?
STRATIGRAPHIC OCCURRENCE.—Bone Spring Formation,
Skinner Ranch Formation (Decie Ranch,
Poplar Tank, and Sullivan Peak members), Hess
Formation (Taylor Ranch Member), Cathedral
Mountain Formation and Cathedral Mountain
(Wedin Member), Cibolo Formation.
LOCALITIES.—Bone Spring: AMNH 492, 625, 628,
631, 658, 660, USNM 725c, 728e, 728f, 728h; Decie
Ranch: USNM 707a; Poplar Tank: USNM 707h,
707ha, 718v, 718z; Sullivan Peak: USNM 707d,
707g, 707-1, 713c, 714y, 722h, 722-1, 727a; Skinner
Ranch (low): USNM 705a, 715v; Skinner Ranch
280
(high): USNM 705r, 714y; Taylor Ranch: USNM
702d, 702e; Cathedral Mountain: AMNH 500,
500K, USNM 700x, 702, 702a, 702 (low), 702un,
703bs, 708, 712o, 721u, 723u; Wedin: USNM 700-1,
700x, 714w, 717e, 723v, 727p; Cibolo Formation:
USNM 725v, 738r, 738s.
DIAGNOSIS.—Small Diplanus usually with strongly
and narrowly umbonate brachial valve and strong
costellae anteriorly.
TYPES.—Holotype: YPM 11399; figured paratypes:
YPM 11398a, b; figured hypotypes: USNM
150444a, 150446a, b, c, d, 150454a, 150541a,
150459a, 150462a, b, 150470a, 153498a-c, f, 153499a,
153501, 153502a, b, 153503a, b, 153504, 153505,
153506, 153507; measured hypotypes: 150450a-i,
150446a, b, 150454a, 150455a, b, 150462a, 152588a, b.
COMPARISON.—Diplanus lamellatus is characterized
primarily by its relatively wide pseudodeltidium
and subquadrate to trapezoidal outline with
widest part anterior to the midline. The hinge
commonly appears to be narrower than in D. catatonus
and in D. redactus, new species. It is further
distinguished from the latter species by its normally
more deeply conical pedicle valve with
higher and more narrow interarea. Wolfcampian
and Leonardian species are distinguished by the
short brachial valve interarea, the lack of welldefined
lamellae, and the nonflaring nature of the
costellae at the anterior. On the inside, the thickness
and narrowness of the cardinalia are distinctive.
SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
Diplanus rarus, new species
PLATE 30: FIGURES 11-12; PLATE 50: FIGURES 1-14, 21-31;
PLATE 93: FIGURES 20-29
Fairly large for genus, longer than wide, sides
broadly rounded but anterior somewhat narrowly
rounded; pedicle valve conical, moderately elongated;
hinge narrower than midwidth and with
small auriculations. Attachment surface occupying
at least half of ventral surface. Costellae fairly even
in size, about 6 in 5 mm at front of large specimen.
Pedicle valve moderately deep and moderately
convex; interarea forming broad triangle, pseudodeltidium
occupying about one-fourth the width;
pseudodeltidium moderately convex. Ridge margining
interarea sides grooved on anterior side.
Anterior moderately curved in dorsad direction
where free from attachment.
Brachial valve with umbonal region narrowly
swollen, moderately steep umbonal slopes leading
to the ears. Median region strongly swollen; anterior
forming steep slope; lateral slopes steep. Interarea
short, lying at slight angle to pedicle valve
interarea and not overhanging opposite interarea.
Pedicle valve interior with thick, closely spaced
teeth. Brachial valve interior with moderately long
cardinal process and thick socket plates.
MEASUREMENTS (in mm).—
pedicle brachial
valve valve maximum hinge interarea
length length width width length thickness
USNM 714p
150472a (holotype) 18.5 13.5 15.6 11.4 5.4 12.4
150472b 14.0 14.0 18.8 15.4 11.5 20.5
STRATIGRAPHIC OCCURRENCE.—Skinner Ranch
Formation (Decie Ranch, Sullivan Peak Member);
Cibolo Formation (Breccia Zone of Udden).
LOCALITIES.—Skinner Ranch: USNM 714p; Decie
Ranch: USNM 707a; Sullivan Peak: USNM 733j;
Cibolo: USNM 728-1.
DIAGNOSIS.—Fairly large Diplanus with median
swollen brachial valve and fairly even ornament.
TYPE.—Holotype. USNM 150472a; figured and
measured paratype: 150472b; figured paratypes:
153497a, b; unfigured paratypes: 150472c-e; figured
specimens: 153049a, b, 153512a-c.
COMPARISON.—In size this species approaches D.
apochordus, but the pedicle valve is not so elongated,
the umbo of the brachial valve is not arched,
and the costellae are fairly even in size. It approaches
D. catatonus in size, but it has a stronger
brachial valve and somewhat narrower pseudodeltidium.
DISCUSSION.—This species comes from the Decie
NUMBER 15 281
Ranch Formation as does D. apochordus, but the
two have completely dissimilar appearance. They
both occur in bioherms with Scacchinella and
Eolyttonia, suggesting a tendency toward diverse
speciation in different bioherms.
Diplanus redactus, new species
PLATE 50: FIGURES 32-45
Low, shallow, irregular cone; brachial valve
gently convex, pedicle valve low conical. Outline
nearly circular, truncated by relatively narrow,
straight hinge line. Pedicle interarea short for
genus, a broad-based triangle bisected by very narrow
pseudodeltidium occupying one-fifth to onefourth
of hinge width. Brachial valve interarea
short, continuing plane of pedicle interarea, or
slightly concave, bisected by chilidium of low relief.
Shell thick, constructed of circum-umbonal
laminae, wide spaced for genus; costae quite regular,
with 1 weak costa inserted by intercalation
between stronger costae that originated farther back
on umbo; costae only slightly interrupted by laminae.
Pedicle valve interior unknown, presumed to be
devoid of plates and similar to that of other species
of Diplanus.
Brachial valve interior shallow, concave, with
short, stout, bifid cardinal process fused with dentifers
that diverge widely below process. Muscle
area well defined, slightly raised, bisected by very
low, rounded median ridge. Sockets shallow.
MEASUREMENTS
USNM 701e
150475a
USNM 700a
150474a
150474b
(in mm).—
pedicle
valve
length
19.4
10.6
13.2
brachial
valve
length
16.6
9.4
10.8
maximum
width
21.7
10.9
10.5
hinge
width
15.0
6.3
7.3
interarea
length
7.0
3.0
5.0
thickness
12.0
4.7
4.0?
STRATIGRAPHIC OCCURRENCE.—Gaptank Formation
(middle and upper bed 10 of P. B. King,
Uddenites-bearing Shale Member).
LOCALITIES.—Bed 10: USNM 700, 700a; Uddenites:
USNM 701, 701e, 701-1, 701v.
DIAGNOSIS.—Generally depressed and rounded
Diplanus with fairly regular ornament and moderately
prolonged interarea on the pedicle valve.
TYPES.—Holotype: USNM 150475a; figured paratype:
150474a, 150475b; measured paratypes:
150474a, b; unfigured paratype; 150474b.
COMPARISON.—Diplanus redactus is characterized
by its low, broad interarea with relatively narrow
pseudodeltidium and by its unusually regular ornamentation.
The low interarea and regular ornamentation
are the most obvious differences from
D. catatonus. Its narrower pseudodeltidium differentiates
it from similarly shaped specimens of D.
lamellatus. The brachial valve interior seems to
have more widely divergent dentifers than in typical
specimens of other species of Diplanus, but the
description of this interior is based on a single
specimen, so the range of variability is not known.
DISCUSSION.—Our collection of D. redactus is
small, only nine specimens; however, these maintain
their characteristic features through considerable
range in size, and we believe that they
represent a valid species.
Subfamily DERBYOIDINAE Thomas, 1958
Orthotetidae, usually of large size, having cuplike
sockets but with the secondary median septum
of the pedicle valve incipient to well formed.
Derbyoides was separated by Dunbar and Condra
(1932) from Derbyia because of difference in the
cardinalia. Actually, a difference also exists in the
ventral septa of the two genera, that of Derbyia
being strong, crested, and united with the pseudodeltidium,
whereas that of Derbyoides is secondary
and usually in an incipient state of development.
The other members of this subfamily represent
other extremes. Tapajotia is almost identical to
Derbyoides, but it has a somewhat lesser development
of the ventral median elevation, which is an
incipient ridge. Permorthotetes is distinguished by
a strongly developed median septum that forms a
small apical chamber with false dental plates of
small size.
282 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
Genus Derbyoides Dunbar and Condra, 1932
PLATE 26: FIGURES 1-4; PLATE 34: FIGURES 1-8; PLATE 35:
FICURE 18; PLATE 43: FIGURE 2; PLATE 126; FIGURES 48, 49
Derbyoides Dunbar and Condra, 1932:114.-Mendes, 1956:18.-
Campbell, 1957:21.
Tapajotia Dresser, 1954:33.-Mendes, 1956:149.
Convexiconcave, flatly biconvex, planoconvex to
shallow conical; outline transversely subovate to
quadrate; hinge narrower than midwidth, occasionally
slightly auriculate. Costellae moderately strong,
rounded to sharp, added anteriorly by insertion,
weakly crenulate; growth interruptions of lamellae
moderately strong, more frequent near margins.
Pedicle valve nearly flat to moderately conical; anterior
profile normally concave; interarea wide,
short to moderately long, slightly convex or concave,
rarely flat; perideltidial area plainly marked;
pseudodeltidium widely expanding, completely
arched, deeply notched for chilidium, normally
with shallow median groove or median flattening.
Brachial valve nearly flat to moderately convex;
interarea present but short; chilidium strong, straplike,
fitting into arcuate notch of pseudodeltidial
arch.
Pedicle valve interior with strong hinge teeth
projecting forward at edges of pseudodeltidium, extending
apically as convergent dental ridges, meeting
at apex of valve; median septum low, thickened
along free edge, bisecting muscle area, apical end
independent of dental ridges, or braced to them by
shell thickening or small secondary plates of adventitious
callus. Muscle area flabellate, excavated
or raised, occupying one-third to two-thirds of valve
length, the proportion greater in deeper valves; adductor
scars elongate, on each side of low septum
or myophragm; diductor scars broadly flabellate,
lateral to and surrounding adductors. Floor of valve
striate, striae stronger near margins.
Brachial valve interior with short, thick, bilobed
cardinal process, each lobe longitudinally grooved
and the proximal end partially covered by chilidium;
dentifers thick, divergent, forming shallow
cuplike sockets, joining beneath digits of cardinal
process, often with median septum or carina between
myophores, which is extended ventrally as a
thick point; erisma absent, muscle area bilobate,
normally bisected by low myophragm. Valve floor
pustulose and striate, striae stronger near margin.
TYPE-SPECIES.—Derbyoides nebrascensis Dunbar
and Condra (1932:115, pi. 9: fig. 3, pi. 14: figs. 1-4
[fig. 1: lectotype herein designated]).
TYPES.—Figured hypotypes: USNM 150427a-h.
COMPARISON.—Derbyoides is characterized by its
concave or nearly flat to moderately conical pedicle
valve, wide, normally short interarea, widely expanding
and completely arched pseudodeltidium.
Another distinguishing feature is the low and weak
median ridge that normally is somewhat thickened
along its crest, is cemented at its apical end by
callus, and does not have pseudodental plates to
produce a small chamber or camera. Features of
the brachial valve that distinguish the genus are
the short but thick cardinal process that fits into
the notch of the pseudodeltidium, rather than extending
under it and straddling the median septum
of the pedicle valve; the large brachiophore
plates that recurve toward the hinge to form cuplike
sockets and lack of supporting plates.
Derbyoides is easily distinguished from Derbyia
Waagen (emended, Girty, 1908) by its low pedicle
median ridge, widely expanding and completely
arched pseudodeltidium, short cardinal process, recurved
brachiophore plates, and lack of supporting
plates. Presence of a median septum in the pedicle
valve distinguishes Derbyoides from Schuchertella
Girty, Schellwienella Thomas, and Pulsia Ivanov,
which are the three genera like it externally. Presence
of a camera or chamber at the juncture of the
median septum with the dental ridges has not been
observed in Derbyoides. This is the chief distinction
between it and Orthotetes, which commonly
has a small primary chamber in the apical part of
the pedicle valve. The chamber is often filled by
callus, which makes differentiation of the two difficult.
The cuplike sockets and the internal details of
Goniarina suggest Derbyoides, but the known species
of that genus are generally small, conical forms
that do not have a strong myophragm or median
ridge in the pedicle valve and in which the brachial
valve is provided with a club-shaped ridge anterior
to the adductor field. The type-species of Derbyoides
has a low myophragm in the adductor field
that extends anterior to the anterior margin of the
field, but it seems not to develop the club shape
and anteriorly confined position of the ridge in
Goniarina, nor does it have the long dentifers of
NUMBER 15 283
Goniarina. The two genera appear sufficiently close
to be placed in the same family.
DISCUSSION.—We are using genus Derbyoides for
species having cuplike sockets in the brachial valve
that are formed by the welding of the dentifer to
the cardinal process and to the side of the valve.
These species also have a median ridge or myophragm,
often reaching the proportions of a septum
in the pedicle valve. This, however, is not fused to
the dental ridges to form a small chamber, as in
Orthotetes.
Derbyoides is rare in the Glass Mountains and
comes from the Gaptank Formation, the Uddenitesbearing
Shale Member of the Gaptank Formation,
and the upper 15 feet of the Gray Limestone of
P. B. King. The specimens are poorly silicified,
fragmentary, or not silicified.
Derbyoides dunbari, new species
PLATE 35: FIGURES 27-30
Average size for genus, flatly biconvex, often
slightly distorted and asymmetrical outline transversely
subovate to nearly semicircular; hinge
slightly narrower than midwidth, normally not auriculate;
commissure rectimarginate or slightly
wavy. Costellae strong, rounded or sharp, added
anteriorly by insertion, numbering about 20 in 5
mm; intertroughs shallow rounded, weakly transversely
filate; growth interruptions moderately
strong, widely spaced, closer near margins.
Pedicle valve flatly convex to shallowly conical
at apex; anterior profile convex, concave or flatly
sigmoidal; no attachment scars visible. Interarea
wide, long, nearly flat to slightly convex, meeting
plane of commissure at small to moderately large
obtuse angle, commonly asymmetrical; perideltidial
area well marked, about half width of interarea;
pseudodeltidium widely expanding, broadly and
completely arched with median flattening as shallow
groove, deeply notched at anterior for reception
of dorsal chilidium and cardinal process.
Brachial valve moderately convex; chilidium
strong, arcuate; interarea very short or absent.
Pedicle valve interior with strong, widely divergent
hinge teeth, extending apically as strongly
convergent, low, rounded dental ridges, meeting at
apex, where they are often buried in callus; median
septum low, upper edge rounded, thickened, bisecting
muscle area, apical end buried in callus.
Muscle area bilobate, slightly elevated or depressed,
adductor scars along median septum, diductor scars
wide, lateral and anterior to adductors. Valve floor
weakly striate, more strongly so near margins.
Brachial valve interior with short, wide, strong
bifid cardinal process having underside with median
ridge, attached end partly covered by chilidium,
dentifers fused to sides of process, mostly
buried by callus. Muscle area broad, bilobed,
slightly excavated or raised, bisected by low myophragm.
Floor of valve weakly striate, stronger
near margins.
MEASUREMENTS (in mm).—
pedicle
valve
length
USNM 701
150424a (holotype) 42.5
150424b ?
150424c 41.5
brachial
valve
length
p
27.3
?
maximum
ividth
51.2
35.3
55.0*
hinge
width
44.6
30.0
38.8?
interarea
length
13.4
?
7.8
thickness
?
6.3
?
STRATIGRAPHIC OCCURRENCE.—Neal Ranch Formation
(upper 15 feet of bed 2, bed 4, both of P.
B. King).
LOCALITIES.—USNM 701, 701-1.
DIAGNOSIS.—Irregularly distorted Derbyoides
with strongly apsacline to procline interarea.
TYPES.—Holotype: USNM 150424a; figured paratype:
15042b; unfigured paratypes: 150424c-f;
measured paratypes: 150424c.
COMPARISON.—Derbyoides dunbari is characterized
by its somewhat distorted, flatly concave pedicle
valve with wide, short interarea that meets the
plane of commissure at a small obtuse angle, and
its strong, normally rounded costellae. It is much
flatter and larger than D. marathonensis, new species,
with which it occurs at USNM 701, and its
pseudodeltidium is wider, the median septum and
hinge teeth stronger, and its cardinal process wider
and more heavily built. This species resembles the
type-species, D. nebrascensis Dunbar and Condra,
284 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
but it differs primarily in its less regular shape,
more elongate outline, stronger costellae, interarea
that meets the plane of commissure at a smaller
angle, its brachial median ridge not terminating as
a knob, and by the presence of low crural plates
bordering the muscle area.
DISCUSSION.—This species is very rare. The
specimens are not well silicified, especially in the
region of the muscle scars, which were greatly
thickened in life.
Derbyoides marathonensis, new species
PLATE 35: FIGURES 19-26
Small for genus, biconvex to nearly planoconvex,
shallow to moderately deeply conical; outline transversely
semiovate to subquadrate; hinge slightly
narrower to slightly wider than midwidth; occasionally
weakly auriculate. Costellae moderately
strong, rounded to sharp, weakly crenulated, added
anteriorly by intercalation and numbering about 14
in 5 mm on both valves; intertroughs narrow to
nearly as wide as costellae; growth lines widely
spaced, moderately strong, more frequent near
margins.
Pedicle valve with concave anterior profile; attachment
scars obscure; interarea moderately long,
wide, normally convex, rarely concave, occasionally
asymmetrical, meeting plane of commissure at small
obtuse angle; perideltidial area less than half width
of interarea; pseudodeltidium wide, completely
arched, with median flattening or shallow groove,
deeply notched for reception of chilidium.
Brachial valve nearly flat to gently convex; chilidium
arcuate, projecting posteriorly; interarea
absent. Sulcus irregularly developed.
Pedicle valve interior with hinge teeth projecting
forward at edges of pseudodeltidium, extending
apically as dental ridges, meeting at apex of valve;
median septum low, upper edge thickened, apical
and independent of dental ridges, or cemented to
it by callus. Muscle area bilobate, bisected by
median septum, raised or forming a shallow excavation,
adductor scars wide, flabellate, located in
delthyrial cavity, diductor scars wider, anterior to
adductors. Valve floor striated, striations stronger
near margins.
Brachial valve interior with short, bifid cardinal
process, with attached side partly covered by chilidium,
secondary shell or socket plates fused to sides
and underside of process, forming large, shallow
sockets; dentifers divergent, projecting bluntly into
body chamber, ends recurved slightly toward hinge;
muscle field nearly circular, bisected by low myophragm
continuous to median notch of cardinal
process. Floor of valve striated, with stronger striae
near margins.
MEASUREMENTS
150425a (holotype)
150425b
(in mm).—
pedicle
valve
length
12.3
11.5
brachial
valve
length
?
p
maximum
width
18.0?
14.2?
hinge
width
18.0
12.9
interarea
length
5.4
?
thickness
5.4
1.9
STRATIGRAPHIC OCCURRENCE.—Neal Ranch Formation
(upper 15 feet of bed 2 of P. B. King).
LOCALITY.—USNM 701.
DIAGNOSIS.—Small with subconical pedicle valve
and fairly long median ridge in the pedicle valve.
TYPES.—Holotype: USNM 150425a; figured paratypes:
150425c-e; unfigured paratypes: 150425b,
f-h; measured paratype: 150425b.
COMPARISON.—Derbyoides marathonensis is characterized
by its small size, its conical pedical valve
with small, poorly developed median septum, relatively
narrow pseudodeltidial arch, and short
narrow cardinal process. These features distinguish
it from D. dunbari, new species, with which
it occurs at USNM 701, and from D. nebrascensis,
the type-species.
Derbyoides species 1
PLATE 62: FIGURES 1, 2
An unsilicified specimen of medium size has the
characteristics of Derbyoides. It is strophomenoid
in form and profile, about 33 mm long and 53 mm
wide, a compressed shell with a thickness of 6.5 mm.
The surface is costellate, the costellae thin and
distant, numbering 8 to 5 mm at the front margin.
NUMBER 15 285
The interarea is short, the brachial valve gently
convex and the pedicle valve gently concave. The
specimen comes from the Gaptank Formation at
USNM 701y.
TYPES.—Figured specimen: USNM 153801.
Derbyoides species 2
A pedicle and brachial valve of large size indicate
another species of Derbyoides, but the specimens
are too poor for naming or detailed description.
The pedicle valve is 54 mm long by 76.5 mm
wide. The brachial valve is 54 mm long by 73 mm
wide and is strongly convex. The pedicle valve is
fairly deeply concave. The costellae are distant and
number 6 in 5 mm at the anterior margin of the
pedicle valve. They come from the upper part of
the Uddenites-bearing Shale Member at USNM
713g.
TYPES.—Described specimens: USNM 153480a, b.
Superfamily DERBYIACEA Stehli, 1954
Costellate Strophomenida with erismata in the
brachial valve.
The Derbyiacea appear first in the early Pennsylvanian
and become abundant in the late Pennsylvanian.
They reach their greatest development
in numbers of species and genera in the Permian.
They are especially abundant in the Wolfcamp,
when they contributed conspicuously to bioherms
in the Neal Ranch and Skinner Ranch formations.
ORTHOTETELLIDAE, new family
Derbyiacea having a primitive type of cardinal
process intermediate between that of the Derbyoidinae
and Derbyiidae.
The character of the cardinal process is the basis
for the family. The myophores are lobate like those
of Derbyoides, and they are cleft medially like
those of Derbyia but are bifurcated. Orthotetella
is also like Derbyia in the presence of long flaring
erismata.
Genus Orthotetella R. E. King, 1931
Orthotetella R. E. King, 1931:51.—Stehli, 1954:302.
Large, thin shelled, biconvex to convexi-concave,
hinge wide, often slightly auriculate; costellae low,
sharp, added by insertion; intertroughs wide, flat,
concentrically ornamented by transverse fila that
have little effect on costellae; growth laminae prominent
near margins, concentric wrinkling prominent.
Pedicle valve normally flatly convex to concave or
forming a shallow to deep cone; interarea laterally
wide, short to moderately long; pseudodeltidium
completely arched, dorsally expanding without
monticulus or median depression. Brachial valve
flatly and evenly convex, with costellae somewhat
stronger and more closely spaced.
Pedicle valve interior with strong teeth projecting
from underside of interarea, extending apically as
dental ridges, converging at apex of valve; median
septum short or absent, often buried by apical
callus; dental plates converging to form Y-shaped
spondylium near apex, but continuing dorsad beyond
its attachment on valve floor, to produce a
U-shaped spondylium fused to crests of dental
ridges, whole structure forming, with pseudodeltidium,
a conical tube. Muscle marks within
spondylium.
Brachial valve interior with short, blunt, bilobed
cardinal process, each lobe longitudinally slit and
serrate, joining to produce median groove of process;
dentifers fused to sides of process, forming
laterally and dorsally open hinge sockets and projecting
bluntly into body chamber; erismata continuous
with dentifers diverging into umbonal
cavity, outlining part of muscle area. Chilidium
usually complete. Muscle area broad, bisected by
low median ridge; muscle marks faint longitudinal
striae.
TYPE-SPECIES.—Orthotetella wolf camp ensis R. E.
King (1931:51, pi. 9: figs. 27-28).
COMPARISON.—Orthotetella differs from Derbyia
externally by its sharp, widely spaced costellae with
transversely filose intertroughs, and its broadly
arched nonsulcate pseudodeltidium. Internally the
long, expanding conical spondylium distinguishes
this genus from all its relatives in the Orthotetacea.
Orthotetella resembles Hypopsia in ornament and
profile, but generally it is larger. The spondylium
of Hypopsia suggests that of Orthotetella in early
stages, but it becomes sessile rather than tubular
in adult specimens.
DISCUSSION.—King (1931:51) remarked the supposed
absence of a median septum, and the ab286
SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
sence of any median seam marking the juncture
of the two spondylial plates. The absence of a seam
is the result of the formation of the spondylium,
not by the junction of two dental plates, as King
supposed, but by splitting of the upper edge of a
small median septum. The spondylium arises from
the floor of the valve, and its sides fuse to the crests
or sides of the dental ridges, but they are structurally
independent of them. In some specimens, including
the holotype (King, 1931, pi. 9: figs. 28a-c),
the medium septum is small or absent, or it may
be buried in callus near the apex, but even in these
the spondylium arises from the floor of the valve
and is not formed by the joining of two dental
plates. This structure is formed in a manner just
the reverse of that in Orthotetes or Ombonia.
Muscle marks were not seen on the outside
surface of the spondylium, as stated by King (1931:
51), but they appear as striae on its inner surface. In
some specimens the outer surface of the spondylium
is gently marked, but these marks are results of
slightly irregular growth of the structure, or reflect
the muscle marks on the inside.
In the juvenile pedicle valve the septum bearing
the spondylium is slender and delicate, but, with
increasing age, it is greatly thickened, although not
much extended along the valve floor in an anterior
direction. The thickening is considerable in some
specimens, is irregular, and appears to have been
laid down in successive layers. In specimens in
which the juvenile was attached on a fairly broad
surface the spondylium is completely sessile and
the septum takes the form of a thick buttress under
the spondylium, where it lifts away from the floor.
In some specimens from the Glass Mountains, which
have a long interarea and in which the pedicle
valve is fairly deep, the spondylium is extremely
long and the septum is likewise longer than usual.
The walls of the spondylium and the material
enlarging the septum are clearly of secondary nature
because they contain pseudopunctae; furthermore,
some specimens show the walls of the spondylium
attached outside the dental ridge, but, in others,
it is exactly continuous with the anterior edge of
the dental ridge. A specimen from USNM 701p
shows this to perfection. The outer thick wall of the
spondylium is of secondary pseudopunctate material
of the fibrous layer, which is laid on the outside
of a thin band of lamellar shell extending from
the tooth and lining the inside of the spondylium.
This is probably the original wall of the spondylium.
Inside this layer a lamellar inner layer
lines the entire inner tubular cavity, the layers
being continuous across the teeth and joining the
spondylial wall with the pseudodeltidium.
The cardinalia of the brachial valve suggest
Derbyia but have some important differences. The
margin of the chilidium is entire and thus the
pseudodeltidial edge is neither sulcate nor does
it bear a raised ridge. In old shells the outer rim
of the chilidium remains entire, but plates are extended
forward over the myophore for some distance,
which must be inserted under the edge of
the pseudodeltidium. These plates are separated
medially by a narrow gap, but they do not seem to
affect the form of the pseudodeltidium.
The myophore is primitive, short, like that of
Derbyoides, and the cleft between the lobes is shallow,
not forked. Each lobe bears a wide slit, and
the underside of the cardinal process medially bears
a short ridge or longitudinal thickening. The dentifer
is small and inconspicuous, but the erismata
are broad and widely extended. The ensemble is
like that of a compressed Derbyia cardinalia in
which the various parts of the cardinal process were
unable to develop ventrad toward the valve interior.
Orthotetella wolfcampensis R. E. King
PLATE 93: FIGURES 4-19; PLATES 94: FIGURES 1-18;
PLATE 95: FIGURES 23-27
Orthotetella wolfcampensis R. E. King, 1931: 51, pi. 9: figs.
27-28.-Stehli, 1954:303, pi. 17: figs. 24-26, pi. 18: figs. 1-2.
Large, biconvex to rarely convexi-concave, shallow
to deeply conical, relatively symmetrical to
strongly distorted, with irregular concentric undulations
and bumps; outline transverse, semiovate to
nearly semicircular; hinge slightly narrower to
slightly wider than midwidth, slightly auriculate
in some specimens; commissure irregular but without
consistent folding. Costellae low, sharp, added
by insertion, often slightly crenulate when well
preserved, numbering about 10 in 5 mm on each
valve, slightly stronger on brachial valve; intertroughs
broad, flat, transversely filose; growth lines
unevenly spaced, becoming stronger and more frequent
near margins.
Pedicle valve flatly to deeply conical, rarely conNUMBER
15 287
cave; interarea short to moderately long, wide,
fairly symmetrical to slightly twisted, normally
flat, rarely slightly concave or convex, meeting plane
of commissure near right angle, normally apsacline
to procline; perideltidium occupying less than half
width of interarea; pseudodeltidium broadly arched,
dorsally expanding.
Brachial valve flatly to moderately and evenly
convex.
Pedicle valve interior with strong teeth projecting
from underside of interarea, forming strong
dental ridges meeting at apex; median septum short
or absent, often buried in callus at apex, bifurcating
near apex to form Y-shaped spondylial plates that
fuse to crests or sides of dental ridges, continuing
dorsally beyond its junction with the valve floor,
to produce a U-shaped spondylium with plates continuously
fused to dental ridges, thus forming an
elongate dorsally expanding cone with the broad
arch of the pseudodeltidium. Muscle marks faint to
deeply impressed longitudinal striae on floor and
sides of spondylium. Valve floor faintly costellate
anteriorly, costellae stronger near margins.
Brachial valve interior with short, blunt, straight,
bilobed cardinal process; each lobe longitudinally
slit for full length, insides of slits finely serrate,
lobes joining to produce median groove of process,
a continuation of notch at free ends; dentifer fused
to sides of process, forming groovelike, laterally
open hinge sockets and projecting bluntly and
slightly into body chamber; erismata continuous
with dentifers, widely diverging into umbonal arch,
defining posterolateral boundaries of muscle area.
Chilidium small, entire. Muscle area, broadly bilobate,
bisected by low myophragm; muscle marks
faint longitudinal striae. Valve floor faintly costellate,
costellae stronger near margins.
MEASUREMENTS (in mm).—
USNM 70lk
151218
USNM 701p
151219
USNM 701h
151217a
151217b
151217c
pedicle
valve
length
5.0
13.0
49.9
47.6
53.0?
brachial
valve
length
?
?
?
47.6
?
maximum
width
7.1
24.0?
64.0?
56.7
70.0?
hinge
width
6.7
19.0?
62.0?
55.2
64.0?
interarea
length
5.7
7.0?
20.0
28.3
?
thickness
?
?
?
44.5
?
STRATIGRAPHIC OCCURRENCE.—Bone Spring Formation,
Gaptank Formation (Uddenites-bearing
Shale Member), Neal Ranch Formation (beds 2,
12-14 of P. B. King).
LOCALITIES.—Bone Spring: AMNH 628, USNM
728e, 728f; Uddenites: USNM 701p, 701x, 703p;
Neal Ranch (bed 2): USNM 701; (beds 12-14):
USNM 701a, 701c, 701h, 701j, 701k, 727d, 727e.
DIAGNOSIS.—Large costellate, subconical shells
with long tubular spondylium in the pedicle valve.
TYPES.—Holotype: YPM 11366; figured hypotypes:
USNM 151040a, b, 151214a, d, e, 151217,
151218a, b, d, 151223d, n, 153479; unfigured hypotypes:
USNM 151214b, c, 151218c, 151223a-m.
COMPARISON.—More than one species may be
present in the specimens studied, but the number
of individuals is too few to be sure. No other species
of the genus is now known.
Orthotetella wolfcampensis is characterized by
its shallow to moderately deeply conical valve with
interarea that meets the plane of commissure near
a right angle, its broadly arched pseudodeltidium,
sharp costellae, and broad, transversely filose intertroughs.
Internally the species is distinguishable by
its long conical spondylium, which extends the
entire length of the underside of the interarea and
is free of the floor except near the apex. The
peculiar spondylium, however, is a generic character,
and, until other species of Orthotetella are
known, it is impossible to determine what features
of the spondylium may be of specific value.
Externally O. wolfcampensis resembles the larger
and deeper species Derbyia profunda, new species,
and D. nasuta Girty. Its characteristic costellation
and especially broadly arched pseudodeltidium
distinguish it from these species. It resembles
288
superficially some individuals of Nothopindax
egregius, new species, but it can be distinguished by
its costellation and broad pseudodeltidial arch as
well as by its characteristic internal features.
DISCUSSION.—Several excellent specimens in the
USNM collection show that the spondylium of
Orthotetella wolfcampensis is not constructed like
that of most other genera. The spondylium in species
of Geyerella, for instance, is formed by two
dental plates that join above the floor of the valve
and thus form a spondylium and median septum.
In O. wolfcampensis the spondylium is produced by
splitting of the upper edge of a small median septum
that arises from the floor of the valve. The
two branches meet and fuse with the dental ridges,
simulating dental plates and forming the conical
tubular spondylium.
Variation in O. wolfcampensis involves the spacing
of the costellae, the angle of projection and
relative width of the interarea, the convexity of
both valves, and the fortuitous irregularities in the
shell walls. In addition, the median septum that
gives rise to the spondylium varies in height and
length: in some specimens, including the holotype
(King, 1931, pi. 9: fig 28c), the septum is so short
and stubby as not to have the appearance of a
septum. Other specimens show the manner of construction
of the septum and spondylium. Re-examination
of those with short septa shows the apical
narrowing of the base of the spondylium that indicates
its origin from a rudimentary septum.
Unsilicified shells of this species show strong
pseudopunctation in the intertroughs between
costellae and also in the septum and walls of the
spondylium. Pseudopunctae are not visible on silicified
shells.
This genus is very rare wherever it occurs. In the
Glass Mountains it occurs from the Uddenites-bearing
Shale Member into the upper part of the Neal
Ranch Formation. It is no more diagnostic of the
Permian than of the Pennsylvanian, but it tends to
bear out the contention that the Wolfcamp fauna
had its beginnings prior to the Gaptank. The
species is also rare in the Bone Spring Formation,
where it occurs in the basal part. Here, it occurs
in a fauna somewhat younger than the Neal Ranch
but, nevertheless, very closely related to it. King
(1931:52) reports it from the Gym Formation
(=Hueco) from the Hueco Mountains.
SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
The present collection is too small to distinguish
species of such variable form in the relatively long
stratigraphic range exhibited by the known material.
Only one complete specimen occurs in the
collection, and this one had to be filled with plaster
to hold it together. The specimens from the Uddenites-
bearing Shale Member are not silicified, but
the one brachial valve is large, measuring 50 by 60
mm. Specimens from the Gray Limestone or bed
2 of P. B. King are extremely delicate and very
variable. These have a spondylium longer and more
delicate than those from the Sierra Diablo. The
septum is also longer and narrower, but this may
be as much due to the size as to difference in kind.
Specimens from the beds 9-12 of Cooper (=beds
12-14 of P. B. King) must have reached enormous
size. A specimen, only pieces of which now remain,
appeared on the bottom of a block, was badly
crushed and could not be held together. This
measured about 100 mm long by about 150 mm
wide before it collapsed. The shells of all the Glass
Mountains specimens are extremely delicate and
are preserved only with great difficulty.
Family DERBYIIDAE Stehli, 1954
Varied and progressive Derbyiacea having wide
and long supports (erismata) to the cardinal process
and pedicle valve with septa or elaborate development
of septa, plates, or spondylium.
The character binding the members of this family
together is the elaborate development of the
cardinal process with its widely divergent lateral
supports. These are striking when compared to
the cuplike socket region of the Orthotetacea. Subfamily
characters appear in the nature of the pedicle
valve whether dental plates meet or whether a
medium septum is present without dental plates.
Subfamily DERBYIINAE Stehli, 1954
Usually large Derbyiidae, pedicle valve with median
septum and elaboration of the septum and
dental plates.
This subfamily is based upon Derbyia, which
appears first in the early Pennsylvanian and extends
to the end of the Permian. The internal cone of
Orthotetella could have been derived from a modification
of Derbyia. Oddly, Nothopindax and OrNUMBER
15 289
thotetella appear at about the same time, but
Derbyia outlived them to a significant degree.
Genera in the Permian of West Texas: Derbyia
and Nothopindax.
Several genera based on minor abberrations of
Derbyia are herein synonymized. Plicatoderbya is
submerged because the plications on which it is
based are developed individually in several stocks
of Derbyia (see below). Derbyaeconcha Licharew
and Grabauellina Licharew are poorly defined
shape variants of a normally extremely variable
genus.
Genus Derbyia Waagen, 1884
Derbyia Waagen, 1884:576, 591.-Hall and Clarke, 1892:261.-
Schellwien, 1900:10.-Girty, 1909:181.-Dunbar and Condra,
1932:75.-Sokolskaya, 1960:219.
Derbyina Grabau, 1931a:259, 262 [ = Grabauelli7ia Licharew,
1934].
Plicatoderbya H. D. Thomas, 1937:13-18.
Derbyaeconcha Licharew, 1934a:507.
Grabauellina Licharew, I934a:507.
Shell planoconvex, convexi-concave or bioconvex,
nearly flat to deeply conical, commonly irregular
and distorted, normally unplicated, but usually ornamented
by weak or strong costellae and growth
lines. Pedicle interior with forward projecting teeth,
apically convergent dental ridges, and high median
septum normally joined to inside of pseudodeltidium
at apex and for variable distance anteriorly,
less commonly septum cemented to outgrowths from
dental ridges anterior to its attachment to pseudodeltidium,
thus forming small shallow camera;
muscle area wide and short to proportionately very
long, excavated to elevated, commonly with elevated
margins, bisected by medium septum. Brachial valve
interior with long or short cardinal process, bifid
at free end, supported by erismata that diverge anteriorly
into umbonal cavity, outlining posterior
edges of muscle area, dentifer a ridge on erismata.
Chilidium small or absent, muscle area wide, short
to long, slightly excavated.
TYPE-SPECIES.—Derbyia regularis Waagen (1884:
594, pi. 53: figs. 1-2, 4). Genolectotype by Hall and
Clark (1892).
COMPARISON.—Derbyia is distinguished from
other genera of the Derbyiinae by its prominent
single median septum that normally joins directly
to the inside of the arch of the pseudodeltidium
near the apex, without dental plates and without
spondylium. In several species the septum may be
joined to the dental ridges by outgrowths from one
or both dental ridges, sometimes producing a shallow
secondary spondylium.
DISCUSSION.—Features of Derbyia deserving special
mention and description appear in both valves.
The occasional development of a spondylium-like
chamber in the pedicle valve needs explanation because
of its confusion with the small apical chamber
that is an important character of Orthotetes.
The palintrope of Derbyia usually has a broad
and flat interarea, and, in some species, it is conspicuously
developed. It is variable, as in other attached
forms, and is often twisted, concave, or
convex, depending on the surface of attachment.
The pseudodeltidium is usually conspicuous. In
some species and many young it is fairly strongly
swollen and is strutted against the dental ridges.
It is flattened in some large individuals, like that
of Meekella or Tropidelasma, and, in those specimens,
a well-developed monticulus is present. A
well-marked groove appears in many specimens
along the center of the pseudodeltidium that corresponds
to a gap in the chilidium. Specimens having
a fairly broad monticulus also have the median
groove well developed. Pennsylvanian and lower
Permian derbyias normally have the pseudodeltidium
fairly swollen and occupying the entire
delthyrium. The larger Permian species and later
ones have the young stages with swollen pseudodeltidium,
but the adult stages have the monticulus
well developed and sides of the pseudodeltidium
flat.
The relation of the median septum of the pedicle
valve to the pseudodeltidium is of interest. The septum
of young specimens is a thin blade that rises
anteriorly to a sharp crest and usually has a steep
anterior descent. The septum is anchored to the
inner, apical part of the pseudodeltidium. In many
specimens this attachment region is obscured by
deposition of adventitious shell. The inner sides
of the pseudodeltidium are margined by the dental
ridges, which are the growth track of the teeth along
the delthyrial edge. These do not unite with the
median septum, but in many specimens shell substance
is laid down from the proximal part of the
dental ridge to the posterior of the septum to form
a more or less complete chamber. This chamber is
290 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
present only in mature or old shells and has not
been observed in young specimens. This chamber
has been confused with that of Orthotetes, which
is present only in young shells and may be completely
covered or filled in adult stages. We see no
confusion between Orthotetes and Derbyia when
this is borne in mind. The camera of Orthotetes is
primary, whereas that of Derbyia is a secondary
character of adulthood or old age. The structure
produced in Permorthotetes seems to be a secondary
character.
The cardinal process of the brachial valve also is
variable, changing with the depth of the pedicle
valve. Usually the longer the beak of the pedicle
valve, the longer the prongs of the cardinal process,
with consequent changes in its other parts. The
chilidium is developed best in the young and in the
Pennsylvanian and Early Permian species. Later
species and the gigantic forms have the chilidium
aborted or absent. The chilidium in the young and
smaller or early species consists of a short convex
plate, usually divided by a deep median groove;
essentially 2 convex plates located just ventrad of
the posterior margin and on each side of the
median line. They lie at the base of the dorsal
surface of the shaft and taper laterally to disappearance.
The chilidium affects the form of the
pseudodeltidium. Specimens in which the median
groove of the chilidium is deep and the sides well
separated have the pseudodeltidium depressed to
fit into the groove. This makes a low ridge on the
under side of the pseudodeltidium and a longitudinal
groove on the outside. This is the reason for
the longitudinal groove seen on the pseudodeltidium
of many species and specimens of Derbyia. In
species of large size in which the chilidium persists
it is usually flattened and worn, in some cases
nearly smooth and almost to a point of disappearance.
Some of the larger species such as D. informis,
new species, and D. magna Branson lack the chilidium
completely; consequently, the pseudodeltidium
is flat and has a monticulus formed from an axial
ridge developed on the cardinal process shaft.
As in other Orthotetidina the parts of the cardinal
process of Derbyia are not easy to distinguish.
The two divergent prongs of the cardinal process
are joined by shell tissue, as in Meekella, into a
more or less elongated shaft. The prongs vary in
length and divergence, long in long-beaked shells
and short in others. The prongs usually are bisected
by the high part of the median septum of
the pedicle valve. The myophore is identified as a
slit in each prong, open posteriorly and distally,
where it usually is crenulated and is the former
site of diductor attachment.
The shaft slopes laterally to form the erismata,
and the dentifer is an oblique ridge on it. No
fulcral plates were seen in any specimens of
Derbyia, the teeth being inserted under the edge
of the palintrope and on the dentifer. The dentifer
is slightly elongated in some specimens to protrude
beyond the supporting erismata. The latter are
consistently widely flaring and may be very long.
Compared to Meekella, the general plan of
Derbyia is similar, both having strong, flaring erismata
and a myophore that is two-pronged. The
cardinal process of Meekella normally is longer
and somewhat compressed laterally; that of Derbyia
is squatter and more spreading. Derbyia develops
neither fulcral plates nor the promontorium that
is so conspicuous in Meekella.
The companion genera Orthotetes and Derbyia
have been subjects for controversy and confusion
since they were established. The characteristics of
Orthotetes were known poorly from the first, and,
after Derbyia was established, it seemed to be a
synonym of Orthotetes as then recognized. Girty
(1909:181, 186) reviewed the problem and restricted
the two names to separate groups of species,
which he and Waagen both recognized as distinct
from one another. Waagen (1884:592) established
two "sections" of the genus Derbyia, calling those
species with the median septum attached directly
to the inside of the pseudodeltidium the "septati,"
and those with the septum attached to the dental
ridges by short lateral plates (forming a little chamber)
the "camerati." Girty (1909) noted that the
holotype of Fischer's Orthotetes radiatus, the typespecies,
belongs to the "camerati," and that Derbyia
regularis Waagen, which Hall and Clarke (1892)
had designated as the type-species of Derbyia, belongs
to the "septati"; therefore, Girty (1909:197)
proposed to restrict the two available names to the
two distinct "sections."
Specimens in the USNM collection present evidence
that, in some species, the possession of a
chamber, or of a septum that attaches directly to
the center of the pseudodeltidium, may be a matter
NUMBER 15 291
of individual variation. On other grounds, Sokolskaya
(1952:52; 1954:148) considered Derbyia to be
synonymous with Orthotetes. She believes that the
type-species, Derbyia regularis Waagen, actually
belongs to the "camerati," and therefore is a species
of Orthotetes. According to Thomas (1958:77), she
did not base this contention on the holotype of
D. regularis but drew her conclusions from specimens
from the Moscow area that she had identified
as the species. G. A. Thomas emphasized the necessity
for re-examination of the holotype of D. regularis
Waagen, not only to see if a camera is present,
but also to determine whether the "socket
plates" are recurved, as he thinks they are in Orthotetes,
or extend into the umbonal arch, as in the
many species that have been called Derbyia. This
difference in the cardinalia of the two genera has
been claimed by Campbell (1957:43) and Thomas
(1958:77) to be a more reliable criterion for their
distinction than the presence or absence of a camera
or spondylium.
Grant had the opportunity to collect numerous
specimens of D. regularis, both calcareous and silicified,
from the type area in the Salt Range. All of
those have the independent septum, and no primary
camera, in contrast to specimens from the
Lenox Hills Formation, where some ventral valves
have one or two secondary plates connecting the
socket ridges (dentifers) to the septum. Derbyia certainly
is not near to Orthotetes morphologically.
Fischer's illustrations (1830, pi. 20: figs. 4a-b;
1837, pi. 20: figs. 4a-c; 1850, pi. 10) of the typespecies,
Orthotetes radiatus, have been reproduced
by Girty (1908, pi. 4: figs. 1-2) and Sokolskaya
(1954, text fig. 57). These show a pedicle valve that
belongs to the section "camerati." Fischer did not
illustrate the interior of a brachial valve. Sokolskaya
has collected specimens from the Moscow
Basin that she identified as Orthotetes radiatus
Fisher (Sokolskaya, 1954: 145, pi. 14: figs. 3-5, pi.
16: fig 7). In addition she offers a schematic drawing
(text fig. 55) of the interior of the brachial
valve of an Orthotetes, showing the cardinal process
and the dorsal plates. This illustration is reproduced
by Thomas (1958, fig. 3B). If these drawings
represent a typical brachial valve from the type area
of the genus in the Moscow Basin, they support the
contention of Campbell (1957) and Thomas (1958)
that the cardinalia of Orthotetes are significantly
different from those of Derbyia. The plates of
Orthotetes recurve and do not extend into the
umbonal cavity.
Specimens of Orthotetes radiatus Fischer in the
USNM collection have the characteristic primary
spondylium in the pedicle valve and cardinalia as
illustrated by Sokolskaya. The structures of these
are exactly like those of specimens in the United
States from Middle and Late Mississippian rocks.
From these and the above data we conclude that
Orthotetes is a recognizable Mississippian genus
and that it does not occur in Permian rocks in its
typical form. It is also clear that Orthotetes and
Ombonia are not synonyms as hinted by Williams
(pers. comm. in Thomas, 1958:13). Inspection of
our plates illustrating the latter genus and the text
describing it make it clear that neither the spondylium
nor the cardinalia are anything like those
of Orthotetes.
The Treatise (Williams, et al., 1965) now recognizes
Ombonia as a valid genus, but it gives no credence
to the Omboniinae of Sokolskaya, which is
justified because of the peculiar spondylium and
cardinalia.
The name Plicatoderbya was introduced by H.
D. Thomas (1937:13-18) for a subgenus of Derbyia.
He based the difference from Derbyia (Derbyia)
on the presence of low plications of the shells
of specimens from the Permian Phosphoria Formation
of Wyoming (type-species: Derbyia (Plicatoderbya)
magna (Branson)). Specimens in our
collections from the Glass Mountains, however,
show that such plication appears sporadically in
individuals of many species, D. cincinnata, D. pannucia,
and D. texta, for example. In some specimens
plication is radial, but in others it is oblique
or irregular. None of the Glass Mountains species
is free of plicated individuals, and in D. pannucia
plicated specimens are nearly as common as nonplicated
ones. This feature alone in Derbyia is not
a reliable specific distinction and therefore certainly
is not a valid feature upon which to base a subgenus.
Furthermore, no stratigraphic significance
can be attached to the secondary plication in Permian
species because it appears early in the Wolfcamp
and extends into the late Guadalupe.
Within the Glass Mountains species of Derbyia
there are two groups. One group includes D. crenulata
Girty, D. laqueata, and D. ftlosa, new species.
292 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
These are characterized by a relatively small average
size and strong costellae that may be strongly or
weakly crenulated. They are suggestive of Derbyaeconcha
Licharew. Apparently crenulation of the
costellae decreases in strength upward in the stratigraphic
section.
The other group is characterized by a relatively
large average size, a deep subconical pedicle valve
with high interarea, and weak, fine costellae that
may or may not be closely crowded and are not
strongly crenulated, although individuals may be
weakly crenulate.
With respect to the "camera" or false camera
that is produced in some species by cementation of
the median septum to the dental ridges by callus
material that mimics dental plates, there seems to
be no natural or consistent grouping of the species.
Within the more strongly costellate group, however,
the presence or absence of the camera is more consistent
in the stratigraphically higher and lower
species than in the intermediate ones; that is, most
individuals of D. crenulata (Wolfcampian) and D.
ftlosa (Guadalupian) have strong tendencies for
development of the callus that produces the camera:
it is entirely absent in only a few. In D. laqueata
(Leonardian) most specimens do not have pseudodental
plates or a camera, but some do. In D.
texta (Leonardian) most specimens have no camera,
but a few do.
In the deeply conical group there is no such
biostratigraphic trend with respect to this feature.
Derbyia bella, new species
PLATE 64: FIGURES 1-45; PLATE 65:
FIGURES 16-34
Small to medium size for genus, outline rectangular,
hinge wide terminating in small ears;
maximum width variable, ranging from hinge to
short distance anterior to midvalve; sides moderately
rounded in anterior half, concave to oblique
in posterior half; anterior margin usually broadly
rounded. Anterior commissure normally rectimarginate,
usually with an eccentric dorsad wave on
one side, in some specimens leading to unequal
bilobation. Surface costellate, costellae narrowly
rounded, closely crowded, with narrower interspaces,
numbering 8 to 10 in 5 mm at 10 mm anterior
to the beak, and 6 or 7 in 5 mm at front
margin of adult 30 mm long. Costellae crenulated,
about 4 crenulations per millimeter at margin of
average specimen. Costellae of pedicle valve less
crowded, with wider interspaces than brachial
valve.
Pedicle valve normally deeper than brachial
valve, concave in lateral profile but varying to flat
or slightly convex; interarea moderately long, usually
apsacline. Pseudodeltidium convex and medially
grooved. Umbonal slopes steep; median region
usually gently convex but forming central convex
region that descends to flanks.
Brachial valve ranging from flat (in young) to
unevenly but moderately convex in lateral profile;
anterior profile broadly convex with long sloping
sides. Interarea vestigial; chilidium reduced; umbonal
region flat; region just anterior to umbo
swollen and rounded forming poorly defined
mound; anterior half medially flattened or gently
sulcate and tending to bilobation. Lateral slopes
of cardinal extremities gentle.
Pedicle valve interior with small elongated teeth;
median septum (uniseptum) reaching to about midvalve,
elevated and thin and attached to the posterior
half of the pseudodeltidium. Muscle scars
not impressed.
Brachial valve interior with short, forked myophore,
small dentifer, and broad shallow sockets.
STRATICRAPHIC OCCURRENCE.—Neal Ranch Formation
(beds 2 and 4 of P. B. King).
LOCALITIES.—Bed 2: USNM 701; bed 4: 701-1,
727e.
DIAGNOSIS.—Small to medium size, strongly
costellate and crenulate, usually with a wide hinge.
NUMBER 15 293
MEASUREMENTS
USNM 701-1
151025a
151025b
151025c (holotype)
151025d
151025e
151025f
151025g
151025h
1510251
151025J
(in mm).—
pedicle
valve
length
28.9
26.0
22.7
19.6
20.8
17.2
18.4
13.3
9.6
8.2
brachial
valve
length
28.7
25.0
19.0
17.9
18.7
17.0
14.6
12.1
8.1
6.5
maximum
width
37.6*
31.4
26.8
25.1
24.0
23.3
19.0
14.7
10.8
8.3
hinge
width
32.7
30.3
25.5
22.4
21.7
24.0
18.0
15.1
8.7
7.4
interarea
length
13.2
9.2
7.4
10.0
6.3
7.7
6.4
6.9
3.9
3.5
thickness
20.8
18.7
15.2
15.2
12.6
13.2
11.8
8.5
5.7
5.2
TYPES.—Holotype: USNM 151025c; figured paratypes:
151025b, c, e, h, 153189a-f, 153279a-d,
153280a-e, 153285a, b; unfigured and measured
paratypes: 151025a, a, d, f, g, i, j ; unfigured paratypes:
153279a.
COMPARISON.—This species attains approximately
the same size as D. carteri, new species, but it is
somewhat more square and the young are definitely
less transverse than the young of D. carteri. Costellae
are stronger and are more strongly crenulated
than those of D, carteri.
Derbyia bella has about the same strength of
costellae and crenulations as D. crenulata Girty,
but it does not attain the large size of that species,
it is not so strongly transverse, and it usually has
a longer interarea than the Sierra Diablo species.
Derbyia crenulata often is thickened at the anterior
by growth at right angles to the shell margin. Derbyia
bella also has this feature, but the anterior
margin is not so ragged as that of D. crenulata, a
feature well marked in the holotype of D. crenulata.
DISCUSSION.—Derbyia bella, like D. carteri, forms
clusters of shells and many of the specimens etched
from the rock are attached to their brothers and
to any other handy species.
Derbyia carteri, new species
PLATE 30: FIGURES 2-6; PLATE 65: FIGURES 1-15;
PLATE 66: FIGURES 1-47
Derbyia buchi R. E. King (not D'Orbigny), 1931:59, pi. 8:
figs. 4-6.
Medium to large for genus, wider than long and
transversely rectangular in outline; hinge wide,
equal to, or slightly exceeding, width anterior to
hinge; cardinal extremities variable, usually near
right angle but occasionally auriculate. Sides
slightly oblique to gently rounded. Anterior commissure
usually deformed, variable often with
reversed wave in the form of broad S. Surface
multicostellate, costellae increasing by intercalation
in at least 3 generations, 12-14 costellae in 5 mm
at 10 mm anterior to beak and about 8 in 5 mm
at anterior margin of large adults. Surface often
concentrically wrinkled and with strong growth lamellae.
Pedicle valve gently convex to nearly flat and
often anteriorly geniculated in lateral profile; anterior
profile broadly and moderately convex; interarea
short; pseudodeltidium broad, strongly convex
but median groove not prominent. Median
region somewhat swollen longitudinally, with flanks
sloping gently to the margins.
Brachial valve fairly evenly and moderately convex
in lateral profile; broadly domed, with flattened
top and short steep sides in anterior view. Interarea
and chilidium vestigial; umbonal region flattened;
median region with poorly defined sulcus
extending from the swollen anteroumbonal region
to margin.
Pedicle valve interior with uniseptum not usually
reaching mid-valve; septum thin and delicate even
in thick-shelled specimens; septal crest variable,
usually near the middle, septum and dental ridges
294 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
forming small chamber in some specimens. Muscle
area moderate in size, rim thickened and completely
bisected by uniseptum.
Brachial valve interior with modified bilobed
MEASUREMENTS (in mm).-—
chilidium, and moderately long, narrowly forked
myophore, dentifers short and blunt; supporting
plates elongated and wrapping around the outside
of muscle field.
USNM 701k
151020a (holotype)
151020b
151020c
151020d
151020e
151020f
151020g
151020h
151020i
151020j
151020k
151020-1
pedicle
valve
length
35.0
36.9
27.8
37.8
27.5
28.5
25.0
24.7
21.2
17.0
12.2
7.7
brachial
valve
length
33.6
31.8
27.8
29.8
26.0
25.1
23.7
20.4
18.8
16.2
12.0
6.8
maximum
width
49.0
46.6
38.9
43.5
33.8
33.0
32.8
28.4
27.8
22.4
18.0
10.2
hinge
width
48.5
48.2
42.6
44.0
33.9
31.6
30.6
29.6
24.0
21.7
15.6
10.0
interarea
length
7.8
10.8
10.4
11.7
7.7
7.1
8.6
7.0
9.0
5.6
2.9
3.0
thickness
25.8
20.5
22.3
19.7
19.5
14.6
13.4
11.6
15.2
8.5
5.8
4.6
STRATIGRAPHIC OCCURRENCE.—Gaptank Formation
(Uddenites-bearing Shale Member), Neal
Ranch Formation (beds 2-12 of P. B. King).
LOCALITIES.—Uddenites: USNM 701f, 701q; Neal
Ranch (bed 2): 701; (bed 4): 701d, 721g, 727e;
(bed 12): 701a, 701a1, 701c, 701h, 701k, 742c
DIAGNOSIS.—Large crenulate Derbyia with fairly
strong costellae, wide hinge, and fairly short interarea.
TYPES.—Holotype: USNM 151020a; figured paratypes:
151020b, c, f, j , 153281a-g, 152282a-c,
153283; unfigured measured paratypes: 151020b, d,
e, g-i-
COMPARISON.—This species is best compared with
D. crenulata Girty, which is often wide hinged and
auriculate, but D. carteri is more finely and more
evenly costellate than the Sierra Diablo species
and also is usually not ragged along the anterior
margin. Derbyia carteri does not attain the large
size reached in some specimens of D. crenulata.
Derbyia bella, new species, is not to be confused
with D. carteri because the latter usually is larger,
with finer and more even costellae. The young of
D. bella are more nearly square than those of D.
carteri, which generally are more transverse in the
adult form as well.
DISCUSSION.—The apex of the pedicle valve of
D. carteri is the site of deposition of considerable
callus. This usually obscures the place of contact
of the median septum with the pseudodeltidium.
If the deposition is not complete, a small gap may
be left between the septum and the roof of the
pseudodeltidium, which will simulate the chamber
characteristic of Orthotetes.
This species forms large clusters and predominates
in the bioherms in which it occurs. Many
specimens are cemented into clusters and many
are surrounded by possible algal material to make
patch reef assemblages. Occurring with them and
cemented on them are individuals and clusters of
Teguliferina. Derbyia carteri is abundant in its
particular bioherm, but it is not widely distributed.
The species is named for John L. Carter, Carnegie
Museum, Pittsburgh, who helped us collect in
1963.
Derbyia cincinnata, new species
PLATE 79: FIGURES 1-21; PLATE 80: FIGURES 1-17
Small to large, flatly convex, thin walled, normally
symmetrical; outline transversely subelliptical
to semicircular; hinge slightly narrower than widest
part of shell, auriculate in some specimens; commissure
wavy but without consistent folds; both
valves discontinuously plicate, with plications undulating
in their courses, producing alternately
bumps and hollows in braided pattern. Costellae
moderately strong, somewhat alternating in
NUMBER 15 295
strength, weakly crenulate, relatively little displaced
by irregularities in shell; number on either
valve near 17 in 5 mm; growth lines weak, irregularly
spaced over surface of valve, not necessarily
more frequent near margins.
Pedicle valve nearly flat, anterior profile flat to
slightly concave or convex; interarea low, flat, or
nearly so, meeting plane of commissure at right or
small obtuse angle; arch of pseudodeltidium wide,
with shallow median groove; perideltidium reaching
beyond half distance from midline to edge of
interarea at hinge.
Brachial valve flatly convex, more convex than
pedicle valve, braided irregularity of shell in more
distinctly radial pattern, approaching genuine radial
plication.
Pedicle valve interior with long hinge teeth;
extending posteriorly as dental ridges along edges
of pseudodeltidium, converging at apex of valve;
median septum low because valve is flat, upper
edge forming large obtuse angle, apical and buried
in callus that also buries junction of dental ridges.
Muscle area as long as median septum, normally
rather long because valve is flat, occupying more
than half length of valve, weakly impressed, with
faint muscle marks consisting of longitudinal striae.
Valve floor bumpy, faintly costellate, costellae becoming
strong near margins.
Brachial valve interior with short, weak, curved
cardinal process, shallowly bifid at free end, each
prong longitudinally slit, with serrations in the
slits; dentifer fused to sides of process, forming very
shallow, open hinge sockets; projecting slightly into
body chamber; erismata continuous with dentifers
diverging widely and deeply into umbonal arch
defining posterolateral boundaries of muscle area
Chilidium present, well developed, bisected by con
tinuation of median groove of cardinal process
Muscle area anteriorly expanding, faintly im
pressed, bisected by low median ridge, muscle marks
consisting of faint longitudinal striae occupying
about one-third length of valve. Floor of valve
bumpy and plicate, faintly costellate, costellae
strong near margins.
MEASUREMENTS
USNM 702c
151136a
151136b
151136c
151136d
151136e (holotype)
151136f
151136g
USNM 703d
151135a
151135b
USNM 710u
151139a
(in mm).—
pedicle
valve
length
5.3
16.9
19.5
26.8
32.6
38.6
29.0
41.7
53.0
42.6
brachial
valve
length
5.6
17.8
20.3
27.2
35.0
p
28.0
?
?
38.4
maximum
width
7.7
22.4
25.8
31.2
39.9
54.0
33.9
56.5
75.8
52.3
hinge
ividth
6.8
12.0?
19.0
22.0
33.4
33.6
27.0?
40.0?
62.8
45.2
interarea
length
1.9
11.0?
7.8
6.2
12.0
11.0
14.5
c.14
7.5
16.9
thickness
3.2
16.0?
17.6
17.2
c.25
?
24.2
?
?
28.8
STRATIGRAPHIC OCCURRENCE.—Cathedral Mountain
and Road Canyon formations.
LOCALITIES.—Cathedral Mountain: USNM 702,
72lu, 726o, 726u, 726x, 735g; Road Canyon:
AMNH 503, USNM 702c, 703, 703c, 703d, 707e,
709c, 710u, 716xa, 719x, 720d, 721j, 721o, 721s, 721t,
721y, 721z, 722e, 722g, 724a, 724b, 724c, 724d, 726d,
726e, 726f, 726z, 726za, 732j, 736x.
DIAGNOSIS.—Derbyia of moderate size with
strongly "braided," bumpy ornament.
TYPES.—Holotype: USNM 151136e; figured paratypes:
151131a, 151134a, 151135a, 151136c, 151137a,
151139a, 151141a, 151143a, b, 151150a, b, 153284;
unfigured paratypes: 151131b, 151134b, 151135b,
151136a, b, d, f, g, 151137b, 151141, 15150b; measured
paratypes: 151135a, b, 151136a-d.
COMPARISON.—Derbyia cincinnata is characterized
by strong bumpy ornamentation that gives the
surface of the shell a braided appearance, by a low
and wide interarea, low convexity of both valves,
wide pseudodeltidial arch, relatively well-developed
chilidium, strong but rather crowded costellae, me296
SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
dian septum and dental ridges that are buried in
callus despite the near right angle at which the
interarea meets the plane of commissure, and short
and weak, but nevertheless curved, cardinal process.
Most of these features distinguish it from the
species that it most resembles: D. pannucia, new
species. The latter may have irregularities of the
shell that approach the pattern on D. cincinnata,
but a narrow pseudodeltidial arch (and consequently
no chilidium), a thicker shell wall, finer
and more closely spaced costellae, normally deeper
pedicle valve, and much stronger cardinal process.
In its plication and costellation D. cincinnata is
similar to Orthotetes magnus Branson (1930:26),
which H. G. Thomas (1937:14) designated as the
type-species of his subgenus Derbyia (Plicatoderbya).
Derbyia cincinnata differs in its transverse
rather than elongate outline, smaller average and
maximum size (Branson's smallest specimen is 7
mm longer than the largest specimen from the
Glass Mountains, and his largest specimen is more
than twice as long), stronger plication that is less
continuous and more bumpy, its flatter pedicle
valve with lower and wider interarea and wider
pseudodeltidial arch. Internally D. cincinnata differs
in its weaker and shorter cardinal process.
DISCUSSION.—Despite its other distinctive characteristics,
Derbyia cincinnata is based primarily on
its peculiar plication. At first we thought that these
wrinkled shells were aberrant individuals of several
other species, but it was impossible to determine to
which species the specimens might belong.
The species varies primarily in its auriculation,
in its convexity, and in the pattern of the wrinkling
of the shells. The extremes range from relatively
random scattered nodes to nearly straight plications.
The more regular and continuous plications
occur on brachial valves, whereas the typical pedicle
valve best exhibits the braided or discontinuously
plicate pattern. Smaller shells are more
convex, larger shells flatter. Convexity is greater
in the brachial valve.
The collection of this species is too small to give
a significant distribution pattern in a count of the
density of costellation.
Derbyia complicata, new species
PLATE 81: FIGURES 4-38; PLATE 88: FIGURES 1-6
Small, narrow hinged, subquadrate in outline
and with the length and width variable; hinge commonly
auriculate; maximum width usually anterior
to midvalve, but variable. Anterior commissure
variable, with wave toward either valve. Sides usually
oblique to concave posteriorly but rounded
anteriorly; anterior margin broadly rounded to
slightly emarginate. Surface unequally costellate,
costellae strongly crenulated, size varying, stronger
ones setting off bundles of smaller. Costellae averaging
about 13 at 10 mm anterior to beak, 10 mm
at anterior margin of brachial valve; costellae on
pedicle valve averaging about 11 at 10 mm anterior
to beak, 10 at anterior margin.
Pedicle valve usually gently concave in anterior
profile, but broadly and gently convex in anterior
profile; interarea varying from nearly procline to
apsacline, usually the latter; interarea variable but
usually moderately long; pseudodeltidium usually
prominently arched but with median depression
varying from barely visible to absent. Perideltidial
area not clearly visible. Umbonal region moderately
swollen; umbonal slopes moderately concave
to notched anterior to auricles.
Brachial valve unevenly convex, umbonal and
anterior region moderately curved, but median region
flattened to swollen in lateral profile; anterior
profile gently to moderately domed. Umbonal
slopes steep, lateral, and anterolateral slopes gentle
to moderately steep.
Pedicle valve interior with strong, long teeth, not
strongly thickened dental ridges uniting at apex;
median septum delicate, short, forming obtuse
angle in lateral view and with steep anterior slope;
muscle region not strongly impressed, marginally
thickened and reaching from one-third length to
about midvalve.
Brachial valve interior with prominent bilobed
chilidium; cardinal process short, not deeply bifurcated,
lobes slightly divergent, but each lobe
marked by deep serrated slit; dentifers not strongly
developed; erismata widely divergent but short.
NUMBER 15 297
MEASUREMENTS
USNM 714w
151198a
151198b
151198c
151198d
151198e
151198f
151198g
151198h (holotype)
151198i
151198J
151198k
151198-1
USNM 702
151192
(in mm).—
pedicle
valve
length
23.2
22.4
17.5
18.0
13.1
13.4
9.3
21.0
17.1
14.2
11.8
16.2
23.7
brachial
valve
length
18.5
20.1
14.7
15.3
12.5
11.7
7.5
18.7
17.1
13.1
9.3
16.2
18.9
maximum
width
27.9
24.9
16.4
18.3
15.4
14.7
9.7
24.4
22.4
16.1
11.4
21.7
23.7
hinge
width
17.3
16.4
11.5
12.3
10.2
10.2
7.7
18.0
19.1
13.2
10.6
18.3
17.6
interarea
length
7.0
6.0
6.9
4.9
4.1
4.6?
3.7
6.9
6.7
6.4
5.0
6.0
4.0
thickness
15.5
15.9
13.3
10.4
10.0
7.9
4.9
16.0?
13.5?
10.0
8.1
11.9
11.4
STRATIGRAPHIC OCCURRENCE.—Cathedral Mountain
Formation (Institella beds) and Road Canyon
Formation.
LOCALITIES.—Cathedral Mountain: AMNH
500H, 500N, USNM 700-1, 700x, 702, 702 (low),
702un, 703b, 708, 714w, 714wa, 717e, 721u, 723u,
723v, 726o, 726u, 727p; Road Canyon: USNM 703,
703a, 703c, 703d, 707e, 716x, 719x, 721y, 724a, 726d,
732j, 736x.
DIAGNOSIS.—Small, auriculate Derbyia with
strong and unequal crenulate costellae and radial
plications.
TYPES.—Holotype: USNM 151198h; figured paratypes:
151198c!, i, j , m-q, 151190a, 151192,
I53450a-c; measured paratypes: 151198a-g, i-1,
151192; unfigured paratypes: 151198a-c, e-h, k, 1.
COMPARISON.—This may be compared with Derbyia
texta, new species, more than with any other
species. It differs from the Word form in having
more diversified ornament, auriculate hinge, and
the stronger development of radial plications. The
brachial valve of D. texta appears to be less convex
than that of D. complicata and the pseudodeltidium
of the opposite valve is more distinctly grooved
medially than that of the Cathedral Mountain species.
DISCUSSION.—Although plication of the shell in
Derbyia is known in many species, it usually takes
the form rather of oblique wrinkling than of uniform
radial folding. Some specimens of D. complicata
are so strongly and regularly folded as to
be confused with Meekella or Kiangsiella. Such
folding would be regarded as generic in character
if it were persistent and permanent. Some specimens
of D. complicata, however, have the plication
scarcely developed or only incipient. These specimens
are difficult to separate from D. texta, but
usually the ornament is sufficiently different to
make separation possible. The plicated forms make
an interesting study in a homeomorphic development
because they so closely parallel Kiangsiella
and Meekella.
Derbyia crenulata Girty
PLATE 75: FIGURES 10-28
Derbyia! crenulata Girty. 1909:183, pi. 26: figs. 5-5d.
Derbyia crenulata Girty.—Stehli, 1954:301.
Not Derbyia? crenulata R. E. King (not Girty), 1931:58.
Moderately large to large, thick walled, biconvex,
comparatively flat to slightly conical, shape
modified by attachment, but not normally greatly
distorted; outline transversely subelliptical to subquadrate;
hinge slightly narrower to slightly wider
than midwidth, normally somewhat auriculate;
commissure usually with a tendency to sulcation,
rarely with slight irregular plication. Costellae
strong, high, weakly to strongly crenulate, increasing
by insertion, with earliest costellae near beaks
commonly remaining strongest, giving ribbed appearance;
costellae on pedicle valve normally somewhat
weaker, sharper, more widely spaced, fewer
in number, 6 to 7 in space of 5 mm; costellae on
298 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
brachial valve stronger, more rounded, often with
concave sides, closely crowded, more strongly crenulate,
6 in space of 5 mm, all costellae remaining
strong to shell margins and often protruding to
make a rough edge, especially in the young. Growth
laminae normally strong only near margins.
Pedicle valve forming shallow, irregular profile
moderately concave to nearly flat, less commonly
convex; interarea short and wide, flat, slightly concave
or convex, rarely attenuate; strongly apsacline;
pseudodeltidium broadly arched, anterior expanding,
bisected by shallow groove; perideltidium
slightly raised above lateral edges of interarea, extending
less than half way from midline to hinge
end on each side, border of perideltidium usually
not parallel to lateral border of interarea.
Brachial valve flatly and uniformly convex,
slightly greater convexity of any region dependent
upon distortion of shell; median region anteriorly
sulcate, sulcus irregular, ranging from perceptible
to deep.
Pedicle valve interior with large, stout teeth,
converging posteriorly as dental ridges along underside
of pseudodeltidium, meeting at apex of
valve, or slightly anterior to apex; medium septum
bladelike, height directly dependent upon convexity
of valve, upper edge with definite change in
slope, angle depending upon height of septum, posterior
of septum joining underside of pseudodeltidial
arch between dental ridges near apex of valve,
normally cemented to dental ridges by shell material
arising from wall of valve independently of
ridges or septum, confluence of ridges, septum, and
shell-wall material forming shallow chamber for
reception of cardinal process in some specimens,
and normally obscuring direct attachment of septum
to underside of pseudodeltidial arch. Muscle
area as long as median septum, occupying about
]/s the total valve length, excavated or raised, with
obscure borders or high bordering rim, more than
one kind may occur in one valve, on either side of
septum. Floor of valve with obscure costellae becoming
stronger near edges.
Brachial valve interior with short to moderately
long, slightly curved cardinal process, shortly bifid
at free end, retaining groove between prongs right
to hinge edge, thus bisecting chilidium, each prong
longitudinally slit along most of length of posterior
edge, slits finely serrate for reception of muscle attachments;
dentifers firmly cemented to sides of
process, projecting anteroventrally beneath process
forming open hinge sockets, projecting bluntly into
living chamber; erismata diverging into umbonal
arch, bounding posterior margins of muscle area.
Chilidium small but distinct, bisected by groove in
cardinal process, appearing as 2 small pads on each
side of process and just beneath hinge of pedicle
valve. Hinge straight, with very short palintrope
or bearing edge near center, tapering to knife edge
laterally. Muscle area large, lobate, not strongly
impressed, normally occupying about % length of
valve, longitudinally striate. Floor of valve radially
costellate, with costellae becoming stronger near
edges.
MEASUREMENTS
USGS 3764
118499 (holotype)
AMNH 625
151048
USNM 705a
151045a
151045b
(in mm).—
pedicle
valve
length
19.7
47.4
30.6
28.5
brachial
valve
length
19.4
?
26.7
?
maximum
width
26.4
66.7?
31.2
40.5
hinge
width
28.2
54.6
26.5
33.5
interarea
length
5.0
16.4
9.4
8.3
thickness
11.0
15.0?
22.3?
9.6?
STRATIGRAPHIC OCCURRENCE.—Basal Bone Spring
Formation, Skinner Ranch Formation (base, top,
Decie Ranch, Poplar Tank, Sullivan Peak members),
Hess Formation (Taylor Ranch Member),
Cibolo Formation.
LOCALITIES.—Bone Spring: AMNH 625, 628, 631,
696, 699, USGS 3764 (green), USNM 728e, 728f,
728h; Skinner Ranch (base): USNM 705a,
707w, 71 lp, 715v, 720e, 720f, 728g; Decie Ranch:
USNM 720g; 707g; Skinner Ranch (top): AMNH
520, USNM 705r, 727a; Poplar Tank: USNM
707ha; Sullivan Peak: USNM 707d, 710d, 722h,
NUMBER 15 299
722-1, 727a; Taylor Ranch: USNM 702d, 702e;
Cibolo: USNM 728-1.
DIAGNOSIS.—Small Derbyia with fairly even, crenulated
costellae.
TYPES.—Holotype: USNM 118499; figured hypotypes:
151045c, d, 151047a, b, 151048, 153287; unfigured
hypotypes: 151045a, b.
COMPARISON.—Derbyia crenulata is characterized
by short interarea with normally auriculate hinge
ends, thick strong costellae that are crowded together
but relatively few in 5 mm and are normally
strongly crenulated. Internally it is characterized
by the cementation of the posterior end of the
median septum to the dental ridges anterior to the
apex of the valve and by the relatively well-developed
chilidium on the brachial valve.
This species most closely resembles Derbyia
texta, new species, and D. laqueata, new species.
It differs from the former in its usually unplicated
brachial valve, wider hinge, shorter interarea, lower
convexity, and its strongly crenulate costellae. Internally,
the median septum of D. crenulata
normally is braced to the dental ridges of pseudodental
plates or amorphous callus, whereas the
septum of D. texta normally remains independent
of the ridges. Derbyia crenulata differs from D.
laqueata in its normally less convex and thinner
shell, wider hinge, and shorter interarea, weaker
and less frequent growth lines, stronger costellae
that are fewer per unit distance, and in its pseudodental
plates.
Another coarsely costellate species is D. filosa,
new species, which occurs high above D. crenulata,
in the Word Formation. It differs from D. crenulata
in its stronger, less densely spaced and more
coarsely crenulate costellae, smaller maximum size,
lower interarea, and shorter cardinal process.
Derbyia profunda, new species, is very different
in appearance, and the two are unlikely to be confused.
Derbyia profunda is normally larger, much
deeper, nonauriculate, weakly costellate, weakly
crenulate, and its median septum is attached for a
long distance anteriorly to the inside of the pseudodeltidial
arch of one or both dental ridges. Derbyia
nasuta Girty occurs with D. crenulata. It is deeply
conical like D. profunda and differs from D. crenulata
in many of the same features. In addition, the
average number of costellae per 5 mm is much
greater in D. nasuta than in either D. crenulata or
/ ) . profunda.
Other species of Derbyia from the Glass Mountains
are readily distinguishable from D. crenulata.
They have more and weaker costellae per unit
distance, none are as strongly crenulate, and all
are more deeply conical or thicker. Derbyia texta,
new species, normally is smaller, somewhat plicate,
and has the median septum completely free of the
dental ridges to the apex of the pedicle valve.
Derbyia profunda, new species, is much larger,
deeper, and has weaker noncrenulate costellae.
Derbyia pannucia, new species, also much larger,
is very irregular, bumpy, and distorted, has the
dental ridges separate from the median septum,
and lacks a chilidium. Derbyia cincinnata, new
species, is very flat, irregularly wrinkled, and plicated,
and has low, rounded costellae that may not
be crenulate.
A species similar to D. crenulata is D. arellanoi
Cooper (1953) from the Permian of Sonora, Mexico.
Its costellae are high and blunt, but they are
not crenulate, and apparently are just as strong
and as dense on the pedicle valve as on the brachial;
the brachial valve is more strongly convex and
has maximum convexity at the umbo; the perideltidium
extends on each side more than half the
distance from the median groove of the pseudodeltidium
to the hinge ends; the shell shows no
tendency to be auriculate or sulcate. Derbyia
arizonensis McKee (1941:226, under the name D.
regularis) is similar, but it differs from D. crenulata
in having weaker, less strongly crenulate costellae
that are much more widely separated, numbering
only 6-7 in the space of 5 mm.
Among other American Permian species, D.
crenulata differs from D. multistriata (Meek and
Hadyen), as illustrated by Dunbar and Condra,
(1932:101, pi. 10: figs 1-5), by its characteristic
ornamentation and especially by its flatter brachial
valve and less concave valve. Derbyia cymbula Hall
and Clarke (1892:348; also Dunbar and Condra,
1932;97) has a strongly concave pedicle profile, finer
ornamentation, and proportionately narrower
hinge than D. crenulata. Derbyia hooserensis Dunbar
and Condra (1932:92) has weakly crenulate
costellae, and its size and shape are similar to D.
crenulata. It differs primarily in its lower and
weaker costellae.
300 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
The Pennsylvanian species D. bennetti Hall and
Clarke (see Dunbar and Condra, 1932) and D.
deercreekensis Dunbar and Condra (1932:90) resemble
D. crenulata in their coarse costellae, which
may be crenulate. Both of these species are more
convex than D. crenulata, especially in the brachial
valve, and D. bennetti has a higher interarea, proportionately
narrower hinge, and stronger laminae
of growth. Derbyia crassa (Meek and Hayden) also
is similar to D. crenulata, differing primarily in
its noncrenulate to weakly crenulate costellae that
number only 5-10 in 5 mm and in its proportionately
narrower, nonauriculate hinge. Derbyia crassa
var. texana Dunbar and Condra is even more similar
to D. crenulata, differing only in the abovementioned
features of ornamentation and in the
slightly less developed tendency for auriculation.
No foreign species of Derbyia bears close resemblance
to D. crenulata. Those described from the
Salt Range of Pakistan by Waagen (1884) and Reed
(1944) have weaker costellae that are not crenulate.
The same is true of those described by Grabau
(1931) from Mongolia and by Licharew (1932) from
the Caucasus.
Derbyia elevata R. E. King
Derbyia elevata R. E. King, 1931:59, pi. 8: fig. 7.
This species at present is completely unintelligible
because the holotype is so poorly preserved
and the specimen so incomplete that its real characters
cannot be determined. It is preserved in solid
chert and most of the anterior has been lost and the
beak region and most of the pedicle valve have
been destroyed. Furthermore, the brachial valve is
revealed only partially, and a fraction only of the
interarea of the pedicle valve is preserved.
That the species is a Derbyia cannot be questioned
because of the large median septum in the
pedicle valve, the remnants of forked cardinal
process on each side of it, and the fine radial
costellae on the only exterior surface preserved. The
species was unusual in having a flattened brachial
valve with a flattened umbonal region. The specimen
is much flatter than the view given in R. E.
King (1931, pi. 8: fig. 7a), which has been trimmed
inaccurately.
This remnant of a specimen does not conform to
any we found in the Glass Mountains. Its identity
with Girty's Derbyia species is very doubtful. Not
only is there a size difference, but also the shape
is entirely unlike the Capitan species, being strongly
depressed in the direction of valve length. At present
we are unable to identify any specimens as D.
elevata and are unable to make a sensible reality
out of the species.
STRATIGRAPHIC OCCURRENCE.—Identified by King
as "Word Formation" but from float "lying on the
surface of the upper Vidrio."
LOCALITY.—R. E. King 265.
TYPE.—Holotype: YPM 11417.
DISCUSSION.—In view of the poor quality of the
specimen and the uncertainty of its stratigraphic
position, the species can be given no significance in
this work.
Derbyia filosa, new species
PLATE 82: FIGURES 1, 2, 11-36
Small to moderately large, biconvex, relatively
thin walled, shallowly conical, some shells moderately
distorted; outline transversely subelliptical;
hinge from half as wide to slightly wider than midwidth,
normally slightly auriculate; commissure
distorted with shell, most shells broadly rugose
concentrically, slight tendency for sulcation of
brachial valve, with some brachial valves gently
plicate. Costellae strong, moderately high, some
weakly crenulate, primary costellae stronger; number
in 5 mm on pedicle valve between 10 and 16,
growth lines conspicuous only near margins, where
they form laminae. Obscure radial costae on some
specimens.
Pedicle valve nearly flat to moderately convex,
anterior profile gently convex or nearly flat, rarely
concave; interarea low to moderately high, slightly
concave or flat, rarely convex, meeting plane of
commissure between right and straight angle, normally
a small obtuse angle; pseudodeltidium with
broad arch, normally lacking median groove; perideltidium
reaching about half way to hinge ends.
Brachial valve normally flatly and evenly convex,
rarely strongly convex, sulcus shallow and narrow
when present.
Pedicle valve interior with large teeth, extending
posteriorly along underside of interarea and edges
of delthyrium, meeting anterior to apex, or connected
to median septum by outgrowth of shell
NUMBER 15 301
material, either condition producing a shallowchamber
beneath pseudodeltidial arch for reception
of cardinal process; median septum bladelike,
height depending upon depth of valve, apical end
in most shells joined to dental ridges, upper edge
making angle more obtuse in shallower valves,
near right angle in deeper valves. Muscle area as
long as median septum, occupying from one-third
to about one-half total length of valve, may be impressed,
slightly raised or outlined by raised border;
muscle marks normally faint, anteriorly expanding
grooves separated from one another by narrow
ridges. Floor of valve weakly costellate, edges more
strongly costellate.
Brachial valve interior with short straight cardinal
process, shallow, bifurcate at free end, each lobe
longitudinally slit, with serrations within slits;
dentifers fused to cardinal process, projecting
bluntly forward, supported by erismata that diverge
widely into umbonal arch in some valves, recurving
toward hinge in others. Chilidium well developed,
bisected by continuation of median groove of cardinal
process. Muscle area in umbonal arch, posterolateral^
bounded by cardinal process and short
crural plates, occupying about one-third to one-half
length of shell; muscle marks faintly impressed,
normally separated into 2 groups by low median
ridge. Valve floor faintly costellate, edges more
strongly costellate.
MEASUREMENTS
USNM 706b
151154a
151154b
151154c
151154d
151154e
151154f
151154g
151154h
151154i
151154J
151154k
USNM 706
151152a
151152b
USNM 706e
151158a
151158b
USNM 706d
151151a
151151b
USNM 706e
153290c (holotype)
(in mm).—
pedicle
valve
length
9.2
18.2
22.0
24.6
34.2
16.9
?
?
-J
}
?
15.0
36.3
21.4
27.2
47.0
62.5
32.0
brachial
valve
length
7
2
?
?
?
14.6
12.6
21.8
24.0
29.4
29.3
?
p
?
?
?
?
p
maximum
width
9.6
20.2
26.2
28.4
39.8
20.4
16.7
28.4
31.1
38.9
37.8
20.4
44.0
27.4
33.8
55.4
90.0?
39.6
hinge
width
7.5
14.3
17.8
18.6
27.6
17.0
11.5
26.4
22.0
31.0
34.9
15.4
32.3
20.3
22.5
51.0*
86.0?
28.9
interarea
length
3.4
8.0
5.9
6.8
10.0
4.3
?
?
?
}
?
3.4
8.7
6.2
6.8
7.5
14.8
9.6
thickness
3.9
7.9
6.1
6.1
9.4
6.4
4.0
8.4
7.9
9.0
8.6
4.5
8.8
7.8
12.6
?
?
?
STRATIGRAPHIC OCCURRENCE.—Road Canyon Formation,
Word Formation (China Tank, Willis
Ranch, and Appel Ranch members; lens between
the last two members), Cherry Canyon Formation
(Getaway Member).
LOCALITIES.—Road Canyon: USNM 703d, 706f,
716x; China Tank: USNM 706c, 713, 732s, 733q;
Willis Ranch: AMNH 505, 506, USNM 706, 706b,
706e, 723t, 723w, 724u; Appel Ranch: USNM 704,
706d, 714o, 715i, 719z, 722t, 726t; Getaway: AMNH
512, USNM 728, 730, 732.
TYPES.—Holotype: USNM 153290c; figured paratypes:
151154f, j , 1, m, o, 151165a, b, 153288, 153291;
measured paratypes: 151154a-k, 151152a, b, 151158a,
b, 151151a, b; unfigured paratypes: 151154a-e, g-i,
k, n, 153290a, b; figured specimen: 153288.
COMPARISON.—Derbyia filosa is characterized by
302 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
its flatly convex pedicle valve, strong relatively uncrowded
costellae that may be weakly crenulate,
normally auriculate hinge, and especially by short
bar or plates that join the median septum to the
dental ridges, in all but a few shells. It most closely
resembles the other coarsely costellate species from
the Glass Mountains: D. crenulata Girty, D. laqueata,
and D. texta, new species. Stronger costellae
that are strongly crenulate, a lower interarea, and
thicker shell wall distinguish D. crenulata. Derbyia
laqueata has strong growth laminae, a narrower
hinge, and normally is much more convex. Derbyia
texta has a plicate pedicle valve, thick walls, webbed
ornamentation on the brachial valve, and internally
it has the median septum entirely separate from
the dental ridges. Other Glass Mountains Derbyia
are not similar to D. filosa and can be distinguished
by a variety of features, primary among which is
their finer and more closely crowded costellation.
DISCUSSION.—Derbyia filosa varies in the convexity
of both its valves, the proportional width of the
hinge, the angle of posterior projection of the interarea,
the height of the interarea, and in the number
and strength of its costellae. Most shells have
slight auriculation of the hinge ends, but some are
nonauriculate. Most shells are somewhat distorted,
but they are not truly irregular like D. pannucia,
new species. The following tabulation illustrates
the variation in number of costellae per 5 mm in
shells from the two localities:
number of costellae/5 mm
pedicle valves (USNM 706)
10 11 12 13 14 15 16
number
number
of
of
number of
number of
number
number
of
of
specimens
costellae/5
specimens
costellae/5
specimens
costellae/5
mm
mm
mm
brachial
pedicle i
brachial
valves
valves
valves
(USNM 706)
11
1
(USNM 706b)
(USNM 706b)
12
12
3
13
3
13
4
14
6
14
5
11
4
15
7
15
5
12
7
16
6
16
4
13
8
17
4
18
2
14
12
18
3
19
2
15
10
19
1
20
1
16
4
20
number of specimens 9 10
Derbyia informis, new species
PLATE 76: FIGURES 1-8; PLATE 77: FIGURES 1-12; PLATE 78:
FIGURES 1-20; PLATE 81: FIGURES 1-3
Large, strongly biconvex, surface irregular;
strong discontinuous concentric undulations, radial
folds, or combinations producing bumps and nodes;
outline transversely subelliptical to nearly semicircular;
hinge from about half as wide to nearly
as wide as maximum width of shell, normally auriculate;
commissure wavy and irregular, but without
consistent folds. Costellae fine, weak, closely
crowded, may be finely crenulate, numbering on
pedicle valve between 16 and 24, in 5 mm, averaging
18; on brachial valve between 17 and 26, averaging
21; growth lines moderately strong, becoming
laminae near margins.
Pedicle valve irregularly convex, anterior profile
convex, rarely nearly flat; interarea wide, moderately
high, edges uneven, normally flat, but may be
concave or rarely convex; meeting of commissure
near right angle; arch of pseudodeltidium narrow,
low, straight sided or slightly expanding anteriorly,
normally with shallow median groove or median
flattening; perideltidium wide, edges more than
half way from median line to hinge ends.
Brachial valve irregularly convex in lateral
profile, broadly and depressed convex in anterior
profile, normally not as bumpy and irregular as
pedicle valve, beak may overhang slightly;
nonsulcate.
Pedicle valve interior with strong teeth projecting
forward from underside of interarea, extending
posteriorly along interior edges of delthyrium as
convergent dental ridges, meeting at apex of valve;
median septum normally high because valve is
deep, upper edge forming sharp angle, closer to
right angle in deeper valves, more obtuse in shallower
specimens, apical end of valve attached to
inside of pseudodeltidial arch for variable distance
NUMBER 15 303
anteriorly, normally free of dental ridges except at
apex of valve, in some specimens septum cemented
to dental ridges by callus that may partly bury
dental ridges. Muscle area as long as median septum,
occupying about half valve length, raised or
slightly depressed, in some having raised borders;
muscle marks elongate anteriorly expanding grooves
separated by narrow raised divides on floor of
muscle area, faint striae on median septum, roughly
parallel to anterior edge of septum. Floor of valve
finely and weakly costellate, costellae becoming
stronger near margins.
Brachial valve interior with moderately long,
curved, deeply bifurcate cardinal process, each lobe
with longitudinal slit along posterior edge, insides
of slits finely serrate; dentifers fused to sides of
process, forming laterally open hinge sockets, projecting
bluntly anteriorly into body chamber; erismata
continuous with dentifers, diverging into
umbonal arch, outlining posterolateral margins of
muscle area. Chilidium very small or absent.
Muscle area broad, bilobate, bisected by low median
ridge, muscle marks faint longitudinal striae, extending
about one-third length of valve. Floor of
valve irregular, finely and weakly costellate, costellae
becoming stronger near margins.
MEASUREMENTS
USNM 702
151056a
151056b
USNM 702 (low)
151062
151056c
USNM 702c
151059a
151059b
151059c
151059d
USNM 703a
151066a
USNM 702un
151064
USNM 702
151056b
151056d
151056e
USNM 703a
152606c (holotype)
(in mm).—
pedicle
valve
length
4.0
7.9
10.8
13.9
14.2
24.2
28.4
30.8
30.5
37.3
45.7
56.8
57.0
73.4
brachial
valve
length
?
5.3
9.5
11.8
14.5
16.9
24.5
29.6
30.8
37.1
40.0
45.3
58.0
63.7
maximum
width
5.4
7.3
11.8
13.9
20.1
23.0
29.5
33.6
41.1
52.0
45.0?
61.4
58.6 +
85.2
hinge
width
4.4
6.8
11.0
11.0
17.1
17.9
20.7
28.7
34.0
34.1
31.8
36.0
31.5
61.9
interarea
length
1.9
4.0
9.4
5.0
3.5
8.4
10.4
9.9
10.0
13.8
21.9
17.0?
22.5
24.6
thickness
?
4.7
13.0
9.0
9.0
20.0
21.8
18.9
20.7
25.0
39.0
36.3
44.0
49.0
STRATIGRAPHIC OCCURRENCE.—Cathedral Mountain
Formation (Wedin Member), Road Canyon
Formation.
LOCALITIES.—Cathedral Mountain: AMNH 500,
500B, 500L, 500X, USNM 702, 702b, 702inst,
7021ow, 702un, 703b, 703bs, 72lu, 723p, 726o, 726u,
714w, 732u; Road Canyon: AMNH 503, USNM
702c, 703, 703a, 703c, 703d, 707e, 708c, 709c, 72 lo,
721t, 721y, 724b, 724j, 726d.
DIAGNOSIS.—Large variable Derbyia with fine
costellae.
TYPES.—Holotype: USNM 152606c; figured paratypes:
151055a, b, 151056e, 151059b, d, 151073a, c,
152607a, 153286a, b, 153292; unfigured paratypes:
151056a^d, 151059a, c-q,151073b,152607b.
COMPARISON.—Derbyia informis is characterized
by its large maximum and average size, strong convexity
of both valves, auriculate hinge, narrow
pseudodeltidial arch with narrow groove, fine and
weak costellae that are rather closely crowded, its
very irregular, wrinkled pedicle valve and somewhat
less irregular brachial valve, and its normally
independent dental ridges and median septum. Its
closest relative in the Glass Mountains is D. pannucia,
new species, which may be a descendant.
Derbyia informis differs in its more convex pedicle
304 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
valve, less irregular brachial valve, more auriculate
hinge, less frequently buried dental ridges and
median septum attachment, grooved pseudodeltidial
arch, normally higher interarea, and weaker costellation.
The density of costellae is about the same
in the two species, and the differences enumerated
above are subtle, commonly requiring several
specimens for their identification. The median
septum of D. informis is higher than that of D.
pannucia because the pedicle valve is deeper and
throughout species of Derbyia the height of the
septum increases with depth of the pedicle valve.
The length of the cardinal process normally depends
on the height of interarea of the pedicle
valve, but in D. pannucia this relationship does
not hold consistently, and its cardinal process is
commonly as long as that of D. informis.
Derbyia informis differs from D. profunda, new
species, and D. nasuta Girty in its stronger convexity,
lower interarea, great irregularity of shell,
and finer costellae. In addition, the greater density
of costellae distinguishes it from D. profunda.
This species attains a size as great as that of D.
grandis Waagen, from the Salt Range of Pakistan.
It is much more irregular than that species, as well
as more convex in both valves and much more finely
and densely costellate. Derbyia regularis Waagen
also attains large size, but it is more regular and
undistorted even than is D. grandis, as its name
implies.
Individuals of D. cymbula Hall and Clarke may
resemble D. informis in their convex pedicle valves,
and interareas that meet the plane of commissure at
right angles. But, D. informis has finer and more
closely spaced costellae, reaches larger size, has a
typically longer and stronger cardinal process,
narrower pseudodeltidial arch, is much more distorted,
and the average specimen is more convex
than the average D. cymbula.
DISCUSSION.—Variation in Derbyia informis is
extreme. Specimens may have nearly undistorted
brachial valves, although the pedicle valve of every
specimen is distorted, and the brachial valve of
most is somewhat irregular. The outline of most
specimens is transverse, but a few specimens are
elongate. Most individuals are strongly convex,
and have a convex anterior profile of the pedicle
valve; some are flatter, and have nearly a straight
or rarely convex anterior profile. Costellae are fine
and weak; they range in density as shown on the
following tabulation:
pedicle valve, USNM 702, 703a
number of costellae/5 mm
number of specimens
number of costellae/5 mm
brachial
16 17
4 5
valve, USNM 702, 703a
17 18 19
18
11
20
19 20
10 9
21 22
21 22 23
3 0 0
23 24 25
24
1
26
number of specimens
Internally the median septum normally attaches
directly to the inside of the pseudodeltidial arch,
without callus cementing it to the dental ridges.
This condition is due in part to the near right
angle at which the interarea meets the plane of
commissure. In those specimens where this angle
is more obtuse, the ridges tend to be buried near
their apical ends in callus that also obscures the
attachment of the median septum.
Derbyia laqueata, new species
PLATE 74: FIGURES 1-26; PLATE 75: FIGURES 1-9
Small to medium size, biconvex moderately thick
walled, shallowly conical, some shells moderately
distorted; outline slightly to moderately transverse,
subelliptical to nearly quadrate; hinge slightly narrower
than widest part of shell, normally auriculate;
commissure normally straight, with tendency for
shallow sulcation in some shells. Costellae strong,
high, sharp or rounded, weakly to strongly crenulate,
many shells with stronger primary costellae
on either valve, intertroughs wide, costellae uncrowded,
numbering between 10 and 17 in 5 mm on
pedicle valve, averaging about 13; between 12 and
18 on brachial valve, averaging 15; growth laminae
strong, relatively closely and evenly spaced.
Pedicle valve flatly to moderately conical, anterior
profile normally convex, but frequently nearly flat
or concave; interarea short to moderately long,
wide, flat, or concave, more rarely convex, meeting
plane of commissure between right and straight
NUMBER 15 305
angle, normally small obtuse angle; pseudodeltidium
with wide arch and shallow median groove;
perideltidium wide, edges more than half distance
from median groove to hinge ends.
Brachial valve flatly to strongly convex, maximum
convexity anterior to beak, broadly convex in anterior
profile; sulcus shallow when present.
Pedicle valve interior with large teeth projecting
forward from underside of interarea, extending as
convergent dental ridges beneath interarea, along
edges of pseudodeltidium, normally meeting at
apex of valve, and without addition of callus material,
but with apical ends buried in callus in a
few individuals; median septum bladelike, height
depending on depth of valve, apical end normally
attached to inside of pseudodeltidial arch, but attached
to dental ridges by secondary plates or ridges
of callus in some valves, thus forming shallow
chamber, not a true camera; upper edge of septum
bent at obtuse angle, straighter in shallower valves.
Muscle area as long as median septum, occupying
between one-third and one-half length of valve,
normally shallowly impressed, but with raised border
in some; muscle marks shallow, separated by
low longitudinal ridges on floor of valve, forming
faint striae on sides of median septum. Floor of
valve weakly costellate, costellae stronger near
margins.
Brachial valve interior with short but strong,
slightly curved cardinal process, shallowly bifurcate
at free end, each lobe longitudinally slit, with insides
of slits serrate; dentifers fused to sides of
process, forming shallow open hinge sockets;
slightly and bluntly projecting into body chamber;
erismata widely divergent into umbonal cavity,
outlining posterolateral margins of muscle area.
Chilidium well developed, bisected by continuation
of median groove of cardinal process. Muscle area
nearly circular, lightly impressed, muscle marks
consisting of faint longitudinal or slightly radial
striae, occupying about one-third of length of valve,
bisected in some by low median ridge. Floor of
valve faintly costellate, costellae stronger near
margins.
MEASUREMENTS
USNM 702c
151080a
151080b
151080c
151080d
151080e
151076b
151080f
151080g
151080h
USNM 703a
151090a
151090b
151090c (holotype)
151090d
USNM 702
151076a
USNM 702un
151087
(in mm).—
pedicle
valve
length
3.5
4.9
6.4
14.7
15.2
21.0
21.0
23.8
29.9
10.6
22.8
30.0
34.0
11.4
47.0
brachial
valve
length
3.7
4.7
6.6
14.4
13.5
15.8
18.9
23.8
28.4
9.7
21.6
27.3
34.0
10.0
39.5
maximum
width
4.7
6.9
7.4
17.7
20.0
21.7
20.7
32.9
39.2
13.7
29.9
40.0
43.0
15.2
58.4
hinge
width
3.4
5.9
6.7
16.7
19.9
20.9
17.5
32.0
44.5
12.0
25.5
34.6
41.0
14.4
45.0
interarea
length
2.0
1.5
3.6
5.0
5.5
6.0
10.0
6.0
6.5
c.6
6.8
7.4
12.5
6.9
9.7
thickness
2.4
2.9
4.9
13.1
11.1
13.0
15.8
15.7
21.6
8.0
12.4
15.3
27.4
11.5
27.0
STRATIGRAPHIC OCCURRENCE.—Cathedral Mountain
Formation, Road Canyon Formation.
LOCALITIES.—Cathedral Mountain: AMNH 500,
500A, 500B, 500F, 500H, 500J, 500K, 500L, 500M,
500N, 500Q, 500X, 501, 509; USNM 702, 702a, 702b,
702ent, 702inst, 702-low, 702un, 703a1, 703b, 703bs,
708, 714w, 717e, 721u, 723u, 726o, 726u, 733m;
Road Canyon: USNM 700v, 702c, 703, 703a, 703c,
703d, 707e, 709c, 710u, 716x, 716xa, 719x, 720d,
721j, 721r, 721t, 721w, 721x, 721y, 722f, 722v,
723o, 723x, 724b, 724c, 726e, 726f, 726x, 726z.
DIAGNOSIS.—Crenulate Derbyia of moderate size,
306 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
with fairly long interarea and median septum not
joining dental ridges.
TYPES.—Holotype: USNM 151090c; figured paratypes:
151080J, k, -151086a, b, 151087, 153293,
153294a, b, c, 153295, 153296; measured paratypes:
151076a, b, 151080a-h, 151090a, b, d, 151087; unfigured
paratypes: 151080a-h.
COMPARISON.—Derbyia laqueata is characterized
by moderate size, strong and normally sharp crenulate
costellae, strong shingle-like growth laminae,
auriculate hinge, and commonly separate median
septum and dental ridges. This species closely resembles
D. crenulata Girty and may be descended
from it. Derbyia laqueata differs in its sharper and
more angular aspect, greater thickness, and longer
(average) interarea, and primarily by its sharper,
finer, more closely crowded costellae, and median
septum that normally is not braced against the
dental ridges by any callus.
Other species like D. laqueata found in the Glass
Mountains are: D. filosa, new species, and D. texta,
new species. The latter has a thicker shell, normally
plicate pedicle valve, and fewer costellae per unit
distance. Derbyia filosa attains larger size, normally
is flatter, has the median septum joined to the
dental ridges by pseudodental plates, and also has
less dense costellae. Neither of these species has
costellae that normally are as high, sharp, and
strongly crenulate as those of D. laqueata.
All other species of Derbyia from the Glass
Mountains differ strongly from D. laqueata and are
not likely to be confused with it. A Pennsylvanian
species from Texas, D. ciscoensis Dunbar and Condra
(1932:104, pi. 10: figs. 6-8), is somewhat similar
in shape to D. laqueata. Differences are the more
auriculate hinge, more strongly convex brachial
valve, and especially the finer, noncrenulate costellae.
According to Dunbar and Condra (1932:103),
D. multistriata (Meek and Hayden) from Early
Permian Fort Riley Formation of Kansas resembles
D. ciscoensis, but it differs from D. laqueata in
most of the same features.
DISCUSSION.—Derbyia laqueata is one of the most
variable and least unified of the Glass Mountain
species of Derbyia. No single feature distinguishes
it or differentiates it from all other species. Apparently
it is intermediate between some of the more
consistent and well-characterized species that occur
above and below its range. Its interarea is somewhat
longer than is normal in D. crenulata (Girty),
but many individuals have proportionately short
interareas. The median septum is typically free of
the dental ridges, but in some specimens callus
material unites them as in D. crenulata or D. filosa.
Many specimens have brachial valves with strong
primary costellae that, with the strong growth
laminae, produce an interfering ornamentation approaching
the webbed pattern of D. texta, but these
are not accompanied by plicated pedicle valves. The
number of costellae in 5 mm is close to that of all
the other stronger costellate species, and their distributional-
patterns overlap, as comparison of the
following tabulation with those for other species
shows:
pedicle valve (USNM 703a)
number of costellae/5 mm 11 12 13 14 15
number of specimens 3 7 9 7 4
brachial valve (USNM 703a)
number of costellae/5 mm 12 13 14 15 16 17 18
number of specimens 2 4 6 6 7 2
pedicle valve (USNM 702)
number of costellae/5 mm 11 12 13 14 15 16 17
number of specimens 7 8 8 6 4 0 1
brachial valve (USNM 702)
number of costellae/5 mm 12 13 14 15 16 17 18
number of specimens 4 6 2 3
Derbyia nasuta Girty
PLATE 70: FIGURES 1-11; PLATE 71: FIGURES 1-9; PLATE 72:
FIGURES 1-12; PLATE 73: FIGURES 1-18; PLATE 89: FIGURES 14-23
Derbyia nasuta Girty, 1909:182, pi. 26: figs. 6-6c—?R. E.
King, 1931:59, pi. 8: figs. 1-2.
Not Derbyia nasuta Girty.—McKee, 1938:225, pi. 44: figs. 1-2.
Usually very large, thin walled, biconvex, moderately
to deeply conical, somewhat distorted by
attachment, normally concentrically undulating,
some subtly plicate; outline transversely subelliptical;
hinge half to nearly as wide as greatest shell
width, some specimens slightly auriculate; commissure
even, nonsinuate, except for wave near
hinge in some shells. Costellae low, fine, even, rarely
alternating, added by insertion, rarely weakly crenulate,
with narrow intertroughs, more crowded
anteriorly.
Pedicle valve usually deeply conical, narrowly to
broadly expanding, anterior profile slightly to
NUMBER 15 307
strongly convex; interarea short to very long, concave
or flat, rarely convex, meeting plane of commissure
at nearly right angle; pseudodeltidium with
narrow arch with or without median groove; perideltidium
spreading on each side to about half
distance between midline and hinge end.
Brachial valve flatly, evenly convex except for
slightly more convex beak. Anterior profile broadly
and gently convex; umbonal region swollen; anteromedian
region flattened, not sulcate.
Pedicle valve interior with large teeth, converging
posteriorly beneath edges of delthyrium as
dental ridges, meeting at apex of valve; median
septum high, bladelike, free edge bent at right
angle, apical end joining directly to underside of
pseudodeltidial arch completely independent of
dental ridges. Muscle area as long as median septum,
bisected by it, occupying slightly less to
slightly more than half length of valve, muscle
marks faint longitudinal ridges and depressions in
muscle area and on sides of median septum. Floor
of valve with moderately strong costellae becoming
slightly stronger toward margins.
Brachial valve interior with cardinal process
long (corresponding to normally long interarea
of pedicle valve), very strong, bifid; notch between
lobes exceptionally deep, each lobe longitudinally
slit throughout its length, insides of slits minutely
serrate; dentifers firmly cemented to sides of process,
projecting anteriorly into chamber of valve,
forming shallow, open hinge sockets; erismata high,
strong, widely divergent, extending into umbonal
arch of valve, around posterolateral margins of
muscle area. Chilidium small, bilobed, remnantal,
or absent; narrow ginglymus along hinge edge. Muscle
area bilobate, muscle marks well impressed, shallow,
longitudinal grooves with narrow separating
ridges; floor of valve with fine costellae that become
slightly stronger near margins.
MEASUREMENTS
USNM 707a
151030a
151030b
151030c
151030d
151030e
151030f
151030g
151030h
151030i
151030J
151030k
151030-1
151030m
USNM 720e
151038h
(in mm).—
pedicle
valve
length
25.0
44.6
40.4
56.3
62.0
76.3
74.2
75.8
67.7
80.3
4.6
5.2
8.8
57.5
brachial
valve
length
16.0
32.2
40.4
54.0
51.8
65.5
74.2
70.6
44.8
64.0
3.9
5.0
7.5
56.6
maximum
width
19.0
39.7
55.5
58.4
66.0
74.0?
76.4
87.4
37.8
59.6
5.0
6.2
10.5
75.6
hinge
width
16.8
34.6
43.0
41.7
44.6?
43.0
58.0
58.9
27.2?
36.8
4.4
4.7
9.2
48.8
interarea
length
10.8
24.0?
29.5?
37.9
37.4
26.7
36.5
21.3
40.7
37.0
2.7
3.5
6.0
25.3
thickness
17.5
37.8
42.0
61.2
61.8
63.0
58.7
52.8
56.0
58.0
2.6
3.3
5.5
48.0
STRATIGRAPHIC OCCURRENCE.—Basal Bone Spring
Formation, Skinner Ranch Formation (Decie
Ranch Member, Sullivan Peak Member), Cibolo
Formation (Breccia Beds).
LOCALITIES.—Bone Spring: AMNH 625, 628, 629,
631, 696, 699, USNM 725c, 728e, 728f; Decie Ranch:
USNM 707a, 707w, 707z, 708q, 709w, 714t, 715v;
Sullivan Peak: USNM 707d, 707, 722-1, 733j; Skinner
Ranch: USNM 714p, 716t, 723s, 724p; Lower
Skinner Ranch: USNM 705a, 720e; Cibolo: AMNH
703, USMN 738r.
DIAGNOSIS.—Very large Derbyia with fine ornament
and usually long interarea.
TYPES.—Figured hypotypes: USNM 151029,
151030e, h, i, 151038a, c-f, g-j, 153297a, b, 153298,
153299, 153547a-c; unfigured measured hypotypes:
151030a-d, f, g, j-m.
COMPARISON.—Derbyia nasuta is characterized by
its large average and maximum size, fine and closely
spaced costellae that normally are nearly equal in
strength, but without conspicuous alternation, its
normally deeply conical pedicle valve with attend308
SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
ant long interarea, narrow pseudodeltidial arch,
median septum that is independent of dental
ridges, long, strong, and deeply notched cardinal
process, and its weak or absent chilidium. It resembles
D. profunda, new species, in its deep pedicle
valve, but it differs in its larger size, proportionately
narrower hinge, finer and more closely
crowded costellae that normally are not crenulate,
its narrower pseudodeltidial arch, independent
median septum, and more rugose or undulating
shell surface marked by more conspicuous laminae
of growth. For a group of specimens in hand, the
sure diagnostic distinction is the greater average
number of costellae per unit space.
A related species is D. pannucia, new species,
from the Word Formation. Derbyia nasuta has a
deeper pedicle valve, an interarea that meets the
plane of commissure at more nearly a right angle,
normally flatter brachial valve, and much more
regular, less bumpy, and less deformed shell. Many
individuals of D. pannucia have the median septum
independent of the dental ridges, as in D.
nasuta, but most have the septum cemented to the
ridges by deposits of shell material near the apex
of the pedicle valve.
DISCUSSION.—Derbyia nasuta Girty is not highly
variable in its specific characters. The nasute pedicle
valve is distinctive, and only a few individuals
have the atypical short interarea: these are unusually
inflated and obese individuals. The pseudodeltidial
arch, which is typically narrow, may be
wide in some individuals, and may possess a median
groove, indistinguishable from that of D. profunda.
We have seen no specimen in which the median
septum of the pedicle valve is cemented to the
dental ridges or in which the space between the
ridges and the septum is filled.
This species is preserved most abundantly as
calcareous steinkerns or calcite-filled, partly silicified
shells. Only about 50 specimens in the national collections
have been freed by treatment in acid and
show features of the interior. The calcareous specimens
have the characteristic shape that is typical
of the species and can be identified on that basis,
as well as on the basis of their association with a
few relatively complete and free shells.
Apparently Girty (1909:182) based this species
on a single specimen, which now is fragmented very
badly, especially the anterior parts, but, nevertheless,
with all except the anterior of the brachial
valve present. His description of the material is
inaccurate in some details. He states that the ventral
valve is "inclined backward so that the cardinal
area makes a rather strongly obtuse angle with the
plane of the edge." To the contrary, King (1931:59)
says that the interarea lies "at nearly right angles
to the margin." Our examination of the holotype,
as well as of specimens in the national collection
leads us to agree with King. Girty (1909:183) says
that the "Iirae number 8 to 11, usually 10 or 11,
in 5 mm," and King (1931:59) counted "10 to 14
in the space of 5 mm., varying on different specimens."
We count 12 in 5 mm on the pedicle valve
and 18 on the brachial. These discrepancies of D.
nasuta probably arise from the fragmentary condition
of the holotype, but we now have a sufficiently
large collection to compose a reliable description
of the species, not just of the holotype specimen.
A count of the number of costellae in 5 mm on
some shells from USNM 705a gave the following
results:
number of costellae/5 mm 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
number of specimens 1 1 1 1 0 0 1
The holotype of D. nasuta is from Girty's (1909:
512) station 3764, which is said to be north of the
Hazel Mine in the Sierra Diablo. Several other
species that are based on material from station
3764, such as Meekella attenuata Girty, Enteletes
dumblei Girty, and Derbyia crenulata Girty, are
identical with, or closely related to, species that
occur in the fauna of the Decie Ranch Member of
the Glass Mountains rather than in the Leonardian
as postulated by Girty (1909:295, ftn. a) or by Stehli
(1954:268).
Derbyia pannucia, new species
PLATE 68: FIGURES 1-3; PLATE 83: FIGURES 1-12; PLATE 84:
FICURES 1-8; PLATE 85: FIGURES 1-7; PLATE 86: FIGURES 1-11
Large, moderately thick walled, flatly to moderately
biconvex, normally irregular, shape modified
NUMBER 15 309
by attachment or spontaneously deformed; outline
transversely subelliptical to nearly semicircular;
hinge from about three-fourths as wide as, to
slightly wider than, midwidth, slightly auriculate or
not; commissure without consistent sinuosities,
very irregular and wavy in detail; either or both
valves irregularly radially plicate, and/or concentrically
rugose, in erratic patterns, rarely relatively
smooth and free of distortion. Costellae fine, weak
to moderately strong, rounded, some slightly crenulate
or bumpy, maintaining strength to margins,
equal in strength, or with slightly stronger primary
costellae, increase by insertion; number on
pedicle valve between 15 and 30 in 5 mm, average
21; growth laminae moderately well developed.
Pedicle valve flattish to strongly convex; anterior
profile may be concave, nearly flat, convex, or
flexed; interarea wide, low to moderately high,
edges irregular, meets plane of commissure at obtuse
(apsacline) or nearly right angle, normally
flat, less commonly concave, rarely convex; pseudodeltidium
with narrow arch, either high and ridgelike,
or nearly flattened, without median groove;
perideltidium wide, spreading nearly to edge of
interarea at hinge, not necessarily parallel to edge
of interarea.
Brachial valve moderately to strongly convex,
may have strongly overhanging beak.
Pedicle valve interior with hinge teeth projecting
forward from underside of interarea, extending
posteriorly along edges of pseudodeltidium as convergent
dental ridges, meeting at, or slightly anterior
to, apex of valve; median septum low to
moderately high, depending upon depth of valve,
upper surface flexed nearer right angle in deeper
valves, at large obtuse angle in flatter valves; apical
end of septum may be independent of dental ridges,
more commonly cemented to ridges by callus shell
material that may partly bury apical ends of ridges
and septum, none with true camera. Muscle area
as long as median septum, occupying normally
about half, but exceptionally up to three-fourths of
total length of shell, raised or thickened in many
shells, many with edges bounded by thickening;
muscle marks elongate shallow grooves separated by
narrow ridges on floor of valve, faint striae on sides
of median septum. Floor of valve irregular, faintly
costellate, with stronger radial costellae near edges.
Brachial valve interior with strong, long, curved
cardinal process, bifid, deeply notched, with widely
divergent prongs, each longitudinally slit along
posterior edge, insides of slits finely serrate; dentifers
fused to sides of process, projecting bluntly into
chamber of valve; hinge sockets open posteriorly
and laterally; erismata strong, high, diverging into
umbonal cavity, outlining posterolateral margins of
muscle area. Chilidium not present. Muscle area
bilobate, bisected by low median ridge, occupying
about one-third of length of valve, beneath arch of
cardinalia. Floor of valve irregular, may be faintly
costellate, with slightly stronger radial costellae at
margins.
310 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
MEASUREMENTS
USNM 706e
151122a
151122b
151122c
151122d
151122e
151122f
151122g
151122h
1511221
151122J
151122k
151122-1
151122m
151122n
151122o
USNM 706c
151119a
USNM 706b
153346 (holotype)
(in mm).—
pedicle
valve
length
5.0
5.7
10.5
15.6
19.4
20.6
23.0
32.8
39.8
37.0
50.5
76.2
64.6
67.0
59.0
49.0
72.2
brachial
valve
length
}
55.6
>
68.8
maximum
width
5.6
7.0
9.4
15.8
17.3
27.6
27.1
35.7
40.3
50.6
80.7
89.5
94.8
87.9
76.0
64.6
85.0
h inge
width
4.4
6.0
7.7
12.5
16.8
21.0
23.6
24.2
32.5
47.3
59.7
62.6
66.6
77.0
51.9
48.8
7.4
interarea
length
1.6
2.6
4.0
6.0
7.8
6.0
14.3
9.5
15.8
15.5
15.5
24.5
18.6
22.0
13.8
23.7
56.7
thickness
35.5
?
55.0
STRATIGRAPHIC OCCURRENCE.—Word Formation
(China Tank, Willis Ranch, Appel Ranch members
and lens between last two), Cherry Canyon
Formation (Getaway Member).
LOCALITIES.—China Tank: USNM 706c, 713,
726r, 733q; Willis Ranch: AMNH 506, USNM 706,
706e, 718d, 723t, 724u; lens: USNM 706b; Appel
Ranch: USNM 706d, 714o, 715i, 719z, 722t, 727j;
Getaway: AMNH 512, 600, USNM 728, 730, 732.
DIAGNOSIS.—Very large Derbyia with strong, irregular
wrinkling and no chilidium.
TYPES.—Holotype: USNM 153346; figured paratypes:
USNM 151115, 151117, 151119b, 151121 a-f,
151122e, g, k, m, n, p, q, r; measured paratypes:
151122a-o, 151119a; unfigured paratypes: 151119a.
COMPARISON.—Relatively irregular specimens of
Derbyia cymbula Hall and Clarke bear superficial
resemblance to relatively regular individuals of D.
pannucia. In the former, however, the irregularity
is confined mostly to the pedicle valve, whereas
both valves of D. pannucia are wrinkled. Furthermore,
the costellae of D. cymbula are more widely
spaced, the pseudodeltidial arch is wide, a welldeveloped
chilidium is present, and the cardinal
process is comparatively short and weak. Derbyia
grandis Waagen attains a size comparable to that
of D. pannucia, but the Salt Range species has
sharper, coarser, and more widely spaced costellae,
wider pseudodeltidial arch, and narrower perideltidium.
Apparently a chilidium is present in D.
grandis, although Waagen's (1884, pi. 51-53) illustrations
do not show it clearly, and it is not well
preserved on the specimens in the national collection
(USNM).
DISCUSSION.—Derbyia pannucia is the most variable
of the Glass Mountain species of Derbyia. The
pedicle valve may be deep and convex, although it
normally is shallow and rather flat, the hinge may
be sufficiently narrow to make the outline of the
shell oval, or it may be the widest part of the shell,
even slightly auriculate. Wrinkling of the surface
is weak in some specimens, normally is strong, but
the pattern is not regular: in some it consists of
dominantly radial plications; in others, of dominantly
concentric rugae; in others, of discontinuous
bumps and nodes; in others, of connected bumps
produced by interfering radial and concentric wrinkles.
The narrow pseudodeltidial arch, which is
considered to be characteristic of the species, is
rather wide on many juvenile shells, near the beak
of some mature shells, and may bear a distinct
median groove at that stage.
Internally, the dental ridges and median septum
normally remain unconnected, but in many individuals
the ridges are buried in callus, connecting
them to the septum, and in some the ridges apNUMBER
15 311
pear to converge on the septum anterior to the
apex of the valve. The cardinal process is large
and strong, a reliable and consistent feature of almost
all specimens, but a few have that structure
comparatively short and weak.
The number of costellae per 5 mm varies within
the figures mentioned in the description of the species.
The following tables show the pattern of distribution:
pedicle valves (USNM 706)
number
number
number
number
number
number
number
of costellae/5
of
of
of
of
of
of
specimens
costellae/5
specimens
costellae/5
specimens
costellae/5
mm
mm
mm
mm
brachia.
pedicle
brachial
I valves (USNM 706)
17 18
1 0
19 20
3 4
valves (USNM 706b)
14
1
valves (USNM 706b)
16 17 18 19
21
5
15
3
20
17
1
22
5
16
9
21
18
9
23
4
17
8
22
19
7
24
2
18
6
23
20
4
25
2
19
4
24
21
3
26
2
20
2
25
22
2
27
1
21
2
26
23
4
28
1
22
1
27
number of specimens 6 11 10 1 1
Derbyia profunda, new species
PLATE 67: FIGURES 1-27; PLATE 68: FIGURES 4-11
Derbyia cymbula Hall and Clarke, 1892:398, pi. 11B: figs.
2, 3 R. E. King, 1931:59, pi. 8: figs. 3a, b.
Large, moderately thick walled, biconvex, moderately
to deeply conical, shape modified by attachment
but otherwise not greatly distorted; outline
transversely subelliptical to semicircular; hinge
slightly narrower than widest part, cardinal extremities
usually obtuse, rarely auriculate; commissure
broadly sulcate, with minor fortuitous contortions;
incipient in some specimens. Psedodeltidium
narrow, not strongly arched, and with a prominent
impressed median groove. Costellae strong but fine,
moderately high, sharp near beaks, becoming
straight sided and blunt toward edges of shells,
crowded together with narrow intertroughs, primary
costellae slightly stronger, giving fairly regularly
alternating pattern, increase by insertion,
crenulation weak and obscure; costellae similar in
shape on both valves, slightly less crowded on pedicle,
numbering 10 to 18 in 5 mm, averaging 15,
those on brachial valve numbering 12 to 21, averaging
16 in 5 mm; growth lines faint except near
edges of shell, where several laminae may be present.
Pedicle valve moderately to deeply conical,
broadly expanding, anterior profile normally convex,
but more rarely nearly flat or concave; interarea
high and wide, flat or concave, more rarely
convex, meeting plane of commissure at nearly
right angle or slanting posteriorly, rather evenly
tapered to attenuate; pseudodeltidium with broad
arch bisected by shallow groove; perideltidium
slightly raised above lateral parts of interarea,
spreading to about half distance between midline
and hinge edge, not necessarily paralleling edge of
interarea.
Brachial valve lidlike, unevenly and flatly to
moderately convex longitudinally, with maximum
convexity near beak; anterior profile nearly flat;
anteromedian region usually flattened, not sulcate.
Pedicle valve interior with large teeth converging
posteriorly along underside of delthyrial edges
as dental ridges, meeting at apex of valves; median
septum high, bladelike, upper edge strongly angular
longitudinally, obtuse in shallower valves with
flat or concave profile, nearer right angle in deeper
valves; anterior end of septum reaching anterior
edge of muscle area, apical and variably attached,
in some shells septum attached directly to underside
of pseudodeltidial arch, remaining free of dental
ridges, in others shell material filling space
between septum and ridges, becoming drawn out
anteriorly as pseudodental plates, many specimens
with pseudodental plates continuing sufficiently far
forward along septum and plates to form deep
camera as edge of septum and inside of pseudotieltidial
arch diverge; some specimens with only 1
312 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
such plate developed, clearly showing median septum
free of arch except immediately anterior to
apex of valve. Muscle area as long as median septum,
normally slightly less than half valve length,
not deeply impressed, and with faint muscle marks
on sides of septum. Floor of valve with obscure
costellae becoming slightly stronger near edges.
Brachial valve interior with moderately strong,
normally long, slightly curved cardinal process
(length dependent upon height of pedicle interarea),
shortly bifurcate at free end, but longitudinally
grooved throughout length, each lobe
longitudinally slit, with insides of slits minutely
serrate; dentifers firmly cemented to sides of process,
forming open hinge sockets, and projecting
almost directly ventrally; erismata low, diverging
into umbonal arch, outlining posterolateral parts
of muscle area. Chilidium fairly prominent, not
completely bisected by median groove of cardinal
process; hinge with narrow bearing-surface (ginglymus)
of uniform width, not tapering toward hinge
ends; muscle area bilobate, ill defined, with faint
longitudinal muscle marks; interior surface of valve
faintly costellate, slightly more deeply marked near
edges.
MEASUREMENTS
USNM 701k
151015a
151015b
151015c
151015d
151015e
151015f
151015g
151015h
1510151
151015J
151015k
151015-1
151015m
151015n
153348 (holotype)
(in mm).—
pedicle
valve
length
3.5
5.6
8.0
10.2
13.2
18.5
22.2
23.9
38.5
44.2
52.0
45.8
50.0
54.2
53.5
brachial
valve
length
3.0
4.5
6.4
6.6
11.6
16.0
22.0
23.2
26.0
33.8
41.4
41.6
47.0
54.6
48.3
maximum
width
3.4
6.0
8.3
10.4
16.5
23.4
24.7
32.9
36.6
45.3
49.0
53.5
61.0
66.5
60.5
hinge
width
3.0
4.6
6.8
9.5
13.9
19.0
19.7
27.9
28.0
37.2
41.0
48.2
53.0
56.5
49.6
interarea
length
1.5
3.0
5.0
5.4
7.8
10.9
14.4
11.6
13.3
22.0
21.4
33.5
37.8
29.6
15.0
thickness
2.2
3.4
6.0
4.6
10.9
15.0
23.9
21.3
19.6
27.5
32.9
52.8
43.0
47.6
39.6
STRATIGRAPHIC OCCURRENCE.—Gaptank Formation
(Uddenites-bearing Shale Member), Neal
Ranch Formation (beds 2-14), Lenox Hills Formation.
LOCALITIES.—Uddenites: USNM 701u, 713u;
Neal Ranch: 701, 701a, 701a1, 701a3, 701c, 701d,
701g, 701h, 701k, 701-1, 712w, 715e, 721g; Lenox
Hills: 705, 707j, 715.
DIAGNOSIS.—Large Derbyia with gently convex
brachial valve, which has a flattened umbonal region.
TYPES.—Holotype: USNM 153348; figured paratypes:
151015c, e, g, j , 153347a-c, 153349; unfigured
measured paratypes: 151015a, b, d, f, h, i, k-n.
COMPARISON.—Derbyia profunda is a very distinctive
and easily recognized species characterized
by its deep conical pedicle valve with narrow,
grooved pseudodeltidial arch, relatively flat brachial
valve with well-developed chilidium, weakly crenulate
costellae that are much lower than in D. crenulata,
but average only 15 and 16 per 5 mm on the
pedicle and brachial valves respectively. Internally
the species is distinguished by its high median septum
and strong dental ridges that may or may not
attach to the septum by callus filling or pseudodental
plates. The deep pedicle valve with high
interarea, and the weaker costellae that number
nearly the same in 5 mm, and the larger average
size distinguish this species from D. crenulata Girty
and D. carteri, new species. In addition, the hinge
of D. profunda is not auriculate and, although wide,
is not the widest part of the shell, and the cardinal
extremities are usually obtuse. The only species
that might be confused with D. profunda is D. nasuta
Girty, which also has a high interarea and
attains a larger size. That species differs in its
NUMBER 15 313
flatter pseudodeltidial arch, poorly developed or absent
chilidium, noncrenulate costellae that average
about 20 in 5 mm and that are all nearly uniform
in strength, not alternating. No other American
species of Derbyia has the large size, wide hinge,
and long inetrarea of D. profunda.
Internally D. profunda is interesting because it
contains individuals with the true Derbyia-like arrangement
of the dental ridges (completely separate
from the median septum), some with deep
chambers formed by a plate from each dental ridge
attaching to the top of the septum, and the septum
remaining detached from the inside of the
pseudodeltidium except at the apex. The latter
condition is similar to the plate arrangement of
Orthotetes. In addition, there are many intermediates
of various kinds: some individuals have a plate
uniting the top of the septum to only one of the
dental ridges, others with the chamber between
the top of the septum and the underside of the
pseudodeltidial arch completely or partly filled
with shell material, producing chambers of varying
depth. This is not the only species in the
Glass Mountains fauna that has individuals with
secondary characters simulating those of Orthotetes.
Derbyia scitula, new species
PLATE 73: FIGURES 19-32; PLATE 82: FICURES 3-10
Small, strongly inequivalve, brachial valve much
shallower than strongly conical pedicle valve;
hinge narrow, usually auriculate, about threefourths
of maximum width, which is anterior to
midvalve. Sides oblique to concave; anterolateral
extremities narrowly rounded; anterior margin
gently rounded, narrowly emarginate in some specimens.
Anterior commissure usually sulcate; lateral
commissure straight to strongly convex in dorsad
direction. Surface costellate, costellae subequal,
tightly crowded on brachial valve, less so on pedicle
valve, numbering 11-13 in 5 mm at 10 mm anterior
to beak and 7-8 in 5 mm at anterior margin
of large specimens on brachial valve and 1 or 2
less on pedicle valve.
Pedicle valve triangular in lateral profile, long
side being nearly flat to unevenly concave; anterior
profile irregular; interarea moderately long with
well-marked perideltidial area occupying about half
interarea on each side of pseudodeltidium, which
is fairly broad and arched and often medially
grooved. Beak usually deformed, which is over
fairly broad surface in some specimens. Median
region swollen to form ill-defined fold; flanks usually
steep.
Brachial valve varying from moderately to
strongly convex in lateral profile; anterior profile
broadly and moderately convex and usually with
a median depression. Umbonal region varying from
nearly flat to moderately swollen; sulcus narrow,
usually present, narrow, moderately rounded, giving
valve bilobed appearance; sides short and moderately
steep.
Pedicle valve interior with small teeth and low
dental ridges; median septum delicate reaching
about to midvalve, forming obtuse angle in lateral
view and apically attached to the pseudodeltidium,
not producing false dental plates and apical chamber.
Muscles lightly impressed.
Brachial valve interior with strong, bilobed chilidium,
short, slightly cleft myophore and short,
widely divergent supporting plates. Muscles not
strongly impressed.
MEASUREMENTS (in mm).—
pedicle
valve
length
USNM 701
151202a (holotype) 18.9
151202b 14.2
151202c 12.2
151202d 13.0
151202e 9.4
151202f 6.4
151202g 5.1
brachial
valve
length
18.9
13.4
11.8
12.0
8.8
6.0
5.0
maximum
width
21.5
16.0
15.4
12.8
10.5
7.6
6.0
hinge
width
15.6
12.0
12.4
9.4
7.4
6.0
5.6
interarea
length
8.2
7.5
6.0
4.9
4.0
4.0
3.6
thickness
16.9
17.2
11.4
10.3
7.7
5.6
4.0
314 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
STRATIGRAPHIC OCCURRENCE.—Neal Ranch Formation
(upper 15 feet of bed 2 of P. B. King).
LOCALITIES—USNM 701, 701 c, 70Id.
DIAGNOSIS.—Small, thick strongly costellate Derbyia
with sulcate brachial valve.
TYPES.—Holotype: USNM 151202a; figured paratypes:
151202d, h, 153289a, c, d, 153345; measured
paratypes: 151202b-g; unfigured paratypes:
153289b.
COMPARISON.—No species from the Glass Mountains
is like this one, but it is similar to Derbyia
bennetti Hall and Clarke. Both have the same general
form, that of a somewhat triangular outline
with the anterior expanded somewhat laterally. The
Permian species differs from the Pennsylvanian one
in having somewhat stronger costellae near the
beak, a less deep brachial valve, more even sulcation
of the pedicle valve, and a generally smaller
size.
DISCUSSION.—Possibly the true size of this species
is fully exhibited by the material studied. The largest
specimens measure about 25 mm in length and
width, which may be the maximum size, but the
large specimens are few. Attached forms are fixed
by a large part of the ventral surface of the pedicle
valve, but the majority of specimens have broken
free of their moorings. Since no false dental plates
were seen in any of the pedicle valves, no specimens
have the orthotetid-like chamber noted in some
species of Derbyia. In the brachial valve the supporting
plates are widely divergent but variable,
not having been very extended in some specimens.
Derbyia strophomenoidea, new species
PLATE 69: FIGURES 1-9
Large, strophomenid in lateral profile, subrectangular
in outline wider than long; hinge slightly
less in width than midwidth; cardinal extremities
approaching, or slightly greater than, right angle;
sides gently rounded; anterior margin broadly
rounded to subtruncate. Anterior commissure
broadly sulcate; surface multicostellate, costellae
more crowded on brachial valve than on opposite
one; costellae numbering on brachial valve 11 in
5 mm at 10 mm anterior to beak, 9 in 5 mm at 20
mm anterior to beak and 7 at anterior margin;
costellae on pedicle valve numbering 10 at 5 mm
anterior to beak, 7 at 20 mm anterior to beak and
7 at anterior margin.
Pedicle valve in lateral profile convex in posterior
half, but gently concave in anterior half; anterior
profile gently concave. Interarea short,
strongly apsacline and with wide perideltidial area.
Median region gently swollen; flanks and anterior
flattened.
Brachial valve moderately and evenly convex in
lateral profile, but broadly and fairly strongly convex
in anterior profile. Interarea extremely short;
chilidium short. Umbonal region flatly convex, but
median region well inflated but with long moderately
steep slopes.
Pedicle valve interior with strong dental ridges
and median septum welded to under side of pseudodeltidium;
teeth long and slender. Length of
septum not known.
Brachial valve interior with moderately long and
thick cardinal process with lobes narrowly forked;
dentifers short, slightly protuberant but supporting
plates long and thick. Myophragm low but
thick.
MEASUREMENTS (in mm).—Paratype (USNM
151215a): pedicle valve length 46, brachial valve
length 42.5, maximum width 62.8, hinge width
52.0 plus, interarea length 13.8, thickness 19.2; holotype
(USNM 151213b): pedicle valve length 56.0,
brachial valve length 52.6, maximum width 59.4,
hinge width 52.3, interarea length 14.0, thickness
25.0?
STRATIGRAPHIC OCCURRENCE.—Neal Ranch Formation
(bed 4 of P. B. King).
LOCALITY!—USNM 701-1.
DIAGNOSIS.—Large slender Derbyia having a
strophomenoid profile.
TYPES.—Holotype: USNM 151213b; figured paratype:
151213a.
COMPARISON.—This species differs from D. profunda
in the compressed strophomenoid form, the
shallow brachial valve, and the character of the
ornament. Derbyia wabaunseensis Dunbar and
Condra and D. kansasensis Dunbar and Condra are
strophomenoid in form and resemble D. strophomenoidea.
The former is smaller, with a narrower
hinge and shorter interarea than the Neal Ranch
species. Derbyia kansasensis is a square species,
with a less concave pedicle valve than the Glass
Mountains species. These comparisons are based
on few specimens.
DISCUSSION.—This is a rare species and has been
NUMBER 15 315
seen only at USNM 701-1. The large paratype
shows the two valves in contact from the inside and
makes clear the role of the socket ridge in articulation.
It locks with a notch in the tooth to make
for a stronger articulation.
Derbyia texta, new species
PLATE 87: FIGURES 1-42
Small, thick walled, biconvex, forming shallow
cone, usually undistorted; outline subcircular to
semicircular; hinge from slightly to one-third narrower
than widest part of shell, slightly articulate
in some specimens; commissure even, without consistent
sinuosities; most shells regularly plicate,
stronger on pedicle valve. Costellae strong, rounded,
crenulate, relatively uniform on pedicle valve, but
with several markedly stronger primary costellae
on brachial valve, intertroughs nearly as wide as
costellae; in space of 5 mm costellae numbering
between 10 and 17 on pedicle valve, averaging 14,
between 11 and 20 on brachial valve, averaging 15;
growth laminae strong, more frequent toward
margins, relatively evenly concentric on pedicle
valve, but scalloped between strong primary costellae
on brachial valve.
Pedicle valve with lateral profile normally gently
convex or nearly flat, less commonly concave; anterior
profile moderately domed; interarea moderately
long, flat, or slightly concave or convex,
usually strongly apsacline, evenly expanding from
apex; pseudodeltidium with proportionately wide
arch, but shallow or absent median groove; perideltidium
wide, edges near, but not parallel to,
edges of interarea.
Brachial valve evenly convex, normally rather
flat, less commonly strongly convex. Median region
forming most convex part; anterior part faintly to
moderately sulcate.
Pedicle valve interior with strong, compressed
teeth; dental ridges converging posteriorly toward
apex along edges of delthyrium, meeting at apex,
with space between them only rarely filled by
callus; median septum low to high, depending on
depth of valve, upper edge marking nearly right
angle in deep valves, increasingly obtuse angles in
progressively shallower valves, septum normally
attached directly to underside of pseudodeltidial
arch, free of dental ridges, but joined to them
by callus in valves with interarea meeting plane of
commissure at greatly obtuse angle. Muscle area as
long as median septum, occupying from 0.3 to 0.7
valve length, normally nearer 0.3; lightly impressed,
with raised borders in some valves, muscle marks
normally faint, conspicuous in some, consisting
of anteriorly expanding shallow grooves, separated
by low longitudinal ridges; sides of median septum
bearing faint muscle marks. Floor of valve costellate,
with costellae stronger near margins.
Brachial valve interior with strong but short,
straight cardinal process, bifurcation at free end
shallow, each lobe longitudinally slit, with serrations
within slits; dentifers fused to sides of process,
forming open hinge sockets, projecting bluntly,
and supported by short divergent erismata extending
into umbonal arch, continuing as low ridges
around posterolateral borders of muscle area. Chilidium
well developed, medially scored by continuation
of median groove of cardinal process. Muscle
area bilobate, bisected by low, indistinct median
ridge, muscle marks faint radial or longitudinal
striae. Floor of valve faintly costellate, with stronger
costellae at margins.
316 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
MEASUREMENTS
USNM 706b
151177a
151177b
151177c
151177d
151177e
151177f
151177g
USNM 706c
151179a
151179b
151179c
151179d
151l79e
USNM 715i
151184
USNM 716x
152618
USNM 707e
152616a
152616b
152616c
152616d
152616e
152616f
152616g
152616h
USNM 706e
153449b (holotype)
(in mm).—
pedicle
valve
length
4.1
11.1
13.7
15.3
16.1
16.7
14.6
6.8
8.2
20.9
18.7
15.5
24.0
17.8
25.6
24.6
14.1
12.1
11.2
?
?
?
16.5
brachial
valve
length
p
p
?
p
p
p
p
p
?
?
p
13.6
20.8
14.6
P
p
12.7
10.2
8.7
15.5
18.0
15.8
14.0
maximum
width
4.9
10.2
10.7
11.7
13.3
15.9
16.5
5.8
9.3
19.1
24.0?
18.0
25.6
16.8
24.5
21.0
17.9
13.0
11.7
20.6
20.6
18.4
20.0
hinge
width
3.9
9.0
7.7
9.6
10.0
12.6
11.8
5.5
8.0
15.0
19.2
12.6
14.2
13.5
18.4
16.3
11.8
9.6
9.3
18.3
14.1
15.6
13.0
interarea
length
2.5
3.9
4.3
6.5
5.0
7.0
6.0
3.4
3.6
6.9
7.3
5.0
5.0
4.6
8.2
4.4
3.0
2.6
3.3
?
?
?
6.8
thickness
?
?
?
?
p
?
?
?
?
?
?
7.0
10.0
8.8?
10.0?
4.6
7.0
3.7
3.7
3.8
7.7
4.3
9.6
STRATIGRAPHIC OCCURRENCE. — Cherry Canyon
Formation (Getaway Member), Road Canyon Formation,
Word Formation (China Tank, Willis
Ranch, Appel Ranch members and lenses between
the last two), Bell Canyon Formation (Hegler,
Racier, and Lamar members).
LOCALITIES.—Getaway: Moore 31, AMNH 505,
506, 512, 519, 600, USNM 728, 732, 736; Road Canyon:
USNM 703, 703c, 703d, 707e, 716x, 724a,
726o; China Tank: USNM 706c, 713, 726r; Willis
Ranch: USNM 706, 706e, 724u; lens: USNM 706b,
732c, 742b; Appel Ranch: USNM 704, 706d, 714o,
715i, 719z, 727j; Hegler: USNM 731; Rader:
AMNH 403, USNM 725f, 725g; Lamar: USNM
725e, 738b.
DIAGNOSIS.—Small Derbyia with strong costellae
and poorly formed radial plications.
TYPES.—Holotype: USNM 153449b; figured paratypes:
151179e, 151176, 151184, 151186, 153449c, e,
f; measured paratypes: 151177a—g, 151184, 152616ah,
152618; unfigured paratypes: 153449d.
Derbyia filosa has the same average number of
costellae per 5 mm as D. texta and occurs in many
of the same samples. Those two species are not
closely similar, however. Derbyia filosa attains a
maximum size about three times as large as the
largest D. texta and does not have the webbed
ornament, plicate brachial valve, and, most distinctively
it has the dental ridges and median
septum fused so that a small recess for the cardinal
process is produced beneath the pseudodeltidial
arch (not a true camera).
DISCUSSION.—Derbyia texta varies in the convexity
of its valves, width of hinge, and angle between
the plane of commissure and the interarea. Its other
features are rather consistent and vary only within
narrow limits. Of course size changes with growth,
NUMBER 15 317
and the number of costellae per unit distance on specimens from two localities illustrate this
ranges about a mean. Counts of costellae in 5 mm variation:
number of costellae/5 mm
pedicle valves (USNM 706b)
11 12 13 14 15 16 17
number of specimens
number of costellae/5 mm
number of specimens
number of costellae/5 mm
number of specimens
number of costellae/5 mm
brachial valves (USNM 706b)
12
2
pedicle valves (USNM 706c)
brachial valves (USNM 706c)
13
3
10
1
11
1
14
5
11
4
12
6
15
8
12
8
13
5
16
9
13
9
14
10
17
6
14
12
15
5
18
2
15
3
16
2
19
1
16
2
17
1
20
1
17
1
18
number of specimens 1 1
Derbyia species
Many specimens of Derbyia collected by us and
members of parties from the American Museum of
Natural History cannot be identified with the
species described herein or elsewhere. This is owing
to poor material or to specimens that are too few
or too variable to resolve into understandable species.
Although such specimens occur in nearly all
of the formations collected, the largest number
occur in the members of the Bell Canyon Formation.
At least three species occur in these beds, but
all of the specimens are dissociated valves, many of
them with ragged edges and many of them immature.
Remarks on these are given below.
Derbyia species 1
PLATE 88: FIGURES 7-31
Werbyia species a Girty 1909:184, pi. 11: fig. 1 [probably
not pi. 10: fig. 11].
Moderately large for genus, outline subrectangular,
width slightly greater than length. Sides
rounded; anterior margin broadly rounded, slightly
Iinguoidal; hinge wide but not equalling maximum
width at about midvalve. Cardinal extremities varying
from obtuse to narrowly auriculate. Costellae
fine, variable in size, intercalcated in 3 generations,
crenulated and more numerous on brachial valve,
more distant on pedicle valve. Costellae numbering
(brachial valve) 13 in 5 mm at 10 mm anterior
to beak; (pedicle valve) numbering 9 in 5 mm at
10 mm anterior to beak and same number at
margin.
Pedicle valve flatly convex in lateral profile,
gently convex in anterior profile; interarea short,
apsacline. Teeth small; median septum short, delicate,
reaching about one-third valve length.
Brachial valve moderately convex in lateral profile
with maximum curvature in umbonal region;
anterior region profile broadly convex; sulcus
moderately broad, shallow, originating just anterior
to umbonal curvature, persistent at all states of
growth represented in collection. Median region
moderately swollen. Chilidium small, strongly
bilobed; cardinal process short; supporting plates
flaring but short.
MEASUREMENTS (in mm).—Pedicle valve (151205a):
length 35.0 (estimated), maximum width 41.6, hinge
width 34.0, interarea length 5.9, thickness 5.0 (estimated);
brachial valve (151205b): length 34.2,
maximum width 43.7, hinge width 32.8, thickness
9.0.
STRATIGRAPHIC OCCURRENCE.—Bell Canyon Formation
(Lamar Member).
LOCALITIES.—AMNH L-2, 37, 38, 40, 347, 373,
385, 398, 430L, 430M, USNM 725e, 728p, 738, 738b.
TYPES.—Figured specimens: USNM 151205b, c,
153465a, b, 153466a, b, 153467a-c.
DISCUSSION.—We refer here the large specimen
figured by Girty as "Derbyia species a," which has
essentially the same form and profile of brachial
valves of the silicified specimens from the Lamar
Limestone. This has a length of 57 mm and an
estimated width (based on half measure) of 77 mm.
318 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
If the suggested relationship ultimately proves correct,
this species will be one of the larger derbyias
of the Permian. A few specimens of larger posterior
parts preserving the cardinal process indicate a
huge Derbyia in the Capitan and its equivalents.
Derbyia species 2
This species is represented by a brachial and a
pedicle valve. The brachial valve is unlike any
other found in the West Texas Permian. It is
strongly alate and mucronate, the hinge being very
wide and drawn into long points. The median
region is marked by a deep sulcus that extends from
the umbo to the anterior margin, where it is deep
and causes an indentation in the anterior margin.
The ornament consists of the usual fine costellae,
but these are superimposed over numerous narrow
plications that originate on the anterior slope about
10 mm anterior to the beak. About 10 plications
appear on each side.
The pedicle valve is less well preserved than the
brachial and is not complete. It is moderately
swollen medially. The interarea is short and curved
and apparently apsacline. The median septum is
partly covered but appears to have been very long.
The specimens come from the Road Canyon
Formation at USNM 703d.
TYPES.—Described specimens: USNM 152615a, b.
Derbyia species 3
A large brachial valve 61.5 mm long by 95 mm
wide near midvalve represents a species of gigantic
proportions of which good material is yet to be
found.
STRATIGRAPHIC OCCURRENCE.—Lenox Hills Formation.
LOCALITY.—USNM 715.
TYPES.—Mentioned specimen: USNM 155029.
Nothopindax, new genus
[Greek nothos (false) + pyndax (bottom of a vessel) ]
Large, wider than long, biconvex, the pedicle
valve often subconical; hinge not equal to widest
part, which is at about midvalve; interarea long;
pseudodeltidium narrow, flattened distally and with
prominent monticulus; anterior commissure not
conspicuously folded; surface costellate, costellae
fine, crowded.
Pedicle valve interior with strong teeth and
dental ridges; apex with small triangular chamber
formed of false dental plates uniting with median
ridge that, in turn, supports spatula-like muscle
platform from ventral side.
Brachial valve interior with no chilidium but
long, slightly curved bifurcated cardinal process
with obscure dentifer, with long widely divergent
supporting plates (erismata).
TYPE-SPECIES.—Nothopindax egregius, new species.
DIAGNOSIS.—Derbyiinae having a distally free
muscle platform and small apical chamber.
COMPARISON.—The brachial valve interior of this
genus indicates relationship to Derbyia as shown by
the reduced dentifer and widely divergent supporting
plates. The myophore and shaft are actually
longer than usually seen in Derbyia and are more
like Meekella in this respect. In spite of its length
the cardinal process is more derbyoid for the reasons
first stated. The distinctive generic characters
are seen, however, in the pedicle valve.
The combination of characters in the pedicle
valve are unlike any other known genus. The presence
of a median septum and apical chamber suggest
Orthotetes, but the median septum is not
attached to the valve floor. The triangular chamber
is based posteriorly on the posterior edge or side of
the proximal part of the median septum, but the
septum is the support for a muscle platform having
the shape of a spatula, widening distally, and attached
to the anterior edge of the median septum.
This combination is unique among Derbyiacea.
DISCUSSION.—All elements of the pedicle apical
apparatus are variable. Actually no two specimens
are really alike except in gross form. The triangular
apical chamber ranges from shallow and small
to elongate and tubular, and in one specimen the
chamber is completely closed by callus deposition.
The sides of the chamber in some specimens join
the posterior edge of the septum, but in the largest
specimen the sides of the chamber attach to the
sides of the septum. The spatuloid muscle platform
varies from narrowly spatulate to distally widely
spatulate. In some specimens this plate narrows
so strongly apically that it scarcely overlaps the
sides of the septum at the apex. In another specimen
NUMBER 15 319
the plate maintains considerable width toward the
apex and widely overlaps the septum.
The muscle platform is also buttressed from
beneath in some specimens. In one it is bolstered by
a fold of the shell rising to its base and uniting
with it. In the other valves an oblique or nearly
vertical plate is built up on one side of the muscle
platform. This plate is not placed medially as
one might expect, but it is generally off center. A
single specimen shows the plate buttressed by a
pair of supporting plates symmetrically placed. In
several specimens, including the type, the muscle
platform is supported only by the median septum.
Nothopindax egregius, new species
PLATE 96: FICURES 1-14; PLATE 97: FIGURES 1-10;
PLATE 98: FIGURES 1-15
Very large, biconvex, broad to deeply conical,
relatively symmetrical to greatly distorted; shell
wall greatly but erratically undulating to very
bumpy and concentrically or irregularly ridged;
outline uneven, transversely subelliptical to nearly
semicircular; hinge between 0.65 and 0.85 total
shell width, auriculate on one or both sides in some
specimens; commissure irregular in detail, but
without consistent folding. Costellae low, rounded,
added anteriorly by insertion, not closely crowded,
numbering between 12 and 22 on brachial; growth
lines moderately strong, becoming laminae near
margins.
Pedicle valve flatly to strongly convex to deeply
conical; lateral profile convex to concave, commonly
abruptly flexed at one or several places;
interarea wide, moderately long, flat, concave or
convex, often twisted, meeting plane of commissure
near right angle, at large acute angle (projecting
forward) or small obtuse angle (apsacline
to catacline to procline); perideltidium occupying
at least half of width of interarea; pseudodeltidium
narrow, evenly expanding anteriorly, with monticulus,
strongly arched, nearly constant in width,
2 lower and gentler lateral ridges at edges of
pseudodeltidium, marking traces of forward
growth of hinge teeth. Brachial valve strongly convex,
normally not as irregular as pedicle valve,
maximum convexity near beak; umbonal and
median regions swollen; lateral slopes steep.
Pedicle valve interior with strong teeth projecting
forward from underside of interarea, extending
posteriorly along edges of pseudodeltidium as converging
dental ridges, meeting at or near apex of
valve; dental plates along posterior half of ridges
strong, converging and fusing to top of median
septum, thus producing long, narrow, shallow chambers
like that of Orthotetes. Median septum long
but low, posterior half of its upper edge braced by
dental plates, lower edge laterally widened and
flattened into a broad muscle platform; base of
muscle platform fused to valve floor near apex,
rising anteriorly free of floor except for median or
lateral bracing by adventitious plates, whose location
depends upon local undulations of valve floor;
sides of platform gently diverging from apex of
valve, suddenly widening at some distance anterior
to apex, then again widening gently, converging,
or remaining subparallel to end of septum,
there converging to form gently rounded to slightly
nasute distal end of platform. Muscle marks on
sides of median septum and on top and bottom of
muscle platform. Floor of valve bumpy, faintly
costellate, costellae stronger near edges.
Brachial valve interior with long, strong, curved
cardinal process, bifid at free end, prongs divergent,
each longitudinally slit along posterior edge, with
serrations for muscle attachment within slits, prongs
fusing posteriorly, the junction forming low median
crest of process; dentifers small, an extension projecting
slightly and bluntly into body chamber;
erismata continuous with dentifers, high, strong,
divergent into umbonal cavity, outlining posterolateral
boundaries of muscle area. Chilidium absent.
Anterior edges of muscle area obscure on all known
specimens, probably similar to that of Derbyia pannucia,
new species. Valve floor irregular, finely
costellate, costellae stronger at margins.
320 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
MEASUREMENTS
USNM 701h
151225a
151225b
151225c (holotype)
151225d
151225e
151226a
151226b
(in mm).—
pedicle
valve
length
10.5
p
31.8
43.9
80.3
71.5
78.0
brachial
valve
length
9.6
p
31.8
P
?
71.5
78.0
maximum
width
11.4
55.5
35.0
63.0?
125.0?
90.7
96.4
hinge
width
10.5
44.5
28.8
36.0?
112.9
51.8
46.5
interarea
length
8.8
26.0
24.5
20.0
46.4
20.4
29.0
thickness
13.0
26.8
30.8
?
?
60.5
67.6
STRATIGRAPHIC OCCURRENCE.—Neal Ranch Formation
(beds 9-12 of Cooper=bed 12-14 of P. B.
King).
LOCALITIES.—USNM 701a, 701h, 701k.
DIAGNOSIS.—Large Nothopindax with rough and
irregular surface.
TYPES.—Holotype: USNM 151225c; figured paratypes:
151225a, b, d-f, 151226a, c, d, e, 151227a,
b, 153468; unfigured paratypes: 151226b, d.
COMPARISON.—Nothopindax egregius is characterized
by its bumpy and irregular shell that is moderately
to strongly biconvex or deeply conical, its
wide and moderately long interarea with narrow,
triple-arched pseudodeltidium, absence of chilidium,
strong and crested cardinal process, high supporting
plates, and especially by its raised muscle platform
and the pair of short dental plates that brace the
upper edge of the median septum and form a long
but shallow camera. The platform and narrow
triple-arched pseudodeltidium distinguish the species
from all species of Derbyia; the narrow median
arch of the pseudodeltidium and the dental plates
and camera distinguish it from most species of
Derbyia.
This species differs from Orthotetella King in its
narrow median pseudodeltidial arch, raised platform,
and narrower spondylium formed by plates
that are extensions of the dental ridges rather than
by independent plates.
DISCUSSION.—The collection of N. egregius is
small, but the specimens are well preserved. The
species is rather broadly conceived and, with larger
collections, may be found to include more than one
species. All specimens are from three localities in
beds 9 to 12 (of Cooper) of the Neal Ranch Formation
in the Wolfcamp Hills. Of the three different
varieties that might be distinguished, all occur
at USNM 701h. The following characterization of
these varieties is intended to indicate the amount
and nature of known variation and to point out
what later may be considered new species. As it is,
the collection is treated as a small sample from the
population of one variable species.
Variety A. This variety contains the holotype
of N. egregius. It attains large size, has the muscle
platform gradually expanding toward its free end,
and is suddenly widened and spatulate near that
end. The support of the base of the muscle platform
is short, single, and median, or nearly so. The
shell is gently convex to conical.
Variety B. These shells are shallow to deeply
conical, relatively unwrinkled, have expansion of
the spatulate muscle platform very near the apex,
normally near the place where the platform rises
free of the valve floor. Support beneath the platform
normally is double, consisting of two short, longitudinal
lateral plates. The platform in some is
supported by one lateral plate, and an adventitious
bump in the valve floor that rises to meet the other
side of the platform. In this variety the entire septal
apparatus is proportionately shorter and broader
than in varieties A or C.
Variety C. This variety is represented by a
single pedicle valve in which the septa are proportionately
long, the muscle platform expands to its
widest near the apex of the valve and gradually
narrows toward the free end of the septum, and
the platform is supported by a plate on one side
and by a fortuitous intersection with a bump in
the floor on the other side near the free end. This
specimen may be an atypical example of variety
B, one in which the septal apparatus is exceptionally
elongate.
NUMBER 15 321
Subfamily OMBONIINAE Sokolskaya, 1960
Costellate, nonplicate Derbyiacea having dental
plates that make narrow, long spondylium in pedicle
valve, and short myophore but long supporting
plates (erismata) in brachial valve.
This subfamily at present has only the single
genus Ombonia. The cardinal process with its small
myophore but enormous erismata seems to us to be
an aberration of the Derbyiidae. Sokolskaya (1960:
218) assigns Geyerella and Orthotetes to the subfamily
evidently on the presence of spondylia, but
the spondylia and cardinal process are so different
in each genus as to deny the two genera admission
to the same subfamily. Several other genera related
to Orthotetes or having a cardinal process like that
of Meekella also have been placed here, but we
reassign Perigeyerella and Sicelia to the Meekellidae,
because of their elongated cardinal process,
and Werriea and Permorthotetes to the Derbyoidinae,
because of the short schuchertelloid cardinal
process with cuplike sockets. Orthotetella R. E.
King, in spite of its anomalous cardinal process,
is closer to Derbyia than to Ombonia. The idea
that Ombonia is related, even remotely to Orthotetes,
is entirely counter to our views because of
the differences in cardinalia and spondylia.
Genus Ombonia Caneva, 1906
Ombonia Caneva, 1906:54; 1907:438, pi. 9: figs. 6-12.—Merla,
1930:79.
Shell small to moderately large, shallow to deeply
conical; often distorted; outline transversely subelliptical
to nearly circular; hinge narrower than
midwidth; anterior commissure rectimarginate to
uniplicate; costellae fine, delicate, increasing anteriorly
by insertion, slightly more densely crowded
on brachial valve; intertroughs narrow, sharp;
growth lines faint to strong, normally only slightly
more closely spaced near margins.
Pedicle valve semiconical, evenly expanding to
attenuate, apex sharp or blunt; lateral profile normally
convex, flat, or concave in some specimens;
interarea relatively wide, short, or long, slightly
concave to slightly convex, meeting plane of commissure
near right angle or strongly apsacline; perideltidium
narrow or wide, obscurely delimited;
pseudodeltidium completely arched. Brachial valve
flatly to strongly convex, convexity even or strongest
near beak, which overhangs interarea.
Pedicle valve interior with long hinge teeth at
edges of pseudodeltidium, converging apically beneath
interarea as dental ridges, meeting at apex,
extending toward floor of valve as thin ventrally
convergent dental plates, meeting above floor to join
the median septum, which extends about to midvalve;
muscle marks faint.
Brachial valve interior with short to moderately
long, straight or slightly curved cardinal process,
bifid for short distance at free end, each branch
longitudinally slit, with serrations within slits,
branches joining to form low median crest of process,
attached end may be partly covered by small,
distinct, medially grooved chilidium, or chilidium
may be absent. Dentifers well developed, fused to
sides of process, curving along length of process
and projecting slightly ventrally below it, forming
shallow hinge sockets; erismata continuous with
dentifers, narrowly and straightly diverging into
umbonal cavity, outlining posterolateral margins
of muscle area. Muscle marks faint, within lobate
muscle area, may be subdivided by low median
ridge.
TYPE-SPECIES.—Ombonia canevai Merla (1930:80,
pi. 7: figs. 13-21).
DIAGNOSIS.—Derbyiacea with fine costellae and
without plications, having a long narrow spondylium
in the pedicle valve and a short cardinal process
with unusually long divergent erismata in the
brachial valve.
COMPARISON.—Ombonia is a very distinctive
genus with its fine even costellae, lenticular profile,
generally wide hinge, and elongated interarea.
Texas specimens seem not to be so readily distorted
as some of the related genera although the living
habits of Ombonia undoubtedly were the same as
those of most Derbyiacea. Two features of the interior
are distinctive: one of them is the spondylium,
which suggests relationship to Orthotetes,
and the other is the cardinal process, which is suggestive
of Derbyia. A number of authors have considered
Ombonia and Orthotetes to be the same
because each has a spondylium and have recommended
discarding Ombonia, which is.the younger
name. The type of spondylium of Ombonia is so
different from that of Orthotetes that confusion
seems unlikely. If it should not be conceded that
the spondylia of the two genera are unlike, the difference
in the cardinalia should dispel any doubts.
322 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
In Orthotetes the cardinalia are not provided with
supporting plates of any sort, whereas in Ombonia
the cardinalia are buttressed by widely divergent
and extremely long erismata that reach midvalve
in some specimens.
DISCUSSION.—It is important to discuss the shell
anatomy of Ombonia in some detail because of the
confusion between it and Orthotetes. Silicified specimens
of Ombonia from the Guadalupe Mountains
and Glass Mountains show the details of anatomy to
perfection and should eliminate all doubt as to the
distinctness of the two genera.
The type-species of the genus and the specimens
from Texas are distinctive externally as well as
internally. The costellae are generally low, fine,
numerously intercalcated, but large and small ones
are not usually strongly differentiated and are not
set into zones of fine ones bounded by thick ones.
The shell itself is generally well proportioned and
not usually greatly distorted, having a broadly
elliptical outline and conical profile. It is probable
that Ombonia lived the early part of its life attached,
and thus some specimens were subject to
distortion. The interarea of the attached shells is
considerably elongated and twisted in some fashion.
Such specimens are not common in the Texas
material.
The interarea is usually long, generally flat, but
some specimens have this feature concave or slightly
convex. The perideltidium is usually well developed
and strongly marked by vertical striae. The pseudodeltidium
commonly is strongly arched and usually
has a depressed median line that corresponds to the
gap in the chilidium, exactly opposite to the monticulus
of Meekella. This gap produces a sag in the
anterior edge of the pseudodeltidium at a point
where it makes contact with the chilidium. This is
a feature common in Derbyia.
Inside the pedicle valve the spondylium is very
distinctive. It is narrowly like that of Geyerella and
its general construction is similar. The dental plates
buttress the sharp and long teeth as dental ridges,
which expand posteriorly to form thin and delicate
dental plates. These converge rapidly to form a V,
which is attached to a low, delicate median septum,
producing a Y-shaped cross section. Anteriorly this
slopes rapidly to the valve floor and is not continued
anteriorly. Ombonia invecta, new species, has a
spondylium that does not reach to midvalve, but
that of O. guadalupensis (Girty) reaches about to
midvalve in adults.
The spondylium is variable in the height of the
median septum, in the width of the V-shaped chamber
and the amount of recession of the dental plates.
The anterior edges of the dental plates are generally
concave toward the apex, strongly in O.
guadalupensis, but less so in the Glass Mountain
species. In the species from the Getaway Member
the median septum is very low and some of the
spondylia seem almost to rest on the valve floor.
A sufficiently large number of juveniles has not
yet been found to determine definitely at what stage
the dental plates form the spondylium. One specimen
of O. invecta, only 3 mm long, appears to have
a sessile spondylium, but a juvenile of O. guadalupensis,
5 mm long, has a well-formed spondylium.
We have not found muscle scars around the base
of the spondylium on the valve floor, and muscle
marks in the spondylium are obscure. To what
muscles these should be assigned is a matter of
conjecture.
Inside the brachial valve the cardinal process and
associated structures are as characteristic of Ombonia
as is the spondylium. The chilidium is a
prominent bilobed structure forming two narrowly
convex lateral lobes with a deep groove between.
These lie over the posterodorsal or proximal extremities
of the myophore and are firmly strengthened
by a lateral extension that covers the interarea
and is anchored on the sloping outer face of
the myophore. Like the Derbyiidae the myophore
is forked, the two prongs divergent, but usually
not widely so. The cleft between the lobes is usually
short. Each lobe is slit and the sides of the slit are
crenulated as usual. The surprising fact about the
myophore is its brevity, because it does not protrude
into the valve as far as the ends of the dentifers,
yet Ombonia is a relatively deep shell.
Anterior to the myophore for a short distance
occurs a narrow ridge or fold on the long sloping
outer face of the cardinal process, which is the
upper surface of the dentifer and which, at the
same time, helps to define the socket. This ridge
is compared to the promontorium of the elaborate
cardinal process of Meekella. In Ombonia this ridge
is never so greatly developed as in Meekella. Anterior
to the dentifer is another ridge, which in this
genus is unusually protuberant. Furthermore, an
NUMBER 15 323
anterior line can be discerned running across the
sloping face of the cardinal process. This line and
the dentifer are equivalent to the brachiophore and
make a broad, flat blade. Anterior to the lower
defining line of the brachiophore is the long sloping
face of the supporting plate. The erismata are
slender but strong and are divergent in different
degrees, depending on the species, but are constant
within limits. These buttress plates define the large
adductor field, but individual scars have not yet
been identified in the genus. A rudimentary myophragm
appears at the middle of this region in
some specimens, but it is not a constant or important
feature.
A final feature of the brachial valve is seen along
the hinge, a narrow interarea that usually does protrude
when the valves are articulated. It is not
concave and thus is probably not a ginglymus.
Anterior to the interarea on the inside of some
specimens is a narrow parallel groove bounded by
a low ridge. In old shells this becomes a broad,
flat thickening that helps to strengthen the hinge
region.
In the Guadalupe Mountains Ombonia is commonest
in the debris from reefs and in calcarenites.
The shells in the Capitan Formation are usually
single valves, but a small percentage of specimens
can be recovered with both valves in contact. In
the acid residues of the Capitan equivalents, Lamar
and Rader limestones, the genus has not yet been
taken with both valves in contact. These members
are thought by some geologists to represent slide
from the reefs. Consequently, considerable breakage
and separation of valves is to be expected. No
direct evidence on the life habits of Ombonia has
been seen, but no reason is apparent that they lived
in a manner unlike that of the other Derbyiidae.
Slightly distorted beaks, thinned beak regions, and
noncostellate patches on the umbonal region of the
pedical valve all point to attachment. Probably
early attachment and later freedom, as in many
species of Derbyia, was the usual habit.
Greco (1942:146), Licharew, and other authors
regarded Ombonia and Orthotetes as synonyms.
Their arguments were based on the fact that the
two genera share in common a spondylium that is
an unusual structure in these brachipods. These
authors did not consider the unlike character of the
spondylia of the two genera as important, nor did
they consider the great differences in the cardinal
processes. The latter structure long has been overlooked
in the taxonomy of these difficult shells,
but it has been brought into notice by G. A.
Thomas (1958:12), who suggests its great importance
in the Orthotetacea as well as in other major
groups, where it has been more successfully used.
The rich fauna of the Sosio Limestone in
Palermo Province, Sicily, includes many types of
Orthotetacea, including some forms referred to
Ombonia. These are robust species, usually with
somewhat distorted beaks and showing evidence of
attachment in a reefy environment. These long
beaked forms have a greatly elongated cardinal
process entirely different in type from that of
Ombonia, and only a modest development of the
supporting plates is indicated. It is probable that
these forms represent a different development of
Ombonia from an entirely different stock and are
probably an aberration of Sicelia. They conform
well to Wang's (1955:346) genus Perigeyerella.
Ombonia occurs in the Cherry Canyon and Bell
Canyon formations. In the former it has been taken
from the Getaway Member, but it appears to be
very rare and the few specimens in the national
collection are not sufficient for the establishment of
a species, although clear differences from O. guadalupensis
(Girty) and O. invecta, new species, are
indicated. Ombonia is abundant in many parts of
the Capitan limestone and is rare in the Rader but
common in the Lamar Member of the Bell Canyon
Formation.
In the Glass Mountains, Ombonia is one of the
rarest of prizes, having been found only in a Road
Canyon lens taken at the base of the Word Formation
about 25 feet above the main part of the
Road Canyon Formation in Gilliland Canyon and
in one place in the Sierra del Norte. In the Road
Canyon it occurs with Geyerella, an association that
made separation of the two genera very difficult. At
USNM 720d it is heavily coated with a possible
algal smear. Other associates of Ombonia in this
lens suggest relationship with the Road Canyon
fauna rather than with the Word above.
Ombonia guadalupensis (Girty)
PLATE 90: FIGURES 1-33; PLATE 91: FIGURES 1-16;
PLATE 92: FIGURES 26-38
Orthotetes guadalupensis Girty, 1909:199, pi. 10: figs. 1-5.
Orthotetes declivis Girty, 1909:200, pi. 10: figs. 6-8a.
324 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
Shell usually small, shallow to deeply conical,
symmetrical to slightly distorted; outline transversely
subelliptical to subquadrate; hinge slightly
narrower than midwidth; sides rounded; commissure
normally broadly uniplicate. Costellae low,
fine, numbering between 15 and 25 in 5 mm, averaging
about 21 on pedicle valve and about 22 on
brachial; intertroughs narrow; growth lines faint,
visible only near margins.
Pedicle valve evenly expanding to attenuated,
beak usually sharp, more rarely blunt; lateral profile
normally gently convex, often flexed; anterior
profile broadly to flatly convex; interarea moderately
wide, short to long, slightly concave to slightly
convex, usually flat, apsacline; perideltidium obscure,
less than half width of interarea at hinge;
pseudodeltidium completely arched, with shallow
median groove anterior with short tongue in folded
specimens.
Brachial valve flatly to strongly but evenly convex,
without prominent or overhanging beak;
median region swollen; young adults flattened anteromedially,
but old shells with obscure fold.
Pedicle valve interior with long pointed teeth
projecting forward from underside of interarea,
extending posteriorly as sharp convergent dental
ridges, meeting at apex of valve, and extending
anteriorly as convergent dental plates, meeting the
median septum to produce a long, narrow triangular
spondylium reaching to nearly midvalve;
anterior edges of dental plates curved forming
apically curved arc; muscle marks faint striae
within spondylium. Floor of valve weakly costellate,
costellae stronger marginally.
Brachial valve interior with short, slightly curved
cardinal process having a shallow bifurcation at
free end, each branch longitudinally slit, with minute
serrations within slits; branches of process
joining to form low crest with median groove
along most of length; attached end embossed with
small but distinct bilobed chilidium; dentifers
fused to sides of process, projecting in nearly same
direction as branches of process, only slightly more
anteriorly; erismata long, narrowly and straightly
diverging into umbonal arch of valve, bordering
posterior of muscle area. Muscle marks faint, within
anteriorly curved, weakly impressed muscle area,
bisected by a low median ridge in some specimens.
Valve floor weakly costellate, costellae stronger
near margins.
MEASUREMENTS
USGS 2926
118502a (lectotype)
118502b
USNM 737a
147757a
USNM 750
147763a
147763b
AMNH 430
151005
AMNH 389
152607
(in mm).—
pedicle
valve
length
15.8
16.4
27.2
17.6
12.9
23.9
?
brachial
valve
length
14.2
15.0
22.5
15.5
11.0
?
24.1
maximum
width
19.6
18.6
33.0
20.2
14.3
30.0
32.1
hinge
width
12.6
12.6
20.1
15.2
10.7
22.8
25.1
interarea
length
7.3
9.3
8.8?
9.4
12.0?
9.8
?
thickness
11.3
13.3
16.3
17.0
15.7?
9.6
9.8
STRATIGRAPHIC OCCURRENCE.—Capitan Formation,
Bell Canyon Formation (Lamar Member).
LOCALITIES.—Capitan: AMNH 725, USGS 2926,
USNM 725g, 725p, 737a, 750; Lamar: AMNH L-2,
L-3, L-6, 25, 37, 38, 39, 40, 347, 348, 389, 430,
USNM 725e, 728i, 728p, 728q, 738, 738b.
DIAGNOSIS.—Moderately large Ombonia with
very fine costellae, generally symmetrical shells and
long narrow spondylium.
TYPES.—Holotype: USNM 118502a; unfigured
paratype: 118502b; figured hypotypes: 150996a, f,
150997a, -1 151000a, 151003a, b, 151005, 152607,
153478a—i, 153552a, b; measured hypotypes:
147757a, 147763a, b, 150996b-e, 151005, 152607.
Ombonia guadalupensis differs from "Ombonia"
NUMBER 15 325
magna Greco (1942:147) from the Sosio Limestone
of Sicily in its smaller and less distorted shell, shallower
and sharper pedicle valve, much weaker
growth lines, and completely arched pseudodeltidium
that accommodates a chilidium. The Sicilian
species is more coarsely ornamented, deeper,
and lacks a chilidium because of the very narrow
median arch of its pseudodeltidium. As noted
above, these two may be generically distinct.
Ombonia invecta, new species
PLATE 35: FICURES 1-17; PLATE 62: FIGURES 3, 4
Usual size for genus, broadly elliptical in outline,
elongate conical in profile; hinge narrower
than maximum width, which is at midvalve; sides
rounded; anterior margin broadly rounded to
slightly flattened; anterior commissure rectimarginate.
Surface costellate, costellae low, flatly
rounded, and closely crowded, appearing by intercalation
in several generations, about 20 in 5 mm
at 10 mm anterior to beak and 18 at anterior margin
of adult brachial valves.
Pedicle valve triangular in lateral profile, interarea
and ventral side forming acute angle with long
side of angle faintly concave or flat; anterior profile
broadly and gently rounded; interarea long,
varying from slightly concave to slightly convex,
procline to apsacline; perideltidial area prominent,
width greater than half width between pseudodeltidium
and valve edge; pseudodeltidium with slight
median groove, narrow, and strongly convex. Umbonal
region flattened; median region usually flattened
to concave. Lateral slopes rounded.
Brachial valve evenly and moderately convex in
lateral profile, broadly domed in anterior profile,
sides moderately steep; median region strongly
swollen with moderately steep umbonal and lateral
slopes; anterior slope moderately steep.
Pedicle valve interior with receding dental plates
forming short narrow spondylium with short median
septum not reaching midvalve.
Brachial valve interior with small bilobed chilidium;
myophore lobes short, slightly convex anteriorly,
with short cleft; dentifers broad and flat,
bounding small socket; erismata diverging at about
60° and extending about one-third valve length.
Muscle marks not impressed.
MEASUREMENTS
USNM 720d
150995a (holotype)
150995b
150995c
150995d
150995e
150995f
150995g
(in mm).—
pedicle
valve
length
15.8
12.8
11.0
12.5
p
p
p
brachial
valve
length
p
p
j
p
15.2
14.4
11.0
maximum
width
19.4
17.2
14.6
13.9
22.4
18.6
14.1
hinge
width
14.0
10.9
11.5
8.8
19.0
15.5
9.8
interarea
length
13.3
9.0
8.2
6.5
?
p
?
thickness
13.3
8.7
8.5
5.8
6.5
3.9
3.8
STRATIGRAPHIC OCCURRENCE.—Road Canyon Formation
(lens 25 feet above Road Canyon limestones
and ammonite bed).
LOCALITY.—USNM 720d, 737n.
DIAGNOSIS.—Broadly elliptical Ombonia with
predominantly long interarea and short narrow
spondylium.
TYPES.—Holotype: USNM 150995a; figured paratypes:
150995d, e, i-m; measured paratypes:
150995b-g; unfigured paratypes: 150995b, c, f-h.
COMPARISON.—This species attains approximately
the same size as O. guadalupensis, but it differs in
having generally a longer interarea, yet, at the
same time, a shorter spondylium, the median septum
of which does not reach midvalve. The costellae
appear to be slightly stronger than those of
specimens from the Guadalupe region, but they
are partly obscured on the specimens available and
the counts are not entirely satisfactory.
DISCUSSION.—Like all of the other interesting
species occurring in the blocks at this locality, the
shells are covered by a siliceous crust. This has a
sort of pattern that leads to the belief that the
crust may have been an algal deposit of some sort.
The crust covers either or both sides, obscuring
many details. Fortunately, sufficient specimens were
326 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
recovered to exhibit most of the details of the species,
but making satisfactory photographs of them
was difficult.
The significant feature of this species is the
brevity of its spondylium. This is a delicate structure,
very narrow, and attached to a short median
septum, which is short both dorsoventrally and in
the valve length. In the young the spondylium has
a very low septum, and it is possible that early
juveniles have the spondylium sessile. The anterior
edge of the spondylium is generally straight,
rather than concave posteriorly, as in O. guadalupensis.
The pseudodeltidium is definitely grooved medially,
which is a response to the bilobed chilidium
and is a feature characteristic of Derbyia and its
allies. The brachial valve presents no unusual features,
but the brachiophore is generally very well
marked and strongly protuberant.
This species is rare in the Glass Mountains,
where it is associated with species characteristic of
the Road Canyon Formation, although the lens
from which the specimens were taken occurs about
25 feet above the top of that formation.
Ombonia species 1
PLATE 90: FIGURES 34-41
A third species of Ombonia is indicated by fragmentary
specimens from the lower Getaway Member
of the Cherry Canyon Formation at USNM 732.
Of the 16 valves (11 of them brachial valves)
available for study, not one is complete enough to
get more than a general idea of the species. It is
roundly elliptical in outline with a strongly conical
pedicle valve, having a long interarea, and with a
wide perideltidial region and a broad, sulcate pseudodeltidium.
The teeth are short inside the pedicle
valve, but the spondylium is fairly wide (5 mm
in a specimen 32 mm wide) with sides moderately
concave posteriorly. The median septum is very
low and short, not extending anterior to the spondylium.
The brachial valves do not present any structural
peculiarities, but their features are well marked
because the shells are fairly thick. The dentifer in
one specimen is unusually long. On the exterior
the costellae appear coarser than the other two
species, and on one brachial valve stronger costellae
are intercalated among the finer ones.
MEASUREMENTS (in mm).—USNM 147758a (pedicle
valve): length 22.0, maximum width 32.0*,
hinge width 22.0, interarea length 11.0, thickness
9.0; USNM 147758b (brachial valve): length 14.6,
maximum width 21.8, hinge width 20.0*?, thickness
4.7.
TYPES.—Figured specimens: USNM 147758a-c.
Family STREPTORHYNCHIDAE Stehli, 1954
Derbyiacea without dental plates or septum in
pedicle valve but with cardinal process having erismata.
Exterior costellate, costate or both.
Most species formerly referred to Streptorhynchus
are now placed in different categories. Genera recognized
in the Glass Mountains are: Chelononia,
new genus; Bothrostegium, new genus; and Tropidelasma
Cooper and Grant, 1969.
Genus Streptorhynchus King, 1850
PLATE 40: FIGURE 1
Small, subconical, usually broadly sulcate, outline
subelliptical, weakly to strongly costellate,
with strong fila and well-marked growth lines;
hinge narrower than greatest width; pedicle valve
interior devoid of dental plates or septa, teeth
projecting forward from underside of interarea and
continuing posteriorly toward apex as dental
ridges flanking interior of pseudodeltidium; muscle
marks normally obscure.
Brachial valve nearly flat to strongly convex,
interarea short, not usually well marked; interior
with strong cardinal process, notched or bifurcate
distally, with 2 lobes longitudinally slit along posterior,
which bear minute serrations; erismata fused
to underside of cardinal process, forming inner surface
for deep, circular, or slotlike sockets; lateral
ends of dentifers fused to posterior wall of valve,
producing shallow socket just inside hinge line.
TYPE-SPECIES.—Terebratulites pelargonatus Schlotheim
(1816:28-29, pi. 8: figs. 21-24).
TYPES.—Figured specimen: YPM 27901.
DISCUSSION.—Streptorhynchus is distinguished
from Diplanus Stehli (1954) by its different and
more regular ornament, weaker growth lamellae,
lack of well-developed brachial interarea and pitted
umbo, smaller hinge teeth, unthickened lateral interior
parts of pedicle interarea, much narrower
median arch in pseudodeltidium, and by the small
flanking arches of pseudodeltidium that mark the
NUMBER 15 327
paths of forward growth of the hinge teeth. Normally
the shell of Streptorhynchus is thinner than
that of Diplanus. Diplanus has no development of
erismata.
Streptorhynchus differs from Kiangsiella Grabau
and Chao (1927), which also is devoid of internal
plates, by the lack of plications in the shell.
We have not seen any specimens in the Glass
Mountains or Guadalupe Mountains that conform
precisely to the generic diagnosis of Streptorhynchus,
perhaps because all of these American localities
are older than the Upper Permian (Zechstein)
in which the type-species occurs.
Streptorhynchus perattenuatum Girty
See Tropidelasma perattenuatum.
Streptorhynchus gregarium Girty
See Tropidelasma gregarium.
Streptorhynchus undulatum R. E. King
See Tropidelasma undulatum.
Chelononia, new genus
Medium size, pyramidal, pedicle valve elongated;
flatly convex to slightly concave in profile; hinge
narrower than greatest width near midvalve; auriculate;
pseudodeltidium strongly arched, brachial
valve strongly convex, and not medially depressed;
chilidium short; anterior commissure faintly sulcate.
No brachial valve interarea. Surface marked
by costellae of unequal size crossed by fine concentric
fila.
Pedicle valve interior without dental plates;
teeth long and slender; dental ridges not greatly
thickened. Muscle field lightly impressed.
Brachial valve interior with large forked cardinal
process supported by long, strong erismata. Dentifer
a small ridge forming the inner socket wall;
erismata forming blunt points extending anterolaterally;
muscle field thickened and with a thick,
low myophragm.
TYPE-SPECIES.—Chelononia neali, new species.
DIAGNOSIS.—Elongate Streptorhynchidae.
COMPARISON.—This genus is distinguished at
once from Streptorhynchus (sensu stricto) by its
elongate pedicle valve and auriculate cardinal extremities.
Externally it is like Tropidelasma in
having an elongated pedicle valve, but it differs in
the type of pseudodeltidium, which is flat in Tropidelasma.
The cardinal process of Chelononia is
different in having a more prominent dentifer and
more elaborate erismata.
DISCUSSION.—This genus is rare in the Glass
Mountains but one locality, USNM 727e, yielded a
fair number of specimens. The elongate form and
auriculate cardinal extremities are its chief exterior
marks. The pseudodeltidium is strongly rounded
from the margin of the delthyrium and thus unlike
that of Tropidelasma. The chilidium is similar to
that in other Permian Orthotetidina in having a
narrow space between it and the shell body. In
Chelononia the chilidium does not affect the form
and shape of the pseudodeltidium.
The cardinal process is the most conspicuous interior
feature of the brachial valve. It is not as
ponderous as that of Meekella, but it is long and
strong with well-developed erismata, much more so
than in Streptorhynchus. The socket is formed by
the ridgelike dentifer, which is located on the long
sloping side of the erisma. No fulcral plate is present
in Chelononia. The erismata are bluntly
pointed just anterior to the dentifer and probably
serve the same purpose as the crura in the rhynchonellids
to attach the body wall. The myophores
are slits in the ends of the moderately divergent
orongs of the cardinal process.
This genus has been seen only in the Neal Ranch
Formation.
Chelononia neali, new species
PLATE 126: FIGURES 1-47
Large for genus, outline triangular, length
slightly greater than width. Maximum width anterior
to midvalve; sides variable; posterolateral
part nearly straight but anterolateral part narrowly
rounded. Hinge narrow, about half width of large
specimens; cardinal extremities slightly auriculate.
Interarea apsacline, fairly long but narrow, generally
flat; pseudodeltidium narrow, moderately
arched. Anterior commissure broadly and gently
sulcate. Surface costellate, costellae low, usually
alternating strong and fine; 11 costellae in 5 mm
at front margin of holotype; 12 in same distance
at front of specimen 19 mm long.
328 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
Pedicle valve faintly convex to nearly flat in lateral
profile; anterior profile a broad gentle arch
with moderately steep sides. Beak ridges sharp,
strongly overhanging posterolateral margins. Umbonal
region slightly swollen medially to margin
where faint suggestion of ventrad folding can be
detected. Flanks slightly swollen, sides falling off
abruptly and steeply.
Brachial valve evenly and moderately convex in
lateral profile, broadly convex in anterior profile
with median depression at the top of dome. Posterolateral
extremities deflected to form small ears;
umbonal region fairly strongly swollen. Sulcus
originating on umbo deepening and widening to
anterior margin.
Pedicle valve interior with long, thick, narrow
teeth, dental ridges, low but strong. Diductor field
narrowly flabellate.
Brachial valve interior with chilidium modified;
cardinal process long-shafted with myophore prongs
well separated but subparallel or slightly divergent.
Sockets wide, bounded internally by dentifers; cardinal
process buttressed by strong erismata. Adductor
field deeply entrenched, heart-shaped, myophragm
low.
MEASUREMENTS
USNM 727e
152646a
152646b
152646c
152646d
152646e
152646f (holotype)
(in mm).—
pedicle
valve
length
10.8
14.1
14.5
18.8
20.8
24.6+
brachial
valve
length
8.6
12.0
12.5
15.3
17.0
20.0
maximum
width
9.0
12.6
14.0
16.5
19.8
24.0
hinge
width
5.1
8.0
8.3
9.8
10.7
33.0?
interarea
length
3.2
4.0
3.2
4.4
6.4
8.4
thickness
4.3
5.0
7.2
8.2
10.7
12.2
STRATIGRAPHIC OCCURRENCE.—Neal Ranch Formation
(beds 2 and 4).
LOCALITIES.—Bed 2: USNM 701; bed 4: 727e.
DIAGNOSIS.—Large Chelononia with hinge
slightly more than half the maximum width.
TYPES.—Holotype: USNM 152646f; figured paratypes:
152646a, b, d, e, g—m; measured paratypes:
152646a-e; unfigured paratypes 152646c.
COMPARISON.—This species suggests Chelononia
straminea, new species (—Streptorhynchus pyramidale
R. E. King; not Newberry, 1861) but its
interarea is much shorter, the costellae are not so
crowded, and the proportions are entirely different.
DISCUSSION.—Two features of considerable interest
in this species are the development of the chilidium
and the nature of the dentifer as defined
herein. The chilidium in young shells is divided
into two parts, each consisting of a narrow arch
on each side- of the midpoint of the hinge and
separated by a narrow groove. As growth proceeds
in a ventrad direction, the chilidial plates grow
out over the cardinal process shaft for a considerable
distance and the ventrad face is inserted
against the distal interior face of the pseudodeltidium.
The part of the chilidium growing over
the cardinal process shaft is smooth because in
opening and closing of the shell the surfaces moved
against one another. The chilidium grows ventrally
for a considerable distance and forms a thick
boss at the posterior that tapers anteriorly along
the cardinal process shaft. The depression between
the two branches is never obliterated and leads to
the cleft between the myophore prongs. On the
exterior the chilidium retains its concentrically layered
appearance, but it may be deeply inset because
of posterior shell growth over the inner surface.
In such cases the expanded chilidium overhangs
the hinge, and a deep gap appears between
the hinge line and the chilidium. The deep groove
in the chilidium appears not to affect the pseudodeltidium,
which is moderately and smoothly
arched without the median groove seen in some of
the derbyias and Bothrostegium.
The dentifer as defined herein is unusually well
developed in this species. It appears as a strong
oblique ridge located on the flank of the cardinal
process and buttressed by the erisma. This plate
forms the inside of the socket against which the
outside of the tooth rested. Additional articulation
in the older specimens was provided by a
NUMBER 15 329
growth of adventitious shell from the distal edge
of the chilidial plate growing laterally and joining
the hinge across the proximal end of the socket.
The erisma is strongly developed in this species,
and an extension of it protrudes anterolateral^ to
give the appearance of a brachial process as it
would probably be interpreted.
The species is named for Bill Neal, owner of the
Bill Neal Ranch and proud possessor of the type
sections of the Wolfcamp Series and the Neal
Ranch Formation.
Chelononia straminea, new species
PLATE 95: FIGURES 1-22
Streptorhynchus pyramidale R. E. King, 1931:50, pi. 4:
figs. 7-9 (not fig. 10) [not Streptorhynchus pyramidalis
Newberry, J. S., 1861:126, pi. 2: figs. 11-13].
Elongate, flatly conical, rectimarginate to slightly
sulcate; outline lyre-shaped, with growth of flared
hinge producing acute beak ridge along pedicle
valve edge; valves unequally convex but subequal
in depth; costellae strong, fasciculate, interrupted
by prominent growth laminae widely and evenly
spaced over anterior three-fourths of shell. Hinge
from one-third to one-half total width of shell.
Costellae numbering 8-10 in 5 mm at anterior
margin.
Pedicle valve flattened, with extremely long triangular
interarea bisected by wide and high arched
pseudodeltidium, about one-fourth as wide as interarea;
interarea making gentle angle with plane
of commissure slightly apsacline. Brachial valve
with greatest convexity near beak, hinge flaring and
auriculate as on pedicle valve; sulcus shallow, wide,
originating posterior to midvalve.
Pedicle valve interior broadly concave and shallow;
teeth long, strong, projecting forward from
underside of interarea, forming strong dental ridges
along delthyrial edge. Muscle marks faint, elongate,
lobate, occupying low depression or callosity on
floor and sides of valve, bisected by low myophragm;
adductor marks lobate, straddling myophragm;
diductor marks longitudinally striate,
extending up onto sides of narrow beak cavity.
Brachial valve interior with short, stout, bifid
cardinal process, each prong longitudinally slit
and with fine serrations lining edges of slit; dentifers
narrow ridges defining wide hinge sockets;
erismata extending short distance along sides of
valve, outlining posterolateral margins of muscle
area. Muscle area bilobate, excavate, divided by
low myophragm, each scalloped at edges, with pallial
marks extending radially from them as grooves
and ridges.
MEASUREMENTS
USNM 701 d
147883a
147883b
147883c
147884
147885
(in mm).—
pedicle
valve
length
38.9
41.0 +
31.0
41.3
?
brachial
valve
length
p
22.0
17.8
24.4
20.2
maximum
width
16.5
25.6*
19.2
22.0
24.0
hinge
width
11.3
11.4
8.8
14.4
12.9
interarea
length
21.0
19.6+
14.8
19.6
?
thickness
11.6
18.7
12.3
17.6
9.0
STRATIGRAPHIC OCCURRENCE.—Neal Ranch Formation
(beds 2, 9-14 of P. B. King).
LOCALITIES.—R. E. King 93; USNM 701d, 701h.
DIAGNOSIS.—Chelononia with exceptionally long
pedicle valve.
TYPES.—Holotype: YPM 11392a; figured paratypes:
YPM 11392b, c; figured hypotypes: USNM
147883b, c, 147884.
COMPARISON.—Chelononia straminea is characterized
by its thatchlike ornamentation, lyre-shaped
outline, and by the flange along the pedicle beak
that is produced by forward growth of the flaring
hinge. This is the only species in the Glass Mountains
that has a narrow median sulcus, although
Tropidelasma culmenatum Cooper and Grant may
have a broad and shallow sulcus. The pedicle valve
of C. straminea is a flat cone with a very gentle,
obtuse angle between the plane of commissure and
the interarea. It is similar in this respect to Streptorhynchus
pelargonatum (Schlotheim), the typespecies
of that genus, from which C. straminea may
330 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
be distinguished by its great length, ornament, and
flaring hinge.
Chelononia straminea differs from C. neali in
having a much more elongated pedicle valve.
DISCUSSION.—Chelononia straminea is rare in the
Glass Mountains. It has been found only at three
localities; however, it is very distinctive, and cannot
be confused with other species.
R. E. King (1931:50) declared that the shell is
very thick. Our specimens were prepared by treatment
in acid and may not show the true thickness
of shell throughout, probably because of incomplete
silicification. King's specimen of a brachial
valve (1931, pi. 4: fig. 7) is completely silicified and
quite thick. Our description of the muscle area in
the brachial interior is based largely on study of
that specimen.
Aside from differences in size and proportion
that are due to growth, this species varies within
rather narrow limits, in comparison with variation
in other species of Derbyiacea from this area. The
beak of the pedicle valve is regular and undistorted
in some individuals, but it is slightly bent or
twisted laterally or dorsally in others. Its length
is variable, ranging from a blunt point to a long
and narrow projection, with the proportions mentioned
in the description of the species. The brachial
valve varies but little, mostly in the depth
of the median sulcus, which never is very deep.
Bothrostegium, new genus
[Greek bothros (trench) + stegion (roof, dim) ]
Small, commonly attached Derbyiacea having
conical pedicle valve and brachial valve of varying
convexity, usually low. Anterior commissure usually
slightly sulcate or rectimarginate. Pedicle valve
interarea usually apsacline but varying to procline;
pseudodeltidium large and convex, marked by impressed
line along middle. Surface finely costellate;
growth lamellae usually distant.
Pedicle valve interior with large, thick teeth but
low, thick dental ridges. No other features developed.
Brachial valve with large well-developed chilidium
with median cleft occupied by narrow ridge
on underside of pseudodeltidium. Cardinal process
with deeply incised, usually short prongs; dentifer
short, erismata short. Adductor field subcircular,
short ridge or boss at anteromedian extremity.
TYPE-SPECIES.—Bothrostegium derbyoideum, new
species.
DIAGNOSIS.—Small S t r e p t o r h y n c h i d a e with
grooved pseudodeltidium and large chilidium.
COMPARISON.—This genus is essentially a Derbyia
without dental plates. The cardinalia are like
those of Derbyia except that they have only short
erismata. The pseudodeltidium, with its impressed
groove down the middle, is like that of Derbyia.
The genus differs from Streptorhynchus, which it
resembles in size and outline, by the presence of
the impressed line on the pseudodeltidium and a
more prominently developed chilidium. In size and
general form, Bothrostegium is like Diplanus, but
that genus is lamellose and has a much longer interarea
on the brachial valve but no impressed line
on the pseudodeltidium. Internally the cardinalia
are unlike those of Diplanus in having laterally extended
erismata like those of Streptorhynchus.
DISCUSSION.—The chief feature of interest in the
pedicle valve of this genus is the pseudodeltidium,
which is so much like that of Derbyia, with an
impressed line along the crest. The line is caused
by an indentation in the median part of the chilidium
into which the pseudodeltidium grows in
the younger stages. As the pseudodeltidium grows,
so also does this slight trough, which is expressed
as a ridge under the small depression in the top.
The brachial valve of Bothrostegium does not develop
like that of Diplanus, although they have
much in common. In the latter, the chilidium is
advanced in a ventrad direction along with the interarea
as the shell enlarges. In Bothrostegium, this
does not take place; consequently, the interarea
remains very short while the chilidium grows dorsally
to adapt to the expanding shell. The cardinal
process is built against the inside of the chilidium.
As the chilidium grows, its central cleft deepens
and this becomes reflected in the median trough of
the pseudodeltidium of the opposite valve. In
Diplanus, on the other hand, the groove in the
chilidium is not deepened, and, in many cases, it
is less pronounced in the late stages of adult growth.
Bothrostegium compactum, new species
PLATE 62: FIGURES 22-36
Small, thick shelled, elongate rectangular in outline,
pedicle valve flattened, misshapen, conical,
NUMBER 15 331
brachial valve transversely subrectangular; hinge
wide, nearly equal to maximum width (near midvalve
or slightly anterior to it); sides gently
rounded; anterolateral extremities narrowly
rounded; anterior broadly convex to faintly
emarginate. Interarea long, generally flat, occasionally
convex, apsacline, strongly convex wide
pseudodeltidium marked medially by impressed
line. Surface finely costellate, growth lamellae distant.
Pedicle valve triangular in lateral profile, long
side usually flat but also weakly convex to faintly
concave. Anterior profile broadly and gently convex.
Umbonal region usually convex, commonly
narrowed and passing into broadly flattened to
slightly convex median region; lateral slopes short
but very steep.
Brachial valve evenly and gently convex in lateral
profile, broadly, evenly, and moderately convex
in anterior profile; umbonal region scarcely
swollen; median region moderately inflated with
short anterior and lateral slopes. Sulcus shallow,
narrow, poorly defined, originating near midvalve.
Pedicle valve interior with long, thick teeth but
low, thick dental ridges. Pseudodeltidium strengthened
medially by a thickening on inner, concave
surface. Muscle region not defined; no myophragm
developed.
Brachial valve interior with short, thick cardinalia;
chilidium well developed, medially divided;
cardinal process with short prongs deeply incised.
Dentifer narrow. Adductor field small, deep, circular,
anterior median myophragm thick.
MEASUREMENTS (in mm).—
152599a
152599b (holotype)
152599c
152599d
152599e
152599f
152599g
152599h
pedicle
valve
length
7.8
8.7
8.7
7.8
?
?
?
p
brachial
valve
length
p
p
?
p
6.8
5.6
4.8
4.0
maximum
width
7.5
8.1
7.3
6.1
8.2
5.9
6.4
5.5
hinge
width
7.5
7.9
6.4
5.0
6.4
6.0
6.0
5.0
interarea
length
4.5
4.7
3.4
3.3
?
?
p
p
thickness
3.7
4.3
3.2
3.2
2.5
1.9
1.9
1.4
STRATIGRAPHIC OCCURRENCE.—Road Canyon Formation.
LOCALITY.—USNM 703c.
DIAGNOSIS.—Small, thick-shelled, compressed, conical
Bothrostegium.
TYPES.—Holotype: USNM 152599b; figured paratypes:
152599a, e, i, j ; measured paratypes 152599c,
d, f-h.
COMPARISON.—This species is thicker shelled,
smaller, and more compressed than B. derbyoideum,
new species. It is intermediate in size between
the latter and B. pusillum, new species, but
it is larger, more uniform, as regards the interarea,
possesses a ridge or boss anterior to the adductor
field in the brachial valve, and the cardinalia are
not so strongly compressed laterally as those of
B. pusillum.
Bothrostegium derbyoideum, new species
PLATE 62: FIGURES 5-14; PLATE 63: FIGURES 1-46
Small in size but fairly large for genus, variable,
adults usually longer than wide but juveniles wider
than long. Pedicle valve subcorneal; brachial valve
usually moderately to flatly convex; hinge approximately
equal to midwidth or slightly alate; sides
gently rounded; anterior broadly rounded. Anterior
commissure faintly to moderately sulcate.
Interarea broad, long, usually apsacline but varying
to procline; usually flat but occasionally curved
and with fairly strongly convex pseudodeltidium
bearing median impressed line. Surface finely
costellate; growth lamellae distant.
Pedicle valve triangular in profile, long side flat
to slightly concave; anterior profile broadly but
moderately convex, usually slightly humped medially.
Umbonal and median regions longitudinally
swollen; lateral slopes steep; cardinal extremities
slightly deflected.
Brachial valve gently convex in lateral profile and
most convex in umbonal region; anterior profile
332 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
broadly and gently convex. Umbonal region gently
swollen; median region forming shallow and poorly
defined sulcus that produces a broad ventrad wave
of anterior commissure. Cardinal extremities somewhat
flattended. Posterolateral slopes short and
gentle.
Brachial valve gently convex in lateral profile
and most convex in umbonal region; anterior profile
broadly and gently convex. Umbonal region
gently swollen; median region forming shallow and
poorly defined sulcus that produces a broad ventral
wave of anterior commissure. Cardinal extremities
somewhat flattened. Posterolateral slopes short and
gentle.
Pedicle valve interior with strong, thick teeth
and low dental ridges. Muscle scars not impressed,
no myophragm developed.
Brachial valve interior with moderately long cardinal
process with fairly deeply incised prongs;
dentifers broad with short laterally extended supporting
plates. Chilidium well developed, deeply
indented medially.
M E A S U R E M E N T S
USNM 721y
152595a
152595b
152595c
152595d
152595e
152595f
152595g
USNM 721t
152596a (holotype)
152596b
152596c
USNM 724b
152597a
USNM 721w
152598a
( i n m m ) .—
pedicle
valve
length
8.2
11.8
7.2
7.1
6.4
6.0
4.7
12.3
12.0
10.8
6.3
10.6
brachial
valve
length
7.4
10.0
6.9
6.4
6.0
4.8
4.4
9.1
8.7
9.1
5.7
8.7
maximum
width
9.6
12.2
8.3
8.3
8.2
6.8
5.6
10.5
10.5
10.2
7.3
10.0
hinge
width
8.4
10.5
6.9
7.8
8.2
6.2
4.7
8.7
8.0
7.8
6.4
7.8
interarea
length
5.0
7.2
3.7
4.6
3.7
4.0
3.7
6.4
5.8
5.5
3.7
3.7
thickness
8.2
10.5
6.4
5.8
4.9
5.0
4.1
7.3
7.9
9.5
5.8
6.5
STRATIGRAPHIC OCCURRENCE.—Road Canyon Formation.
LOCALITIES.—USNM 710u, 720d, 721t, 721w,
721y, 724b.
DIAGNOSIS.—Fairly wide-hinged Bothrostegium
with thin shell and moderately convex brachial
valve.
TYPES.—Holotype: USNM 152596a; figured paratypes:
147891a-c, 152595a, b, d, 152596c, d, 152597a,
152598b, 153338; unfigured paratypes: 152595c, e-g,
152596b, 152598a; measured paratypes: 152595a-g,
152596b, c, 152597a, 152598a.
COMPARISON.—This species is larger and has a
thinner shell than either B. pusillum, new species,
or B. compactum, new species. The brachial valve
of B. pusillum is generally more convex than that
of B. derbyoideum, and the cardinalia are more
laterally compressed in the former. The hinge of
B. compactum is wide and the valves slightly alate
as in B. derbyoideum, but the former species is not
so deep and the cardinalia of the two are unlike.
Furthermore, B. compactum has a thick median
boss anterior to the adductor field in the brachial
valve.
Bothrostegium pusillum, new species
PLATE 118: FIGURES 8-21
Small for genus, thick shelled, commonly distorted,
subconical, usually slightly longer than
wide; maximum width usually anterior to midvalve;
sides unevenly rounded; hinge narrower than
greatest width; cardinal extremities slightly alate;
interarea long, commonly convex, usually strongly
to moderately apsacline pseudodeltidium moderately
wide, strongly convex, marked medially by
deeply impressed line. Brachial valve interarea
short, not strongly developed. Surface costellate,
about 3 costellae per mm at anterior of large specimens;
lamellae poorly developed.
NUMBER 15
Pedicle valve triangular in profile, ventral side
forming hypotenuse of the triangle, varying from
faintly convex to faintly concave but usually nearly
flat; anterior profile broadly rounded. Umbonal
region narrowly rounded; medial region usually
flattened; beak ridges strong; anterior slope long,
moderately steep; flanks short and steep.
Brachial valve fairly evenly and moderately convex
in lateral profile, anterior profile broadly and
fairly evenly convex; umbonal region slightly swollen;
median region inflated with flanks and anterior
slope fairly steep, the former steeper. Median region
marked anteriorly by shallow, poorly defined
sulcus.
Pedicle valve interior with long, thick, bluntly
pointed teeth and thick dental ridges; muscle marks
and septa not impressed or developed.
Brachial valve interior with thick and ponderous
cardinalia and deep, open sockets; cardinal process
short; prongs not elongated or widely separated;
dentifers elongated, narrowly divergent and supported
laterally by short erismata. Adductor scars
not clearly visible and myophragm only slightly
developed.
MEASUREMENTS (in mm).—
152594a (holotype)
152594b
152594c
152594d
152594e
152594f
152594g
152594h
152594i
152594J
152594k
152594-1
152594m
152594n
pedicle
valve
length
4.7
5.1
5.0
4.4
6.4
5.3
5.6
6.7
?
?
?
?
?
?
brachial
valve
length
3.8
4.7
?
?
?
3.8
4.2
?
3.9
3.7
4.3
5.3
5.0
6.4
maximum
width
4.6
5.5
4.2
4.7
6.2
4.4
5.5
7.3
4.4
4.6
5.3
6.0
6.6
7.5
hinge
width
3.8
4.4
3.7
3.7
4.6
3.5
4.3
5.3
3.3
4.0
4.2
4.7
4.2
5.3
interarea
length
3.5
2.8
3.9
2.8
3.0
3.2
2.8
4.8
?
?
?
?
?
?
thickness
4.1
3.8
3.2
3.3
3.2
5.2
3.7
4.6
1.6
1.7
1.8
?
2.2
2.5
STRATIGRAPHIC OCCURRENCE.—Road Canyon Formation.
LOCALITY.—USNM 722e.
DIAGNOSIS.—Small, thick-shelled Bothrostegium
with poorly defined lamellae and thick narrow cardinalia.
TYPE.—Holotype: USNM 152594a; figured paratypes:
152594b, e, j , n; measured paratypes:
152594b-n; unfigured paratypes: 152594a, c, d, f-n.
COMPARISON.—This species is most like B. compactum,
but it differs in having a narrower hinge
and stronger costellae. It differs from B. derbyoideum
in the same features.
Genus Tropidelasma Cooper and Grant, 1969
Tropidelasma Cooper and Grant, 1969:3.
Small to moderately large, variable in shape and
outline from triangular to elongate triangular,
valves very unequal. Pedicle valve subconical,
elongate and convex, brachial valve short, faintly
to strongly convex and usually elliptical to circular
in outline. Hinge narrower than greatest width
(usually near midvalve). Anterior commissure rectimarginate
to strongly sulcate. Surface finely
costellate. Shell substance pseudopunctate.
Pedicle valve with long interarea marked medially
by flat to slightly convex pseudodeltidium
anteriorly notched, midline narrowly folded to
form elongate monticulus. Teeth strong, forming
thick ridges under delthyrial margin. Area under
palintrope lateral to teeth notched to form a narrow
cavity. Muscle field poorly defined and lightly
impressed. Anterior margin very finely costellate.
Brachial valve with short, inconspicuous interarea;
chilidium vestigial, forming medial boss or
node at midvalve; cardinal process large, bilobed,
lobes long and slender and slit medially on the
posterior surface. Sockets narrow and deep; dentifers
small, obscure, forming ridge on sloping sur334
SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
face of the cardinal process shaft. Outside of socket
bounded by a small oblique ridge. Adductor field
rounded, divided medially by a slender often elevated,
serrated myophragm. Erisma gradually being
eliminated, often buried in adventitious shell
tissue.
TYPE-SPECIES.—Tropidelasma culmenatum Cooper
and Grant (1969:3, pi. 1: figs. 27-29).
DIAGNOSIS.—Elongate streptorhynchid brachiopods
having a flat keeled pseudodeltidium, finely
costellate ornament, remnantal brachial valve interarea
with vestigial chilidium.
COMPARISON.—Tropidelasma differs from Chelononia,
which it resembles in shape by the absence
of cardinal auriculations, the flat pseudodeltidium
with monticulus, and the greater extension of the
cardinal process shaft. Tropidelasma differs from
Streptorhynchus in shape, ornament, the development
of the pseudodeltidium, greater development
of the cardinal process, and failure to develop
erismata except spasmodically.
DISCUSSION.—In studying the streptorhynchiform
brachiopods in the Glass Mountains, it was noted
that the pseudodeltidium of some of the species
deviated from the kind seen in the type-species of
Streptorhynchus. The variations recorded in this
structure also pointed to some differences in the
cardinalia of the brachial valves of the Glass Mountains
species. The details of the pseudodeltidium
of many of the Glass Mountains species are more
like those of Meekella than of Streptorhynchus.
Tropidelasma has the general expression of streptorhynchid
brachiopods with a large pedicle valve,
usually with a much elongated beak. The brachial
valve is lidlike and is usually fairly convex. The
shell was attached by the pedicle valve. The point
of attachment was often rather small, and many
specimens must have broken from their natal moorings
and lived loose on the sea bottom. Specimens
have been found in clusters of attached valves, and
others have been found cemented in clusters with
Derbyia, Geyerella, or Meekella.
The exterior surface of Tropidelasma is covered
by fine costellae that are interrupted by growth
lamellae. The costellae in some species are closely
crowded but more distant in others. No regularity
in the spacing of the lamellae has been seen, and
in many specimens they are closely crowded at the
anterior.
The most significant and perhaps interesting
morphological feature of this genus is the interarea
of both valves and their deviation from Streptorhynchus.
The interarea of Tropidelasma is usually
an elongated triangle with a narrow base and a
greatly elongated apex. The pseudodeltidium is
the prominent part of this structure. As viewed
between the teeth, it is not an arch but a flat plate
lying on the inside edge of the teeth. Its midline
is narrowly arched or keeled, the keel running from
beak to anterior end, where it is narrowly notched.
The keel, now called monticulus, corresponds to
a protruberance on the midline of the cardinal
process. The pseudodeltidium is buttressed or
welded to solidity by deposition of adventitious
shell on its under side and on the sides of the
dental ridges.
It is interesting to note that Tropidelasma does
not have a perideltidial area, a feature common
on Meekella, Derbyia, and several other genera.
Another feature is the conspicuous socket on the
outside of each tooth, just on the underside of the
palintrope. This socket is more conspicuous in
some species than in others, but most of them
have it. The sockets may be created by the movement
of the brachial valve hinge in opening and
closing the valves, and it articulates with the ridge
or "tooth" often bounding the outside of the socket
in many species.
The cardinalia of the brachial valve are welded
into a solid piece, the component parts of which
are difficult to identify. The cardinal process has
two prongs, the upper or posterior side of each
prong bearing a deep slit serrated on the sides in
which the muscles were inserted. The prongs of
the fork are closely welded in some specimens, but,
in others, they are much elongated and divergent.
The posterior face of the cardinal process is narrowly
curved and ends in a small bilobed knob.
The curved face of the cardinal process is marked
medially by a narrow groove representing the dividing
channel between the cardinal process lobes.
This groove is continued onto the knob and bisects
it. This small knob is inserted under the
monticulus of the pseudodeltidium, the monticulus
being the growth track of this projection. The
knob is thought to be a remnant of the chilidium,
which otherwise is not developed. Furthermore,
the interarea and palintrope of this valve are reNUMBER
15 335
duced to small, widely triangular areas with obtusely
angular apex.
The shaft of the cardinal process makes a long
double-barreled extension with a median groove on
the posterior side. On the opposite side this is a
smooth concave trough, the sides of which are composed
of a plate extending anterolaterally and
probably representing the brachiophore or dentifer.
The anteroventral edge of this plate is narrowly
rounded or extended as a small point that might
suggest a crus. These oblique extensions grow in
a dorsad direction, extending under the overhang
of the hinge to attach to the valve floor. The extensions
appear to be reduced erismata, but in old
shells they are almost completely buried by adventitious
shell and the cardinalia thus suggest those
of the Schuchertellidae. A lateral thickening often
simulates erismata in some specimens.
The musculature is not clear on any of the Glass
Mountains silicified specimens. But a strong serrated
septum is present at the posterior under the
cardinal process of well-preserved specimens. In
T. gregarium (Girty) it is irregular and may take
the form of a point extending anteroventrally at
the posterior end of the septum.
Tropidelasma is common only locally, where it
is an important member of bioherm assemblages.
This is true of T culmenatum and T. rhamphodes,
which are found clustered with other derbyiacean
or cemented aulostegids such as Scacchinella. Specimens
from the Word Formation are rare and no
evidence points to them having lived in a biohermal
assemblage.
Tropidelasma anthicum, new species
PLATE 59: FIGURES 1-36; PLATE 60: FIGURES 1-39
Widely conical, semicircular to transversely subelliptical
in outline, rectimarginate, ornamented by
weak radial costellae interrupted by moderately
strong growth laminae; hinge narrower than maximum
width of shell. Pedicle valve normally flared
toward margin, interarea flat, moderately long,
commonly slightly twisted or bent, transversely
scored by straight growth lines, bisected by pseudodeltidium
with narrow, low, indistinct median arch
and 2 lower lateral arches marking paths of growth
of hinge teeth. Brachial valve moderately to
strongly convex, with tendency for most strongly
convex valves to be distorted, umbo overhanging
pedicle interarea; growth laminae more closely
spaced toward margin.
Pedicle valve interior with short blunt hinge
teeth projecting forward from beneath interarea,
extending posteriorly as low convergent ridges
along sides of pseudodeltidium, ridges becoming
lower toward apex of beak, disappearing anterior
to apex in some individuals. Muscle marks faint,
occupying large part of floor of delthyrial chamber,
consisting of longitudinal striae that may be subdivided
by low, rounded median ridge. Anterior
and lateral margins of valve minutely radially serrate.
Brachial valve interior shallow to deeply cupshaped;
cardinal process long, wide, stout, and with
shallow to deeply bifurcated notch and with each
branch longitudinally split and having fringelike
serrations in slots; splits and bifurcation partly or
completely fused with growth to produce slight
grooves along length of process. Dentifers fused to
sides of cardinal process, projecting very slightly
or not at all, forming inner slope for round to slotshaped
sockets. Lateral thickening of secondary
shell outlines part of muscle area, in others diverging
widely parallel to hinge, producing inside the
margin a shallow groove just anterior to hinge.
Muscle area depressed, lying under arch of cardinal
process, often bisected by short, low myophragm;
margins of valve finely serrate radially.
336 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
MEASUREMENTS
USNM 706b
147861a (holotype)
147861b
147861c
147861d
147861e
14786H
USNM 706
147852a
147852b
USNM 706c
147856
(in mm).—
pedicle
valve
length
27.3
26.4
17.7
?
p
10.4
26.5
24.3
25.4
brachial
valve
length
22.2
p
p
17.2
20.0
p
p
p
p
maximum
width
24.9
21.6
20.0
21.5
21.9
9.6
26.7
30.6
33.0
hinge
width
17.5
16.9
14.6
15.0
15.5
6.4
19.7
22.5
24.2
interarea
length
14.3
14.4
16.5
?
?
5.4
15.0?
20.0
18.8
thickness
27.2?
13.7
18.0
7.7
10.0
7.6
17.0
19.7?
17.8
STRATIGRAPHIC OCCURRENCE.—Word Formation
(China Tank, Willis Ranch, and Appel Ranch
members; lens between Willis Ranch and Appel
Ranch members).
LOCALITIES.—China Tank: USNM 706c, 713,
726r, 733q; Willis Ranch: AMNH 506, USNM 706,
706e, 723t; lens: USNM 706b; Appel Ranch:
USNM 715i, 722t, 727j.
DIAGNOSIS.—Tropidelasma of moderate size with
narrowly conical, flaring pedicle valve and long
stout cardinal process.
TYPES.—Holotype: USNM 147861a; figured paratypes:
147861b, d, e, g, 153555a, b, 153556,
153557a-c; measured paratypes: 147861b-f, 147852a,
b, 147856; unfigured paratypes: 147861c, f; measured
paratypes: 147861b-f, 147852a, b, 147856.
COMPARISON.—Tropidelasma anthicum is characterized
by its moderately deep conical pedicle valve,
which normally flares outward at the margin and
bears a low, often indistinct monticulus on the
pseudodeltidium and short hinge teeth that make
only low and gently rounded ridges on the underside
of the interarea. The brachial valve is moderately
to strongly convex with a long cardinal
process, which, in combination with brachiophores
that are fused to its sides, forms a broad arch over
the umbonal cavity.
This species most closely resembles T. culmenatum,
the type-species, but it differs by its nonsulcate
anterior, less convex brachial valve, shorter
hinge teeth that make weaker internal ridges, less
deeply conical, more widely flaring pedicle valve
with flatly arched median ridge on the pseudodeltidium.
These features plus its much weaker
growth lines also distinguish T. anthicum from T.
rhamphodes, new species. It differs from T. strobilum,
new species, by its much shorter and normally
less distorted pedicle beak and especially by its
short hinge teeth that make weak internal ridges.
The somewhat more deeply bifurcate cardinal process,
much less distinct, less bladelike dentifers, very
low or absent brachial myophragm, and weaker
hinge teeth distinguish S. anthicum from T. gregarium
(Girty) of the Guadalupian (Bell Canyon
Formation).
DISCUSSION.—The collection of 5. anthicum is
comparatively small, and, for this reason, may not
contain the complete range of variation of the species.
Most specimens conform to the pattern given
in the description, but some do not have the flaring
pedicle valve. These are similar in shape to
T. rhamphodes and must be distinguished on the
basis of features other than external shape (see
"Comparison"). Some brachial valves of S. anthicum
are so strongly convex that they grew irregularly,
becoming distorted like the conical pedicle
valve. Distortion normally involves the beak and
hinge regions. The cardinal process is uniformly
long and wide, making a broad arch by fusion
with the dentifer. Sockets are round as in other
species of the genus, but some are slotlike, converging
posteriorly toward the convex side of the cardinal
process.
The outline of S. anthicum normally is transverse,
but some specimens are distorted so that the
outline is elongate. Only distorted specimens have
any folding of the margin, and even in them it is
slight; the normal condition is rectimarginate.
NUMBER 15 337
Tropidelasma corniculum, new species
PLATE 58: FIGURES 28-36
Moderately large for genus, conical in outline
and profile; hinge narrower than maximum width
(just anterior to hinge); sides and anterior strongly
rounded, brachial valve roundly elliptical. Anterior
commissure rectimarginate. Interarea usually long
broad and flat, pseudodeltidium depressed, nearly
flat, marked by a narrow, monticulus and median
notch. Brachial valve interarea fairly long. Surface
finely and densely costellate.
Pedicle valve triangular in lateral profile, hypotenuse
moderately convex; anterior profile roundly
domed; pedicle valve strongly conical, one side
flattened, anterior flaring widely; beak ridges
rounded. Umbonal region narrowly swollen, beak
variable. Median region somewhat swollen; lateral
slopes very steep.
Brachial valve moderately but unevenly convex,
umbonal region most convex, anterior somewhat
flattened. Anterior profile broadly and gently convex.
Umbonal region strongly swollen, antero- and
lateromedian regions flattened.
Pedicle valve interior with short, thick teeth and
low, thick dental ridges. Muscle field and septa not
developed.
Brachial valve with long forked cardinal process,
prongs not strongly divergent. Sockets shallow.
Dentifer broad and gently sloping. Myophragm
low extending to about midvalve; adductor field
lightly impressed.
MEASUREMENTS
USNM 720d
152592a
152592b
152592c
152592d
152592e
152592f
152592g
152592h
152592i
152592J
152592k
152592-1
152592m
152592n
152592o
USNM 721z
152593
USNM 724d
153562 (holotype)
(in mm).—
pedicle
valve
length
14.4
13.4
14.4
11.5
12.3
6.1
?
?
?
?
?
?
30.0+
16.8
16.0
?
45.0
brachial
valve
length
?
?
?
?
?
?
12.4
11.2
11.2
10.0
10.7
11.7
P
?
14.8
27.1
42.3
maximum
width
12.4
14.0
14.3
11.7
14.6
6.2
15.6
11.8
12.7
11.6
11.0
12.3
32.2
19.6
14.0
31.3
46.7
hinge
width
8.0
9.7
7.2
6.7
9.4
3.4
11.5
6.7
9.1
7.8
6.5
7.8
25.0
13.8
11.4
21.2
30.5
interarea
length
6.6
5.1
4.1
4.5
6.0
1.9
?
?
?
?
?
?
22.0?
11.4
6.0
?
21.9
thickness
6.6
6.2?
5.2
5.6
6.2
2.5
6.1
3.8
5.0
3.5
5.2
4.9
25.5
12.8
12.3
9.8
37.0
STRATIGRAPHIC OCCURRENCE.—Road Canyon Formation.
LOCALITIES.—AMNH 503, USNM 700v, 703,
703a, 706f, 707f, 707e, 720d, 721j, 721t, 721z, 724c,
724d.
DIAGNOSIS.—Tropidelasma of fairly large size
with rectimarginate anterior commissure and
strongly inflated umbo on the brachial valve.
TYPES.—Holotype: 153562; figured paratypes:
152592m, 152593; measured paratypes: 152592a-o;
unfigured paratypes: 152592a-l, n, o.
COMPARISON.—This species suggests T. culmenatum,
the type-species, and T. rhamphodes, new
species. It differs from the former in having a
rectimarginate anterior commissure rather than the
moderately strong fold of T. culmenatum. The
Road Canyon species does not have the sinuate anterior
and consequently longitudinal swollen median
region of the pedicle valve that is prominent
on the Neal Ranch species. Tropidelasma corniculum
is more strongly umbonate dorsally than either
T. culmenatum or T. rhamphodes. It also differs
338 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
from T. rhamphodes in having no anterior sulcus
on the brachial valve although this is flattened
without affecting the anterior commissure. It has
a smaller and less elongated cardinal process with
more flaring and less steep dentifer than in T.
rhamphodes.
DISCUSSION.—This genus is fairly common in the
Road Canyon Formation northwest of the Hess
Ranch and on the east side of Gilliland Canyon,
but most of the specimens in the latter location are
immature. A few adult specimens have been found
and the description is based on them. Some variation
is seen in the ornamentation of the young, but
that of the adults is insufficiently preserved to be
sure that we are dealing wholly with variation
rather than with differently ornamented species.
Tropidelasma costellatum, new species
PLATE 58: FIGURES 16-27
About medium size for genus, moderately to
strongly elongated; pedicle valve a poorly formed
cone, and brachial valve broadly elliptical in outline;
sides usually somewhat narrowly rounded;
anterior commissure usually with narrow to broad
ventrad wave. Exterior costellate, costellae of
several sizes and intercalated, about 13 costellae
of all sizes in 5 mm at front of adult.
Pedicle valve unevenly convex in lateral profile,
the anterior half more strongly convex; anterior
profile strongly convex and with steep sides. Beak
small and narrow; interarea widening rapidly;
pseudodeltidium with raised monticulus throughout
its length, sides flattened only in anterior half;
median region longitudinally swollen to form
poorly defined fold. Attachment surface variable,
usually large.
Pedicle valve interior with small teeth and low
dental ridges. Not greatly thickened under
palintrope.
Brachial valve moderately but fairly evenly convex
laterally; moderately and broadly domed in
anterior profile; umbonal region not strongly swollen;
median region slightly inflated; lateral and
anterior slopes gentle.
Brachial valve interior with long slender cardinal
process, narrowly rounded, with moderate
development of dentifers; myophragm threadlike.
MEASUREMENTS (in mm).
147823a
147823b
147823c
147823d
(holotype)
pedicle
valve
length
15.1
14.5
13.5
?
brachial
valve
length
13.3
11.9
10.3
14.4
maximum
ividth
15.5
14.7
12.0
17.8
hinge
width
11.8
8.0
7.2
11.2
interarea
length
13.5
6.8
5.8
?
thickness
13.5
10.3
9.4
5.2
STRATIGRAPHIC OCCURRENCE.—Hess Formation
(Taylor Ranch Member).
LOCALITY.—USNM 702d.
DIAGNOSIS.—Tropidelasma of moderate size with
distant costellae.
TYPES.—Holotype: USNM 147823a; figured paratype:
147823d; unfigured and measured paratypes:
147823b, c.
COMPARISON.—The distant costellae separate this
species from T. gregarium (Girty) and T. curtum,
new species, which are nearest it in size.
DISCUSSION.—This is a rare species because only
12 specimens of it are known. These include an
incredible range of variation, but all seem to have
the same pattern of costellae. That this is a biohermdweller
is clear because the specimens were taken
with the large Heliospongia and numerous other
sponges at USNM 702d.
Tropidelasma culmenatum Cooper and Grant
PLATE 51: FIGURES 1-36; PLATE 52: FIGURES 1-32; PLATE 53:
FICURES 12-27; PLATE 58: FIGURES 15, 3 7 ^3
Tropidelasma culmenatum Cooper and Grant, 1969:3.
Large, conical, deeply or broadly sulcate, rarely
rectimarginate; outline subtrigonal or transversely
subelliptical; costellae weak, bifurcating fasciculate,
growth lines slightly stronger, becoming more frequent
toward margin, growth lamellae flat, not
protruding. Pedicle valve beak deeply conical, commonly
twisted or bent; interarea long, triangular,
NUMBER 15 339
bisected by pseudodeltidium with narrow monticulus
and lower ridge on each side marking paths of
growth of hinge teeth; interarea transversely scored
by straight growth of hinge teeth; interarea transversely
scored by straight growth lines; anterior
slope of valve below sulcus forming ridge; broadly
rounded in outline, concave in profile. Brachial
valve moderately convex, deeply bowed anteriorly
in sulcate specimens; hinge narrower than maximum
width.
Pedicle valve interior with teeth protruding anteriorly
from underside of interarea, extending
posteriorly as strong, ridges along flanks of pseudodeltidium,
converging toward apex. Muscle area
slightly depressed; muscle marks consisting of faint
longitudinal striae on valve.
Brachial valve interior with long, wide, bifurcate,
posteriorly ridged cardinal process, ridge on process
short, located near beak, making continuation
of median ridge of pedicle pseudodeltidium; each
branch of cardinal process cylindrical, with posterior
longitudinally slit for part of length, edges of
slit with fringelike serrations.
Brachial valve interior with dentifers fused to
sides of cardinal process and to posterior wall of
valve, forming wide arch over deep umbonal cavity
and providing inner walls for deep hinge sockets;
lateral terminations of dentifers form inside edge
of shallow groove just anterior to hinge. Muscle area
in umbonal cavity, poorly defined, divided by low,
short myophragm; inner margin of valve radially
serrate.
MEASUREMENTS
USNM 701h
147829a
147829b (holotype)
147829c
147829d
147829e
147829f
147829g
147829h
147829i
147829J
147829k
147838
(in mm).—
pedicle
valve
length
50.5
40.5
26.5
24.2
17.8
16.0
14.0
6.3
3.3
24.3
27.6
15.3
brachial
valve
length
30.6
28.7
25.0
18.6
14.4
16.0
9.0
4.3
3.3
17.0
22.3
13.7
maximum
width
50.7
37.8
27.9
21.5
16.3
18.6
9.7
5.4
3.2
21.6
30.4
15.0
hinge
width
45.5
34.3
19.4
17.8
11.8
11.6
7.3
4.6
2.4
17.0
22.9
11.4
interarea
length
35.7
43.2
12.0
19.7
15.6
10.0
7.0
3.7
2.1
15.3
15.2
19.5
thickness
35.0
47.0?
21.6
26.4
22.0
16.0
10.6
4.0
3.0
20.0
27.6
24.3
STRATIGRAPHIC OCCURRENCE.—Neal Ranch Formation
(beds 12-14).
LOCALITIES.—USNM 701, ?701a, 701c, 701d, 701g,
701h, 701k, 701v, 727d, 727e.
DIAGNOSIS.—Large, wide-hinged Tropidelasma
with pedicle valve elongated and anteriorly
geniculated.
TYPES.—Holotype USNM 147829b; figured paratypes:
147829a, c, e, h, i, k, 1; figured hypotypes:
147838, 147839, 147842, 147865a, b, 147875, 153559a,
b, 153560a-d; measured paratypes: 147829a, c-k,
147838.
COMPARISON.—Tropidelasma culmenatum is characterized
by its subtrigonal to transverse outline,
wide hinge, the geniculation of the anterior of the
pedicle valve toward the dorsal side to produce
a concave profile along the anterior slope, weak
costellae, and relatively flat growth lamellae. It
most nearly resembles T. rhamphodes, new species,
from which it is distinguished by the above features,
most especially the concave anterior profile
of the pedicle valve, subtrigonal outline of that
valve, and the less protruding growth lamellae. The
sulcus ridge distinguishes this species from T. anthicum,
new species, and T. strobilum, new species,
and the much larger size and weaker costellation
differentiate it from T. pygmaeum Girty. The
deeply conical pedicle valve distinguishes Chelononia
straminea, new species (=Streptorhynchus
pyramidale King), from similar European and
Asian species that also are nearer Streptorhynchus
pelargonatum Schlotheim. The more deeply conical
pedicle valve, sulcate margin, subtrigonal outline,
340 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
and greater maximum size distinguish T. culmenatum
from T. gregarium (Girty).
DISCUSSION.—No single diagnostic feature distinguishes
T. culmenatum from T. rhamphodes,
although difference in curvature of anterior profile
most nearly approaches being diagnostic. Each
species is variable and contains a few specimens
that are almost intermediate morphologically. In
some specimens of T. culmenatum, distortion of the
pedicle beak has produced a convex profile in place
of the normal geniculation and concave anterior
slope. The margin of T. culmenatum ranges from
deeply sulcate to nearly rectimarginate, but those
that approach being rectimarginate are widely transverse.
The pedicle beak and interarea may be
shallow and broad or deep and slender, probably
reflecting variety in place and mode of attachment
to the substrate while the shell was living. As is
typical of most West Texas species of this genus,
very small specimens have relatively wide median
arches. Normally, these appear after the interarea
has attained a height of about 5 mm.
Two bioherms produced a large quantity of this
species of all sizes making it possible to see how
the species grew. An interesting feature of this
species is the small attachment surface for such a
large shell. A favorite site for its life is a recess in
the large lamellar bryozoans that make up a fair
part of some bioherms.
Most of the material of this species comes from
the Neal Ranch Formation from beds 4-14 of P. B.
King. We have specimens from USNM 701 that
are from the upper 15 feet of the bed 2 or Gray
Limestone of P. B. King, placed by Ross (1961) in
the top of the Gaptank. We are unable to separate
these specimens from the higher ones, perhaps
because we have so few of them. It is evident, however,
from the fact that a large Tropidelasma
(species 2) is known from the Uddenites-bearing
Shale Member that this genus became established
and flourished in Gaptank time.
Tropidelasma curtum, new species
PLATE 58: FIGURES 1-14
Small for genus, slightly longer than wide, pedicle
valve forming short, misshapen cone; brachial valve
broadly elliptical. Sides rounded; anterior margin
broadly rounded to subtruncate. Hinge narrower
than midwidth, about three-fourths maximum
width. Anterior commissure broadly and gently
sulcate in adult. Surface costellae, narrower than
interspaces, 3-4 occupying 1 mm at anterior.
Growth lines producing a lamellar appearance to
anterior.
Pedicle valve narrowly triangular in lateral profile;
ventral side convex, anterior half having
greater curvature; anterior profile broadly but
fairly strongly rounded and with moderately steep
sides. Interarea broad, pseudodeltidium flattened.
Area of attachment small, confined to umbonal
region. Anteromedian region swollen, forming
poorly defined fold.
Brachial valve fairly strongly and evenly convex
in lateral profile and gently domed with long
moderately steep lateral slopes in anterior profile.
Interarea fairly long and broad, prominent. Umbonal
region not swollen. Anterior slope fairly
steep.
Pedicle valve interior with small teeth and narrow,
not thickened, dental ridges. Ridges ventrad to
palintrope narrow. Muscles not impressed. Brachial
valve interior with fairly long, narrow cardinal
process with distal extremity not widely divergent.
Sockets moderately deep; dentifers short. Myophragm
small.
MEASUREMENTS (in mm).—
152590a
152590b
152590c
152590d
152590e
(holotype)
pedicle
valve
length
17.3
15.5
12.8
?
?
brachial
valve
length
?
?
?
12.4
8.9
maximum
width
17 A}
13.9
13.8
14.5
10.5
hinge
width
12.4
8.0
10.5
9.2
7.3
interarea
length
8.9
4.6
6.5
?
?
thickness
8.0
5.3
6.3
5.3
3.9
STRATIGRAPHIC OCCURRENCE.—San Andres Formation.
LOCALITY.—AMNH B188-8.
DIAGNOSIS.—Small Tropidelasma, thick shelled,
NUMBER 15 341
with short, conical pedicle valve and brachial valve
having a wide cardinal process.
TYPES.—Holotype: USNM 152590b; figured paratype:
152590d; unfigured measured paratypes:
152590a, c, e.
COMPARISON.—This is a small species and need
be compared only with the species of similar moderate
size. It is most like T. gregarium (Girty), but
it differs in having a somewhat less elongated pedicle
valve, thicker shells, generally smaller size, and
more regular costellae. It is smaller and more regularly
formed and has different costellation than T.
costellatum. Tropidelasma pygmaeum (Girty) is
much smaller and more distantly costellate.
DISCUSSION.—This species is known only from
14 specimens, but, although they vary among
themselves, the amount of variation is less than that
seen in other species of like size. For thick-shelled
forms, the notch on each side of the teeth and just
under the palintrope is poorly developed compared
to some other species.
Tropidelasma furcillatum, new species
PLATE 53: FIGURES 1-11
Conical, medium, rectimarginate to broadly and
shallowly sulcate; outline transversely subelliptical
to subquadrate; costellae and growth laminae moderately
strong. Pedicle beak blunt to elongate, commonly
twisted or bent; interarea flat, bisected by
pseudodeltidium with comparatively wide monticulus
and low lateral ridges marking traces of growth
of hinge teeth. Brachial valve moderately to strongly
convex, with overhanging umbo and/or very low
interarea and chilidium; hinge slightly narrower
than maximum width of shell.
Pedicle valve interior with moderately strong
hinge teeth protruding from underside of interarea,
continuing posteriorly as convergent dental ridges
along sides of arch of pseudodeltidium; hinge
straight, with shallow groove extending laterally
from distal side of each tooth to posterolateral
corners of valve; muscle marks obscure, muscle possibly
occupying shallow depressions in floor of
valve.
Brachial valve interior wide with short to moderately
long cardinal process notched at end by
short Y-shaped incision, dividing process into 2
short longitudinally split prongs, with serrations
along sides of each slit. Dentifers fused to underside
of cardinal process supported by adventitious shell.
Muscle area faintly defined, bisected by low median
ridge; muscle marks faint. Margin of valve radially
serrate.
MEASUREMENTS
USNM 732
147881a
147881b
153561a
153561b
(holotype)
(in mm).—
pedicle
valve
length
16.7
?
17.3
P
brachial
valve
length
?
16.9
?
16.4
maximum
width
16.4?
19.6
15.7
19.6
hinge
width
11.0
13.3
11.2
12.6
interarea
length
6.4
?
6.7
?
thickness
7.0
8.5
?
7.04-
STRATIGRAPHIC OCCURRENCE.—Cherry Canyon Formation
(Getaway Member).
LOCALITIES.—AMNH 512, USNM 728, 732.
DIAGNOSIS.—Tropidelasma of medium size with
shallow notch in cardinal process.
TYPES.—Holotype: USNM 153561a; figured paratype:
153561b; measured paratypes: 147881a, b,
153561b.
COMPARISON.—Tropidelasma furcillatum is distinguished
from other species of the genus by its
shallowly notched, rather than deeply bifurcate,
cardinal process, its bladelike dentifers, and by the
presence in some individuals of a low brachial
interarea. It differs from species of Diplanus by its
pseudodeltidium with low monticulus and lateral
ridges that mark the paths of growth of the hinge
teeth, by the comparatively weak hinge teeth, poorly
developed or absent brachial interarea, unpitted
brachial umbo, unthickened internal lateral walls
of the pedicle interarea, and especially by the
weaker costellation and less prominent growth
laminae. The average size of T. furcillatum is that
of a large specimen of any species of Diplanus, and
the maximum size is larger than the largest known
specimens of Diplanus. Therefore, despite the few
342 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
ambiguous features of this species, it clearly belongs
with Tropidelasma, rather than with Diplanus.
DISCUSSION.—Tropidelasma furcillatum has features
that would appear to link it to some branch
of the Diplanus group; however, this species occurs
high in the stratigraphic section, well above
the highest known occurrence of Diplanus, and so
it cannot be a truly intermediate form. Probably it
represents a convergence by the Tropidelasma
stock toward a Diplanus morphological type that
it does not reach in this species.
Tropidelasma gregarium (Girty)
PLATE 61: FIGURES 1-37; PLATE 89: FIGURES 5-10;
PLATE 745: FICURE 69
Streptorhynchus gregarium Girty 1909:177, pi. 11: figs. 3-7.
Small for genus, variable in shape and outline;
pedicle valve an elongate, often misshapen cone
with gently convex to somewhat flattened lateral
profile. Interarea forming elongated triangle with
narrow hinge as bases, apex making acute angle.
Pseudodeltidium narrow, not well defined. Both
valves costellate, costellae numbering 22 in 5 mm
at anterior margin of lectotype.
Brachial valve elliptical to subcircular, maximum
width at about midvalve; hinge narrower than
midwidth; sides broadly to narrowly rounded.
Greatest convexity near midvalve; umbonal region
moderately convex; anterior slope steep. Anterior
commissure irregular.
Pedicle valve interior with elongate teeth and
stout dental ridges, musculature not impressed.
Brachial valve interior with long shafted cardinal
process having narrow prongs distally; dentifers
low ridges welded to cardinal process shaft, but
usually obscured by adventitious shell laid down
on lateral and anterior surfaces. Median septum
high, thin, serrate, dividing circular adductor field.
MEASUREMENTS (in mm).—
pedicle
valve
length
USGS 2926
118494d (lectotype) 14.4
118494a 15.6
118494e 9.7
brachial
valve
length
11.8
12.4
7.6
maximum
width
15.4
13.6
6.2
hinge
width
8.5
9.4
6.0
interarea
length
7.0
?
3.6
thickness
14.1
13.0?
7.8
STRATIGRAPHIC OCCURRENCE.—Bell Canyon Formation
(Hegler thru Lamar members), Capitan
Formation.
LOCALITIES.—Hegler: USNM 732a; Pinery:
AMNH 435, 537, USMN 733, 736; Rader: AMNH
397, 410, USNM 725f, 725g, 740a; Lamar: AMNH
L-2, L-3, L-6, 25, 37, 38, 39, 40, 347, 430, 528,
USNM 725e, 728i, 728p, 728q, 738, 738b; Capitan:
USGS 2926, USNM 740n, 750.
DIAGNOSIS.—Small Tropidelasma with erismata
partially concealed and strong median septum in
the brachial valve.
TYPES.—Lectotype: USNM 118494d; paratypes:
118494a-c, e, 155106; figured hypotypes: 152591a,
d, e, 1, n-q, 153545a, b.
COMPARISON.—The interior details of the cardinalia
distinguish this species. It suggests T. curtum
but it has a longer interarea on the pedicle valve,
and the dorsal median septum is higher and longer.
It differs from T. furcillatum in the presence of
the strong dorsal septum. It is much smaller than
other described species.
DISCUSSION.—The type lot of this species consists
of five specimens, all of them with both valves in
contact, all exfoliated and generally damaged. As
usual with this genus, no two of them are alike.
These factors all combine to make the selection of
a type specimen and identification with our silicified
material very difficult. Specimen 118494e is immature
and specimens 118494a and c are too badly
damaged, both having incomplete pedicle valves.
Specimen 118494b differs from the rest in having
a fairly narrowly elliptical brachial valve and a
longer interarea than the others. These features
are probably a result of crowded growth, as Girty
(1909:11) speaks of his type lot as having been
found in a crowded condition. Specimen 118494d is
thus left as the choice for a lectotype, and we chose
this specimen, although it too is imperfect. Part
of its right side is missing when viewed from the
dorsal side, but the preserved half shows little
NUMBER 15 343
deformation and the brachial valve is fairly well
preserved. Small patches of shell bearing the ornament
are preserved on the pedicle valve.
Although the sockets of this species are formed
by the sloping face of the dentifer, they are closed
by secondary shell laid down on their anterior and
distal edges. This secondary shell forms a ridge
parallel, or nearly so, with the posterior margin.
In some specimens this forms a small trough and
shelf anterior to the posterior margin. A small
vertical ridge extending from the posterior margin
to the secondary shelf bounds the outer side of the
socket. A few specimens show ridgelike extensions
anteroventrally from the cardinal process, suggesting
buried erismata, but they are not universal
and not present in the young.
The pedicle valve has a narrow slot bounded
anteriorly by a shelf and parallel to the hinge margin.
This slot evidently accommodates the dorsal
shelf of the opposite valve.
Tropidelasma perattenuatum (Girty)
Streptorhynchus perattenuatum Girty, 1909:180, pi. 29: figs.
3-3c.
The specimen on which this species is based is
under 5 mm in length and width. The fine costellae
of the exterior are like those of Tropidelasma, but
the pseudodeltidium is not differentiated into the
usual parts seen in that genus. The specimen is
obviously a young one. The young Tropidelasma
usually have a uniformly swollen pseudodeltidium,
but this develops the median keel (monticulus) as
adulthood is reached. Girty's species is undoubtedly
the young of a species whose adult characters are
unknown.
STRATIGRAPHIC OCCURRENCE.—Delaware Mountain
Formation.
LOCALITY.—USGS 2962.
TYPES.—Holotype: USNM 118496.
Tropidelasma pygmaeum (Girty)
Streptorhynchus pygmaeum Girty, 1909:178, pi. 30: figs.
3-6.—R. E. King, 1931:49, pi. 4: figs. 25.
Streptorhynchus} species a Girty, 1909:180, pi. 30: fig. 7.
Shell small, irregularly conical; rectimarginate;
outline transversely subelliptical to subquadrate;
ornamented by moderately strong costellae alternating
with slightly weaker ones, producing fasciculate
pattern, all crossed by weak lines of growth;
hinge slightly narrower than maximum width.
Pedicle valve evenly expanding or flaring, beak
commonly bent or twisted, irregularly indented by
contact with substrate during growth; interarea
flat, traversed by weak growth lines, bisected by
convex, large pseudodeltidium with relatively wide
median arch, and flattened sides.
Brachial valve moderately convex, umbo meeting
pedicle interarea between 90 and 180 degrees.
Pedicle valve interior with radial striae becoming
deeper toward margin; hinge teeth thick, projecting
forward from underside of interarea, extending posteriorly
as strong convergent ridges under arch of
pseudodeltidium; muscle marks not visible. No
thickening lateral to teeth under palintrope.
Brachial valve interior with weak radial striae
becoming deeper toward margin; cardinal process
long, stout, slightly notched at distal end, with
dentifers fused to underside, extending forward for
about one-third length of process and producing
large sockets; lateral terminations of dentifers fused
to posterior valve wall, forming inside edge of
shallow groove parallel to hinge, just inside hinge
margin; muscle area slightly depressed, bisected by
low thick myophragm; muscle marks obscure.
MEASUREMENTS (in mm).-
pedicle
valve
length
118495a (lectotype) 3.6
118495b ?
118495c ?
118495d ?
brachial
valve
length
?
4.7
5.0
4.5
maximum
width
4.5
4.8
5.6
5.2
hinge
width
3.5
4.0
3.0
3.6
interarea
length
2.8
?
?
?
thickness
2.9
1.9
2.1
1.6
STRATIGRAPHIC OCCURRENCE.—Uncertain (see discussion
below).
LOCALITY.—USGS 3763 (green).
DIAGNOSIS.—Small, thick-shelled Tropidelasma
with fairly strong costellae.
344 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
TYPE.—Lectotype: USNM 118495a; paratypes:
118495b-d.
COMPARISON.—Tropidelasma pygmaeum is characterized
by its small size, comparatively strong costellation,
and slightly notched cardinal process.
Small individuals, similar in size to Girty's cotypes,
are relatively uniform in shape. Larger specimens
tend to be more distorted and variable. The gross
shape of some of the larger specimens approaches
that of Diplanus, from which they differ in their
weaker ornamentation and lack of brachial interarea.
This species is morphologically closest to T.
furcillatum, new species, which occurs in the Guadalupian
of West Texas. Tropidelasma pygmaeum
differs in its slightly stronger costellation, less convex
brachial valve, less prominent socket plates, and
much smaller maximum size.
DISCUSSION.—Were it not for the fact that the
valves of T. pygmeaum are unusually thick, it
would be thought that these specimens represent
an immature form; however, they appear to be
mature and will have to be so regarded until
others are found to disprove the point. The locality
from which Girty's specimens came is not
known. King furnished no information on this
point, but he identified the species from the Leonard,
Hess, and Word formations. We did not obtain
any specimens that, in our opinion, are identifiable
with this species.
We chose the pedicle valve (USNM 118495a) as
lectotype because this is the only specimen in the
lot that has definite generic characters.
Tropidelasma rhamphodes, new species
PLATE 54: FIGURES 1-39; PLATE 55: FIGURES 1-14
Large, irregularly conical, evenly expanding, not
flaring; rectimarginate to slightly sulcate; brachial
valve outline nearly circular to moderately transversely
subelliptical or subquadrate; hinge narrower
than widest part; costellation fine, crowded, costellae
numbering 3-5 per mm on large specimens and
4 per mm at front of holotype. Growth lines strong,
closely spaced on pedicle valve and near edges of
brachial valve, producing rugose shell surface.
Shell also marked by irregular concentric
undulations.
Pedicle valve beak deeply conical, normally
curved posteriorly, producing convex anterior profile,
commonly twisted slightly to left or right;
interarea long, usually posteriorly concave, bisected
by flat pseudodeltidium with narrow monticulus
scarcely higher than flanking traces of the dental
ridges. Lateral profile usually fairly evenly convex.
Brachial valve moderately to strongly convex in
lateral profile, greatest convexity at umbo. Anterior
profile having posterior margin variable, nearly in
plane of pedicle interarea, or strongly overhanging.
Anterior of old shells with steep anterior slope.
Pedicle valve interior with hinge teeth protruding
from underside of interarea, continuing posteriorly
as strong convergent dental ridges along sides
of pseudodeltidium; interior surface fairly smooth,
irregularities reflecting exterior undulations; muscle
marks not preserved; valve edge radially serrate.
Brachial valve interior with strong bifid cardinal
process, each branch longitudinally slit, with serrations
along edges of slits; dentifers narrowly
divergent, fused to underside of process; erismata
present, defining deep and sharply arched umbonal
cavity containing faintly impressed muscle area and
short low myophragm, sockets relatively shallow.
Margins of valve radially serrate, weakly in juveniles,
but strongly in medium to large adults, and
with serrations bearing rows of sharp papillae.
NUMBER 15 345
MEASUREMENTS
USNM 707a
147882a
147882b (holotype)
147882c
147882d
147882e
147882f
147882g
147882h
147882i
147882]
147882k
147882-1
147882m
147882n
147882o
(in mm).—
pedicle
valve
length
42.4
35.4
25.4
30.3
36.0
27.8
23.9
22.0
18.0
18.2
16.0
13.2
8.7
6.1
4.0
brachial
valve
length
34.0
32.7
25.7
26.1
30.5
22.8
20.0
19.0
18.4
14.8
14.8
13.0
8.5
6.0
3.6
maximum
width
38.4
34.4
30.6
29.6
29.7
25.3
26.3
23.7
19.3
15.2
16.6
13.8
9.6
7.0
4.2
hinge
width
7.3
22.4
31.0
25.0
22.5?
20.6
15.2
14.6
13.5
11.5
12.2
8.8
7.0
5.2
3.0
interarea
length
24.5
33.5
38.0
23.0
26.0
17.7
13.6
15.8
15.7
12.7
11.0
6.8
5.4
4.3
2.0
thickness
40.7
48.6
48.8
35.1
34.7
24.0
23.4
21.7
20.4
17.2
16.0
11.7
7.8
6.2
3.0
STRATIGRAPHIC OCCURRENCE.—Skinner Ranch Formation
(Decie Ranch Member).
LOCALITIES.—USNM 707a, 707h, 707u, 707z, 708z,
712p, 714t, 714y, 715j, 715v.
DIAGNOSIS.—Large, moderately elongated Tropidelasma
with moderately umbonate brachial valve
and rounded outlines dorsally.
TYPES.—Holotype: USNM 147882b, 147809,
147902, 147882a, d, f, h, j , m, p, 153554a-e; unfigured
paratypes: 147882c, e, g, i, 1, n, o; measured
paratypes: 147882a, c-o.
COMPARISON.—Tropidelasma rhamphodes is characterized
by its deeply conical shape, nearly circular
to roundly subelliptical outline, relatively convex
brachial valve, straight to slightly flexed margin,
papillate edge of brachial valve interior, especially
by the rugose ornamentation produced by its
prominent growth lamellae, and by the broadly
convex anterior profile of the pedicle valve.
This species is closest to T. culmenatum of the
Wolfcampian (Neal Ranch Formation), and a few
specimens closely approach the form of that
species. The above characteristics, especially the
crowded costellate ornament, straight anterior commissure,
and convex anterior profile, distinguish
them. Tropidelasma anthicum of the Word Formation
is also rectimarginate, but its shallow flaring
pedicle valve and nonpapillate inner margin
of the brachial valve distinguish it from T. rhamphodes.
The greatly elongate pedicle valve and
usually more slender form distinguish this species
from T. strobilum, new species, of the Lenox Hills
Formation.
DISCUSSION.—Variation in Tropidelasma rhamphodes
is typical for a species that lived attached.
The pedicle valve may be deep or shallow, and it
may be twisted or indented by irregularities in the
object to which it attached during growth or
against which it impinged. The brachial valve is
moderately to strongly convex, and a few specimens
in which the margin is slightly folded may
be slightly concave near the anterior edge. A few
specimens have flaring pedicle valves that produce
a straight or even concave anterior profile that resembles
T. culmenatum. No single diagnostic feature
distinguishes T. rhamphodes from all other
species, but the combination of characters is quite
distinctive and the species is easy to recognize.
Specimens in the USNM collections are preserved
as calcitic or siliceous replacements. Silicification is
not normally complete; consequently, shells that
appear in the acid residues are fragile and do not
show fine details of the interiors, such as muscle
marks. Ornamentation on the outside may be partly
obscured on some specimens, but normally the external
detail is better preserved by the silicification
than is the internal. Somewhat more than half of
the specimens are preserved as calcareous steinkerns
or calcareous replacements filled with calcite. These
can be identified by their characteristic shape and
ornamentation. The calcareous specimens make
346 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
possible direct comparison with specimens of other
species that are similarly preserved.
This species is anomalous in having what appear
to be well-defined erismata extending from the anterior
margin of the dentifers anterolateral^ around
the posterior of the muscle area. These are not
buried in adventitious shell but stand out boldly.
The few specimens preserving the brachial valve
interior all show the same character. This is a departure
from the majority of the species of Tropidelasma
in which this character appears spasmodically
or ambiguously.
Tropidelasma robertsi, new species
PLATE 56: FIGURES 1-27
Large, pyramidal brachial valve strongly convex,
pedicle valve elongated, sides narrowly rounded,
anterior margin very broadly rounded. Anterior
commissure often twisted but without definite fold
toward either valve. Hinge narrower than maximum
shell width. Surface finely costellate, about
3 per mm at anterior margin.
Pedicle valve greatly elongated: hinge width
about 0.7 midwidth; interarea usually flat or
somewhat undulated; pseudodeltidium flat but
marked medially by narrow monticulus extending
full length of valve; ventral valve profile elongate,
triangular, apex usually narrow, varying from 65°
to 90°. Median region somewhat swollen, anterior
of large adults flattened or depressed.
Brachial valve fairly strongly convex in lateral
profile, broadly convex in anterior profile, sides
somewhat flattened. Umbonal region swollen; beak
inconspicuous. Slopes to cardinal extremities moderately
steep.
Pedicle valve interior with thickened dental
ridges and small, sharp teeth; other details obscure.
Brachial valve interior with long, slender cardinal
process having short erismata. Other details obscure.
MEASUREMENTS
153558c
153558d
153558h
153558g (holotype)
153558i
(in mm).—
pedicle
valve
length
18.2
30.3
30.0
55.7
?
brachial
valve
length
16.5
30.3
23.4
37.3
47.5
hinge
width
12.6
25.6
25.0
39.0
53.7
midwidth
20.0
33.7
29.0
57.4
67.6
thickness
17.2
29.8
31.2
56.2
?
STRATIGRAPHIC OCCURRENCE.—Skinner Ranch Formation
(Sullivan Peak Member).
LOCALITY.—USNM 733j.
DIAGNOSIS.—Large Tropidelasma with wide,
strongly convex brachial valve.
TYPES.—Holotype: USNM 153558g; figured
paratypes: 153558a—f, h; measured paratypes:
153558c, d, h, i.
COMPARISON.—This is the largest named Tropidelasma
in the Glass Mountains. In addition to size,
it differs from T. culmenatum in having a twisted
anterior commissure, whereas that of the Neal
Ranch species is strongly sulcate. It is also less
swollen medially, and the brachial valve is more
convex than that of T. culmenatum and has welldefined
erismata. Tropidelasma rhamphodes is a
smaller, more chunky species with a nearly circular,
moderately convex brachial valve, a sulcate
anterior commissure and rounded outlines.
DISCUSSION.—Tropidelasma robertsi was taken
from the Coscinophora bioherm at USNM 733j,
where it was so intimately cemented among the
Coscinophora that it proved difficult to obtain good
specimens for description. Also, most of the specimens
are riddled by borings. This species is named
for John Roberts, University of New South Wales,
Australia, who collected with us in 1968.
Tropidelasma strobilum, new species
PLATE 57: FIGURES 1-20
Shell irregularly conical, usually long and narrow,
rarely wide and abruptly tapered; outline subcircular
to transversely subelliptical; hinge narrower
than widest part; costellae moderately strong,
closely crowded, numbering 5 per mm, 3 large and
2 small, growth lines weak. Pedicle valve bent or
twisted in any direction; interarea long, bisected
by pseudodeltidium with narrow monticulus and
NUMBER 15 347
lower lateral ridges marking traces of dental ridges.
Brachial valve moderately to strongly convex,
bumpy and irregular, umbo overhanging hinge.
Pedicle valve interior with strong hinge teeth and
thick dental ridges; muscle marks not seen. Brachial
valve interior with long bifurcated cardinal
process supported by cuplike plates fused to underside
and arching over umbonal cavity, lateral extremities
defining limits of slightly depressed muscle
area with low myophragm; hinge sockets on each
side of process round, deep; margins of valve finely
serrate radially.
M E A S U R E M E N T S
USNM 705k
147780a
147780b (holotype)
147780c
147780d
147780f
147780g
147780h
147780i
I47780J
( i n m m ) .—
pedicle
valve
length
46.3
36.4
39.6?
21.7
20.5
19.6
15.0
14.4
16.9
brachial
valve
length
30.9
29.3
20.5
20.4
20.5
17.6
15.0
8.9
10.9
maximum
width
38.5
36.7
26.0
23.4
27.0
18.5
16.6
10.7
12.4
hinge
width
25.0?
20.0?
18.9
?
19.0
12.4
10.7
6.7?
8.8
interarea
length
45.2
33.4
49.0
29.6
19.6
16.5
5.8
11.5
10.5
thickness
46.4
44.8
58.6
41.0
25.6
24.0
8.7
20.0
14.5
STRATIGRAPHIC OCCURRENCE.—Lenox Hills Formation
(Scacchinella bed).
LOCALITIES.—USNM 705, 705k, 705m, 705q.
705s, 707j, 707u, 709w, 715.
DIAGNOSIS.—Large, usually greatly elongated
Tropidelasma with strongly umbonate brachial
valve.
TYPES.—Holotype: USNM 147780b; figured paratypes:
147780a, c, g, 147793; Unfigured paratype:
147780d-f, h-j; measured paratypes: 147780a, c-j.
COMPARISON.—Tropidelasma strobilum is characterized
by its elongate and twisted pedicle beak,
large size, bumpy, irregular surface with fine costellation,
weak circum-umbonal growth lines. It most
closely resembles T. rhamphodes from which it is
distinguished by its more irregular growth, longer
pedicle valves, more frequent twisting and bending
(especially anterior curvature of the beak, making
the pedicle interarea convex), and much weaker
lines of growth. Tropidelasma strobilum differs
from T. culmentum by its nongeniculated anterior
and lack of a ridged anterior slope of the pedicle
valve, as well as a more convex brachial valve, narrower
hinge, and generally more irregular and distorted
shell. It differs from T. pygmaeum (Girty)
by its much greater maximum size and relatively
weaker ornamentation, and from Chelononia straminea
by its high conical shape, unflared hinge and
interarea, and much weaker costellation. Its normally
longer and narrower pedicle valve, more irregular
shape and larger maximum size distinguish
it from T. anthicum of the Word Formation.
DISCUSSION.—Tropidelasma strobilum is the most
variable species of the genus in the Glass Mountains.
It is characteristically bent or twisted, and
ranges from very long and nail-shaped to low and
abruptly tapered. All specimens of this species are
preserved as calcite replacements or internal molds;
none is silicified. This makes it difficult to compare
with some of the species that are preserved only as
siliceous replacements; however, the species that is
closest to T. strobilum is T. rhamphodes, new species,
of which many specimens are preserved as calcareous
replacements, although most are silicified.
Several specimens are broken in such a way that
the cardinal process, hinge teeth, and brachial muscle
area are exposed. These features are characteristic
for the genus, but none is peculiar to the
species.
Tropidelasma undulatum (R. E. King)
PLATE 108: FIGURES 1-5
Streptorhynchus undulatum R. E. King, 1931:51, pi. 4: figs,
l l a - d (probably not figs. 12 and 13) [= Tropidelasma
rhamphodes Cooper and Grant].
STRATIGRAPHIC OCCURRENCE.—Skinner Ranch Formation
(low).
LOCALITY.—R. E. King 211.
348 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
TYPES.—Lectotype: YPM 11406.
DISCUSSION.—Two of the specimens figured by
King (1931, pi. 4: figs. 12, 13) are exfoliated individuals
and not helpful in obtaining a good idea of
this species. The holotype is a badly damaged
silicified specimen with both sides missing and the
middle part exfoliated. It preserves enough of the
exterior to show the fine crowded costellae, and
the interarea and beak are well displayed. The
character of the pseudodeltidium with its flattened
sides and narrow monticulus is characteristic of
Tropidelasma. The beak is too mineralized to indicate
the presence or absence of septa. In spite
of this the specimen is best assigned to Tropidelasma
because the pseudodeltidium is tropidelasmoid
rather than like that of Derbyia. No radial
costae prevent relationship to Meekella, whose pseudodeltidium
is like that of Tropidelasma. King's
type specimen is thus probably correctly assigned
to Tropidelasma, but identification of its specific
characters is more difficult.
Tropidelasma is common in the Decie Ranch
Member of the Lenox Hills, but the specimens do
not appear to accord with the specific characters
determinable from King's holotype of S. undulatum.
Specimens described herein as T. rhamphodes
occur abundantly at the west end of the Lenox
Hills, but they are generally more elongated, have
a more convex adult brachial valve, are narrower,
and are not so strongly wrinkled. We are unable
to identify these specimens with King's species.
King reports his species from his locality 17 at
the east end of the Lenox Hills. This collecting
place appears to be in the Sullivan Peak Member,
rather than in the Scacchinella beds of the Decie
Ranch Member. Other localities (105, 211) listed
by King are in the Scacchinella beds of the lower
Skinner Ranch Formation ( = Decie Ranch Member)
on the northwest side of the Hess Ranch Horst.
The horizon of King's locality T9 is uncertain. It
is possible that King's type specimen was derived
from a different biohermal assemblage, and is thus
specifically different from the species of this genus
west of it. It appears to be a fact that a great part
of the speciation in the Glass Mountains took place
on, or in the vicinity of, bioherms. We therefore
recognize King's species as separate from those described
herein, but we were unable to find additional
specimens.
Tropidelasma undulatum has a more strongly
elevated and wider fold on the pseudodeltidium
than T. rhamphodes, is thinner-shelled, and has a
less convex and less even brachial valve.
Tropidelasma species 1
Fairly large, pedicle valve elongated, interarea
broad and flattened, pseudodeltidium depressed.
Lateral profile of pedicle valve convex near midvalve,
narrowly domed in anterior profile, sides
nearly straight. Anterior commissure strongly sulcate.
Hinge almost equal to midwidth. Brachial
valve flatly convex, fairly strongly sulcate anteriorly.
Surface marked by numerous crowded, fine costellae
about 4 per mm at front. Cardinal process very
long and prominently forked.
MEASUREMENTS (in mm).—Pedicle valve length
21.4, brachial valve length 15.5, maximum width
18.2, hinge width 15.3, interarea length 13.0, thickness
17.0.
STRATIGRAPHIC OCCURRENCE.—Skinner Ranch Formation
(Sullivan Peak Member).
LOCALITY.—USNM 714y, 723-1.
TYPES.—Described specimens: USNM 147850a-e;
Hi2006a^TTyseg "T'Sp 3
DISCUSSION.—This species is known only from a
few fragmentary specimens, but it clearly is unlike
any other in the Glass Mountains. The closely
crowded costellae of the exterior and the somewhat
geniculated lateral profile of the pedicle valve are
distinctive. Although Tropidelasma is common in
the Scacchinella beds of the Decie Ranch Member,
it has been found in a few places in the Sullivan
Peak Member, the fauna of which is similar to that
of the Decie Ranch Member.
Tropidelasma species 2
PLATE 57: FIGURES 21, 22
Unusually large, wide, ornament delicate, costellae
of several sizes, unevenly alternating. About
5 costellae per mm at midlength, 3 costellae of first
magnitude, alternating with ones of secondary size.
Figured specimen about 48 mm long, 56 mm wide,
interarea approximately 25 mm long and estimated
30 mm wide. Pseudodeltidium broad, flat, about
13 mm long at anterior end. Lateral profile flatly
convex bulging near anterior.
NUMBER 15 349
STRATIGRAPHIC OCCURRENCE.—Gaptank Formation
(Uddenites-bearing Shale Member).
LOCALITY.—USNM 702q.
TYPES.—Described and figured specimen: USNM
147888.
DISCUSSION.—This is another of the peculiar species
having strong Permian aspect and affinities that
occur in the Uddenites-bearing Shale Member. The
Pennsylvanian elsewhere in North America has not
produced any streptorhynchids of large size or Permian
aspect. The specimen described above is undoubtedly
a new species as it is larger than any
other species described from the Glass Mountains,
is differently ornamented and differently shaped.
Unfortunately, it is represented by a single pedicle
valve.
Tropidelasma species 3
PLATE 101: FICURES 15-19
Species about medium size, indicated by 15 specimens
of rather poor preservation. Pedicle valve
conical, interarea fairly short, apsacline; valve
fairly deep, long side moderately convex in profile.
Brachial valve very strongly swollen, with long
cardinal process.
MEASUREMENTS (in mm).—USNM 152602: pedicle
valve length 20.3, brachial valve length 16.3,
maximum width 19.0, hinge width 11.6, interarea
length 8.0, thickness 15.8.
STRATIGRAPHIC OCCURRENCE.—Skinner Ranch Formation
(top).
LOCALITIES.—USNM 723-1, 714y, ?727a. _ u
TYPES.—Figured specimens: USNM 152600a, 16.
DISCUSSION.—This is almost certainly an undescribed
form as shown by the great inflation of the
brachial valve. The ornament is too poorly preserved
to define. Specimens from USNM 727a are
much misshapen and may or may not belong here.
More specimens are needed from both localities.
Tropidelasma species 4
PLATE 30: FICURES 7-10; PLATE 61: FIGURES 38-43;
PLATE 124: FICURES 11-13
Mostly immature specimens and one large adult
brachial valve suggest a species similar to T. rhamphodes
having a flaring and sulcate anterior. Large
brachial valve elongate elliptical, with long cardinal
process but well-defined erismata in some specimens.
Exterior sulcate anteriorly, with costellae
somewhat bundled but obscure. Outer margin flattened
on inside.
MEASUREMENTS (in mm).—Pedicle valve (USNM
152601a): length 14.2, brachial valve length?, maximum
width 12.6, hinge width 8.0, interarea length
7.6, thickness 8.4?; brachial valve (USNM 152601b):
length 20.2, maximum width 21.4, hinge width 15.4,
thickness 5.5.
STRATIGRAPHIC OCCURRENCE.—Cathedral Mountain
Formation (lower).
LOCALITY.—USNM 72 lu.
TYPES.—Figured specimens: USNM 152601a, b,
152603a, b, 153829.
DISCUSSION.—This species suggests T. rhamphodes,
but it differs in being attenuated anteriorly,
more narrowly hinged, and having maximum width
near midvalve.
Tropidelasma species 5
A single specimen represents a fifth undescribed
species of Tropidelasma. This one has well-differentiated
costellae, strong alternating with weaker,
very strongly umbonate, and anteriorly spreading
brachial valve and narrowly conical pedicle valve.
The pseudodeltidium is flat, but it is marked medially
by a monticulus.
MEASUREMENTS (in mm).—Pedicle valve length
10.0?, brachial valve length 11.4, maximum width
13.2, hinge width 8.0?, interarea length 6.0?, thickness
7.7?.
STRATIGRAPHIC OCCURRENCE.—Skinner Ranch Formation
(top).
LOCALITY.—USNM 705r.
TYPES.—Described specimen: USNM 152602.
DISCUSSION.—This may be an immature form
related to Tropidelasma species 3.
Family MEEKELLIDAE Stehli, 1954
Costellate to costate Derbyiacea having separate,
well-developed dental plates or spondylium in pedicle
valve and strongly developed cardinal process
in brachial valve.
The three genera from West Texas in this family
are generally much alike in external appearance,
but they are most closely related by high specialization
of the cardinal process. This structure is
350 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
greatly elongated and has a platform of considerable
size, the promontorium, developed in connection
with the socket.
Genera found in the Glass Mountains are:
Meekella White and St. John, 1867; Niviconia, new
genus; and Geyerella Schellwien, 1900a.
Genus Meekella White and St. John, 1867
Meekella White and St. John, 1867:120.—Hall and Clarke,
1892:264; 1894:155.—Girty, 1909:205.—R. E. King, 1931:
52.—Dunbar and Condra, 1932:124.—Sokolskaya, 1954:
152 Stehli, 1954:303.—Williams, et al., 1965:H405.
Conical, costate to plicate, with lidlike brachial
valve (specimen lived attached by pedicle valve
apical region); dental plates present, separate on
floor of pedicle valve or fused at point of contact
along floor to form pseudospondylium; cardinal
process long, curved, distally bifurcate, with dentifers
fused to shaft with fossettes for dental ridges
and teeth; and forming promontorium; erismata
divergent, extending into umbonal arch of brachial
valve, and delimiting posterior part of flabelliform
muscle area.
TYPE-SPECIES.—Plicatula striato-costata Cox
(1857:568, pi. 8: fig. 7).
DISCUSSION.—Meekella has been known for a long
time and its external details are familiar to all
students of late Paleozoic fossils. Its interior, however,
is much less well known except for generalities.
The reason for lack of knowledge is the
difficulty of obtaining good interiors. Meekella is
fairly well articulated, so separated valves are not
easy to obtain. Where they are common, as in the
Bone Spring Formation, it would be almost impossible
to obtain a free cardinal process were it
not for silicification. This is true also of other details
of the interior, which have hitherto been
unknown or not clearly seen. The Glass Mountains
and Sierra Diablo specimens, thus, offer a
great opportunity to understand this interesting
genus. The Capitan Limestone and its equivalents
in the Guadalupe Mountains have thus far not
yielded many specimens of Meekella, silicified or
otherwise.
Information on the dental plates and muscle
marks of the pedicle valve has been obtained from
many of the silicified specimens. The dental plates
in various species usually have a different lateral
profile or anterior edge. Those that are herein
termed receding usually have the plate extending as
a dental ridge under the palintrope edge for some
distance ventrally before it expands into a full
plate and extends to the floor. In others this distal
narrowness extends for only a short distance, and in
still others not at all. The receding plate lateral
profile shows a deep notch in the dental plate.
The dental plates meet the valve floor at varying
distance from each other. In some specimens
they are so close, they nearly touch. In these, a
union between the two may be achieved by deposition
of callus between the plates on the floor of the
valve. This structure may be described as a pseudospondylium.
This condition is not uniform in
any species, but it is more frequent in some than
in others. In many specimens the dental plates extend
almost vertically to the floor and maintain a
fair distance from each other at the floor. It is more
usual, however, for the dental plates to converge
but not to meet. In many species their anterior
ends are extended anteriorly along the floor.
It has been generally believed that the dental
plates bounded the area for muscle attachment, but
evidence revealed by some large specimens from
the Glass Mountains shows that this may not be
correct. These specimens of M. enormis, new species,
have a large and elevated muscle field anterior
to, and surrounding, the distal extremity of the
dental plates. These scars were seen only in old
and very large specimens. They are not seen in
most specimens because of the usual thin shell and
lack of old-age thickening. The strong costation or
plication of the exterior is not materially changed
within the muscle field, which is revealed by the
strongly thickened and elevated anterior rim. Although
the muscle field was revealed in only two
specimens, it must have existed in all the others,
and Meekella anatomy has been misinterpreted.
This new information suggests that the dental
plates of Meekella are in reality equivalent to the
median septum of Derbyia, which is surrounded
by a large and flabellate muscle scar like that of
Meekella.
The pseudodeltidium of Meekella is like that of
Tropidelasma in the Derbyiacea and of Triplesia
in the Triplesiacea. It is flat between the dental
plates and teeth, a phenomenon that defines the
delthyrium, but especially in old specimens the
pseudodeltidium is often outlined by narrow deNUMBER
15 351
pressions that run from just inside the teeth to the
apex. The Meekella pseudodeltidium is also
marked by a narrow, elevated ridge or fold, termed
the "monticulus," along the middle from the anterior
edge to the apex. This narrow fold is formed
by the chilidial boss, which is inserted into its anterior
opening. The notch produced by the open
end of the monticulus is bounded on each side by
a lobe of the pseudodeltidium that produces two
small scooped-out hollows, where these lobes moved
in the opening and closing of the valves. The
monticulus is often mistaken for the pseudodeltidium,
but actually it is only a part of it (Sokolskaya,
1954:59, fig. 59).
The cardinal process of the brachial valve is the
most distinctive structure of the genus. It is like
that of several other genera, but it is displayed to
perfection in some species of Meekella. The length
of the cardinal process generally is closely correlated
with the length of the interarea of the pedicle
valve. Species with long interareas generally have
a long cardinal process, whereas its length is retarded
in the species with wide and short interareas.
The following analysis of the meekellid cardinal
process is based partly on beautifully preserved
specimens of Niviconia globosa (King), in which
all features are similar to Meekella but exaggerated
so that the component parts are easily seen
(Figure 40). The cardinal process consists of several
elements welded together to form a long curved
plate, U-shaped in cross-section and with the open
part of the U facing anteriorly. The upper, solid
rounded base of the U is termed the "shaft" and
may be compared with this part of the cardinal
process in other genera having an elongated cardinal
process, such as Triplesia. The shaft forks
distally and each prong of the fork is slit longitudinally
for nearly its full length on the posterior
side, but on the anterior edge or side the slit is
short and divides each extremity into two small
lobes. Widening of these slits at the distal end
may produce a quadrilobed cardinal process in
large or old specimens. The longitudinally slit
tines of the fork are the myophore of the cardinal
process. The inner margins of the slits are serrated
and show evidence of muscular attachment.
The proximal end of the upper surface of the
shaft at its junction with the beak has a thick triangular
boss, herein designated the "chilidial boss,"
which is in the position of the chilidium and is
thought to represent a modification of that structure.
This boss fills the median notch of the narrow
ridge or monticulus that extends longitudinally
for the length of the pseudodeltidium of the pedicle
valve. On each side of the chilidial boss are
two small depressions that mark the path of the
proximal distal lobes of the pseudodeltidium, which
lie on each side of the notch at the butt of the
monticulus. In some species a conspicuous keel or
axial ridge extends along the crest of the shaft to
about the position of the base of the forked myophore.
On the anterior side of the shaft a flat or concave
FIGURE 40.—Niviconia globosa (R. E. King) : Dorsal valve, showing cardinal process and its
parts (cb=chilidial boss, den£=dentifer, e—erisma, /p—fulcral plate, g—gusset, fe=keel, ms
—myophore slit, pr=promontorium, sftr=shaft).
352 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
plate unites the shaft with the dentifer. The edge
of the dentifer is sharp and thin, extending distally
into a blunt, free point, which extends beyond the
ends of the forked myophore. In a proximal direction
the dentifer passes into the widely flaring
erismata, supporting plates or broad struts that
buttress the shaft of the cardinal process and tie it
to the wall of the valve. The plate uniting the
dentifer to the cardinal process shaft is herein
termed the "gusset." This plate is variable in width
and direction, but unusually large and steeply inclined
in Niviconia globosa, but in some species
of Meekella it flares laterally to produce a more
expanded cardinal process.
Outside of the gusset and buttressing the brachiophore
is another winglike plate, herein termed the
"promontorium," that terminates proximally in a
sharp bend and thickened ridge bounding the inside
wall of the socket (toward the brachiopod's
body). This seems to have the same function as
the socket ridge of rhynchonellids. The promontorium
is termed such because it looks out over
the shell cavity and forms the lateral high point
on the cardinal process. This plate, which is variously
developed among Meekella species but most
strongly formed in Niviconia globosa, is a buttress
for the socket and for the dentifer as well. Its edge
curves from the socket anteroventrally to form a
strengthening ridge on the outside of the dentifer.
In N. globosa the promontorium and the gusset
define a deep cup on each side of the shaft, but this
is the only species in which they are so concave
and strongly pronounced (Figure 40).
The sockets of Meekella are defined by wellformed
fulcral plates that appear at the angle of
the promontorium, where it forms a ridge on the
side of the socket. The fulcral plate is variable, but
it appears to be a definite plate, not merely an
excavation in the shell tissue.
The growth of the promontorium can be traced
from the ridgelike dentifer in immature specimens
to the complex adult structure. It forms by the
widening and deepening of the gusset and the
lateral expanding of the dentifer. The promontorium
is thus an expanded dentifer plus the gusset.
The fulcral plate is variable, but it appears to be
a definite plate, not merely an excavation in the
shell tissue.
Species of Meekella from the Glass Mountains
are highly variable. Each species has a characteristic
aspect that is apparent when a large sample
is viewed in the aggregate. Unless a single isolated
specimen is very near the norm for its species it
may be impossible to identify. No single simple
character suffices to distinguish species of Meekella
from one another; moreover, not all specific characters
are such that they can be observed on each
specimen; for instance, maximum size, average size,
range of variation in certain characters like plications
and dental plates, and changes that take
place with growth are important specific characters
in this genus.
The necessity of having a group of specimens
for specific identification makes it difficult to establish
with certainty the identity of most earlier
named species. All of Girty's (1909) species are
based on fragmentary, immature, or otherwise
scanty material, some of which have inaccurate locality
data. One of these species, Meekella attenuata
Girty, has come to have a certain meaning
through the work of Stehli (1954) despite the inadequacy
of the holotype and paratypes. Apparently
the holotype was collected in the Sierra
Diablo, although some doubt about this exists
(Girty, 1909:512, USGS 3764). Young of the species
that Stehli called M. attenuata Girty actually
appear conspecific with the holotype. We have not
been able, however, to recognize M. attenuata in
the Glass Mountains.
King (1931) used the name "M. attenuata Girty"
for some of his specimens from the Glass Mountains.
His description of that species, especially of
the exceptionally fine-ribbed specimens that he mentions,
seems to fit our M. caperata, new species,
although most of his illustrations (pi. 5: figs. 2, 4,
5, 7) are of specimens of M. skenoides Girty, and
one (fig. 4) shows M. calathica, new species. We
agree with R. E. King's (1931:54) suggestion that
M. multilirata Girty is based on characters that are
highly variable and are not reliable for distinction
of species. The name "M. multilirata" should be
confined to its holotype.
R. E. King (1931:55) recognized Meekella mexicana
Girty in the Glass Mountains, but large collections
from the Wolfcamp Formation have produced
a series of specimens with features transitional
from those he identified as M. mexicana
Girty to those that he called M. irregularis texana
NUMBER 15 353
King (now called M. texana King). Since Girty's
holotype and paratype specimens of M. mexicana
differ in several features from King's "M. mexicana
Girty," we have used King's name instead of the
doubtfully applicable name "M. mexicana."
Species of Meekella in the Glass Mountains all
differ from European and Asian species of the
genus. None is as weakly plicate and strongly
costellate as M. ufensis Tschernyschew (1902:587)
or M. baschkirica Tschernyschew (1902:586), except
juveniles of M. texana R. E. King. Meekella
eximia (Eichwald) (Tschernyschew, 1902:582) resembles
M. prionota, new species, but it is more
weakly plicate and the pedicle valve is less convex.
Judging from the variability of Texas species, however,
we doubt that all three of these so-called
"species" of Tschernyschew are more than variants
within a normal population of a single species,
especially because all were collected from a single
zone, the Productus cora "horizon." These three
species plus the specimens that he called M. striatocostata
(Cox) have a narrower range of variation
combined than does M. texana King or even the
least variable of our Texas species, M. prionota.
Probably M. timanica Tschernyschew (1902:585) is
distinct from the others; it differs from all Texas
species by its wide, low interarea and its very weak
plication. No Texas species gets as large as M.
timanica without becoming much more strongly
plicated. Meekella uralica Tschernyschew (1902:583)
resembles M. texana King in its gross external form,
but it is much more weakly plicated for its size.
Also, specimens of M. texana as large as Tschernyschew's
illustrated specimens (pi. 51: figs. 1, 2) are
much more deeply conical, and the interarea has
curved to meet the plane of commissure at nearly
a right angle instead of maintaining the large obtuse
angle of M. timanica shown in figure lb of
plate 51 (Tschernyschew, 1902).
Meekella multiplicata Licharew (1932:24, 44)
most nearly resembles M. grandis R. E. King
(Licharew compared it to M. occidentalis Newberry,
which we believe is the same as King's species).
Its plications are much finer and more
numerous, however, and, to judge from Licharew's
illustrations (pi. 6: fig. lb), the brachial valve is
more strongly convex.
Huang (1933:27) described Meekella kueichowensis
from the Permian of China. His figures (pi.
3: figs. 19, 20; pi. 4: figs. 1-4) show a large Meekella
that is similar to M. grandis King (= M. occidentalis
(Newberry)). Meekella kueichowensis is
closer to M. occidentalis and differs from M. grandis
in its smaller and more numerous plications,
lower convexity, and less transverse outline. The
interiors of M. kueichowensis and M. occidentalis
are known only from internal molds.
Schellwien (1900a: 19-24) described several species
of Meekella from the Carnic Alps. Of these, M.
irregularis Schellwien most nearly resembles a
Texas species that R. E. King (1931:55) named as
a new variety, M. irregularis var. texana, which
we now consider to be specifically distinct. Some
individuals of M. texana King closely resemble
Schellwien's illustrations of M. irregularis (pi. 2:
figs. 8, 9), but most of the population of M. texana
is made up of individuals less transverse, more
coarsely and irregularly plicate, with plications beginning
farther forward of the beak. Meekella
evanescens Schellwien is not similar to any of the
Texas species, being weakly plicate, deeply conical,
and with an auriculate hinge.
Meekella depressa Schellwien is small, scarcely
plicate, and shallowly conical. Probably it represents
a suite of juvenile shells from one or more
of his other species. Meekella procera Schellwien
closely resembles M. irregularis and differs from
M. texana in most of the same respects. In addition,
most specimens of M. texana that are as large
as the illustrated specimen (pi. 3: figs. 1, 2) of M.
procera have the interarea meeting the plane of
commissure at nearly a right angle. In M. procera
the beak is slanted strongly backward, and the
interarea and plane of commissure intersect at a
large obtuse angle.
Meekella angustiplicata, new species
PLATE 102: FIGURES 1-39
Medium size for genus, pedicle valve moderately
long, conical, brachial valve convex, dorsal view
subcircular to slightly elliptical. Sides and anterior
rounded; anterior commissure not regularly folded.
Hinge narrow, slightly auriculate. Surface costellate
and finely costate, costae narrowly rounded
and closely crowded, increasing by bifurcation anterior
to umbo, numbering 4 in 5 mm at front
margin of adults. Umbonal region for about 10
mm anterior to beaks finely costellate.
354 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
Pedicle valve triangular in lateral profile, ventral
side gently convex; anterior profile moderately
domed. Interarea long, flat, or gently convex; anterior
profile moderately domed. Interarea long,
flat, or gently concave, nearly at right angle to lateral
commissure. Pseudodeltidium flat, with monticulus.
Beak ridges strong. Beak usually forming
acute angle.
Brachial valve moderately convex in lateral profile,
umbonal region swollen and convex; anterior
profile fairly evenly and broadly convex. Umbonal
slopes somewhat swollen and steep. Anterior slope
gentle.
Pedicle valve interior with small teeth, strongly
receding dental plates converging toward floor but
seldom uniting.
Brachial valve interior with long, proximally
spreading cardinal process, deeply forked at distal
end. Promontorium slightly protuberant. Erismata
short and wide. Myophragm low in old specimens.
MEASUREMENTS
USNM 725c
150886a
150886b
150886c
150886d
150886e
150886f
150886g (holotype)
150886h
150886i
(in mm).—
pedicle
valve
length
6.7
7.6
9.5
10.6
17.4
21.5
22.7
30.5
?
brachial
valve
length
5.9
6.4
9.5
?
15.4
18.0
20.6
?
27.4
maximum
width
6.5
8.0
11.8
10.9
18.5
22.3
25.8
29.6
30.0
hinge
width
4.6
5.6
8.7
7.8
12.0
15.9
16.7
20.0*
19.3
interarea
length
2.8
3.4
5.0?
9.2
8.9
13.4
14.0
13.0
?
thickness
3.5
4.3
8.0?
7.5
16.2
21.6
22.6
14.0
10.5
STRATIGRAPHIC OCCURRENCE.—Bone Spring Formation
(100 and 120 feet above base).
LOCALITIES.—AMNH 696, 697, USNM 725c, 725s,
728t.
DIAGNOSIS.—Medium-sized Meekella with fine,
closely crowded and numerous costae.
TYPES.—Holotype: USNM 150886g; figured paratypes:
150886b, e, j-q; measured paratypes:
150886a-i; unfigured paratypes: 150886a, c, d, f-i.
COMPARISON.—Only Niviconia globosa (R. E.
King) and M. caperata, new species, need be compared
with this species. The two share in common
a similar profile and outline and more uniform
costae than are usual in the genus. Niviconia globosa
attains a much larger size than the Bone
Spring species, is more coarsely costate, and the
costae are angular, more elevated, and less numerous
than those of M. angustiplicata. Moreover,
the interiors of both valves of M. angustiplicata are
less exaggerated than those of the Glass Mountains
species. The cardinal process is not nearly so ponderous,
erismata are shorter and more widely spread
than in N. globosa. Dental plates of the Bone
Spring species are more receding and much shorter
than those of the Glass Mountains species.
Meekella angustiplicata resembles M. caperata in
the number of costae, but it differs in having costae
much more closely crowded together and the brachial
valve is more transversely elliptical rather
than subcircular in the Bone Spring species.
DISCUSSION.—Specimens of this species are difficult
to obtain in uncrushed form or without siliceous
fillings. Clean shells are rare, but, when
obtained, they show their details with exceptional
clarity.
Meekella attenuata Girty
PLATE 103: FIGURES 1-34; PLATE 104: FIGURES 11-20
Meekella attenuata Girty, 1909:205 (?), pi. 24: figs. 7-9a, pi.
25: figs. 4-4d.—R. E. King (part), 1931:52.—Stehli,
1954:304, pi. 18: figs. 6-11.
Meekella hessensis Stehli (not King), 1954:305, pi. 18: figs.
3-5.
Girty's holotype is a small and immature specimen,
his paratypes are somewhat exfoliated specimens,
less youthful than the holotype, but nevertheless
young. The holotype is said to come from
the Sierra Diablo, eight miles north of the Hazel
Mine, Van Horn (30') Quadrangle, Texas. ParaNUMBER
15 355
types are from the Bone Spring Limestone about
two miles south of El Capitan. The holotype probably
is from the lower Bone Spring, but the paratypes
give no indication of the level from which
they may have been taken, probably high in the
Bone Spring. Stehli (1954:304) evidently regarded
the paratypes as conspecific with the holotype, more
representative of his large collection of Meekella
from the lower Bone Spring Formation. We have
compared the holotype with immature specimens
from Stehli's localities in the national collection
and find specimens that duplicate it in many details.
Probably this is the stratigraphic level from
which the type came. Meekella attenuata appears
to be common at this level, and it may be obtained
in abundance by dissolving lower Bone Spring
Limestone. The specimens consist chiefly of separated
valves, as noted by Stehli, but they are well
preserved and show the anatomical details to perfection.
Meekella attenuata is about medium size, conical,
subcircular (in dorsal view). The hinge is narrow,
sides widen rapidly to midvalve and narrow to
the broad anterior curve. The anterior commissure
is rectimarginate. The costae are narrowly rounded,
direct, only rarely bifurcated; interspaces are narrower
than the costae. The maximum number of
costae is 22 in a large individual and about 15 in
smaller ones. The posterior is costellate and nonplicate
for 8 to 12 mm, the holotype being nonplicate
for about 10.5 mm.
The pedicle valve is gently convex in lateral
profile and broadly and gently convex in anterior
profile. The interarea is narrow and short, the
beak attenuated and somewhat abruptly curved.
The interarea and commissure in most specimens
are at an acute angle.
The brachial valve is moderately convex in lateral
and anterior profiles about as deep as the opposite
valve. The valve is full medially, but some
anterior flattening occurs in some specimens.
The pedicle valve interior has strong dental
plates and long, slender teeth, the former only
slightly convergent and usually narrowly separated
along the valve floor. The brachial valve has a
moderately long cardinal process, slightly forked
distally and with a narrow, shallow promontorium.
The erismata are unusually short and widely divergent.
MEASUREMENTS
USNM 728e
151043c
151043d
151043e
151043f
151043g
151043h
(in mm).—
pedicle
valve
length
22.8
?
?
?
17.0
17.7
brachial
valve
length
?
27.1
22.8
23.0
17.1
16.0
maximum
width
27.3
33.2
29.5
25.5
22.6
21.1
hinge
width
17.8
23.8
19.3
16.2
16.0
17.0
interarea
length
9.7
?
?
?
6.0
7.3
thickness
10.2
10.0
7.3
8.7
12.0
10.2
STRATIGRAPHIC OCCURRENCE.—Bone Spring Formation
(lower).
LOCALITIES.—AMNH 625, 629, 631, 632, 696, 699,
USNM 728e, 728f, 728h, 741.
DIAGNOSIS.—Medium-sized Meekella with short
interarea, incurved acute beak, and costae ranging
from 14 to 22 in the adult.
TYPES.—Holotype: USNM 118514; figured hypotypes:
150894k, n, 151043a, 153517a-n.
COMPARISON.—Meekella attenuata most resembles
M. skenoides Girty from the Word Formation and
the Getaway Member of the Cherry Canyon Formation,
but it differs in being less deep, in having
a less elongated interarea and fewer costae. Meekella
prionota, new species, can be distinguished
readily from M. attenuata by its more convex brachial
valves, broad rounded plications, deep pedicle
valve, and the broad sulcus of the brachial valve.
Meekella intermedia, new species, occurs near the
same stratigraphic level as M. attenuata, but it is
deeper, with more elongated interarea and much
more numerous costae.
DISCUSSION.—Although Meekella attenuata, like
all Meekellas, is variable, its variability seems not
to be so wide as that of many other species. Aside
from the misshapen forms produced by crowding
356 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
and other consequences of an attached mode of
life, the range of costation is not great, the interarea
is seldom greatly elongated, and usually it
maintains the same relationship to the commissure
as is characteristic for the species. The number of
bizarre and malformed specimens in our collection
is small.
The broad-ribbed forms referred to M. hessensis
by Stehli are herein placed in the synonymy of
Girty's species. They have essentially the same form,
the same costellate posterior, but the costae are
less numerous. They are regarded as a paucicostate
phase of M. attenuata.
Meekella calathica, new species
PLATE 111: FIGURES 1-43; PLATE 112: FIGURES 1-24; PLATE 113:
FIGURES 1-15; PLATE 114: FIGURES 11-26
Meekella difficilis R. E. King (not Girty), 1931:53, pi. 4:
figs. 16a-d, 17, pi. 5: figs, la, lb.
Adults large, biconvex, shallowly to deeply conical;
outline transverse to nearly semicircular, ends
of hinge prominently auriculate; hinge width proportionately
constant, rarely outside limits of 0.5-
0.8 of maximum width of shell. Plications of adults
strong, fine to very coarse, normally fairly regular
and not strongly interrupted by growth lines, with
1 or 2 on each valve bifurcating, numbering 6 to
21, averaging about 12, crests angular to subangular,
not commonly rounded, beginning between 5
and 10 mm anterior to beaks. Costellae moderately
strong, especially in nonplicate youthful stage,
added by insertion in troughs of plications, anteriorly
converging toward crests of plications;
growth lines weak to moderately strong, more frequent
anteriorly. Commissure rectimarginate
coarsely serrate, with minute denticulation produced
by anterior terminations of costellae.
Pedicle valve beak moderately sharp, short to
moderately long, blunt to attentuate, often slightly
twisted; interarea commonly much wider than long,
normally gently concave toward beak but often
convex in juveniles, nearly right angle in adults,
but without sharp flexure; pseudodeltidium narrow,
only slightly expanding dorsally, occupying
between 0.2 and 0.33 total width of hinge, bisected
by low narrow ridge.
Brachial valve moderately to strongly convex,
maximum convexity near beak, plications equal in
number and strength to those of pedicle valve. Interarea
short.
Pedicle valve interior with short, strong teeth,
triangular in cross section, projecting from underside
of interarea, extending ventrally as nearly
straight, convergent dental ridges supporting inside
of interarea, then curving to floor of valve as dental
plates, slightly bowed, ventrally convergent and
normally anteriorly convergent, occasionally meeting
and fusing at floor to form pseudospondylium.
Brachial valve with large, strongly curved cardinal
process, strongly bifurcate at free end, each
branch with long, finely serrate slit along posterior
crest, branches uniting proximally to form subcarinate
crest of process. Promontorium flat to
slightly concave, projecting laterally from process
and extending along it for somewhat more than
half its length, terminating slightly beyond point
of bifurcation of process, constricting proximally
to accommodate deep and round hinge sockets;
dentifers fused to cardinal process by gusset,
projecting anterolateral^ from it as small plates.
Erismata strong, moderately divergent and forming
deep umbonal chamber. Muscle area flabellate, in
umbonal arch between dentifer supports, bisected
by low myophragm; muscle marks obscure, consisting
of longitudinal striae in muscle area and
along bases of brachiophore supports.
NUMBER 15 357
MEASUREMENTS (in mm).—
USNM 703a
150910a
150910b
150910c
150910d
150910e
150910f
150910g
150910h
150910i
150910J
150910k
150910-1
150910m
150910n
150910o
150910p
150910q
15091Or
USNM 702c
150909a
150909b
150909c
USNM 702c
150909d
150909e
150909f
152604 (holotype)
USNM 702
150605a
150605b
150605c
150605d
150605e
USNM 702un
150607a
150607b
150607c
150607d
150607e
pedicle
valve
length
47.7
48.8
30.8
24.8
31.0
23.8
21.0
23.7
17.4
15.2
12.7
12.6
11.0
10.6
8.4
5.5
4.4
4.8
56.4
35.5
35.4
36.4
31.2
18.7
52.7
41.3
29.0
26.8
24.0
23.7
31.0
29.7
25.5
24.4
18.3
brachial
valve
length
43.5
39.6
27.7
23.7
21.4
21.6
18.8
12.3
14.5
11.7
11.7
10.3
9.3
8.3
7.5
5.5
4.3
3.7
50.4
35.5
34.2
30.0
27.8
14.9
50.6
41.3
28.6
24.0
22.5
20.3
31.0
28.8
24.8
21.5
17.2
maximum
width
57.0
44.4
35.4
28.4
26.5
24.4
23.0
21.3
16.9
14.6
13.6
12.3
11.0
8.9
7.8
6.5
5.5
4.6
58.5
46.4
41.8
33.5
36.0
19.0
52.8
43.7
30.5
29.7
27.2
25.5
35.6
34.0
29.1
26.6
20.6
hinge
width
28.8
29.8
27.3
18.9
19.8
16.0
18.9
15.8
13.4
8.6
9.3
8.2
7.9
6.4
5.1
6.1
4.7
4.1
32.4
32.4
27.5
21.4
28.4
14.0
25.0
27.0
22.8
20.0
19.4
15.3
19.6
26.4
19.5
14.8
12.6
interarea
length
16.8
25.4
13.5
13.4
18.7
11.9
12.8
10.8
6.7
6.7
4T4-
12.2
3.6
4.6
3.5
4.1
3.2
2.2
15.0
15.0
12.9
17.8
15.8
10.7
14.0
13.3?
13.4
8.4
8.0
7.0
10.4
10.5
12.8
6.7
5.2
thickness
34.6
37.0
27.5
22.7
18.8
22.8
20.0
20.7
11.7
9.1
9.3
15.4
7.8
7.8
5.2
5.4
4.0
2.8
49.8
29.4
32.3
30.0
29.0
17.3
43.8
30.2
27.7
22.7
19.7
17.6
26.0
22.6
22.0
17.6
15.0
STRATIGRAPHIC OCCURRENCE.—Cathedral Mountain
Formation (Wedin Member), Road Canyon
Formation.
LOCALITIES.—Cathedral Mountain: AMNH 500,
500D, 500F, 500H, 500J, 500K, 500L, 500M, 500N,
500X, 504, USNM 702, 702a, 702b, 702ent, 702inst,
702-low, 702un, 703a1, 703b, 703bs, 708, 71 lq, 712o,
714v, 721u, 723u, 723y, 726o, 726u, 726x, 726y, 727p,
727w, 727x, 732u, 733m; Wedin: USNM 700-1,
700x, 714w, 717e, 723v; Road Canyon: AMNH 501,
503, USNM 700v, 702c, 703, 703a, 703c, 703d, 706f,
707e, 709c, 710u, 710z, 716x, 719x, 720d, 721j, 721o,
721r, 721t, 721w, 721s, 721t, 721w, 721x, 721y, 721z,
722e, 722f, 722g, 722v, 723a, 723w, 724a, 724b, 724c,
724d, 724j, 726d, 726f, 726z, 726za, 732m.
DIAGNOSIS.—Large Meekella with costellate urnbones,
pauciplicate exterior, and auriculate cardinal
extremities.
TYPES.—Holotype: USNM 152604; figured paratypes:
150481a, b, 150484a-c, 150490a, b, 150605f,
150909b, f, 150910c, e, h, 1, p-r, 153520a-g, 153521-
153524, 153525a, b, 153526, 153527a, b, 153528a, b,
358 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
153529, 153530; measured paratypes: 150484a-m
(plications counted), 150605a-e, 150607a-e,
150910a-r, 150909a-f, 152604; unfigured paratypes:
150605a-e, 150909a, c-e, 150910a, b, d, f-k, m-o.
COMPARISON.—Meekella calathica is characterized
by its strong, normally regular plications, prominent
auriculation of the ends of the hinge, wide
interareas with sides that are concave in outline as
they converge toward the slightly attentate beak,
dental plates that normally are separate at their
anterior ends, and its dentifers and promontorium
that extend beyond the point of bifurcation of the
cardinal process.
This species is distinguished from M. irregularis
Schellwien and M. texana R. E. King by its normally
shorter beak, much stronger and more regular
plication that starts farther back on the beak,
auriculate hinge, weaker costellae, and relatively
longer brachiophores. Its strong plications distinguish
it from M. mexicana Girty (from New
Mexico), and it is distinguished from M. caperata,
new species, and from M. attenuata Girty (from
the Guadalupe and Diablo Mountains) by its
coarser plications, less transverse outline, more auriculate
hinge, and less attenuate beak.
Meekella calathica resembles M. prionota, new
species, in its coarse plication, but it differs in its
auriculate hinge, normally less conspicuous costellation,
relatively longer dentifers, and normally
narrower space between the dental plates. It is
distinguished from M. skenoides Girty by its proportionately
wider hinge and lower interarea,
slightly more prominent auriculation of the hinge,
costellae that arch up to the crest of the plications,
more variable coarseness of plication, and shorter
dentifers and socket plates.
This species differs from M. pyramidalis (Newberry),
from the Kaibab Formation, in its posteriorly
curving beak rather than the anteriorly sloping
beak that gives M. pyramidalis its pyramidal shape
and from M. occidentalis (Newberry) and M. grandis
King in its higher interarea, more transverse
outline, and stronger convexity. Since Newberry's
specimens are internal molds, further detailed comparison
is meaningless.
DISCUSSION.—Meekella calathica varies most in its
gross shape, strength of ornamentation, and in the
number and coarseness of its plications. The shape
may vary in degree of convexity, or in length of
pedicle beak, strength of auriculation of hinge,
width of interarea or the angle at which the interarea
intersects the plane of commissure. Plications
vary in strength, coarseness, and number with
none of these factors directly dependent upon the
size of the shell (except, of course, in the smallest
of juveniles). Thirty-five complete shells were selected
from samples from USNM 702c and one
pedicle valve from USNM 702 with selection based
on uniformity of size. All 36 are between 20 and
32 mm in maximum width. This group includes
about all of the complete shells of that size in sample
702c. The following table shows the number
of plications on these specimens:
number of plications 9 10 11 12 13 14 15 16 17 18 19 20 21
number of specimens 1 1
The largest specimen of this group, 32 mm wide,
has 8 plications. The largest specimen in the national
collection is 59 mm wide and has only 14
plications. Coarseness and strength of plications
depends upon the number present: with many present,
each must be finer and somewhat weaker in
order to fit on the shell. When viewed beside one
another, the end members of the above selected
group are so different from one another that they
appear to belong almost certainly to separate species.
But all stages of transition between the extremes
may be found in any large sample (e.g., USNM 702c
or 703a), and a count of plications in a randomly
selected group produces a normal curve.
5 7 7 3 2 1 0 1 0 0 1
Some specimens of M. calathica have unusually
strong growth lines and costellae that produce a
reticulate or woven effect over the surface of the
shell. Many of the shells with this stronger ornamentation
are more than ordinarily auriculate and
have lower convexity of the pedicle than do those
with weaker ornamentation. All degrees of transition
are present, however, and so many shells are
intermediate that the population cannot be divided
into two groups that are sufficiently distinct to warrant
naming of the reticulate type, not even as a
variety of M. calathica.
Meekella difficilis of R. E. King (1931:53), but
not of Girty (1909), has all of the diagnostic charNUMBER
15 359
acteristics of M. calathica and is not conspecific
with the holotype of M. difficilis Girty (USNM
118510). The specimens illustrated by King (1931,
pi. 4: figs. 16, 17; pi. 5: fig. 1) are more coarsely
plicate than most specimens of M. difficilis, but
they agree in all respects with numerous specimens
of M. calathica in our collections. Furthermore,
M. "difficilis" of King occurs in the Leonard Formation,
whereas M. difficilis Girty (now a synonym
of M. skenoides Girty) is present in the Word Formation.
Meekella caperata, new species
PLATE 89: FIGURES 11-13; PLATE 105: FIGURES 10-34
Small to medium biconvex, deeply conical; outline
transversely subelliptical; hinge straight, between
two-thirds and three-fourths maximum
width, normally not auriculate. Plications fine but
strong, rounded, fairly regular, increasing in number
anteriorly by bifurcation and intercalation,
numbering between 14 and 40, beginning 5 to 15
mm anterior to beaks. Costellae very fine, strongest
on unplicated part of umbo; growth lines faint,
increasing in frequency anteriorly.
Pedicle valve beak sharp, normally attenuated,
commonly twisted; interarea long, wide, nearly flat,
commonly meeting plane of commissure at obtuse
angle, rarely at acute angle; pseudodeltidium narrow,
not widening anteriorly as fast as interarea,
measuring about one-fourth width of interarea at
hinge, bisected by narrow but fairly high median
ridge.
Brachial valve moderately convex; beak slightly
overhanging pedicle interarea; plications equal in
number and strength to those on pedicle valve.
Pedicle valve interior with short, strong hinge
teeth, extending posteriorly as convergent dental
ridges; dental plates convergent toward valve floor,
extending forward along floor only short distance;
normally separate along floor of valve, but rarely
fusing to form pseudospondylium, muscle marks
obscure.
Brachial valve interior with moderately long,
curved cardinal process, bifurcate at distal end,
each branch slit longitudinally and finely serrate
within slits; branches united about midway along
process to form crest along proximal half; promontorium
projecting only slightly from sides of
process, to form crest along proximal half; promontorium
projecting only slightly from sides of
process, terminating proximally as enlarged .bosses
just anterior to partly open sockets; dentifers fused
to sides of process ending distally as 2 short apophyses
from underside of cardinal process, widening
dorsally to join with erismata, as supports into
umbonal arch, there outlining posterior end of
muscle area. Muscle field bilobed, bisected by low
myophragm; adductor scars longitudinally striate
within muscle area and along bases of erismata.
MEASUREMENTS
USNM 705a
150499a
150499b
150499c
150499d
150499e
150499f (holotype)
USNM 707w
150503
(in m m ) .—
pedicle
valve
length
9.6
13.0
16.9
24.2
32.5
29.4
24.4
brachial
valve
length
9.6
11.0
15.9
21.7
25.2
29.4
24.4
maximum
width
11.5
14.5
22.5
24.9
32.7
39.7
28.3
hinge
width
8.0
8.8
16.5
17.4
20.7
25.0
16.2
interarea
length
7.4
7.6
13.0
16.5
21.8
19.8
16.0
thickness
10.0
9.9
18.6
20.2
23.7
32.0
24.1
STRATIGRAPHIC OCCURRENCE.—Skinner Ranch Formation
(Decie Ranch, Poplar Tank, and Sullivan
Peak members), Cibolo Formation.
LOCALITIES.—Decie Ranch: USNM 707a, 707w,
724p, 733h; Poplar Tank: 707h; Sullivan Peak:
707; Skinner Ranch (base): 705a, 720e; Cibolo: 738r.
DIAGNOSIS.—Large Meekella with elongated pedicle
valve and fine plications.
TYPES.—Holotype: USNM 150499f; figured paratype:
150499a, c, f, 150500, 151026, 153531a-d,
153546; measured paratypes: 150499a-e, 150503;
unfigured paratypes: 150499b, d, e.
360 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
COMPARISON.—Meekella caperata is characterized
by its numerous, fine, frequently bifurcating plications
that do not begin as far back as the beak,
nonauriculate hinge, attenuate pedicle beak and
short dental plates. It differs from all other species
in the Glass Mountains except Niviconia globosa
(R. E. King) in the fineness and large number of
its plications. It differs from N. globosa in its
greater maximum number of plications that do not
extend to the ends of the beaks, its nonauriculate
hinge, more transverse outline, and conventionally
attached promontoria that do not form troughs
along the sides of the cardinal process.
DISCUSSION.—R. E. King (1931:53) mentions a
specimen with 38 plications from his locality 38
(basal Leonard, Decie Ranch Member of Skinner
Ranch Formation) that he identified as M. attenuata
Girty. Undoubtedly the specimen belongs to
M. caperata, inasmuch as only that species has so
many plications.
Probably many specimens identified by King as
M. attenuata Girty actually belong to M. caperata,
although most of the specimens illustrated by him
as M. attenuata are M. skenoides Girty (King, 1931,
pi. 5: figs. 2, 4, 5, 7) or M. calathica, (pi. 5: fig. 3);
however, his description of M. attenuata best fits
a species with many fine plications. There is little
basis for identifying anything outside the Bone
Spring Formation with M. attenuata Girty. The
holotype is a juvenile with only 10 weak plications
instead of the "15 to 25" attributed to the species
by Stehli (1954:304) or the "11 to 28 strong, subangular
plications" that R. E. King (1931:53) said
characterize the species. Girty's paratypes (three
specimens, USNM 118507a-c) are poorly preserved
and show a maximum of 14 weak plications; they
are not specifically identifiable by present standards.
It is impossible to obtain topotype specimens that
might shed light on the identity of the holotype,
because the locality from which that specimen was
collected is unknown (Girty, 1909:512, data on
USGS 3764).
Meekella circularis, new species
PLATE 101: FIGURES 1-8
Very large for genus, crudely subcircular in outline,
length and width nearly equal in adults. Sides
and anterior broadly rounded; maximum width
near midvalve. Hinge narrower than maximum
width, about two-thirds width. Interarea short,
curved, approximately catacline. Pseudodeltidium
broad and low on brachial valve, somewhat stronger
on pedicle valve and numbering 8 to 14. Plications
mostly direct, some bifurcating. Entire surface covered
by strong costellae in grooves and on plications.
Pedicle valve gently convex in lateral profile,
most convexity in posterior, flattened anteriorly;
anterior profile broadly and moderately domed.
Umbonal region moderately swrollen; median region
gently convex to flattened. Posterolateral
slopes steep. Brachial valve moderately strongly,
evenly convex in lateral profile; broadly and moderately
domed in anterior profile. Umbonal region
slightly swollen; median region and sides swollen;
lateral and anterior slopes fairly steep. Pedicle
valve interior with large teeth and strong dental
ridges, dental plates short, receding and convergent,
barely uniting on floor in large adults but narrowly
separated in young. Brachial valve interior with
moderately long, wide cardinal process with short
narrowly separated prongs. Promontorium small,
fulcral plates small. Erismata long, widely flaring.
Adductor scars large and subflabellate.
MEASUREMENTS
AMNH 700
152613a
152613b
152613c
152613d (holotype)
USNM 725b
152614a
152614b
(in mm).—
pedicle
valve
length
15.5
20.5
?
52.2
28.9
?
brachial
valve
length
15.0
18.5
30.5
51.9
?
28.0
maximum
ividth
19.6
24.6
38.7
62.4
35.0
37.3
hinge
width
13.0
17.6
23.0*
44.1
24.2
24.7
interarea
length
6.1
5.0
?
18.8
8.6
?
thickness
11.4
12.2
11.3
40.9
?
8.8
NUMBER 15 361
STRATIGRAPHIC OCCURRENCE.—Hueco Formation.
LOCALITIES.—AMNH 700, USNM 725a, 725b.
DIAGNOSIS.—Large Meekella with subdued plications
on the brachial valve and short convergent
dental plates.
TYPES.—Holotype: USNM 152613d; unfigured
measured paratypes: 152613a-d, 152614a, b.
COMPARISON.—This species is best compared with
the huge Meekellas: M. enormis, new species; M.
occidentalis (Newberry); M. calathica, new species;
and M. magnifica, new species. Adults are smaller
than M. enormis and have a much shorter pedicle
valve interarea; they are less strongly plicated than
M. occidentalis and more convex on the brachial
side; they are less convex on both valves and less
strongly and deeply plicated on both valves than
M. calathica.
This species resembles M. magnifica in its robust
form, but it is not as large as that species, has much
more subdued ornament, a rounder outline, and a
much less extended beak and interarea.
Meekella enormis, new species
PLATE 69: FICURES 10-12; PLATE 106: FIGURES 1-25; PLATE 107:
FIGURES 1-17
Very large for genus, deeply conical, wide hinged,
transversely elliptical in dorsal outline. Interarea
broad, nearly at right angles to the lateral commissure;
hinge width varying between 0.6 and 0.75 of
maximum width. Cardinal extremities slightly
auriculate. Sides unevenly rounded, greatest width
at midvalve or slightly anterior; anterior commissure
faintly sulcate, especially in juveniles. Surface
plicate, plications unequal in size on valves, on
brachial valve more distant and lower in adults;
plications rounded, often irregular, few bifurcating,
averaging about 13, ranging from 10 to 21 on largest
specimens. Fine costellae strong, numbering 3
per mm near front of large specimens.
Pedicle valve unevenly and moderately convex in
lateral profile, moderately domed in anterior profile;
interarea moderately long usually with slight
concavity near beak. Pseudodeltidium equal about
one-fourth the hinge width, strong monticulus in
old shells with strong lateral ridges. Beak ridges
strong, elevated, defining concave flanks. Young
specimens weakly folded, obscure in adults.
Brachial valve evenly and moderately convex in
lateral profile, broadly and moderately convex in
anterior profile; umbonal region moderately swollen,
extending slightly posterior to hinge; interarea
short or obsolete; umbonal slopes short and moderately
steep; sulcus shallow and broad in young,
not clearly visible in large specimens.
Pedicle valve interior with small teeth; strong
receding dental plates, well separated in the young
but converging to form pseudospondylium in old
specimens and in aberrant individuals. Muscle field
large, strongly flabellate, anterior rim thickened in
oldest adults, reaching nearly to midvalve, well outside
delthyrial cavity.
Brachial valve interior with cardinal process
moderately elongated, moderately spreading, dentifers
well developed, erismata short in young, long
and thick in adults.
MEASUREMENTS
USNM 720e
150890a
150890b
150890c
150890d
150890e
150890f
150890g
150890h
150890i
15089OJ
150890k
150890-1
150890m
150890n (holotype)
(in mm).—
pedicle
valve
length
7.5
9.7
11.7
17.4
18.4
27.4
22.1
27.6
26.7
31.7
35.0
32.0
49.4
65.0
brachial
valve
length
6.6
9.7
10.3
15.3
18.4
20.1
21.6
25.2
25.6
27.6
31.0
32.0
49.4
60.5
maximum
width
7.8
11.5
13.2
18.0
24.8
24.0
26.7
32.1
30.6
36.6
36.6
40.3
57.0
79.5
hinge
width
6.1
9.8
9.3
11.2
14.9
17.9
18.2
21.0
22.8
27.4
27.3
28.0
44.4
51.0
interarea
length
4.2
4.9
8.2
6.7
9.1
14.8
9.5
11.2
20.7
16.0
13.7
11.7?
33.9
25.5
thickness
5.9
8.0
12.0
15.2
15.2
17.8
18.5
23.8
31.8
29.8
26.6
25.0
51.0
55.8
362 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
STRATIGRAPHIC OCCURRENCE.—Skinner Ranch Formation
(Decie Ranch, Poplar Tank, and Sullivan
Peak members).
LOCALITIES.—Decie Ranch: USNM 707a, 707w,
714t; Poplar Tank: 707h; Sullivan Peak: 707v;
Skinner Ranch (lower): 705a, 714q, 716t, 720e.
DIAGNOSIS.—Very large Meekella with exaggerated
ornament on pedicle valve and an elevated
diductor muscle margin in the pedicle valve.
TYPES.—Holotype: USNM 150890n; figured
paratypes: 150596, 150889, 150890c, e, g, i, j , m,
153448a-c; measured paratypes: 150890a-m; unfigured
paratypes: 150890a, b, d, f, h, k, 1, 153448b.
COMPARISON.—This species attains the largest size
of any Meekella found in the Glass Mountains and
approaches the large species found in the Permian
of Japan, M. gigantea Hayasaka 1933 (not Stuckenberg,
1905). This species suggests M. occidentalis
(Newberry), which attains a large size as seen in
its synonym M. grandis King. This species differs
from M. calathica, new species, in having lower
plications, the plications less differentiated on the
two valves, usually having much less thickness in
the large adults, a longer and narrower beak, narrower
pseudodeltidium, more fully umbonate brachial
valve, and generally narrower hinge.
Some young specimens of M. enormis suggest relationship
to M. hessensis R. E. King, and the
number and arrangement of plications accords with
those of M. enormis. Meekella hessensis is, however,
wider than M. enormis, and M. hessensis occurs
at the top of the Skinner Ranch Formation
rather than at its base. The holotype of M. hessensis
is the only reliable specimen of the species
known, and that has no beak. It is difficult, therefore,
to make a satisfactory determination with the
M. enormis ranging in size from 7.5 mm to 65 mm
in length.
DISCUSSION.—Unusual features of this genus are
the difference in the ornament of the two valves
and the enormous development of the diductor
muscle area inside the pedicle valve of adults. The
difference in ornament is seen best in the large
adults, but it is not as clear in the smaller specimens
or in very young forms. Plications of the
pedicle valve normally are closely crowded, irregular,
and subangularly rounded. At the anterior of
the large specimens the plications are broadened
and the furrows between them are much narrower.
On the brachial valve, on the other hand, plications
are much lower and are spread farther apart
so that the troughs between them are broader.
Spasmodic bifurcation of plications occurs on both
valves, but it is more prominent on the pedicle
valve.
No unusual features are presented in the growth
of this species; it is variable at all stages. The nonplicate
stage is fairly short. The smallest measured
specimen is 7.5 mm in length and does not
exhibit any well-marked plications. The next
longer specimen, about 10 mm, is fairly well plicated
about 7 mm from beak. As usual with attached
forms, length and width are very unreliable
measures. One odd specimen is fairly wide and
suggests M. hessensis.
Meekella enormis lived closely crowded among
large specimens of Scacchinella and Derbyia, usually
liberally covered by bryozoa and other calcareous
material (assumed algal). Some specimens
are literally buried in encrusting material, which
must have been lethal; others are riddled by borings
of acrothoracic barnacles (Schlaudt and
Young, 1960:905). Some shells are so greatly riddled
as to be almost destroyed.
Meekella hessensis R. E. King
PLATE 108: FIGURES 11-31
Meekella hessensis R. E. King, 1931:56, pi. 5: figs. 8, 9.
Medium size for genus, outline transversely elliptical,
widest near midvalve; hinge about two-thirds
width; sides strongly rounded; anterior margin
broadly rounded; anterior commissure usually rectimarginate
to faintly sulcate. Interarea short to
moderately long, usually nearly catacline. Plications
variable, usually narrowly angular, separated
by equally wide troughs, in some adults abruptly
widening and flattening, and occasionally bifurcated
or intercalated, numbering 7-16. Juveniles
strongly costellate until reaching 5-7 mm when
plication originates; costellae strong over body of
shell, diverging laterally in troughs of adults.
Pedicle valve flat to slightly convex in lateral
profile often with break in slope where plications
expand suddenly; broadly and moderately convex
in anterior profile; umbonal region flattened to
gently convex; beak blunt, usually forming wide
angle; median region varying from flattened to conNUMBER
15 363
cave to gently convex; flanks moderately steep.
Pseudodeltidium flat, narrow with elevated monticulus.
Brachial valve evenly and gently convex in lateral
profile, greatest convexity at umbo of adults
and large specimens; broadly and moderately convex
in anterior profile; median region moderately
inflated, median sulcus shallow, only faintly visible
at anterior; umbo gently to moderately swollen,
protruding slightly beyond posterior margin; lateral
and anterior slopes usually gently convex, sloping
gently to margins.
Pedicle valve interior with short receding dental
plates reaching about one-third valve length, dental
plates forming narrow, parallel track on valve
floor. Teeth small, sharp.
Brachial valve interior with long and fairly wide
cardinal process; prongs short, subparallel; dentifers
long, almost reaching ends of cardinal process;
erismata long, moderately wide. Promontorium
well developed. Muscles marks not impressed.
MEASUREMENTS
King 122
YPM 10950
USNM 702e
152608a
152608b
152608c
USNM 702f
152609
AMNH 369
152610
USNM 722-1
152611a
152611b
152611c
USNM 725c
152612a
152612b
152612c
(in mm).—
pedicle
valve
length
(holotype) 27.7 +
22.1
11.8
8.5
23.5
22.5
25.4
p
14.5
21.4
16.8
9.7
brachial
valve
length
24.6
21.8
11.3
7.7
22.9
21.4
?
29.4
12.9
20.2
15.8
9.4
maximum
width
34.4
27.3
13.4
9.0
25.8*
26.6
31.8
36.0
17.3
25.1
18.5
11.7
hinge
width
23.4
16.7
8.9
6.4
15.0
14.3
22.3
25.0
10.3
15.8
14.6
8.9
interarea
length
?
7.0
5.5
4.1
3.5
6.2
10.6
?
3.7
7.0
7.0
5.0
thickness
18.5?
17.4
8.0
5.7
16.5
21.3
12.0?
11.2
11.8
15.5
15.2
7.8
STRATIGRAPHIC OCCURRENCE.—Bone Spring Formation,
Hess Formation (Taylor Ranch Member),
Skinner Ranch Formation (Decie Ranch, Poplar
Tank, Sullivan Peak, and Dugout Mountain members).
LOCALITIES.—Bone Spring: AMNH 369, 492, 497,
591, 624, 628, 658, 660, 697, USNM 725c, 725s, 725y,
728e, 728f, 728g, 728v, 729, 745; Hess: R. E. King
122, USNM 722n, 726n; Decie Ranch: USNM 707a,
720g; Poplar Tank: USNM 707ha, 708e; Sullivan
Peak: USNM 705o, 707b, 707c, 707d, 707g, 707-1,
722h, 722-1, 727a, 733j; Dugout Mountain: USNM
732e; Skinner Ranch: AMNH 520, USNM 723o;
Skinner Ranch (lower): USNM 705a, 709v, 71 lp,
712p, 714p, 715n, 715v, 716t, 720e, 720f, 720g, 727f;
Skinner Ranch (upper): USNM 705r, 714y, 723h,
723-1, 723o; Taylor Ranch: USNM 702d, 702e,
702f, 716m.
DIAGNOSIS.—Transversely elliptical Meekella
with short, conical pedicle valve, variable number
of plications, and strong costellation, especially in
the young stages.
TYPES.—Holotype: YPM 10950; figured hypotypes:
USNM 152608a, 152610, 152611a, b; measured
hypotypes: USNM 152608a-c, 152609, 152610,
15261 la-c, 152612a-c.
COMPARISON.—Meekella hessensis is characterized
by its transverse outline, generally short, nearly
catacline beak, and distinctive ornament. Posteriorly
it has a costellate stage representing the young
form, but the costellae are strong, prominent, and
tend to maintain considerable strength over the
364 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
plicated body of the shell. The plications are usually
narrowly angular, but they are variable. In
some specimens an interruption in growth produced
lower, broader, but still angular costae. It
resembles some forms of M. occidentalis (Newberry),
but it is somewhat wider proportionately
than most specimens of that species of the same
size. Furthermore, its beak is generally blunter and
the interarea short and flat.
DISCUSSION.—R. E. King figured two specimens,
a holotype, designated by him, and a paratype. The
latter is more strongly costate than the holotype
and represents the more broadly plicate form of
the species. The holotype comes from the upper
part of the Skinner Ranch Formation; the paratype
is from the Taylor Ranch Member of the Hess
Formation.
Meekella intermedia, new species
PLATE 105: FIGURES 1-9
Medium size for genus, subconical lateral profile
but subcircular dorsal profile, maximum width at
about midvalve. Sides somewhat narrowly rounded;
anterior margin broadly rounded. Anterior commissure
usually with broad wave toward ventral
side. Costae abundant, narrow, subangular, numbering
about 30 in large adults. Beak region
costellate for about 10 mm, costae arising from enlargement
of 1 costella, or union of 2 or 3. Fine
costellae not reaching anterior margin.
Pedicle valve triangular, lateral profile unevenly
convex on long side, maximum convexity near midvalve;
anterior profile moderately domed. Beak
acute; interarea moderately long, slightly concave,
pseudodeltidium narrow, about one-third hinge
width. Median region forming poorly defined fold.
Brachial valve unevenly convex in lateral profile,
greatest convexity on posterior half, anterior half
somewhat flattened. Anterior profile broadly and
moderately convex. Umbonal region swollen, umbonal
slopes steep; anterior median region depressed
into shallow broad sulcus, flanks gently
swollen. Interarea not noticeably developed.
Pedicle valve interior with strong dental plates,
slightly receding, convergent ventrally but usually
fairly widely separated.
Brachial valve interior with moderately long
cardinal process supported by short, strong, widely
flaring erismata; distal prongs not separated; shaft
with strong axial keel; promontorium narrow.
Myophragm small, located near apex.
MEASUREMENTS
USNM 728f
150902a (holotype)
150902b
150902c
1509O2d
150902e
150902f
1509O2g
15O902h
AMNH 629
152603a
152603b
AMNH 628
150906
(in mm).—
pedicle
valve
length
25.7
28.9
p
25.0
?
20.2
?
15.5
23.0
?
20.8
brachial
valve
length
21.8
p
31.0
}
25.8
?
20.5
p
p
21.4
19.0
maximum
width
26.4
28.8
36.7
27.5
29.0
20.0
23.8
17.8
24.0
26.0*
23.3
hinge
width
14.4
19.6
23.0
18.0
16.8
13.1
13.7
13.0
13.4
14.8
14.0
interarea
length
8.7
13.4
?
12.7
?
9.3
?
5.7
11.0
?
7.7
thickness
17 A
14.6
10.2
11.2
11.0
13.0
8.0
6.8
10.5
13.9
14.8
STRATIGRAPHIC OCCURRENCE.—Bone Spring Formation
(base).
LOCALITIES.—AMNH 625, 628, 629, 631, USNM
725e, 728f, 728h, 745, 746.
DIAGNOSIS.—Meekella with subangular costae and
short interarea.
TYPES.—Holotype: USNM 150902a; figured paratypes:
150902b, c; measured paratypes: 150902b-h,
150906, 152603a, b; unfigured paratypes: 150902d-h.
COMPARISON.—The exterior of this species resembles
that of M. angustiplicata, new species, but
M. intermedia has fewer costae. The ribbing of
NUMBER 15 365
M. angustiplicata is so fine that the species can not
be confused with any other species. Niviconia
globosa is also readily distinguished from M. intermedia
by its longer interarea, more convex brachial
valve, and the greater differentiation between
costellae and costae at the posterior. Furthermore,
the cardinal process of M. intermedia never attains
the ponderous character and great elongation of
N. globosa.
DISCUSSION.—This species is rare in the Bone
Spring Formation. Its shells are usually thin, delicate,
and difficult to recover. The development of
costae can be observed well in this species. The
young shell at about 10 mm length is fairly evenly
costellate with about three or four costellae per
mm. One or two of the four costellae will be larger
than the others. Anteriorly some of these swell to
produce a costa, while two or three may unite to
form a single costa. Other costellae follow the
troughs between the costellae and ultimately disappear.
At the anterior margin of the holotype,
fine costellae are rare on the costae, most of which
exhibit strong, crowded growth lines.
Meekella magnifica, new species
PLATE 100: FIGURES 1-33; PLATE 116: FIGURES 9-18
Meekella mexicana R. E. King (not Girty), 1931:55, pi. 7:
figs. 1-5.
Large, biconvex, shallow to deeply and irregularly
conical; outline semicircular to transversely
subelliptical; hinge straight, width between 0.5 and
0.99 maximum shell width, meeting lateral curve
of shell outline at right or obtuse angle with only
slight auriculation of hinge extremities. Plications
numbering 7 to 21, averaging about 15, rounded on
crests, uneven and irregular, interrupted by growth
lines, normally one or two plications on each valve
bifurcating; plications beginning 5 to 25 mm anterior
to pedicle beak, averaging about 15 mm,
hence, juvenile shells unplicated. Costellae strong,
especially on unplicated area near beak, increasing
in number anteriorly by insertion, continuing
straight forward, converging toward crests of plications
only near anterior margin of large shells.
Growth lines weak on some shells, stronger on
others, becoming stronger and more frequent anteriorly;
commissure coarsely plicate, each plication
finely serrate at anterior ends of costellae.
Pedicle valve beak blunt, commonly twisted, interarea
wide, long, or short, depending on growth
conditions, longitudinally flat or concave, rarely
convex, with posterior hook near apex in mature
individuals, meeting plane of commissure at obtuse
angle in young shells, nearly at right angle in
mature shells; pseudodeltidium sharply or vaguely
delimited from lateral parts of interarea, its edges
marking traces of forward growth of hinge teeth;
width at hinge about one-third or slightly less than
hinge width; bisected by narrow ridge of nearly
uniform width.
Brachial valve lidlike, moderately to strongly
convex, interarea short; beak slightly overhanging
pedicle interarea; plications equal in number to
those on pedicle valve, normally somewhat weaker.
Pedicle interior with strong teeth extending posteriorly
as convergent dental ridges supporting
underside of interarea, then near beak curving
to floor of valve and extending forward as slightly
divergent dental plates. Some specimens with callus
of adventitious shell thickening beneath pseudodeltidium
and between dental ridges. Many specimens
with outwardly bowed, convergent dental
plates meeting and fusing throughout their length
along valve floor, forming pseudospondylium; most
individuals with straight, anteriorly divergent dental
plates, separate at anterior ends, but commonly
fused posteriorly near beak by deposit of adventitious
shell material. Muscle marks between dental
plates, making low corrugations on inner sides
of plates.
Brachial valve hinge surface shallowly concave,
providing bearing-edge for articulation of pedicle
hinge. Cardinal process long, strong, inwardly
bowed, projecting ventrally; free and bifurcate,
each branch with minutely serrate longitudinal slit
along posterior edge. Dentifers flat, bladelike,
projecting from sides of process and nearly parallel
to it, terminating abruptly ventrally where process
bifurcates, constricted dorsally just anterior to deep
circular dental sockets. Erismata short, widely divergent.
Muscle area between erismata bisected by
low median ridge; muscle marks obscure, consisting
of faint irregular striae in muscle area and along
bases of brachiophore supports.
STRATIGRAPHIC OCCURRENCE.—Gaptank Formation
(Uddenites-bearing Shale Member), Neal
366 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
MEASUREMENTS
USNM 701g
150578a
150578b
150578c
150578d
150578e
150578f
150578g
150578h
150578i
150578J
150578k
150578-1
150578m
150578n
150578O
150578p
150578q
150578r
150578s
150578t
150578u
150578v
150578w
150578x (holotype)
150578y
USNM 701a
150570
(in mm).—
pedicle
valve
length
4.2
9.0
9.0
12.0
7.8
11.4
9.7
14.0
16.0
25.5
20.9
16.0
18.9
22.0
23.2
20.5
26.0
28.8
32.7
29.8
28.5
31.5
46.0
46.9
49.7
54.4
brachial
valve
length
5.0
4.6
6.0
7.3
6.5
9.6
9.0
10.7
11.8
14.3
13.3
12.7
15.4
15.7
20.2
18.7
24.6
26.0
23.5
j
j
?
}
43.4
?
49.0
maximum
width
7.0
6.0
8.7
8.8
8.7
12.5
12.5
15.0
15.4
18.0
18.5
17.8
31.0
23.0
25.8
25.8
29.0
31.5
33.0
40.6
32.0
41.8
41.5
48.6
49.7
62.3
hinge
width
6.2
5.6
5.2
6.5
6.9
9.8
9.6
10.3
9.4
13.6
14.6
13.4
17.4
15.8
17.5
17.5
20.0
19.8
22.7
31.0
29.3
34.0
34.8
40.0
41.7
47.8
interarea
length
2.9
5.9
3.8
6.7
3.6
7.4
4.7
4.7
5.7
12.5
10.8
7.6
5.4
7.7
10.3
9.6
11.7
16.9
17.2
18.2
23.4
23.4
39.3
36.0
21.3
29.7
thickness
3.9
5.5
4.4
7.8
5.0
9.4
6.5
8.8
10.0
13.0
11.6
10.4
14.0
3.5
7.9
15.8
23.0
29.0
26.8
21.4
26.0
24.8
41.3
49.0
39.6
50.8
Ranch Formation (bed 2 of R. B. King), Neal
Ranch Formation (beds 2-14), Lenox Hills Formation.
LOCALITIES.—Uddenites: USNM 701x; Neal
Ranch (bed 2): USNM 701; (beds 9-14): USNM
701a, 701a1, 701c, 701g, 715e; Lenox Hills: USNM
705, 705s, 707j, 709t, 709w.
DIAGNOSIS.—Large irregularly plicate Meekella
with broad and long interarea having a long nonplicate
youthful stage.
TYPES.—Holotype: USNM 150578x; figured paratypes:
150570, 150577, 153535a-c, e, g, 150578a, g,
j , q, r; measured paratypes: 150570, 150578a-w, y;
unfigured paratypes: 153535d, f, 150578b-f, h, i,
k-p, s-w, y, 153535d.
COMPARISON.—Meekella magnifica is characterized
by its large maximum size, irregular and
rounded plications, averaging about 15 in number,
that begin far forward from the beak, relatively
strong costellation, and normally nonconvergent
dental plates. Large specimens are distinguished
also by their wide hinges, with consequent wide and
normally long interareas that meet the plane of
commissure at nearly a right angle. The beak of a
large shell normally hooks posteriorly, the result of
the meeting of interarea and commissure at an obtuse
angle in the juvenile shell. The anterior profile
of the pedicle valve normally is only slightly
convex, straight or slightly concave, analogous to
that of Tropidelasma culmenatum, new species.
Meekella magnifica differs from M. irregularis
Schellwien by its stronger plications, especially on
the brachial valve, proportionately wider delthyrium
and longer interarea (longer beak), or proportionately
narrower hinge, and also apparently
by its more convex brachial valve. It differs from
M. mexicana Girty by its normally longer and
blunter beak, longer and wider interarea, and
coarser, normally deeper plications.
Among other species of Meekella from the Glass
NUMBER 15 367
Mountains, M. magnifica differs from M. occidentalis
(Newberry) (= M. grandis R. E. King) by its
much weaker plication, stronger costellation, normally
longer beak in large individuals, proportionately
shorter dentifers, and especially by its lack of
a strongly flared hinge that produces ears at each
end of the hinge. It differs from M. attenuata Girty
and M. caperata, new species, by its fewer and
much coarser (although not necessarily stronger)
plications. It may be distinguished from M. skenoides
Girty by its larger maximum size, more irregular
shape, weaker and more rounded and
irregular plications, and somewhat lower interarea,
i.e., proportionately wider hinge. It differs from
large pauciplicate forms of M. grandis in its normally
longer interarea and greater convexity, and
weaker, more irregular plications that begin farther
from the beak. These differences become increasingly
apparent in the larger shells; a large pauciplicate
M. grandis is very broad, and the pedicle valve
is a low cone, whereas a large individual of M.
magnifica is very deeply conical.
Meekella magnifica is an unusually variable species
of a genus in which wide variation is the rule.
The most drastic differences are not between individuals
at a particular stage of growth, but between
specimens at different stages. The stage of growth
of a specimen often may be recognized by its size,
although size alone is not the most reliable criterion.
Some specimens appear to have matured
while maintaining a relatively small size, and others
seem to have remained juveniles to a rather large
size. Juveniles normally have the interarea meeting
the plane of commissure at an obtuse angle,
which lessened gradually to a right angle as the
individual matured, thus producing a posterior
hook on the beak of mature individuals. In some
the angle remained obtuse and the shell relatively
unplicated and marked only by weak growth lines
to a size of 35 mm (maximum height). Other specimens
have the hook beginning only 4 or 5 mm forward
of the beak and have the coarser plications
and prominent growth lines characteristic of maturity
while having attained a maximum height of
only 20 mm. Unplicated or faintly plicated individuals,
especially those with short beaks, are the
same as King's M. "mexicana." The point of maximum
flexure of the interarea in most individuals is
about the same distance forward as the beginning
of plication. This is not consistently true of other
species of Meekella in the Glass Mountains.
Dental plates in Meekella magnifica are strong,
normally straight, and converge slightly toward the
floor of the valve without meeting. Many mature
shells, however, have dental plates that bow away
from the axial plane, and then converge strongly
toward the floor, meeting and fusing there to form
a sessile spondylium. At first this appears to be a
radical departure from the normal condition of the
species, but specimens can be found in all degrees
of transition from straight and nonconvergent to
strongly bowed and fused. Some large shells with
straight dental plates (normal for the species) appear
to have the plates meeting and fusing near the
beak, but diverging in their forward growth and
distinctly separate at their anterior terminations.
On the other hand, most small specimens have the
plates distinctly separate too. Therefore, the apparent
fusing of the plates may be the result of deposition
of adventitious shell material between the
plates as the shell grew.
Meekella occidentalis (Newberry)
PLATE 117: FIGURES 1-4, 9-13
Streptorhynchus occidentalis Newberry, 1861:126, pi. 1:
figs. 5, 5a.
Meekella occidentalis (Newberry) Hall and Clarke, 1892:
pi. 11B: figs. 18, 19.—McKee, 1938:222, pi. 43: figs. 2, 3.
Streptorhynchus pyramidalis Newberry, 1861:126, pi. 2: figs.
11-13.
Meekella pyramidalis (Newberry) Hall and Clarke, 1892:
266 McKee, 1938:223, pi. 43: figs. 4-6.
Meekella grandis R. E. King, 1931:54, pi. 6: figs. 5-7.
Since this species has been described by Newberry
and King under different names, the salient
features of the species thus have been detailed and
need not be repeated here. The species is rare in
the Glass Mountains. The end members of some
variants of M. calathica resemble M. occidentalis,
but we have concluded that the two are not the
same. More specimens from the Grand Canyon,
and especially a series of all stages of growth, will
be necessary to establish a firm relationship.
368 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
MEASUREMENTS
USNM 768
92468 (holotype)
USNM 768a
92469
King 174
YPM 10589
(in mm).—
pedicle
valve
length
43.7
47.8
56.4
brachial
valve
length
?
42.4
54.5
maximum
zuidth
47.0*
57.0?
67.2
hinge
width
36.6*
35.0?
37.9
interarea
length
11.0?
16.7
19.6
thickness
7.7
22.0?
37.8
STRATIGRAPHIC OCCURRENCE.—Kaibab Formation
(Beta Member), Cathedral Mountain Formation.
LOCALITIES.—Kaibab: USNM 768, 768a; Cathedral
Mountain: R. E. King 174, USNM 702, 726y.
TYPES.—Holotype: USNM 92468; paratype:
92469. Holotype of Meekella grandis R. E. King:
YPM 10589.
DISCUSSION.—Under the name M. occidentalis we
are combining Newberry's species Streptorhynchus
occidentalis and S. pyramidalis and M. grandis
R. E. King. All of these species are large and generally
pauciplicate. Unfortunately, the type specimens
of the first and last species are poor, and the
type of S. pyramidalis appears to be lost. McKee
(1938:224), who discusses these species, regards S.
occidentalis to be a flattened S. pyramidalis because
he was unable to find any specimens like the former
in the Grand Canyon. He did, however, find
specimens identifiable as S. pyramidalis, which
showed a clear relationship to S. occidentalis. It is
thus probable that Newberry's two species are
synonymous. Schuchert (1897:264) expressed the
view that "M. occidentalis Newberry . . . may prove
to be but a large individual of M. pyramidalis."
Although 5. pyramidalis has page preference, we
have selected S. occidentalis for the specific name
because the type specimens of this species are preserved,
whereas those of S. pyramidalis are not
available. Inasmuch as the two appear to be the
same, the one can serve as well as the other. The
holotype of S. occidentalis is the inner filling of a
pedicle valve broken on one side. It has 12 costae,
one of which is obscure. The dental plates as shown
by their impression on the internal cast are convergent
ventrally and anteriorly. These features
and the convergent dental plates can be seen on a
second specimen, a paratype.
Some uncertainty exists as to whether or not the
complete specimen (USNM 92469) is actually a
paratype. The specimen was not figured or referred
to by Newberry, but Hall and Clarke (1892:
266) refer to the two specimens of M. occidentalis
as the "original specimens of the latter species." It
may be assumed, therefore, that Newberry included
the two in his species but that he only figured the
holotype. Newberry's label, preserved with the
paratype, indicates the specimen to be a "type."
The paratype has a strong resemblance to M. grandis
R. E. King.
King's type specimen of M. grandis is the largest
specimen of the species complex here under discussion.
It is slightly flattened, the beak region of
the pedicle valve having been squeezed down onto
the brachial valve and somewhat distorted, the
distortion enhancing the resemblance to the paratype
of M. occidentalis. The L/W ratio of the
brachial valve is 0.8 and the costae number 14 on
one valve and 15 on the other. The characteristic
bifurcation of one or more costae can be seen on
both valves.
Meekella prionota, new species
PLATE 99: FIGURES 1-39; PLATE 124: FIGURES 21-25
Meekella striatocostata (Cox) R. E. King, 1931:56, pi. 7:
fig. 9 [not M. striatocostata (Cox) of authors].
Shell small to moderate size, biconvex, shallow
conical; outline transverse, semicircular to subelliptical;
hinge straight, width fairly constant between
0.55 and 0.75 width of shell, slightly auriculate at
ends. Plications coarse, rounded, strong, numbering
6 to 14, with 9 and 10 most frequent, usually
regular and undistorted, beginning about 6 mm
from beak, some shells with 1 or 2 bifurcating.
Costellae strong, parallel to plications except near
margins of mature shells there converging toward
crests of plications and increasing in number by
intercalation in troughs. Growth lines faint, conspicuous
only near margins; commissure coarsely
plicate and minutely serrate.
NUMBER 15 369
Pedicle valve beak moderately sharp, often
slightly twisted; fold obscure, low; interarea normally
short and wide (about half as high as wide)
except in unusually attenuate shells, longitudinally
concave, meeting plane of commissure at obtuse
angle; pseudodeltidium less than half but more
than one-third hinge width, bisected by narrow,
low, gently rounded ridge.
Brachial valve moderately to strongly convex,
maximum convexity near beginning of plications,
beak projecting posteriorly slightly overhanging
hinge; plications equal in number and strength to
those on pedicle valve. Median region sulcate, sulcus
shallow, most conspicuous at midvalve.
Pedicle valve interior with sharp, moderately
strong hinge teeth, extending posteriorly as convergent
dental ridges toward beak, about half way
to apex, curving toward floor of valve as slightly
convergent dental plates, thence continuing anteriorly
along valve floor, normally nearly parallel
to one another, rarely meeting and fusing along
floor. Muscle marks between plates very weak.
Brachial valve interior with wide, blunt, slightly
curved cardinal process, with short bifurcation of
free end, each branch longitudinally slit for short
distance and minutely serrate within slit. Promontorium
narrow; dentifers thin, fused to elongated
erismata; fulcral plates small. Muscle marks obscure,
consisting of faint longitudinal striae, divided
by low myophragm.
MEASUREMENTS
USNM 701-1
150539a
150539b
150539c
150539d
150539e
150539f
150539g
USNM 701d
150537a
150537b
150537c
150537d
USNM 701k
150616
USNM 727e
153339 (holotype)
(in mm).—
pedicle
valve
length
6.0
8.8
10.6
14.5
17.0
20.6
25.4
25.9
25.6
27.2
34.5
28.4
22.5
brachial
valve
length
5.0
7.0
9.7
12.1
15.3
16.8
18.3
21.8
22.8
26.1
29.5
26.7
2l8
maximum
width
6.0
7.7
11.7
14.6
18.6
20.8
22.0
24.2
25.3
30.0
34.0
32.3
27.6
hinge
width
4.4
6.0
7.5
9.4
13.0
12.6
16.4
13.6
16.0
18.2
22.6
20.9
16.4
interarea
length
1.9
4.3
3.9
7.0
9.4
10.0
8.7
7.4
6.4
9.7
10.0
12.7
11.0
thickness
3.6
5.8
8.8
11.9
15.0
15.0
17.0
19.8
22.7
22.0
24.9
25.6
21.5
STRATIGRAPHIC OCCURRENCE.—Gaptank Formation
(Uddenites-bearing Shale Member), Neal
Ranch Formation (beds 4-14 of P. B. King), Lenox
Hills Formation, Cibolo Formation.
LOCALITIES.—Gaptank: USNM 700a, 700g; Uddenites:
701p, 701v, 702n, 703x, 713o; Neal Ranch:
701, 701a, 701a3, 701c, 701d, 701h, 701k, 701-1,
713h, 721g, 727d, 727e; Lenox Hills: 705, 705k,
707m; Cibolo; 728-1.
DIAGNOSIS.—Medium-sized Meekella with fairly
well-marked sulcus on brachial valve.
TYPES.—Holotype: USNM. 153339; figured paratypes:
150616a, b, 15353#a-^c; measured paratypes:
150537a-d, 150539a-g. *)
COMPARISON.—Meekella prionota is characterized
by its small size and few strong, rounded plications,
relatively low interarea, and shallow conical pedicle
valve beak, strong costellae, slight auriculation of
hinge ends, brachial valve sulcus, and wellseparated
dental plates. Its shape is fairly regular
and undistorted. It may be distinguished from M.
magnifica, new species, which also occurs in the
Neal Ranch, by most of the above features (excepting
only the strong costellae, and the shallow pedicle
valve beak that occurs in M. magnifica but is
not typical).
It may be distinguished from M. occidentalis
(Newberry) by its stronger costellae, normally fewer
plications, and narrower range in number of plications,
its less auriculate hinge ends, and smaller
370 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
maximum and average size as M. skenoides Girty,
but it differs in its fewer and blunter plications,
lower interarea, and shallower pedicle beak,
stronger costellae and normally backward sloping
interarea. It differs from M. attenuata Girty and
M. caperata, new species, by its fewer and much
coarser plications, smaller size, less attenuate and
less transverse shape.
DISCUSSION.—Meekella prionota is one of the
least variable species of Meekella in the Glass
Mountains. It is rare, occurring abundantly at only
one locality and rarely at a few other localities in
Wolfcampian formations. Its greatest variation is
its shape, a condition normal for species of
Meekella. Its size is remarkably consistent, as is
the number and shape of its plications. The plications
may begin farther forward on some specimens
than on others, and a few may begin so far forward
that the shell may resemble an individual of
M. magnifica R. E. King.
This is the species that King (1931:56) equated
with M. striatocostata (Cox), the common Pennsylvanian
"species." Meekella prionota differs from
Pennsylvanian specimens, called "M. striatocostata
(Cox)" by its smaller size, stronger costellae, fewer
and less variable number of plications, and lower
interarea. Most Pennsylvanian species of Meekella
are referred to M. striatocostata. This species name
has little meaning, leading to the belief that several
species are now masquerading under that
name.
Meekella skenoides Girty
PLATE 99: FICURES 40, 41; PLATE 101: FIGURES 9-13; PLATE 104:
FIGURES 1-10; PLATE 108: FIGURES 6-10; PLATE 115: FIGURES
1-32; PLATE 116: FICURES 1-8
Meekella skenoides Girty, 1909:206, pi. 30: figs. 8-9.—R. E.
King, 1931:56, pi. 7: figs. 6-8.—Newell et al., 1953: pi. 21:
fig. 1.
Meekella difficilis Girty, 1909:207, pi. 30: fig. 10. [Not M.
difficilis R. E. King — M. calathica, new species.]
Shell small to moderately large, biconvex, shallow
to deeply conical; outline transversely subelliptical,
to nearly semicircular; hinge straight, between 0.5
and 0.75 maximum width, often slightly auriculate.
Plications fine to moderately coarse, moderately
strong to strong, normally rounded on crests, but
often sharp, numbering 7 to 20, averaging 11 to
14, rarely bifurcating, beginning 3 to 15 mm anterior
to beak, averaging about 6 mm. Costellae
moderately strong near beaks, becoming weaker
anteriorly, growing parallel to plications, converging
over their crests only near margins of large
shells; growth lines faint, conspicuous only near
shell margins. Commissure coarsely to finely plicate,
minutely serrate where costellae terminate.
Pedicle valve beak sharp unless deformed by attachment
surface, interarea long (normally nearly
as long as wide, rarely longer, rarely more than
twice as wide as long), flat to slightly concave, in
adults meeting plane of commissure at right angle;
pseudodeltidium expanding dorsally, sides parallel
to sides of interarea in all but shells with exceptionally
short and wide interareas, edges obscure,
width one-third to slightly more than one-half total
hinge width, bisected by low rounded narrow ridge.
Brachial valve moderately convex, maximum convexity
near beak, projecting only slightly posterior
to hinge.
Pedicle valve interior with strong symmetrical
teeth extending posteriorly as convergent dental
ridges about half way to apex, then expanding and
curving to valve floor with slight convergence,
and extending anteriorly along floor, slightly divergent,
parallel, or more rarely meeting at floor
of valve. Muscle marks on inner sides of plates
parallel to anterior edges of plates.
Brachial valve hinge surface shallow, concave;
cardinal process strong, moderately to strongly
curved, keeled near hinge but bifurcate at free
end, each branch longitudinally slit and finely serrate,
on some shells slit penetrating branch, thus
making end of process quadriramous. Promontorium
slightly concave both longitudinally and
transversely, extending along cardinal process for
more than half length, widening toward proximal
end, contracting abruptly immediately anterior to
hinge sockets; dentifers fused to cardinal process
by gusset; erismata outlining muscle area in deep
umbonal arch. Floor of muscle area uneven, bisected
by low myophragm; muscle marks obscure,
consisting of longitudinal striae on floor of muscle
area and on bases of erismata.
NUMBER 15 371
MEASUREMENTS (in mm).—
USNM 706e
150560a
150560b
150560c
150560d
150560e
USNM 728
150554a
150554b
150554c
150554d
150554e
150554f
150554g
King 192
YPM 11000
USNM 706c
150550a
150550b
150550c
150550d
150550e
150550f
150550g
150550h
150550i
USGS 7417
150949a
USGS 3763 (green)
118508 (holotype)
pedicle
valve
length
26.4
31.5
?
34.3
?
38.5
?
20.6
17.8
12.3
11.9
11.5
23.4
4.6
7.5
7.8
10.4
11.4
15.5
16.5
18.2
5.4
23.7
11.6
brachial
valve
length
26.4
?
33.8
?
44.0
?
28.7
20.6
17.0
10.5
11.6
11.0
22.8
4.4
5.6
7.6
9.7
11.2
14.0
14.9
16.5
?
23.7
11.3
maximum
width
34.2
38.7
44.2
48.0
51.6
45.0
34.0
22.6
21.4
15.6
13.6
12.7
28.2
4.5
5.9
8.2
11.4
13.2
16.9
19.0
21.0
24.5
28.4
12.7
hinge
width
21.5
21.8
20.8
29.5
24.0
24.1
18.5
16.3
15.3
12.0
9.7
8.0
19.6
3.7
3.7
5.7
8.8
7.8
8.2
12.9
12.3
19.6
15.8
7.0
interarea
length
14.6
19.4
?
19.2
?
17.0
?
11.5
8.5
6.4
6.2
6.1
12.0
3.3
3.6
6.0
6.3
11.7
5.5
6.0
10.0
18.0
22.6+
8.0+
thickness
27.8
20.0
18.6
23.8
20.0+
20.7
14.0
19.6
15.2
10.4
10.3
10.6
22.8
3.9
4.6
8.4
9.8
152
13.9
15.0
20.0
17.8
30.8
12.0
STRATIGRAPHIC OCCURRENCE.—Cherry Canyon
Formation (Getaway Member), Road Canyon Formation,
Word Formation (China Tank, Willis
Ranch, and Appel Ranch members, and lens between
the last two), Bell Canyon Formation (Hegler,
McCombs, and Pinery members), Capitan
Formation, Carlsbad Formation?, San Andres Formation.
LOCALITIES.—Getaway: AMNH 28, 512, 519, 496,
585, 600, 652, Moore 31, USNM 728, 730, 732; Road
Canyon: USNM 706f, 707e, 713, 716xa, 732i; Word:
USNM 731m, 731p, 731u, 732c, 732s; China Tank:
USNM 706a, 706c, 706z, 718d, 726r, 726s, 733q,
?USGS 3763; Willis Ranch: AMNH 505, USNM
706, 706e, 723t, 724u; Appel Ranch: USNM 704,
706d, 714o, 715i, 716v, 719z, 722t, 727j; Hegler:
AMNH 635; Pinery: AMNH 398; 537; McCombs:
AMNH 409; Capitan: USGS 7417 (blue); Carlsbad?:
AMNH 417; San Andres: B-188-8.
DIAGNOSIS.—Medium-sized to large Meekella
with strong angular plications averaging 12 in number.
TYPES.—Holotype: USNM 118508; paratype:
118509; figured hypotypes: 150544e, 150554b, c, e,
150559a-d, 150820, 150949a, 153518, 153519,
153534a-c, 153537, 153538, 153542a-k, 155127;
measured hypotypes: 150550a-i, 150554a-g,
150560a-e, 150949a, YPM 11000.
COMPARISON.—Meekella skenoides is characterized
by its moderate size (only rare individuals
attain a width of 50 mm), normally sharp and
fairly regular plications that start far backward on
the beak, slight or missing auriculation of hinge
extremities, commonly separate dental plates, and
proportionately high interarea.
Its sharp and coarse plications, much smaller
maximum size, and more regular shape distinguish
it from M. magnifica, new species. Its less promi372
SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
nent auriculation, smaller size, flatter and higher
interarea, and parallel costellae separate it from
M. occidentalis (Newberry). Meekella skenoides
may be distinguished from M. prionota, by its finer
and sharper plication, slightly auriculate hinge,
lack of sulcus in brachial valve, more regular
shape, normally right angle between interarea and
plane of commissure, and proportionately higher
interarea.
Its stronger costellae, fewer plications, less attenuate
pedicle beak, and shallower promontorium
distinguish M. skenoides from Niviconia globosa
(King). It differs from M. caperata in its fewer and
coarser plications, less transverse outline, and less
attenuate pedicle beak.
DISCUSSION.—Girty (1909:206-207) described two
species of Meekella collected in 1899 by R. T. Hill
from "Comanche Canyon, Glass Mountains, 17
miles northeast of Marathon, Texas." The location
of "Comanche Canyon" may be the valley from
Hess Ranch to Split Tank, and the specimens are
thought to have been collected from the Word
Formation (Willis Ranch Member). Although the
holotypes of Meekella skenoides Girty and M. difficilis
Girty both have the same locality number,
there is little assurance that they were collected at
a single precise locality or were closely associated
in the rock. All that is certain is that they were
collected in "Comanche Canyon." We compared
these holotypes with numerous lots from the upper
Cathedral Mountain, Road Canyon, and Word
formations. They proved completely unlike the
Cathedral Mountain specimens, but individuals almost
identical to them could be seen in collections
plications
from the Word Formation (Willis Ranch Member).
King (1931:53, 56), however, considered them so
remotely associated that he used, erroneously we
think, the name "M. difficilis Girty" for a species
that occurs in the Cathedral Mountain Formation,
but he identified M. skenoides Girty from the
Word.
The holotypes of Meekella skenoides Girty and
M. difficilis Girty are different from one another,
but these differences are the result of growth and
are not specific differences. The holotype of M.
skenoides is a juvenile, and that of M. difficilis an
average-size adult; the two are alike in all significant
features. Study of our large collections has
shown that both of these holotypes fall well within
the limits of variation of a single species of
Meekella. Inasmuch as "M. skenoides Girty" has
already been used by R. E. King in essentially the
same sense as we use it, this is the name we prefer
for the species.
Although we regard the specimens discussed in
this section as belonging to a single species, an
interesting deviation occurs in specimens coming
from the prolific locality USNM 706e. These have
a slightly larger number of plications than those
from the other limestone members of the Word
and from the Getaway Member of the Cherry Canyon
Formation.
The plications on 100 specimens from USNM
706c were counted, and it was found that the most
frequent number in the sample was 11 plications.
The following table illustrates the results of the
count (USNM 706c):
7 8 9 10 11 12 13 14 15 16
number of specimens
From inspection it appeared that the number of
plications on M. skenoides from USNM 706e was
greater than the above, and the plications finer. A
plications
2 4 8 13 33 20 9 7 4 0
count on 100 specimens from USNM 706e gave the
following results:
8 9 10 11 12 13 14 15 16 17 18 19
number of specimens
When combined, the data from these two counts
produce a fairly smooth normal population curve.
The difference in numbers of plications in the two
samples is so slight and other features so consistently
similar that there is no doubt only one
species is involved; however, the difference in num-
1 2 6 10 19 20 21 7 8 3 2 1
bers of plications in specimens from USNM 706e is
real and is obvious enough to be recognized by
inspection, even without counting, if large samples
are available. The average number of plications
on specimens from USNM 706e is 13;
consequently, no significant difference appears.
NUMBER 15 373
Furthermore, separation on the basis of the number
of plications appears completely artificial when applied
to localities other than USNM 706e. Inasmuch
as Girty's types of M. skenoides and difficilis
have 12 plications and the former appears to be a
young form of the latter, it seems best at this time
to recognize one species only, Meekella skenoides.
Meekella texana R. E. King
PLATE 118: FIGURES 1-7
Meekella irregularis texana R. E. King, 1931:55, pi. 6: figs.
2-4 (not fig. 1).
This "variety" of Schellwien's species (M. irregularis)
is represented by a type lot of four incomplete
specimens, three of which are only equivocally
related to the holotype. The first is the specimen
represented by King's figure 1, a more coarsely plicated
specimen than the others, which, as may be
seen in the figure, bears the number "965," but no
number is given in the plate legend or text to show
to what institution the specimen belongs. The rest
of the specimens in the type lot are numbered serially
from 10966 to 10968. It is evident therefore
that the individual depicted by figure 1 belongs in
the series with the number 10965. In any event,
the specimen is so unlike the others that it is excluded
from this association. Moreover, it comes
from the Decie Ranch Member of the Skinner
Ranch Formation, and, if it is from the Wolfcamp
Series, probably it is from the Lenox Hills Formation,
whereas the other specimens are from below it.
The specimen designated as holotype is from the
Gaptank Formation, (Uddenites-bearing Shale
Member) east of Wolf Camp, whereas YPM 10968
is from the same member at Wolf Camp. Neither
of these specimens has very strong characters because
they are exfoliated and incomplete. The latter
could be a variant of the former, but it is
impossible to tell because it varies in ornament as
well as shape. The holotype presents a more attenuated
form with the plications not reaching the
beak.
The fourth specimen, YPM 10967, is a brachial
valve that comes from bed 13 of the Gaptank Formation
in hill 4572 northeast of the Wolf Camp
Hills. Its assignment to the Uddenites-bearing
Shale Member is doubtful because this member is
not definitely known at this place. This specimen
is wider than long, transversely elliptical in outline,
and has an even, gently convex profile in both lateral
and anterior directions. Fifteen costae were
counted; the posterolateral extremities are smooth
or the specimen too exfoliated to see them. A fairly
strong myophragm is present, and the supporting
plates are strong and diverge at an angle of 50°.
This specimen is nearer the holotype than to the
others, but it is not possible to tell if they are the
same. The holotype of this "variety," thus, is the
only specimen left to represent it.
MEASUREMENTS (in mm).—Holotype: length 17.3,
maximum width 24.7, hinge width 16.6?, interarea
length 15.5-)-, thickness 23.4+.
STRATIGRAPHIC OCCURRENCE.—Gaptank Formation
(Uddenites-bearing Shale Member); Lenox
Hills Formation (=Neal Ranch of Ross).
LOCALITIES.—Gaptank: ?R. E. King 95, USNM
700g, 703o, 705q, 708p; Uddenites: R. E. King 88s,
199, USNM 701e, 701f, 701q, 702j, 702k, 702n, 702q,
703-1, 703c, 713b; Lenox Hills: USNM 715b.
TYPES.—Holotype: YPM 10966; figured paratypes:
YPM 10965, 10967, 10968.
DISCUSSION.—King's variety differs from M. irregularis
Schellwien, according to King, in having
"a proportionately shorter hinge-line and wider
deltidium." Comparison with other species from
the Glass Mountains is difficult because of the difference
of preservation between the silicified and
exfoliated specimens. King's variety is not common
in the Uddenites-bearing Shale Member and
good specimens are difficult to obtain. We thought
at first that a strong resemblance existed with M.
magnifica, new species, because some unquestionable
specimens of that species, have been taken from
this zone. But the type specimens of M. irregularis
texana do not give sufficient information on the
interior and details of the ornament. Furthermore,
the brachial valve (YPM 10967) is unusually low
in convexity for our Wolfcampian species. In view
of the difficulties and uncertainties, we have not
used King's name for the common Neal Ranch
species.
Genus Niviconia, new genus
[Latin nivis (snow) + conus (cone) ]
Meekelloid; pedicle valve deeply conical; brachial
valve strongly convex; costae numerous (15-30),
374 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
simple, angular, rather low, beginning at beaks;
costellae very fine and weak; interarea long, narrow,
pseudodeltidium proportionately wide; monticulus
high, thin.
Pedicle valve interior with dental plates moderately
receding below dental ridges, converging but
just not meeting on valve floor. Brachial valve interior
with exceedingly long cardinal process curving
posteroventrally, deeply bifurcate, each prong
slit deeply and serrate; promontorium very wide
near hinge, narrowing anteriorly, producing deep
trough along each side of process and along erismata;
sockets deep; erismata very long, extending
along sides of muscle area on valve floor; dentifers
projecting free beyond wide gussets; myophragm
low or absent.
TYPE-SPECIES.—Meekella globosa R. E. King
(1931:54, pi. 5: figs. 10-12c; pi. 32: fig. 8).
DIAGNOSIS.—Strongly convex Meekella with numerous
low and even costae, nearly convergent dental
plates, and a very long and strong cardinal
process that is clearly differentiated into its component
parts, and is braced by unusually long erismata.
COMPARISON.—In some features this genus might
be considered intermediate between Meekella and
Geyerella. Its nonconjunct dental plates ally it to
Meekella, but the fact that they approach closer
than normal in Meekella suggests Geyerella. The
costation suggests Geyerella to some extent, but actually
it is so distinctive as to make the genus recognizeable
on that criterion alone without recourse
to internal details. The most distinctive feature,
however, is the very long cardinal process that
projects along the inside of the pedicle valve interarea
for nearly its entire length.
DISCUSSION.—Only two species of Niviconia occur
in the Glass Mountains, the type, N. globosa
(King), and N. abrupta, new species. An undescribed
species from the Cutoff Shale Member of
the Bone Spring Limestone is present in the United
States Geological Survey collections, mentioned by
Girty (in P. B. King, 1948:24; locality USGS
7666).
Niviconia abrupta, new species
PLATE 118: FIGURES 22-48
This species is closely related to Niviconia globosa
(R. E. King), as it has the same narrow angular
costae and the auriculate cardinal extremities.
It differs in not attaining the large size of that species
and in having a much shorter beak. The differences
are shown most clearly in the young of
N. abrupta when compared with those of N. globosa.
The former are rounded shells with a short
interarea, whereas the young of TV. globosa are
greatly elongated. Young adults of N. globosa may
suggest N. abrupta, but their ventral beaks are
always much more elongated.
MEASUREMENTS (in mm).—
•:)
u'0.;V
o-O-fi^
153540b
Jl50512d
> 150512e
M50512f (holotype)
pedicle
valve
length
16.2
12.3
14.2
27.9
brachial
valve
length
17.0
12.3
14.1
26.6
hinge
width
12.9
11.0
12.5
19.0
midwidth
20.6
13.8
17.8
31.7
interarea
length
9.8
8.2
9.3
15.0
thickness
17.8
13.6
16.5
27.7
STRATIGRAPHIC OCCURRENCE.—Cathedral Mountain
Formation (upper).
LOCALITY.—USNM 702a.
DIAGNOSIS.—Like N. globosa but small and with
shorter interarea.
TYPES.—Holotype: USNM 150512f; figured paratypes:
150512e, f, 153540a-e; measured paratypes:
153512d, e, 153540b; unfigured paratypes 150512a-c,
153540f.
DISCUSSION.—This species is stratigraphically
younger than N. globosa, which occurs in the lower
part of the Cathedral Mountain Formation.
Niviconia globosa (R. E. King)
PLATE 30: FIGURE 1; PLATE 109: FIGURES 1-44; PLATE 110:
FICURES 1-22; PLATE 114: FIGURES 1-10
Meekella globosa R. E. King, 1931:54, pi. 5: figs. 10-12c,
pi. 32: fig. 8.
NUMBER 15 375
Large, strongly biconvex with swollen brachial
valve and deeply conical pedicle valve; outline
transversely subelliptical to subtrigonal. Hinge extremities
slightly auriculate, hinge one-half to
three-fourths shell width. Plications angular, comparatively
fine but strong, numbering 16 to 29,
average about 22, normally straight and even, only
rarely bifurcating, extending on to umbones; plications
in juveniles resembling costellae. Costellae
very fine and weak, visible only on unplicated
flanks of valves just anterior to interarea; growth
lines weak, most prominent near margins. Anterior
commissure rectimarginate, serrate, each serration
itself minutely serrated.
Pedicle valve beak attenuate, sharp, often
twisted; interarea transversely flat, longitudinally
concave, narrow, normally about as long as wide,
meeting the plane of commissure at obtuse angle
in immature shells, nearly at a right angle in mature
specimens, pseudodeltidium about one-third as
wide as interarea, transversely flat near beak, becoming
transversely concave and sunken dorsally,
bisected by thin, fairly high median monticulus.
Lateral profile moderately convex; anterior profile
fairly strongly and narrowly convex.
Brachial valve lidlike, with strong umbo overhanging
pedicle interarea; plications equaling average
number and strength to those of pedicle
valve. Lateral profile strongly convex, and lateral
profile moderately domed. Umbonal region swollen,
anteromedian region flattened.
Pedicle valve interior with sharp, short, and weak
teeth, extending for short distance posteriorly as
convergent dental ridges beneath interarea,
abruptly widening into thin ventrally and anteriorly
convergent dental plates, normally remaining
slightly separated along valve floor, but converging
and nearly meeting in some specimens. Muscle
marks weak, consisting of striae on inner surfaces
of dental plates.
Brachial valve hinge surface concave, shallow,
forming short interarea; cardinal process long,
strongly curved, extending anteriorly near hinge,
then bending ventrally; free and widely bifurcate,
each prong longitudinally and deeply slit along
posterior surface, the slits containing minute serrations;
prongs converging toward hinge, uniting into
single high ridge. Promontorium wide near hinge,
narrowing along length of process, slanting medially,
making a deep trough along each side of
process and along erismata. Sockets deep, semicircular,
open on side away from process, other side
and bottom formed by fulcral plates. Dentifers
fused to cardinal process by gusset, the free ends
projecting anteroventrally below cardinal process.
Erismata diverging to form umbonal arch, bounding
posterior limits of muscle area, and extending
slightly forward along floor of valve for about onefourth
valve length. Muscle area bilobed, not appreciably
thickened, with plications of exterior
only slightly obscured by callus within area; muscle
marks faint, on valve floor, and on inner bases
of dentifer supports; myophragm low when present.
MEASUREMENTS (in mm).—
USNM 702a
150512a
150512b £t.^
150512c ^c^<<
150512fJ ^ v
USNM 702b
150511a
150511b
USNM 702un
150517a
150517b
150517c
pedicle
valve
length
5.3
6.8
12.0
13.0
14.0
29.1
3.0
19.4
23.8
39.0
50.6
brachial
valve
length
5.0
6.7
11.5
12.2
14.0
27.0
3.0
16.5
19.6
32.7
39.4
maximum
width
6.4
8.5
14.0
14.9
17.9
31.5
4.0
19.6
23.2
39.0
46.1
hinge
width
5.0
5.9
8.0
10.0
13.0
18.5
3.0
12.6
15.5
22.8
29.4
interarea
length
3.7
4.8
6.4
6.9
8.8
16.7
2.2
14.0
19.6
23.8
25.5
thickness
5.3
7.4
11.5
13.7
15.5
27.0
2.9
18.9
28.0
30.2
40.0
376 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
STRATIGRAPHIC OCCURRENCE.—Cathedral Mountain
Formation (Institella zone, Eolyttonia zone),
Road Canyon Formation.
LOCALITIES.—Institella zone: AMNH 500A-C,
F-H, J, L-N, USNM 702, 702b, 702ent, 702inst,
702 (low), 702un, 703b, 703bs, 708u, 711q, 726x;
Eolyttonia zone: AMNH 504, USNM 702a, 703a1;
Road Canyon: AMNH 503, USNM 703a, 703c
DIAGNOSIS.—Large Niviconia with elongate pedicle
valve and narrow, numerous angular plications.
TYPES.—Holotype: YPM 10944; figured paratype:
YPM 10945, T10609; figured hypotypes: USNM
150516b-n, 150517a, 153048, 153532, 153533a-c, e,
g-i; unfigured hypotypes: USNM 150516a, 150517b,
c, 153533d, f; measured hypotypes: USNM
150512a-f, 150511a, b, 150517a-c.
COMPARISON.—Niviconia globosa is characterized
by its numerous and fine, although strong, angular
plications that extend to the beak on each valve,
its attenuate pedicle beak, strongly convex brachial
valve, slightly auriculate hinge, dorsally sunken
pseudodeltidium, and especially by the peculiar
fusion of promontoria to the cardinal process,
which itself is exceptionally long and strongly
curved. The socket plates are fused more loosely
to the process than in other species, and they slant
toward the process so as to form a trough on each
side of it. This loose construction of the cardinal
process complex makes apparent the juncture of
socket plates with dentifers.
This species is closest in size and outline to
Meekella calathica from which it differs in its more
attenuate pedicle beak, less auriculate hinge extremities,
more convex brachial valve, finer and
more numerous plications that extend to the apex,
finer costellae, and peculiar cardinal process. The
numerous, fine plications extending to the beaks
and the odd attachment of the socket plates to
the cardinal process and brachiophores distinguish
this species from M. texana King, M. prionota,
new species, and M. grandis King. Although the
plications on some specimens of M. skenoides Girty
reach nearly to the pedicle beak, its plications are
fewer, its costellae coarser, and its maximum size
much smaller than in N. globosa. Also its dental
plates normally are more widely separated along
the floor of the valve, and the socket plates are
fused more solidly to the cardinal process. Meekella
caperata has numerous fine plications and an attenuate
pedicle beak, and it attains a size similar
to that of N. globosa. But its plications are not as
strong or as angular and do not extend to the beaks
as in N. globosa, its costellae are much coarser,
and elements that attach to the cardinal process are
more strongly constructed. Niviconia abrupta is
like N. globosa, but it is smaller and has a much
shorter pedicle valve.
DISCUSSION.—Niviconia globosa is not as highly
variable as most species of Meekella. Its plications
vary in number only between 16 and 29, and normally
are straight and even, although they curve
as the shell is twisted or is otherwise deformed.
The pedicle beak normally is rather long and attenuate,
not strongly curved and blunt as in King's
(1931, pi. 5: figs. 12a-c) reconstruction.
The most remarkable and characteristic feature
of this species is the manner of attachment of the
dentifers and promontoria to the cardinal process.
The dentifers project more strongly from the main
body of the cardinal process than is typical in other
species of the genus, and the promontoria are not
so strongly fused to the process and dentifers. In
addition, the promontoria slant steeply toward the
process and form a pair of troughs, one running
along each side of the process. The peculiar construction
of the cardinal process complex makes
most specimens of this species easily distinguishable
from most specimens of other species; however,
some individuals of Meekella calathica have similarly
constructed processes, and some specimens of
N. globosa have tighter fusion of the components
than is typical of the species. Other features, such
as number and coarseness of plications, location of
beginning plications on the beaks, and fineness of
costellation, distinguish specimens of these two species
that may have similarly constructed cardinal
process complexes.
Genus Geyerella Schellwien, 1899
Geyerella Schellwien, 1900a:4—Girty, 1909:203 R. E. King,
1931:219 Sarycheva, 1960:219— Williams, et al., 1965:
H405.
Turriculum De Gregorio, 1930:26.
Small to very large, conical, biconvex; outline
strongly transverse to nearly circular; plications
weak to strong, few or many, beginning at, or far
forward of, beaks, regular or irregular, straight or
bifurcating; costellae normally weak, variable in
NUMBER 15 377
strength, parallel to plications, crossing them, or
converging toward their crests anteriorly.
Pedicle valve forming shallow or deep cone, commonly
twisted or bent, deformed by attachment
scars or by contact with foreign objects; interarea
long and narrow, transversely flat, longitudinally
concave or convex, meeting sides at wide angle;
dental plates convergent meeting above valve floor,
uniting with median septum to form Y-shaped
spondylium.
Brachial valve moderately to strongly convex,
with prominent swollen umbo and overhanging
beak; interior with large cardinal process like that
of Meekella with prominent promontorium and
erismata narrowly to widely divergent into umbonal
arch, outlining posterior of bilobed muscle area,
which is divided by low myophragm.
TYPE-SPECIES.—Geyerella gemmellaroi Schellwien
(1900a: 12, pi. 1: figs. 7a, b).
COMPARISON.—Geyerella is characterized by the
union of its dental plates with a median septum
above the floor of the pedicle valve, forming a
spondylium, and by its plicated shell. It differs
from Streptorhynchus King, Kiangsiella Grabau
and Chao, and Tropidelasma Cooper and Grant by
the possession of dental plates and from all but
Kiangsiella also by its plications. It differs from
Meekella White and St. John and from Sicelia
Merla by the juncture of the dental plates to form
a spondylium and from the latter by its plications.
It differs from Ombonia Caneva, which has a spondylium,
by its plications and by the details of the
cardinal process.
DISCUSSION.—Individuals belonging to species of
Geyerella grew attached to the substrate by some
part of the posteroventral surface of the pedicle
valve. Frequently they grew in clusters, closely
pressed against one another. This habit of growth
caused great modification of the shells; they are deformed
or indented at points of contact with the
substrate or other shells, and they are commonly
bent or twisted where growth was inhibited by the
obstruction of foreign objects. This twisting of
the pedicle valve is often a good distinguishing
character of the genus. Such modifications of the
shell produce great variation in the shape of individual
shells, similar to that found in other directly
attached forms.
Features that are relatively stable within the species
of Geyerella and that therefore characterize and
distinguish the species are the maximum and average
size, the twisting of the pedicle valve, the angle
between the interarea and sides of the pedicle valve,
the number, strength, coarseness and place of beginning
of plications, the frequency of bifurcation
of plications, the strength and course of costellation
,and the convexity and prominence of the beak
in the brachial valve. Variable characters that have
no specific significance are the amount of distortion
other than twisting, the outline of the shell, the
proportional width of the hinge or interarea, the
depth of the pedicle valve or the height of the interarea,
the position of the juncture of dental
plates, the forward extent of the extremities of the
median septum of the brachiophore supports, the
length or amount of bending or bifurcation of the
cardinal process, and the manner of attachment of
the dentifers and promontorium to the process.
A few specimens are silicified incompletely, and
the two lamellae of the median septum can be
seen to be separate. This supports Campbell's
(1957:44) belief that "Geyerella was undoubtedly
developed from Meekella by union of the dental
lamellae on the floor of the valve"—an opinion
shared by R. E. King (1931:57) and Stehli (1954:
296).
Geyerella americana Girty
PLATE 89: FIGURE 1; PLATE 125: FIGURES 1-4
Geyerella americana Girty, 1909:204, pi. 11: figs. 2-2b.
Orthotetes distortus Girty, 1909:201, pi. 10: figs. 9-9c.
Orthotetes distortus var. campanulatus Girty, 1909:202, pi.
10: figs. 10-lOc.
The holotype of this species is badly damaged,
exfoliated, and the left side is missing. The breakage
is not all bad because the spondylium is revealed
in detail and assures the identification of
the genus. Girty speaks of a broad and convex
pseudodeltidium being somewhat depressed below
the surface of the interarea. This condition is
brought about by the exfoliation of the shell. What
the observer sees is an impression of the convex
underside of the delthyrial cavity and the adjacent
umbonal chamber. This accounts for the supposed
convexity, because, on the interior, the pseudodeltidium
will not be convex but will be flat as in
Meekella and Tropidelasma. Very little more can
be gleaned from Girty's type other than the fact
378 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
that part of the brachial valve is present and shows
as an inverted V where the cardinal process has
been broken. This indicates a narrow but long
cardinal process that is corroborated by probable
brachial valves newly discovered.
Large brachial valves almost certainly belonging
to this species help to complete the picture of this
poorly known Geyerella. In addition to the two
complete specimens, fragmentary etched posterior
parts of four brachial valves are also available.
The best of the complete specimens is a silicified
valve (USNM 150990) from the Lamar Limestone
Member. It is 42.3 mm long and 52.8 mm wide
and has a thickness of 20 mm. The umbonal region
is narrrowly convex, and the swelling extends to
the midvalve, where it merges in the moderately
convex anterior region. The umbonal slopes are
steep. The hinge is very narrow, less than half
the maximum width. The exterior is paucicostate;
the umbonal region is unplicated, but the anterior
two-thirds have about 30 narrowly angular bifurcating
plications separated by troughs narrower than
the plications.
The interior is provided with a large stout cardinal
process extending almost at right angles to the
lateral commissure plane and descending slightly
anteriorly in a moderate curve. The myophore is
forked and the dentifers small and supported by
short, outwardly curved supporting plates (erismata),
which are slightly concave anteriorly. The
promontorium is small and poorly developed and
is not extended distally to the brachiophore. The
chilidial boss is bilobed in section, large and fairly
long, but with an inconspicuous keel. The posterior
of the umbonal chamber contains a fairly
strong but low myophragm.
Geyerella americana is a large and distinctive
species. It is not as large as G. hessi, is more
strongly and numerously plicated, and has a narrower
umbonal region; it is very rare. Beside the
type, the USNM collection has only a few complete
brachial valves.
Orthotetes distortus Girty and its variety, O. d.
campanulatus Girty, are placed in the synonymy oi
G. americana. The species and variety appear to be
young specimens. They have long spondylia, the
trace of which can be seen where the shells are
thin and exfoliated. The specimens are unplicated,
which is normal for the young.
STRATIGRAPHIC OCCURRENCE.—Capitan Formation,
Bell Canyon Formation (Lamar Member).
LOCALITIES.—Capitan: USGS 2926 (green),
AMNH 725; Lamar: AMNH L-2 (=AMNH 347),
AMNH 384, USNM 725e, 728p, 728q, 738, 738b.
TYPES.—Holotype: USNM 118506; figured hypotypes:
150990, 153543.
Geyerella hessi, new species
PLATE 89: FIGURES 2-4; PLATE 121: FIGURES 1-24; PLATE 122:
FICURES 1-10; PLATE 123; FIGURES 1-21; PLATE 124; FICURES
14-20; PLATE 671: FICURE 19
Geyerella americana R. E. King (not Girty), 1931:57, pi. 7:
figs. 10-13.
Very large, biconvex, deeply conical, most somewhat
distorted; outline transversely subelliptical to
nearly circular; hinge up to 0.9 total shell width
in smallest individuals, normally about half as wide
as shell in all but smallest specimens, ends of hinge
not auriculate but meeting sides of shell with distinct
angularity. Plications strong, moderately
coarse, sharp, irregular or slightly nodular, many
bifurcating, numbering 10 to 30, averaging 20, beginning
about 10 mm anterior to beak. Costellae
fine, converging toward crests of plications only on
moderately large to large shells; growth lines frequent
and rather prominent, producing low
nodules where they interrupt plications. Commissure
coarsely plicate and minutely serrate for sieving
incoming food currents. Pedicle valve deeply
conical, with beak blunt to attenuate, normally
distorted or bent by contact with attachment surface
or other external objects; interarea narrow,
transversely flat, longitudinally concave, meeting
sides of valve with distinct change in slope, meeting
plane of commissure at angle near 90°; pseudodeltidium
occupying about one-third of total width
of interarea at hinge, bisected by low rounded
median ridge. Brachial valve moderately to strongly
convex, with slightly to greatly overhanging beak.
Pedicle valve interior with strong, narrow hinge
teeth, extending ventrally inside interarea as convergent
dental ridges, curving toward floor of valve
as dental plates, meeting and fusing into median
septum above floor of valve, forming Y-shaped spondylium;
median septum continuing short distance
along floor. Muscle marks in spondylium as faint
striae and low crenulations.
Brachial valve interior with strong curved cardiNUMBER
15 379
nal process, with short bifurcated free end, each
branch longitudinally slit along posterior edge,
and with minute serrations within each slit,
branches meeting about midway to form shaft or
proximal half of process. Promontorium narrow,
thick, tapering distally, either at right angles or
sloped toward process to form trough on each side
of process, similar to that in Niviconia globosa
(King); chilidial boss small; proximal ends of
socket ridges flexed to form fulcral plates; erismata
diverging dorsally, meeting floor of valve in umbonal
arch, outlining posterior of muscle area,
extending anteriorly for short distance along floor
of valve. Muscle area between erismata bilobed,
bisected by low myophragm; muscle marks weak,
consisting of longitudinal striae in muscle area
and on bases of dentifer supports.
MEASUREMENTS
USNM 707a
150975a
150975b
150975c
150975d
150975e
150975f
150975g
150975h
150975i
150975]
152605a (holotype)
(in mm).—
pedicle
valve
length
15.5
18.2
27.3
27.6
38.8
41.0
44.4
49.0
59.5
63.0
55.0
brachial
valve
length
10.0
16.0
22.5
27.6
34.5
38.7
44.4
49.0
49.3
50.7
51.4
maximum
width
12.5
18.2
25.9
30.0
38.0
43.0
51.0
48.0
60.5
68.2
53.3
hinge
width
8.2
9.8
12.0
14.6
22.3
24.5
23.0
25.7
31.0
41.7
33.3
interarea
length
11.0
7.0
11.0
14.6
23.0
39.6
38.5
51.8
27.7
44.6
38.0
thickness
12.9
16.8
21.9
28.9
39.0
52.8
53.0
77.3
58.6
72.0
66.0
STRATIGRAPHIC OCCURRENCE.—Skinner Ranch
Formation (Decie Ranch, Poplar Tank, and Sullivan
Peak members), Cibolo Formation.
LOCALITIES.—Decie Ranch: USNM 707a, 707w,
708q, 714t, 727u; Poplar Tank: 707h; Sullivan
Peak: 704y, 707, 707x, 714y, 715f, 715h, 715j, 722-1,
722m, 726-1, 729-1, 733j; Skinner Ranch (lower):
705a, 71 Id, 712p, 714p, 716t; Skinner Ranch (upper):
710r; Cibolo: 738r.
DIAGNOSIS.—Very large Geyerella with an average
of about 20 plications and usually a long twisted
beak.
TYPES.—Holotype: USNM 152605a; figured paratypes:
147735a, 150974, 150975a, c, g, j , 150982a-c,
152605b, c, 153508a-i, 153544a, b.
COMPARISON.—Geyerella hessi is distinguished by
its large size, moderately deep to very deep pedicle
valve, numerous irregular and bifurcating plications
that start near the beak, and distinct angle
between the sides of the pedicle valve and the flat
interarea. Its closest American relative is G. americana
Girty (1909:207) from the Capitan Limestone
of the Guadalupe Mountains, which differs in having
a somewhat depressed interarea, more narrowly
elongate rather than transverse outline, fainter
costellation, and perhaps a more marginally flared
pedicle valve in the juvenile shell. This comparison
is based on the poorly preserved holotype of
G. americana and the associated juvenile shell that
Girty (1909:202) called "Orthotetes distortus var.
campanulatus." King (1931:57-58) recognized that
O. distortus var. campanulatus was in fact a juvenile
of Geyerella americana, and we agree with his
conclusion. There are in the collections of G. hessi
some specimens similar to the holotype of G. americana,
but the total aspect of the collection shows
the above-mentioned differences; however, we realize
that truly accurate comparison cannot be made
on the basis of one or two fragmentary specimens
ol G. americana. The brachial valves attributed
to Geyerella americana are so unlike those of G.
hessi that it seems unlikely the two species can be
the same. The difference is emphasized by the
wide separation of the two species in time.
Geyerella hessi more closely resembles some European
species of Geyerella than G. kingorum, one
of the other new species that occurs in the Glass
Mountains. It differs from the type-species, G.
gemmellaroi Schellwien (1900a:15, pi. 1: figs. 7a-b;
Greco, 1942, pi. 151) in its fewer plications (G.
380 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
gemmellaroi has up to 40, averages near 30) that
start farther from the pedicle beak and that do
not branch more than once per plication (some on
G. gemmellaroi branch up to three times in length
of a plication), its more slender pedicle valve with
interarea that is consistently concave in contrast to
that of G. gemmellaroi, which on many specimens
is strongly convex, and by the sharper angle between
the edges of the interarea and the sides of
the valve. The brachial valve of G. hessi is less
convex, and the beak is blunter and less overhanging.
Costellae on G. hessi normally parallel the
plications or converge toward their crests, but in
G. gemmellaroi they may parallel the plications in
some individuals or on some parts of individuals,
but in most they cross the plications and appear
to be quite independent of them. Geyerella rex
(DeGregorio, 1930:27, pi. 7: figs. 1-2; see also Greco
1942:156, pi. 21: figs. 1-8) differs from G. hessi in
most of the above features, and, in addition, it is
much more elongate and attains much greater size.
DISCUSSION.—This species was considered by King
(1931:57) to be the same as Geyerella americana
Girty. He remarked upon the strange occurrence
of this species both in the Hess and Capitan formations,
but he nevertheless equated the Capitan
and Hess forms, stating that they agree "insofar as
can be told from such an incomplete type specimen'
(1931:57). Despite the fact that they do
agree in many features, we consider it unlikely
that the Hess and Capitan forms are one species,
and we have chosen to consider their differences as
more important than their similarities. In species
as variable as those of Geyerella and Meekella,
which attached directly to the substrate, it is almost
impossible to evaluate specific identity of
single specimens.
Girty (1909:202) identified as Orthotetes distortus
var. campanulatus a small valve that was collected
at the same locality as the holotype of G. americana.
King (1931:57) considered this specimen to
be a juvenile shell of G. americana. Girty had suggested
that the shell might belong to a species of
Geyerella, but he considered the plication to be an
accidental feature. After studying many similar
juvenile shells of G. kingorum, new species, and
a few of G. hessi, we have seen that the beginnings
of plication are quite similar in those species to
that in Girty's specimen, and, therefore, we agree
with King that the plication is not accidental and
that the specimen belongs with G. americana.
Our species is named for the late Mr. Leonard
Hess, who helped our studies with his cordial permission
to collect on his ranch.
Geyerella inexpectata, new species
PLATE 125: FIGURES 5-36
Small for genus, variable, conical profile, brachial
valve strongly convex; roundly elliptical in dorsal
view; hinge narrow; sides rounded; anterior commissure
with strong ventrad wave. Attachment surface
usually small. Posterior unplicated for 5 to
10 mm, but marked by costellae of 2 sizes, larger
ones marking off groups of 1 to 4 finer ones. Plications
originating 5 to 10 mm anterior to beak, generally
low, narrow, distant, variable in number and
size, averaging about L2.
Pedicle valve a misshapen cone, moderately convex
along ventral side and narrowly domed in anterior
profile. Beak region usually slightly curved;
interarea moderately long, flattened, with strong
beak ridges; pseudodeltidium narrow, monticulus
fairly strong. Median region longitudinally swollen
to form ill-defined fold; flanks steep, and somewhat
flaring.
Brachial valve fairly strongly convex, umbonal
region narrowly convex, median region somewhat
flattened, anterior flattened, deflected ventrally.
Anterior profile moderately and broadly convex,
sides flattened and sloping. Brachial valve inflated,
anterior and lateral slopes steep. Anteromedial
region somewhat depressed to form ill-defined fold
and short broadly rounded tongue.
Pedicle valve interior with narrow spondylium
and septum extending to about midvalve or slightly
beyond. Brachial valve with moderately long cardinal
process, narrowly forked distally with narrow
but well-developed promontorium.
NUMBER 15 381
MEASUREMENTS
USNM 720d
150986a
150986b
150986c
150986d
150986e (holotype)
150986f
150986g
150986h
150986i
150986J
(in mm).—
pedicle
valve
length
17.7
16.7
15.7
18.9
22.6
?
?
?
?
?
brachial
valve
length
?
?
?
?
?
20.7
22.4
22.4
21.6
18.3
maximum
width
22.3
20.3
20.5
22.8
28.0
28.4
28.8
26.9
24.0
20.2
hinge
width
13.4
13.0
11.4
13.5
14.2
17.9
16.0
14.0
13.9
10.0
interarea
length
13.0
10.5
10.8
10.3
12.3
thickness
15.0
14.0
13.7
14.7
13.2
11.5
9.8
10.7
8.8
7.7
STRATIGRAPHIC OCCURRENCE.—Road Canyon Formation.
LOCALITIES.—USNM 707e, 719w, 720d, 726e.
TYPES.—Holotype: USNM 150986e; figured paratypes:
150986a-c, g, i, k-m; measured paratypes:
150986a-d, f-j; unfigured paratypes: 150986d-f,
h, j .
DIAGNOSIS.—Small, irregularly costate Geyerella
with narrow pedicle valve strongly domed in anterior
profile.
COMPARISON.—This species, because of its small
size and gently rounded contours, is completely unlike
Geyerella americana Girty or G. hessi, new
species. It is most like G. kingorum, new species,
and attains the size of that species. It is, however,
more plicate than the Wolfcampian species, with
average about 10. The brachial valve of G. inexpectata
is somewhat less umbonate and swollen than
that of G. kingorum, and the anterior margin forms
a distinct tongue unlike the margin of the Wolfcampian
species. The pedicle valve interarea is
more regular and appears to be less distorted than
that of G. kingorum.
DISCUSSION.—Geyerella inexpectata is very rare,
known only from the lenticular limestone bed that
occurs at the base of the Word Formation (but is
assigned to the Road Canyon Formation) on the
east side of Gililand Canyon and in two other localities,
where it is still rarer. The identification
is attended with some difficulty because the species
occurs with Ombonia, a genus similar to Geyerella
in having a narrow spondylium and similar growth
habits. Ombonia is seldom as distorted as Geyerella,
its brachial valve and cardinal process are unlike
those of Geyerella, and it is not costate.
Geyerella kingorum, new species
PLATE 119: FIGURES 1-31; PLATE 120: FIGURES 1-33; PLATE 124:
FICURES 1-10
Orthothetina cf. Orthothetes mutabilis R. E. King (not
Girty), 1931:52, pi. 4: figs. 14, 15.
Small to moderately large, biconvex, shallow to
deeply conical, normally somewhat irregular and
distorted; outline transversely subelliptical to subtrigonal;
hinge proportionately wide in juveniles
(0.7-0.8 total width of shell), becoming narrower
in larger shells 0.5-0.6 width of shell in moderatesize
individuals to 0.35 in largest, ends of hinge
distinct but nonauriculate, meeting sides of valves
at nearly straight angle. Plications very weak to
strong, coarse, rounded, irregular, many bifurcating,
numbering 5 to 20, averaging 10, beginning
10 to 25 mm anterior to pedicle beak, hence juvenile
and young adult shells unplicated. Costellae
fine, fairly straight, often alternating in strength,
added by insertion, converging over crests of plications
near anterior margins of large shells; growth
lines present but not prominent, normally one exceptionally
strong at juncture of plicated and nonplicated
parts of shell. Commissure coarsely plicate
and minutely serrate also broadly undulating in
some specimens.
Pedicle valve beak blunt to moderately sharp,
normally distorted by attachment surface; valve
rarely attenuate, more commonly broadly conical;
interarea narrow, transversely flat, longitudinally
concave to convex, frequently twisted, meeting sides
of valve with only slight break in slope when
meeting plane of commissure at angle of nearly 90°;
pseudodeltidium narrow, between one-half and one382
SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
third as wide as interarea at hinge, bisected by
narrow monticulus.
Brachial valve moderately to strongly convex,
with prominent overhanging beak; umbo swollen;
posteromedian region inflated; lateral slopes short
and steep; anteromedian region flattened.
Pedicle valve interior with strong teeth extending
ventrally inside interarea as convergent dental
ridges, about half way to beak widening into convergent
dental plates that unite above anterior
floor, forming a very short, narrow, Y-shaped spondylium,
meeting median septum that extends for
only a very short distance anteriorly along floor.
Muscle marks consisting of faint striae and ridges
within spondylium.
Brachial valve interior with broad, curved cardinal
process, bifurcated for a short distance at free
end, each branch longitudinally slit along posterior
edge, with minute serrations in each slit, branches
joining about midway to form single crest of process
along its proximal half. Chilidial boss narrow but
thick, merging into convexity of upper convex part
of shaft without a keel. Promontorium narrow but
deep; gusset small; dentifers small, buttressed by
promontorium; fulcral plates small; erismata diverging
slightly into umbonal arch of valve, outlining
a somewhat narrow posterior of muscle area,
extending forward only a short distance along floor
of valve. Muscle area in umbonal arch, slightly
excavate, bisected by low, rounded myophragm;
muscle marks obscure, consisting of longitudinal
striae in muscle area and on inner surfaces of dentifer
supports.
M E A S U R E M E N T S
USNM 701k
150970a
150970b
150970c
150970d
150970e
150970f
150970g
150970h
150970i
150970J
150970k
150970-1
150970m
150970n
150970o (holotype)
USNM 701h
150968b
USNM 727c
153830a
(in mm).—
pedicle
valve
length
3.0
6.2
7.0
8.5
13.2
14.0
14.6
21.3
20.2
21.8
25.7
23.4
26.1
27.6
37.5
38.2
36.5
brachial
valve
length
3.0
5.2
7.0
8.5
9.7
13.3
13.5
16.6
21.0
17.8
25.7
21.6
26.1
27.6
37.5
p
31.5
maximum
width
3.9
7.0
8.3
10.3
12.3
15.0
16.2
17.8
21.0
22.0
25.2
27.7
26.6
27.3
43.7
42.8
36.6
hinge
luidth
3.0
4.9
5.4
6.0
7.0
7.3
9.0
12.8
13.1
10.0
12.0
12.5
12.9
14.9
22.0
23.0
18.7
interarea
length
1.5
2.7
6.4
8.8
10.0
6.0
13.2
15.0
20.8
12.0
13.8
15.9
20.0
23.0
28.2
23.2
24.0
thickness
2.7
4.8
9.0
10.9
15.6
11.0
19.0
22.5
28.2
21.0
29.7
28.0
29.6
36.1
38.8
26.1
37.5
STRATIGRAPHIC OCCURRENCE.—Neal Ranch Formaton
(beds 2 to 14 of P. B. King), Lenox Hills Formation.
LOCALITIES.—Neal Ranch Formation: USNM
701, 701a, 701a2, 701c, 701d, 701h, 701k, 701-1,
722w, 726d, 727e; Lenox Hills: 705.
DIAGNOSIS.—Medium-size Geyerella with few plications
that originate well forward of the beak.
TYPES.—Holotype: USNM 150970o; figured paratypes:
150968b, 150969, 150970c, e, 153509,
153510a-l, 153830a-d, 155104; measured paratypes:
150968a, b, 150970a-n, 153830a; unfigured paratypes:
152594a, c, d, f-i, k-m, 150964, 153830a, e, f.
COMPARISON.—Geyerella kingorum is characterized
by its relatively few and irregular plications
that start far forward of the beak and normally
have rounded crests, by its shallow or bluntly conical
pedicle valve that commonly is twisted or otherwise
deformed, and by its comparatively small size.
The only other species of Geyerella in the Glass
NUMBER 15 383
Mountains comparable to it is G. inexpectata,
which has more plications starting farther back on
the beak and is smaller on the average and more
deeply conical.
Several species of Geyerella from Europe and
Asia have been described, but only one resembles
G. kingorum. That is G. distorta Schellwien
(1900b:35, pi. 3: figs. 6-13), which differs in the
deeper conical pedicle valve of the adult, more
regular and more nodular plications, and greater
maximum size. Other foreign species are larger and
bear many more plications than either G. kingorum
or G. distorta.
DISCUSSION.—The shape of Geyerella kingorum
varies considerably, as in most species that grew
attached directly to the substrate by the pedicle
valve. Most individuals are twisted or distorted,
many with broad scars of attachment near the apex
or along one side of the pedicle valve. Many specimens
have some of the plications stunted by contact
with a foreign object on the substrate or with other
individuals in clusters of shells. A few specimens
have elongate pedicle valve beaks, but most are
rather shallow cones, somewhat flaring toward the
margins and some actually are cup-shaped. The
characteristic twist of the pedicle valve that is so
common in this species is normally rather regular
as though the animal turned quite steadily as it
grew. This twist is not present on all specimens,
but, where seen, it characterizes the species; it is
found commonly in one other species, G. distorta
Schellwien from the Carnic Alps and Sicily. In addition
to the twist, the pedicle valve also may be
bent so that the interarea is concave or less commonly
flat or convex.
Costellation may be weak to barely visible, largely
depending on the preservation, and growth lines
also vary in their strength. Internally, the juncture
of the dental plates takes place high above the floor
of the valve, or just above it; hence, the median
septum may be rather high or very low. Normally
the dental plates are fairly straight and symmetrical,
but in some specimens they bend outward or are
slightly crenulated, and in other specimens one
plate is more strongly bent than the other. The
cardinal process varies in its length, width, curvature,
and depth of bifurcation, but none of this
variation is extreme.
King (1931:52) identified several specimens from
the Gaptank and Neal Ranch formations as "Orthothetina
cf. Orthothetes mutabilis Girty." These
are fragmentary specimens that do not show all
features clearly. His best specimen, that from R. E.
King 91 (R. E. King, 1931, pi. 4: figs. 14a-b), is
broken in such a way as to show two convergent
dental plates, but matrix obscures the short median
septum that lies below the juncture of the dental
plates. Therefore, King considered the arrangement
of plates to be like that of Meekella, rather
than that of Geyerella. The shell is not plicated,
but only obscurely sinuate with what appear to be
the posterior ends of incipient plications beginning
about 22 mm from the brachial beak. Many specimens
of G. kingorum are unplicated at that distance
or farther. King's specimens are identical in
all important features to unequivocal specimens of
Geyerella kingorum in the national collection, and
undoubtedly they belong to that species.
The species is named for the King brothers, who
outlined Glass Mountain geology.
Geyerella species 1
A possible new species of Geyerella was taken at
USNM 705m from the Lenox Hills Formation on
Leonard Mountain. The specimens are incomplete
and poor, but the strong plication of the exterior
and the chunky form suggest a species comparable
to G. hessi. The largest and best-preserved specimen
is in the condition of the holotype of G.
americana, with about half the shell preserved but
with neither side perfect. The spondylium is clearly
visible and the elongated cardinal process can be
seen from the side. The plications are strong, distant,
with 2 occupying a space of 10 mm. A brachial
valve indicates a possible 24 costae on a large specimen.
MEASUREMENTS (in mm).—Length 59.6, width
doubtful but estimated at 65, thickness about 58.
STRATIGRAPHIC OCCURRENCE.—Lenox Hills Formation.
LOCALITY.—USNM 705m.
DESCRIBED SPECIMENS.—USNM 147736a-d.
DISCUSSION.—The four specimens of this species
are all different and show the species to have been
variable. Possibly this Geyerella could be identified
as G. hessi, but, with the small size of the sample
for comparison, it seems best to individualize
it. At any rate, it helps to emphasize the intimate
384 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
relation between the fauna of the Lenox Hills Formation
and that of the Decie Ranch Member of
the Skinner Ranch Formation.
Geyerella species 2
A single brachial valve of Geyerella was recovered
from the residues from locality AMNH 21.
The specimen is poorly preserved and considerably
distorted from having lived in an unfavorable position.
It is very strongly umbonate and the plication
is marginal.
MEASUREMENTS (in mm).—Length 21, width 22,
the hinge about 14.
TYPES.—Described specimen: USNM 150989.
Suborder OLDHAMINIDINA Williams, 1953
Superfamily LYTTONIACEA Waagen, 1883
Ostreiform pseudopunctate brachiopods attached
at posterior end. Pedicle valve varying from flat
expansion to deep cone, having narrow, straight,
simple hinge and series of lateral channels given
off from median groove. Brachial valve pinnate and
lobate, lobes fitting over lateral channels of pedicle
valve. Cardinal process usually bilobed, but may
be modified or aborted.
FAMILIES.—Poikilosakidae, Lyttoniidae.
DISCUSSION.—The Oldhaminidina constitute an
aberrant branch of brachiopods that developed an
ostreiform habit. They are rare in the Pennsylvanian
Period, but they became one of the most
characteristic forms of the Permian. The basic
anatomy is outlined in the foregoing definition and
is described in more detail under the families. Considerable
speculation has centered about the brachial
valve and the musculature that controlled it.
Because the Oldhaminidina appear to divide naturally
into two groups having parallel development,
the questions of anatomy and biology are best discussed
under the separate families.
The more primitive of the Oldhaminidina appear
in the Late Pennsylvanian and continue as an
obscure and rare group at least into the late Guadalupian.
The more advanced types appear very late
in the Pennsylvanian and continue in force into
the Guadalupian in North America.
Grant (1972) suggested that the pinnate brachial
valve of the Oldhaminidina is a modification of the
kind of ptycholophous lophophore that occurs in
Productidina of the family Cooperinidae, Pajaud
(1968). He speculated further (Grant, 1972) that
the general form of the productidine lophophore
was ptycholophous, and that the Oldhaminidina
were derived from the Productidina some time during
the Pennsylvanian.
TERMINOLOGY.—Some of the terms now applied
to the oldhaminidines are not satisfactory and others
are confusing. New terms are offered below to
clarify some parts of the anatomy and to define better
the stages of development.
ANATOMICAL TERMS.—The term cowl is suggested
for the anterodorsad growing shell that produces
the conical shape of the oldhaminidines. Williams
(1953) visualized this as a separate plate having a
suture line between the ventral and dorsal sides of
the shell. This is not the case, because the growth
of the conical forms is holoperipheral, a misshapen
cone being produced when the anterior side grows
faster than the posterior side, but a fairly symmetrical
cone being produced when the two sides
grow at nearly the same rate. Williams' term posterior
flap is best restricted to the posteriorly growing
wash or callus of attachment in oldhaminidines
such as Collemataria, Leptodus, and Oldhamina.
Cowl is used by us for the hoodlike, posterior side
of the cone. When the cowl is prominent and the
shell a fairly well-formed cone, the valve may be
spoken of as cowled. Thus, the flap will be restricted
to the posterior growing attachment, but
cowl is used for the hoodlike structure growing in
the opposite direction (anteriorly), thus producing
a cone. The simpler and more familiar term hood
is not used because of possible confusion with its
use in the loop development of many terebratulid
brachiopods.
Terms at once descriptive and easy to understand
are needed to define the stages of lobe-to-septa development
in the Oldhaminidina. The course of
the evolution of these structures appears to be fairly
well agreed upon, but the present terminology is
inappropriate or confusing. The term loop is unfortunate
because of possible confusion with the
loop of the Terebratulacea. The use of generic
names to define stages of evolution are seldom sufficiently
definitive.
The visceral and mantle cavities of the primitive
Oldhaminidina are surrounded by a wall herein
NUMBER 15 385
called the vallum (flange of Watson). In the primitive
condition this wall probably was circular or
nearly so, but in Poikilosakos, the most primitive
Oldhaminidina having a complete vallum, it is
thrown into lobes, one or more on each side of a
deep median indentation. We suggest that the
lobes that are closed toward the outer margin of
the shell be termed the outlobes and that the ones
closed toward the inside or middle of the shell be
termed the inlobes. In the evolution of the two
families of the Oldhaminidina, the outlobes are
compressed in a direction parallel to the long axis
of the shell. This tends to crowd the lobe walls
together, and ultimately it makes a single ridge or
septum of them. For the primitive condition of a
wide lobe with walls distant the name latilobate is
suggested. The outlobes of Poikilosakos and Keyserlingina
illustrate this condition. The next stage
shows the walls of the outlobes compressed toward
each other with only a narrow space or groove
between. This is called the angustilobate condition
and is characteristic of Eolyttonia and early formed
parts of other genera. When the walls of the outlobes
have been compressed together to form a
single ridge, the condition is termed solidiseptate.
These solid ridges are the septa of most authors
and are best seen in parts of Leptodus, Collemataria,
and other advanced genera. The ultimate
stage of development of the lobes is that seen in
Oldhamina, in which they are thin, with a knife
edge, and strongly oblique. This type is termed
anguliseptate, which, as explained elsewhere, may
develop under conditions that produce a concave
shell. They are also seen in Loxophragmus, but
generally they are rare in occurrence. In one genus
the compressed lobes are broken into beads and
dashes, a condition that is herein called moniliseptate.
All of the names suggested above for the outlobes
can be applied to the median inlobe. This
is compressed laterally from a latilobate condition,
as in Keyserlingina, to an angustilobate form, as in
Eolyttonia, to a solidiseptate character or median
ridge, as in Leptodus, Collemataria, and others. An
angular stage like that of the lateral lobes of Oldhamina
does not occur. A moniliseptate type of
median ridge is seen in several genera, such as
Collemataria and Leptodus, and it is the condition
on which the Termiers based the genus Gubleria.
It is also well formed in Coscinophora. The above
terms define the evolution of the lobes to septa,
but a nomenclature is needed to define the stages
of evolution of the genera.
The stage of the vallum displayed by Keyserlingina,
formerly known as the Keyserlingina-stage,
is herein termed the circumvallate stage in allusion
to the continuous nature of the vallum. When the
vallum is breached, as in Eolyttonia, and compression
of the outlobes and median inlobe occurs, the
condition may be called the pervivallate stage in
allusion to the break in the vallum at the anterior.
This is the Eolyttonia stage of several authors.
Alter this stage the vallum is permanently broken
and the lobes are compressed to form solid septa.
This state is called the septivallate stage, and the
final stage in which the septa become uniform and
sharp-edged is herein called the terminivallate stage
or the Oldhamina stage of authors. Coscinophora
represents a stage in which the outlobes and median
inlobe are broken into beads and dashes. This is
termed the fragmentivallate stage. The foregoing
terms are designed to describe the condition and
fate of the vallum during the phylogeny of the
Oldhaminidina.
GENERIC CHARACTERS OF THE OLDHAMINIDINA.—
Generic characters of the Oldhaminidina appear
on the exterior as well as the interior. The external
form of the pedicle valve, within limits, is a helpful
guide to genera. In the Poikilosakidae the
earliest member is attached by its entire surface, but
later members form cuplike structures. The degree
of complication of the cup is useful in defining
genera.
In the Lyttoniidae the form of the pedicle valve
is also useful in defining genera. None of these
except Paralyttonia is attached by its entire surface,
and all form a conical cup of varying degree of development.
Eolyttonia forms misshapen cones, but
Pirgulia, with its flattened cornicopia shape, is
very distinctive. This cone is so slender and sharply
pointed that speculation regarding its form of
life is certain to arise (Rudwick and Cowen, 1968).
It was undoubtedly attached in the young stage,
but it must have lived loose in the adult stage. The
majority of the Oldhaminidina are flattened or
only gently convex on the ventral side, but Oldhamina
is strongly convex on this side, a condition
helping to distinguish this genus.
386 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
The type of attachment of the pedicle valve is
also helpful, with other characters, in the definition
of a genus. Many genera such as Eolyttonia, Coscinophora,
and Loxophragmus are attached by a small
area at the apex of the cone, but Collemataria,
Petasmaia, and Leptodus have a broad flap at the
posterior that cements them to the substrate. This
is commonly so strong that the specimen, when
broken from its mooring, often carries part or all
of the host with it, when it dies, and is transported
by currents from the site of growth. These two
types of holdfasts involve shells of completely different
form. Oldhamina, in its young stages, seems
to have been affixed like Collemataria, but, on
breaking away from its moorings to live free, the
mantle continued to deposit shell over the posterior
to produce a sort of rump.
The shape of the shell and the kind of mooring
used by it are thus important characters in definition,
but they do not define a genus until they are
combined with various features of the interior.
Interior characters useful in generic definition are:
the hinge, the vallum and its development, and the
muscles. No characters found on the inside of the
brachial valve have proved of value in the genericidentification.
The hinge generally is fairly uniform throughout
the Lyttoniidae except for the new genus Choanodus.
The hinge of the latter is specialized and
more elaborately developed than any other of these
groups of brachiopods. The hinge, thus, has limited
value, but it must be studied and described.
The vallum and its aberrations are extremely
valuable in generic characterization, but they must
be used with caution because of their repetitious
nature within genera and in the same specimen.
In general the Poikilosakidae are characterized by
a complete vallum or by one that is incomplete only
at the anterior. Poikilosakos, therefore, is in the
circumvalate stage and all of the outlobes and the
median inlobes are latilobate. Later members of
this family become pervivallate, the lobes remaining
latilobate, but some specimens show compression
and a tendency toward the angustilobate condition.
Late members of the Poikilosakidae also show a
tendency for the outlobes to alter from strictly
lateral to an anterolateral direction. The Poikilosakidae,
consequently, retain the primitive character
of its vallar lobes, only slightly modified throughout
their phylogeny.
The Poikilosakidae are characterized by the deep
median lobe of the vallum, which is reflected in a
deep median slit in the pedicle valve. This feature
is characteristic of all Poiklosakidae and early Lyttoniidae.
In more advanced Lyttoniidae elimination
and closure of the median slit is characteristic of
the stratigraphically younger genera.
The vallum is the basic pattern for the Lyttoniidae
as well as the Poikilosakidae. The young
of all of the genera in the Glass Mountains have
a well-formed vallum that is in either the circumvallate
or pervivallate stages. Furthermore, the
earliest or first formed lobes remain latiseptate or
become angustiseptate and retain these characters
throughout their life, although lobes added later
are in more advanced stages. Few of the genera are
provided with lobes or septa that are uniform
throughout the shell from posterior to anterior
except in young stages. Early forms of Eolyttonia
have most of the lobes in the lati- or angustiseptate
stages throughout the shell, but later species have
more advanced solidiseptate lobes. Oldhamina and
Coscinophora have fairly uniform development of
lobes throughout, but some individuals of these
two have aberrant lobes. The beaded ridges of
Coscinophora in some specimens pass into a solidiseptate
type of lobe (a remnant?), whereas the rest
of the shell, including the median lobe, is moniliseptate.
The lobes and their end development as
septa are thus difficult to use in the characterization
of genera. Usually the observer must rely on the
predominant development within specimens and
within collections of the same species.
One of the much discussed questions about the
Oldhaminidina is whether or not the brachial valve
could be moved. The presence of muscle marks in
the pedicle valve of several of the genera and the
presence of a cardinal process make it clear that
the valves could be opened and closed. Other considerations
also lead to this conclusion. We have
used the nature of the muscle marks as a means to
separate the Poikilosakidae from Lyttoniidae. The
former family is characterized by a single asymmetric
muscle scar on the right side of the pedicle
valve just anterolateral to the hinge in the interior
of the shell. This scar is conspicuous and is often
made more so by being encased in a sheath. In
NUMBER 15 387
addition, an asymmetrical cardinal process appears
in the brachial valve. Keyserlingina has a conical
form, is in the circumvallate stage, and thus resembles
Pseudoleptodus, but it differs in the lack
of a muscle scar. Thus, the presence of a single
asymmetrical muscle scar is used to distinguish the
Poikilosakidae from the Lyttoniidae. This seems to
be a more substantial character than a general lack
of symmetry in these attached shells, as previously
used (A. Williams, 1953b).
Three genera of the Lyttoniidae, Petasmaia,
Leptodus, and Coscinophora, are provided with
distinct muscle marks, and the sides of the muscle
area are generally bounded by ridges or septa.
Most other genera fail to show distinct traces of
muscles. These muscle patterns differ from those
of the Poikilosakidae in having bilateral symmetry.
In each genus the presence of the muscle scars was
used by us as one of the generic characters. Collemataria,
new genus, for example, has the general
form of Leptodus and is solidiseptate, but septa
are slightly more advanced in the Asian genus. The
chief difference between the two, however, seems
to be the presence of the muscle scars in Leptodus
and their complete absence in the American genus.
In summary, it may be stated that the important
generic characters are the external form of the
pedicle valve combined with various arrangements
of the stages of lobe and septal development. The
brachial valve does not share significantly in generic
characterization. The Oldhaminidina are greatly
different from other brachiopods in their generic
characters, although these too are generally best
defined on external features combined with internal
family characters.
CLASSIFICATION OF THE OLDHAMINIDINA.—
Superfamily LYTTONIACEA Waagen, 1883
Family POIKILOSAKIDAE Williams, 1953
Poikilosakos Watson, 1917
Pseudoleptodus Stehli, 1956
Choanodus, new genus
Sceletonia, new genus
Family LYTTONIIDAE Waagen, 1883
Oldhamina Waagen, 1883
Coscinophora Cooper and Stehli, 1955
Eolyttonia Fredericks, 1923
Gubleria Termier and Termier, 1960
Keyserlingina Tschernyschew, 1902
Leptodus Keyser, 1882
Oldhaminella Wanner and Sieverts, 1935
Pirgulia Cooper and Muir-Wood, 1951
Paralyltonia Wanner and Sieverts, 1935
Rigbyella Stehli, 1956
Collemataria, new genus
Petasmaia Cooper and Grant, 1969
Loxophragmus. new genus
Family BACTRYNIIDAE Williams, 1965
Bactrynium Emmrich, 1855
Family SPINOLYTTONIIDAE Williams, 1965
Spinolyttonia Sarycheva, 1964
REMARKS ON THE CLASSIFCATION OF THE OLDHAMINIDINA.—
The Family Bactryniidae contains a single
genus that is quite aberrant for an Oldhaminidina,
and it might be questioned just where the genus
belongs. The cardinal process of Bactrynium is a
single ridge quite unlike the bilobed structure
characteristic of the Lyttoniidae or even like the
off-median single ridge of the Poikilosakidae.
Furthermore, the brachial valve of Bactrynium is
unlike that of the Oldhaminidina in being a solid
plate, and not pinnate, as in the Permian genera.
A probable separate origin in the Triassic should be
sought.
The subfamily Spinolyttoniidae and its single
genus is looked on by us with extreme skepticism.
This family was created by Williams for the genus
Spinolyttonia Sarycheva (1964:69) for a lyttoniid
"Resembling Leptodus but with septal apparatus
like that of Oldhamina and with spines on external
postlateral areas of the pedicle valve." In our
experience we have not seen spines on any member
of the Oldhaminidina. The USNM collection includes
thousands of specimens, many in exquisite
preservation, but not one has been seen with spines
of attachment. We suggest that the Russian specimen
has been misinterpreted and that the spines attributed
to the lyttoniid actually belong to some
cementing productid whose body has been stripped
off but whose spines have been left adhering to the
lyttoniid. This is not an infrequent occurrence in
the Glass Mountains specimens. We have figured
(Plate 133: figures 5, 6) a specimen so attached to
Institella that it appears to have spines when viewed
from the dorsal side.
The origin of the Oldhaminidina is still not
known. Fredericks suggested that they were derived
from a marginiferoid, the margin of the productid
forming the primitive vallum of the Oldhaminidina.
Invagination of the margin supposedly set off
the evolution of the group. The marginiferids
388 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
were cementing forms only in immature stages and
the spines would have had to be eliminated.
Family POIKILOSAKIDAE Williams, 1953
Lyttoniacea consisting of flat expansions or irregular
cones with interior varying from circumvallate
to early pervivallate stages. Pedicle valve
having single asymmetrical diductor scar and
brachial valve with modified cardinal process. Lateral
lobes usually few in number. Brachial valve
deeply slit medially.
GENERA.—Poikilosakos Watson; Pseudoleptodus
Stehli; Choanodus, new genus; Sceletonia, new
genus.
This family includes the simplest and most primitive
of the Oldhaminidina. It was thought that
Cardinocrania Waagen was the most primitive
member of this family, but it is probably the young
of Leptodus or some kind of richthofeniacean
rather than a separate genus. At any rate, the genus
appears rather late in the geological column for
the originating or most primitive form of the
family, Poikilosakos, which is the oldest known
genus and the most primitive of all. It maintains
its primitive form well into the Permian, although
it is not always easy to decide whether one is dealing
with a primitive Poikilosakos or the young of
Pseudoleptodus.
Perhaps the most primitive species of Poikilosakos
and the oldest so far as known is P. petaloides
Watson, the first described species. This exhibits
its primitive nature by attaching its entire ventral
surface, the margin nowhere turning dorsally except
by accidents of growth. This species also exhibits
well the most distinctive character of the family,
i.e., the single eccentric diductor scar that is commonly
partly encased in an elongated sheath. This
feature and the circumvallate interior characterize
the group as it is now constituted throughout its
life. Generic differentiation takes place, not in
modification of the interior, but rather in the development
of the conical form. This reaches its
maximum in Pseudoleptodus in the Capitan Formation
of the Guadalupian and its equivalents,
the members of the Bell Canyon Formation. It also
reaches a large size in lenses between the Willis
Ranch and Appel Ranch members of the Word
Formation.
Pseudoleptodus is not the only genus in the
family to develop the erect conical form. This was
also adopted by the new genus Choanodus, but, in
addition, this genus developed the most complicated
articulatory apparatus seen throughout the suborder.
The corrugated surfaces established on the
posterior face of a cone of shell substance on each
side of the hinge to articulate with corrugated
flanges on the hinge of the brachial valve are
unique. In addition to the unusual hinge, Choanodus
also developed a strong conical form. Its musculature,
however, is obscure; nevertheless, its typespecies
has an eccentric anterior thickening on the
right side of the posterior region that can be interpreted
only as the site of a large muscle. The
second species assigned to Choanodus—C. perfectus,
new species—fails to show any positive trace of the
muscles and is placed in this genus because of the
complicated articulatory apparatus that it possesses
in common with the genotype.
In his definition of the family Poikilosakidae,
Williams (1953b:287) stressed the irregular development
of the internal lobes of the pedicle valve and
the consequent irregular lobation of the brachial
valve. We believe that much of the irregular development,
as in all brachiopods, is induced by
the accidents of attachment and is not a family
characteristic. Many of the Lyttoniidae also show
irregular development of the lobes, some of which
can be traced to an uneven site of attachment, but
others cannot be so readily explained. For example,
it is common for an otherwise symmetrically formed
oldhaminidine to develop one or more bifurcated
lobes on one or both sides. It seems reasonable to
believe that, given ideal conditions, Poikilosakos
and the genera evolved from it would develop symmetrical
forms, as any other brachiopod would.
Poikilosakos is an extremely rare genus, and its
developmental trends, in view of the few specimens
known, can hardly be said to be well known. We
have, therefore, not emphasized the unequal character
of the lobe development, but we have featured
the eccentric or asymmetrical nature of the musculature,
which is not an evanescent feature dependent
upon attachment. This eccentricity undoubtedly
arose because of the adoption of attachment,
but, once established, it is a uniform feature of the
family.
Williams (1953b:285) placed Cardinocrania Waagen,
Paralyttonia Wanner and Sieverts, and AdriNUMBER
15 389
ana de Gregorio in this family. As noted elsewhere,
we believe Cardinocrania to be the young of
Leptodus. The specimen figured by Wanner and
Sieverts (1935, pi. 6: figs. 1, 2), in our opinion, is
probably the young of a Poikilosakos, probably
P. variabile. Both of the authors' specimens of
"Cardinocrania" exhibit the eccentric muscle on
the right side, as in Poikilosakos. The specimens
probably have nothing to do with Cardinocrania
(=Leptodus) from the Salt Range of Pakistan.
Paralyttonia, in our opinion, was correctly excluded
from the Poikilosakidae by Williams, et al.,
(1965:519) because it has symmetrical musculature.
It does, however, have some features of the Poikilosakidae,
such as the lobed posterior margin of
the brachial valve, a feature that it shares with
Rigbyella Stehli, another genus that suggests the
Poikilosakidae superficially but lacks the requisite
family characters.
Adriana is the last of the genera that we exclude
from the Poikilosakidae and from the Brachiopoda
as well. The figure made by de Gregorio (1930,
pi. 9: figs. 1-5) is very unsatisfactory, and it is not
clear that the object interpreted as the brachial
valve (Williams, et al., 1965:H520, figs. 3a, b) actually
is, in fact, a brachial valve. Assuming that it is,
other details of the interior are lacking that make
it impossible to assign the genus intelligently (see
also Rudwick and Cowen, 1968:43). Licharew
(1964) suggested that these forms are algal, an
opinion that seems very likely to be true. We have
examined Sosio material very similar to that illustrated
by de Gregorio and feel confident that, whatever
the origin of these structures, algal or otherwise,
they are not brachiopods.
Genus Poikilosakos Watson, 1917
PLATE 127: FIGURES 19-32
Poikilosakos Watson, 1917:212-219.—Dunbar and Condra,
1932:272—Wanner and Sieverts (part), 1935:212.
Poikilosakos is a rare genus that forms flat expansions
on other shells, and has a loosely articulated
fragile brachial valve that is not easily found. It
may also be overlooked because of its confusing
shape, masking it in the debris of acid residues.
The original discovery of the genus was unusual
because 20 specimens were found together, attached
to the smooth surface of a nautiloid cephalopod
shell. In the Glass Mountains and Sierra Diablo
the genus has proved unusually rare. It is by the
greatest good fortune that these attached shells
were found or that their brachial valves had been
preserved. The genus is not well known, therefore,
and has not been discovered widely in upper Paleozoic
rocks.
In the United States, Poikilosakos has been found
on several hosts. In the Wayland and Gonzales
shales of the Graham Formation in north-central
Texas, they appear rarely on the broad, smooth,
large nautiloids common to this part of the column.
They also have been found on crinoid stems in the
Wayland Shale. A few have been taken attached
to other brachipods, but they seem to be rare on
such hosts. In the lower Bone Spring Formation
one specimen was found attached to a spreading
bryozoan colony.
Trends noted in the discussion of the family
relate to the external form and the development of
the lobes. Inasmuch as these affect the form of the
brachial valve, they need not be discussed separately
here. The earliest genus is Poikilosakos,
which has the simplest form. It must have resembled
Cardinocrania, now considered as the probable
young of Leptodus, and also it may have resembled,
to some extent, Pseudoleptodus primitivus, new
species, but probably it lacked the strong median
invagination. Perhaps the best-developed Poikilosakos
is P. petaloides Watson, but the brachial valve
interior of this species is still unknown. We are
reserving the name "Poikilosakos" for the flat expansions
and using Stehli's name "Pseudoleptodus"
for subconical and conical poikilosakids.
Throughout the life history of the family the interior
of the pedicle valve has a complete vallum
that is latilobate, although there is some constriction
of the lobes in the latest species of the Capitan
Formation. In the early forms the lobes culminate
medially in a strong narrow emargination that extends
nearly to the posterior. In later genera and
species this median lobe of the vallum becomes
isolated from the lateral lobes. Early isolation of
the median lobe is a feature of the family
Lyttoniidae.
The Poikilosakidae in North America appear in
the lower part of the Cisco Series of Texas and
in the corresponding part of the Virgil Series of
Kansas. It ranges from this part of the Pennsyl390
SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
vanian into the Capitan equivalent (Hegler Member
of Bell Canyon Formation). In Russia one
species, P. tschernyschewi Fredericks, is described
from the Sakmarian Stage. Other described species
are doubtful. Poikilosakos dzhulfensis Sarycheva
(1964) does not have the eccentric diductor nor
do the specimens from Iran referred to by Glaus
(1964). Both of these probably involve the young of
Leptodus.
The entire surface of the pedicle valve of Poikilosakos
is adherent to the substrate. It is only to
this type of shell that we apply the name "Poikilosakos";
the conical forms are referred to Pseudoleptodus
Stehli. The pedicle valve is reminiscent of
an egg about to be fried. The amorphous attachment
of the shell, thin and spreading, but the circumvallate
visceral area corrseponding to a broken
yoke. The spreading attachment is pseudopunctate
and also suggests the callus flap at the rear of the
larger oldhaminidines such as Leptodus. The intervallate
material is like that of the extravallate shell,
finely pseudopunctate and very thin.
Poikilosakos is so simple that few characters are
available for classification. One of these is the hinge,
that, although primitive, is prophetic of all the
Oldhaminidina. It also suggests that of the richthofeniids.
The hinge is essentially the reverse of that
of normal brachipods in that the hinge processes
or "teeth" are in the brachial valve, rather than
the pedicle valve, and the sockets are in the pedicle
valve. The hinge is straight, forming a narrow
transverse groove with elevated margin posterior
to it. The elevated posterior margin may be marked
by one or more fine ridges parallel to the hinge.
At the middle a slight bulge of the posterior margin
overhangs the morphological center of the valve.
Anterior to each side of the hinge are triangular
areas, usually slightly sunken, from which the
vallum extends and which are usually papillose or
minutely striated longitudinally. No definite sockets
appear in this apparatus, the posterior margin of
the brachial valve fitting snugly into the transverse
groove, with the median bulge, when present, helping
to keep the valve in place. This median bulge
is prophetic of the prominent one seen in the new
genus Choanodus.
One of the most important features of the pedicle
valve of Poikilosakos is the musculature, which is
significant for its lack of symmetry. A single elongated
scar appears on the right side when the shell
is seen from the inside. In some specimens this
scar is so long that it extends nearly to midvalve.
Usually it is sheathed wholly or partly by shell material
on its sides. Speculation has centered on the
function of this muscle, whether it opened or
closed the valve or whether it served either function.
The fact that it is in the position of a diductor and
the fact that the groove of the hinge shows signs
of wear indicate to us that this muscle was a functioning
diductor.
The most remarkable feature of the pedicle valve
of Poikilosakos is the lobate wall, herein called the
vallum, that defines the visceral and mantle cavities
of the animal. This originates at each end of the
hinge, extending anterolateral^ and usually sinously
or moderately lobed along its posteriormost
course. Laterally it defines one or more lobes and
terminates in a median lobe that extends posteriorly
for half or more of the length of the valve. This
part of the vallum commonly is produced into a
narrow curve or perhaps a sharp inverted V. Usually
the median lobe is the most elevated of all, and, in
some specimens, it may be excavated at its termination
so as to form a short tube. The vallum is
commonly bevelled or grooved on the inner face
to receive the outer edge of the brachial valve.
Usually the inlobes, toward the animal's midline,
are stronger and more elevated than the outlobes
extending outward toward the animal's periphery.
Except for scraps, the brachial valve of Poikilosakos
hitherto has been unknown, and by 1973 the
interior of the type-species is yet to be found. As
postulated by Watson (1917) and described by
Dunbar and Condra (1932) from fragments, the
brachial valve fits on the inner slopes of the vallum
and conforms to the outlines of this wall. A specimen
from the Plattsmouth Limestone of Kansas
in the United States National Museum (USNM
137498) exhibits the exterior to perfection. The
hinge is very narrow, measuring 2 mm as compared
to the maximum width of 15 mm. On each side
of the hinge are two small ears or points that help
in articulation. The growth of the shell can be
traced in strong concentric lines, showing it to have
originated as a bilobed transverse individual. The
posterior margin is undulating. The median cleft
that surrounded and is in contact with the median
NUMBER 15 391
inlobe of the vallum is wide and partly closed at
its apex by a short web.
The interior of the brachial valve is simple. In
the hinge region the narrowed posterior is bounded
on each side by a triangular area—in some, faintly
striated longitudinally and marked on the anterior
side that faces the interior by a low ridge. The
cardinal process is short, flattened, and gives the
appearance of having been pushed laterally so that
it is oblique to the valve floor with a narrow space
between it and the floor. The myophore is seldom
clear, but it appears to be bilobed. Although the
cardinal process appears to be median in position,
it is asymmetrical like the single muscle scar that
opposes it. The lobe of the right side of the cardinal
process is usually the larger.
The visceral region of this valve lies between
the hinge and the median cleft. This part usually is
moderately deep and is divided anteriorly by a low
median ridge that rises to the proportions of a
median septum in some instances. No adducor scars
have yet been observed on either side of this ridge,
but the animal must have had adductors to close
the valves.
The lateral margins of the lobes generally are
inflected in a ventral direction and are somewhat
thickened where they make contact with the vallum.
No definite structures appear inside the concave
lobes, but, in one shell, low ridges parallel to the
inflected lobe edge are visible; it is not clear what
they mean.
TYPES.—Figured specimens: USNM 137498,
148041, 148045a, b, 148046, 148048a, 148049,
148050a-c, 150708.
Poikilosakos informis, new species
PLATE 132: FIGURES 22-37
Poikilosakos petaloides Stehli (not Watson), 1954:306.
Large, variable without definable shape and attached
by entire surface to substrate. Interior with
slightly elevated vallum forming 2 or 3 lateral and
1 anterior lobe. Median lobe moderately wide,
reaching posterior to midvalve, usually angular and
slightly excavated at angle in old specimens. Adductor
scar short, with marginal thickenings.
Brachial valve with narrow and short body,
usually shallow; lobes 2 to 3 lateral and 1 short
anterior; margins slightly reflected dorsally. Surface
smooth. Interior with low median ridge and minute,
eccentric cardinal process.
MEASUREMENTS (in mm).—Paratype (USNM
150691): length 12.9, maximum width 18.4?, hinge
width 2.3, height nearly flat; holotype (USNM
(152619a): length 22.0, maximum width 22.8?,
hinge width ?, height none; brachial valve of paratype
(USNM 150694a): length 17.2, maximum
width 16.1, hinge width 3.3, height ?; paratype
(USNM 150694b): length 14.0, maximum width
18.7, hinge width 3.3, height?
STRATIGRAPHIC OCCURRENCE.—Bone Spring Formation
(base), Skinner Ranch Formation (base).
LOCALITIES.—Bone Spring: AMNH 625, 628, 629,
631, USNM 728f; Skinner Ranch: USNM 705a.
DIAGNOSIS.—Large Poikilosakos with 3 lateral
lobes and 1 anterior lobe, large and formless, attached
by the entire surface.
TYPES.—Holotype: USNM 152619a; figured paratypes:
152619b, c, 152620a, b, 150693, 150694a, b,
e; measured paratypes: 150694a, b; unfigured paratypes:
150694c, d.
COMPARISON.—It is difficult to compare satisfactorily
specimens as amorphous as Poikilosakos, but,
if enough specimens can be obtained, a general,
vague sort of shape can be defined. The vallum
also has characteristics of its own that may contribute
to species differentiation. Few pedicle valves
of P- informis are known, but several specimens of
the brachial valve have been collected. Compared
with P. petaloides, the vallum is stronger and
thicker in the Pennsylvanian species and the invaginations
of the vallum are much narrower than in
P. informis. Furthermore, P. petaloides has four
lateral lobes in the adult, but P. informis appears
to have only three. According to the form of the
vallum of P petaloides, its brachial valve would
be more elongate than that of P. informis, which
is transverse.
The only described species outside North America
is P. tschernyschewi Fredericks (1927) from Krasnoufimsk.
It differs from both American species in
its transverse form and much larger size.
DISCUSSION.—As might be expected, P. informis is
better represented by brachial valves than by pedicle
valves. The attached forms can only be found
on the larger lumps of bryozoa or other massive
skeletal forms, and these usually are rare in the
392 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
residues. Recognition of the brachial valves because
of their odd form is often difficult.
Poikilosakos species 1
Small, subcircular, about 8 mm in diameter, attached
by entire surface. Lobes irregular, wide,
and with thick margins. Muscle scar unusually
long, measuring about 4 mm, not tubular. Specimen
attached to Reticulatia from USNM 718e.
TYPES.—Described specimen: USNM 150708.
Poikilosakos species 2
PLATE 155: FICURE 7
Small, transversely oval in outline, anterior margin
slightly elevated. Vallum posteriorly and laterally
elevated but nearly obsolete at anterior. Hinge
very narrow; muscle scar long, enclosed on sides
by moderately strong elevation. Median channel
wide but with vallum scarcely visible. Length 11.6
mm, width 17.6 mm, hinge width about 1.5 mm.
Specimen from USNM 706e.
TYPES.—Figured specimen: USNM 153581a.
DISCUSSION.—The lifting of the anterior margin
is a tendency toward Pseudoleptodus. The specimen
is attached on the inside margin of a large
Derbyia pannucia.
Genus Pseudoleptodus Stehli, 1956
Pseudoleptodus Stehli, 1956a:311.
Cowled Poikilosakidae having fairly symmetrical
form, vallum of pedicle valve anteriorly incomplete
in late species. Circumvallate to pervivallate.
TYPE-SPECIES.—Pseudoleptodus gelawayensis Stehli
(1956:312, pi. 41: figs. 2, 5; pi. 42: figs. 1, 3).
COMPARISON.—As mentioned by Stehli (1956),
this genus has the form and other characters of
Keyserlingina of Tschernyschew (1902), which
never was described or figured. All illustrated specimens
of Keyserlingina are matrix filled or in
matrix, making the interior characters difficult to
describe and illustrate. Possibly because of these
difficulties, the several authors who described species
of this genus failed to record the presence of the
median muscle scar and sheath characteristic of
the family Poikilosakidae. This character is sufficiently
conspicuous to be recorded on interior impressions,
as it is in Poikilosakos tschernyschewi
Fredericks (1927). It seems clear, therefore, that
Keyserlingina is in a separate line of development
from that of the Poikilosakidae. The same holds for
Chaoella Licharew, which now is regarded as a
synonym of Keyserlingina. In the description of this
genus, Licharew (1931) made no mention of
asymmetrical musculature.
The conical form, which is strongly developed in
some Pseudoleptodus, is sufficient distinction from
Poikilosakos, a genus that is reserved for completely
attached species.
DISCUSSION.—As herein interpreted, Pseudoleptodus
is a more prolific genus than Poikilosakos.
It probably was fairly abundant locally, but its
attached habit prevented wide distribution. Obviously
the attachment was not strong enough to
prevent many individuals from being ripped from
their moorings, or we would not have in hand as
many specimens as we have collected. Most shells
were attached by an apex of a size varying even
within the species.
The pedicle valve presents few features different
from Poikilosakos except the more advanced character
of the vallum in late species. Some species
of Pseudoleptodus, such as the type-species, have the
outlobes nearly at right angles to the median lobe.
Others, such as P. guadalupensis Stehli, have the
outlobes extending anteriorly at a strong angle to
the median lobe. This condition may be a reflection
of the long, slender form of that species, but there
is a tendency in fairly circular forms such as P.
conicus, new species, for the outlobes to become
moderately to fairly strongly oblique in large and
fully grown specimens.
In all species of Pseudoleptodus, the outlobes
usually are widely separated, but the inlobes in
many species are narrowly compressed (anguistilobate)
and thus resemble the so-called septa of
early members of the Oldhaminidae in an early
pervivallate stage. Anteriorly, in some late species,
the vallum becomes incomplete, the walls of the
median lobe dying out distally as do the walls of
the anteriormost of the outlobes. This is a trend
toward the condition seen in most of the Oldhaminidina.
The brachial valve of Pseudoleptodus is similar
to that of Poikilosakos internally as well as externally.
It is common for one side of the brachial
NUMBER 15 393
valve to be developed differently from the opposite
side, a feature that seems to take place for no
apparent reason in shells that are otherwise symmetrically
formed. It is also common for the posterior
margin of the posteriormost lobe to be undulatory.
Pseudoleptodus may develop more lateral
lobes than usual in Poikilosakos, chiefly because the
conical form permits anterior growth only to the
specific limits of the animal. All specimens of all
species showing the cardinal process indicate that
this character is like that of Poikilosakos and thus
in accordance with the eccentric character of the
pedicle valve musculature.
Species of Pseudoleptodus occur in all parts of
the Glass Mountains sequence and also in most of
the section in the Guadalupe Mountains and the
Sierra Diablo. Although specimens are rare and
usually hard to find in the residues, ultimately a
fair lot of them was obtained and some of their
secrets revealed.
Pseudoleptodus appears also to be represented
outside of North America. Examination of Wanner
and Sieverts' (1935:212, pi. 6: figs. 8b, c) figures of
Poikilosakos vaxiabile indicate to us a relationship
to Stehli's genus. This conclusion is based on the
curved edges of the specimen, indicating a conical
form, and on the presence of the sheathed muscle
scar. The other specimens identified as this species
by Wanner and Sieverts do not have the eccentric
muscle scar, and, in some of them, symmetrical
muscle scars are clearly indicated, suggesting relations
to Leptodus, rather than to the Poikilosakidae.
We believe that the specimens figured by
Wanner and Sieverts (1935, pi. 6: fig. 1, 2) as
Cardinocrania and that possesses the characteristic,
asymmetrical scar of the Poikilosakidae should be
referred to Pseudoleptodus. Most likely they represent
the young "Poikilosakos" variabile, illustrated
on the same plate.
Pseudoleptodus annosus, new species
PLATE 127: FIGURES 2-18
Small, subcircular in outline, conical to subconical
in form, depending on degree of attachment,
those with small attachment surface becoming more
strongly conical. Hinge narrow; lateral and one
short anterior lobe; median region marked by
junction of vallum from each side, strongest and
highest at midvalve, forming narrowly rounded
lobe. Interlobal spaces outside vallum smooth;
adductor scar long and very narrow, located in
nearly completely tubular sheath.
Brachial valve bluntly lobate, lobes broad and
shallow; exterior surface smooth. Interior with minute
excentric cardinal process.
MEASUREMENTS (in mm).—Holotype (USNM
150697d): length 11.2, maximum width 12.2, hinge
width 3.3, height 6.2; paratype (USNM 150697a):
length 10.6, maximum width 13.5, hinge width 3.7,
height 3.0; paratype brachial valve (USNM
150697c): length 8.2, maximum width 10.7, hinge
width 2.0, height?
STRATIGRAPHIC OCCURRENCE.—Word Formation
(Willis Ranch Member), Cherry Canyon Formation
(lower Getaway Member).
LOCALITIES.—Willis Ranch: USNM 706; Getaway:
732.
DIAGNOSIS.—Small, conical to subconical Pseudoleptodus
with thick, median lobe.
TYPES.—Holotype: USNM 150697d; figured paratypes:
150697a-c, 150698a.
COMPARISON.—This species is characterized by
its small size and thus is distinguished readily
from all of the larger species such as P. guadalupensis
(Stehli), P granulosus, new species, and P. getawayensis.
It is larger than P. primitivus, new
species, and has more lateral lobes. Furthermore, the
median lobe of P. annosus is not as strongly tubular
as that of P primitivus, which is extremely developed
in this respect.
DISCUSSION.—Too few specimens of P. annosus
are known to be sure whether this is an adult or a
partially grown form. The fact that specimens of
similar size have been found in the Glass Mountains
and the Guadalupe Mountains suggests that
the specimens represent fully matured individuals.
One specimen (USNM 150697d) that shows its attachment
scar has a large cowl. This specimen was
attached to a cylindrical object and apparently was
forced to develop the cowl to protect itself on its
host. Specimens on flat objects did not develop a
long cowl.
Pseudoleptodus conicus, new species
PLATE 128: FIGURES 6-36; PLATE 129: FIGURES 1-19
Pedicle valve subcircular in outline but variable,
depending on substratum; attaining diameter of
394 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
about 20 mm in largest specimen, forming misshapen
cone. Surface of attachment varying from
small point to large part of surface; lateral and
posterior margins reflected in dorsal direction to
form bounding wall; posterior margin deflected dorsally
and anteriorly to form short cowl, subconical
cup thus suggesting Keyserlingina in form.
Brachial valve exterior with 3 lateral and 1 anterolateral
lobes on each side of deep median lobe.
Exterior smooth.
Pedicle valve interior with wide lobes forming
vallum and defining form of brachial valve; vallum
angular in section and steep-sided; vallum bounding
anterior lobes, meeting usually at point posterior
of midvalve into short and stout median ridge,
slightly excavated where it faces anterior margin.
Hinge narrow, straight, usually poorly visible under
cowl; adductor muscle strongly oblique, narrow,
elongate, and with outside margin thickened and
elevated, inner margin less thickened, position
variable, distal end reaching as far anteriorly as
posterior end of median ridge, but commonly much
shorter.
Brachial valve interior with small ears on cardinal
extremities and small, eccentric cardinal process.
Lobes and shell body moderately deep; median
ridge low and obscure.
MEASUREMENTS (in mm).—
length
USNM 701-d
150701a 15.0
150701e 14.0
150701h 17.7
150701-1 12.8
150701o 10.0
150701p 16.6
150701q 16.0
150701r 12.6
USNM 701-1
150702
(holotype) 28.2 19.5 ? 13.0
STRATIGRAPHIC OCCURRENCE.—Neal Ranch Formation
(beds 4-8 of P. B. King).
LOCALITIES.—USNM 701, 701c, 701d, 701-1, 713h,
718e, 721g, 727e.
DIAGNOSIS.—Pseudoleptodus with elevated marginal
rim around the exterior of the pedicle valve
and a small cowl posteriorly to produce an irregular
cone.
TYPES.—Holotype: USNM 150702; figured paramaximum
width
19.6
16.0
16.0?
16.8
16.7
16.9
18.5
17.0
hinge
width
2.8
2.6
?
?
1.8
2.0
2.2
?
heigh
4.0?
5.0
7.0
4.0
?
6.0
7.0
6.0?
types: 150700a, b, 150701e, g, h, 153650a-k,
153652a-h, 153653, 153654a; measured paratypes:
150701a, e, h, 1, o-r; unfigured paratypes:
150701a-g, i-r, 153654b, c.
COMPARISON.—Pseudoleptodus conicus may be
easily separated from P. getawayensis Stehli and
P. granulosus, new species, because these two species
are very strongly granulose on the exterior of
the brachial valves and have granulose tissue in the
intervallar parts of the inlobes. All parts of the
pedicle valve of P. getawayensis and P. granulosus
not covered by the brachial valve are granulose.
The only other species resembling P. conicus is
P. guadalupensis Stehli, but this is a much narrower
and more elongate species. Internally the two species
are also readily distinguished by the strongly
oblique nature of the lobes of P guadalupensis.
These are much more oblique than those developed
at the anterior of P. conicus.
DISCUSSION.—This species is fairly common at
USNM 701d, 721g, and 727e, where it occurs with
Striatifera and numerous sponges in typical biohermal
assemblages. The specimens show a
variety of sizes, but many of them are incomplete,
the thin posterior attachment ends having been
broken from the cones. A few specimens are shown
in position attached to Striatifera, Diplanus, algal
surfaces, and the cellular face of fenestellid bryozoans.
As usual with attached shells, it is difficult
to define a normal shape, the form that a specimen
living under optimum conditions would develop.
The length of the cowl is variable from
nonexistant to moderately long. When the cowl is
long, the shell produces a well-formed but irregular
cone.
Pseudoleptodus cucullatus, new species
PLATE 130: FIGURES 9-12
Moderately large for genus, irregularly cowled;
apical attachment fairly large. Exterior wrinkled;
profile flattened at apex, but main body of shell
perpendicular to surface of attachment and gently
convex. Interior with long, narrow, strongly
sheathed diductor scar. Vallum latilobate, nearly
complete, obscure anteriorly, forming 3 outlobes
and 1 incipient anterior lobe; median lobe latilobate
for nearly entire length, narrow, with subparallel
sides.
NUMBER 15 395
STRATIGRAPHIC OCCURRENCE.—Cathedral Mountain
Formation.
LOCALITY.—USNM 72lu.
MEASUREMENTS (in mm).—Holotype: length 20.3,
width 17.6, hinge width 3.4, height 12.0, cowl
length 6.0?
DIAGNOSIS.—Well-cowled Pseudoleptodus having
oblique lobes; circumvallate.
TYPES.—Holotype: USNM 153642a; unfigured
paratypes: 153642b, c.
COMPARISON.—This species is most like P. guadalupensis
Stehli in profile, outline, and habit of
growth, but it differs in being a much wider form.
It also suggests P. conicus, but it differs in being
shorter and rounder and in having fewer lobes.
Pseudoleptodus getawayensis Stehli
PLATE 130: FICURES 18-34
Pseudoleptodus getawayensis Stehli, I956a:312, pi. 41: figs.
2. 5, pi. 42: figs. 1, 3.
Pedicle valve moderately large, attaining length
of 30 mm; subconical outline but usually irregular,
with variable cowl. Attachment surface small,
apical, usually forming rough inset scar. Exterior
marked by strong interrupted concentric wrinkles.
Pedicle valve interior with 4 lateral lobes, usually
stout, generally irregular but with median 2 usually
extending farthest laterally. Outlobes broad,
branched distally in some specimens and with floor
within vallum thickened and rounded. Inlobes
usually narrow, with vallum elevated and space
within vallum thickened and strongly granulose.
Median lobe solid for one-fourth to one-half its
length, divided near midvalve, and height of walls
diminishing distally from point of division. Vallum
anteriorly indistinct, but, although low, appearing
to be complete. Muscle scar moderately
long, strongly sheathed. All parts of valve not enclosed
by vallum strongly granulose.
Brachial valve with 4 moderately wide lateral
lobes and 1 short anterior lobe; median 2 lobes
with greatest lateral extent; median cleft deep, occupying
usually about half the valve length, moderately
wide, and narrowly rounded proximally;
posterior shell half of body, moderately convex, and
depressed longitudinally by a narrow, shallow sulcus
representing anterior filling of cleft. Surface
strongly and fairly coarsely granulose. Posterior
margin forming smooth incurved triangular area,
representing joint for hinge movement.
Brachial valve interior with small, spreading
cardinal process with scarcely any shaft developed;
lateral ears strong and demarcated by prominent
diverging ridges; median ridge low, variably developed.
Lateral lobes moderately deep, in some specimens
with raised lines parallel to margins.
MEASUREMENTS (in mm).—
AMNH 512 ( = USNM 728)
AMNH 279341:2 (holotype)
USNM 150704a
USNM 150704b
length
24.6
32.0
16.8
maximum
width
31.0
27.6
21.0
h inge
width
7.2?
8.0
5.0
height
8.8
12.0
?
cowl
length
6.0?
6.7
?
STRATIGRAPHIC OCCURRENCE.-—Cherry Canyon
Formation (Getaway Member).
LOCALITIES.—Getaway: AMNH 512, 519, USNM
728, 732.
DIAGNOSIS.—Thick-shelled, granulose Pseudoleptodus
of large size with narrow inlobes and 4 lateral
lobes.
TYPES.—Holotype: AMNH 279341:2; figured
paratype: AMNH 27934:1; figured hypotypes:
150704b, 153637a-e; measured hypotypes: USNM
150704a, b.
COMPARISON.—This species is readily recognized
by its large size and strongly granular extralobal
surface. It suggests P. granulosus, new species, but
that species is much smaller, with a more evenly
developed vallum and less strongly conical form. It
differs from P. guadalupensis (Stehli) in its less
elongate form, more robust shell, and less oblique
lobes.
DISCUSSION.—As with most of these cementing
forms, this is a rare species. The Guadalupe Mountains
residues produced four fairly complete pedicle
valves and about 25 well-preserved brachial valves.
This valve was unknown to Stehli (1956). One of
the larger pedicle valves in the USNM collection
does not preserve the muscle scars, but it is a worn
396 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
valve and it is likely that this structure did not
survive its rough treatment. Except for this, the
specimen is typical of Pseudoleptodus. Most of the
brachial valves do not preserve the cardinal process
in good condition. This appears to have had little
or no development of the shaft, and the myophore
is fairly spread laterally.
Pseudoleptodus? giganteus, new species
PLATE 130: FIGURES 6-8
Known from brachial valve only; large, with
length and widest part nearly equal; shell body
short and narrow; shell divided into unequal halves
by deep median split extending posteriorly for
about 0.7 valve length; lobes uneven, extending
anterolaterally, 3 on left side and 4 on right. Lobes
moderately wide with strong concentric growth
lines. Surface, in addition to growth lines, finely
papillose.
Interior with valve body shallow but lobes moderately
deep; body with low median ridge and
small, eccentric cardinal process, lobe margins elevated.
MEASUREMENTS (in mm).—Holotype (USNM
150720): length 29.2, maximum width just anterior
to midvalve 32.1, hinge width 5.0.
STRATIGRAPHIC OCCURRENCE.—Road Canyon Formation.
LOCALITY.—USNM 703.
DIAGNOSIS.—Large, multilobed, with narrow
hinge and 3-4 wide lobes.
TYPES.—Holotype: USNM 150720.
COMPARISON.—No other known species except
P. grandis, new species, approaches this one in size,
but the brachial valve of P. grandis is smooth.
DISCUSSION.—We believe this specimen to belong
to Pseudoleptodus because it is fairly concave in
lateral profile, suggesting that it fitted inside a
conical pedicle valve. The exterior is finely granulose.
This is not a good argument for generic
affinity, but several of the Pseudoleptodus species
are so ornamented.
The hinge of this species is very narrow, but it
shows the cardinal process well. Like other species
of Pseudoleptodus, this is slightly pushed laterally
(toward the observer's right) and is bilobed, one
lobe, the left one, being less developed than its
companion. The shaft is short and reaches anteriorly
to a low median ridge that extends to a
cleft in the valve. The margins of the lobes are
moderately incurved, but they are not strongly
thickened as in some species.
Pseudoleptodus grandis, new species
PLATE 133: FIGURES 12-19; PLATE 183: FIGURES 2-10;
PLATE 189: FIGURE 6
Large, cowled, transversely elliptical in outline,
widest near middle; sides narrowly rounded; exterior
wrinkled. Attachment surface variable, usually
broad and substantial.
Pedicle valve interior with 3 lobes defined by incomplete
vallum in pervivallate stage. Lobes varying
from latilobate to narrowly angustilobate.
Median lobe solidiseptate in posterior but narrowly
latilobate anteriorly. Inter and extra vallar surfaces
smooth. Diductor muscle, short, narrow, and
strongly sheathed.
Brachial valve trilobate and externally smooth.
Lobes shallow, but with moderately elevated rims.
Cardinal process small, eccentric; median ridge low.
MEASUREMENTS (in mm).—
maximum hinge cowl
length width width height length
USNM 737w
153567a 31.5 40.6 6.0 13.7 16.8
(holotype)
USNM 732c
153646a 28.4 31.0? 6.8 10.3 5.0
USNM 742b
154525a 15.6 26.0 5.0 none none
STRATIGRAPHIC OCCURRENCE.—Word Formation
(lens between USNM 706b and the Appel Ranch
Member).
LOCALITIES.—USNM 732c, 737w, 742b.
DIAGNOSIS.—Large Pseudoleptodus with smooth
exterior and extra-vallar areas and strongly conical
form in the adult.
TYPES.—Holotype: USNM 153567a; figured paratypes:
153567b, c, 153646a-c, 154525a; unfigured
paratypes: 154525b-d; measured paratypes:
153646a, 154525a.
COMPARISON.—This is the largest species of the
genus thus far found in a complete specimen. It
resembles P. getawayensis Stehli in its cowled form,
but it differs in being smooth, in having wide
loops, and in its advanced pervivallate condition.
It differs from P. giganteus in having a smooth
brachial valve.
NUMBER 15 397
Pseudoleptodus granulosus, new species
PLATE 132: FIGURES 15-21
Normal size for genus, subcircular in outline,
and attached by most of ventral surface, but variable,
some specimens attached for only part of ventral
surface and being gently to moderately concave.
Pedicle valve interior with narrow, straight hinge;
visceral region defined by irregular elevated vallum
forming 2 lateral and 1 anterior lobes. Vallum
united medially to form elevated central reentrant.
Extra vallar areas strongly granulose, granules narrowly
rounded and elevated. Diductor scar narrowly
elongated and with marginal thickenings,
outside strongest and forming half sheath.
Brachial valve variable, irregularly lobed, shape
depending on substrate to which pedicle valve attached.
Lobes generally narrow but expanding distally.
Surface strongly pustulose like that of extravallar
areas of pedicle valve.
Interior with small, eccentric cardinal process;
central part with low median ridge. Margins of
lobes thickened.
MEASUREMENTS (in mm).—Holotype (USNM
150714b): length 13.4, maximum width 15.8, hinge
width 2.4, height?; paratype (USNM 150714c):
length 10.8, maximum width 12.7, hinge width 2.8,
height 3.4; paratype (USNM 150714a): length 11.5,
maximum width 12.0, hinge width 2.5, height?
STRATIGRAPHIC OCCURRENCE.—Bone Spring Formation
(base).
LOCALITY.—USNM 728f.
DIAGNOSIS.—Flattened to subconical with interlobal
areas and the exterior of the brachial valve
strongly granulose and with strongly granulose and
strongly elevated granules.
TYPES.—Holotype: USNM 150714b; figured paratypes:
150714a, c.
COMPARISON.—The strong granulation on the
exterior of the brachial valve and in the extravallar
spaces makes it necessary to compare this species
with two others only. Relationship to P. getawayensis
Stehli is indicated, but this Guadalupian form
is much larger, has a better formed conical pedicle
valve, and a more numerously lobated brachial
valve.
Relationship to "Poikilosakos" variabile Wanner
and Sieverts (1935) is also indicated because this is
a strongly granulose form that probably had a low
conical pedicle valve when complete. The American
species differs in having the muscle scar narrower
and more completely sheathed, the coarsely
granular parts of the pedicle valve in the extravallar
areas, whereas the opposite is true of the
Timor species; P. granulosus has fewer lobes on
the brachial valve.
DISCUSSION.—This is a very rare species, the collection
consisting of three pedicle valves and four
brachial valves, two of the latter being juveniles.
The granules on the younger parts of the brachial
valve are so elevated in two of the specimens that
they are in the category of spines.
Pseudoleptodus guadalupensis (Stehli)
PLATE 128: FIGURES 1-5; PLATE 131: FIGURES 1-42;
PLATE 188: FIGURES 4-14
Adriana? guadalupensis Stehli, 1956a:312, pi. 41: figs. 1, 4, 6, 8.
Large for genus, generally elongate and forming
incomplete cup; attachment area small and apical
and occupied by shell body; anterior side generally
longer than posterior part, which forms cowl of
varying length over hinge region. Exterior surface
marked by concentric growth lines and fairly strong
growth wrinkles.
Interior with vallum complete or incomplete and
forming lobes of varying width but usually crowded
together and narrow. Lobes usually 3 lateral and
1 anterior. Lobes extending anterolaterally at low
angle (20°-45°) to median lobe or indentation.
Median lobe long with narrow interspace, in some
cases closing anteriorly as well as posteriorly, but
in others continuing to margin after interruption.
Diductor scar long and slender, generally well
sheathed.
Brachial valve smooth externally and with strong
angular bend at beginning of lobation; lobes generally
4 in number, 3 lateral and one anterior;
lobes generally narrow. Interior with characteristic
eccentric cardinal process.
MEASUREMENTS (in mm).—
maximum hinge hood
length width width height length
AMNH 475
150718a
150718b
USNM 736
150717a
USNM 731
150715a
26.0
28.3
13.4
21.0
18.0
20.9
14.6
9.7
?
?
2.4?
3.4
12.3
17.7
10.5
10.4
9.0
14.5
5.0
?
398 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
DIAGNOSIS.—Pseudoleptodus forming misshapen
cowled cups with narrow lobes inside the pedicle
valve and lobes of the brachial valve steeply inclined
anterolaterally.
STRATIGRAPHIC OCCURRENCE.—Bell Canyon Formation
(Hegler, Pinery, Rader, and Lamar members),
Capitan Formation.
LOCALITIES.—Hegler: AMNH 635, USNM 731,
740c, 740d, 732a; Pinery: USNM 725n, 733, 736;
Rader: USNM 725f, 740a, 740i, 740j; Lamar:
USNM 728r, 728s; Capitan: AMNH 475, USGS
7404, 7417, 7612.
TYPES.—Figured hypotypes: USNM 150715a,
150717a, b, 152622a, 153651a, c-h, 153659a-c,
153660a-c, e-g, 154524a-d; measured hypotypes:
150715a, 150717a, 150718a, b.
COMPARISON.—This species is not externally
granulose, and, therefore, it need not be compared
to P. nodosus, new species, P. granulosus, new species,
and P. getawayensis Stehli. It is like P. conicus,
new species, in having a smooth shell, but this
is the only similarity because it is a much more
slender shell, which has a longer cowl. Furthermore,
the interior of the pedicle valve is distinguished
readily by the strong obliquity of the outlobes
and, consequently, also by those of the brachial
valve.
DISCUSSION.—This species presents some features
of interest not usually seen in the genus. The
manner of growth is unusual. Specimens are cemented
by a small portion of the umbonal region,
usually 5 to 10 mm. When the animal has attained
the requisite growth for good solid attachment,
the anterior part bends away from the
substrate at approximately a right angle and the
anterior part grows away from the attached portion.
The posterior part develops a cowl to protect
the hinge region. This cowl is of varying length,
and the degree of its development determines the
form of the shell. Specimens with long cowls develop
fairly complete cups. Most of the specimens
do not retain any evidence as to the substrate, but
two specimens are attached to narrow strips of
bryozoa.
Several of the specimens are fairly strongly
elongated and have modified the lobes. In Poikilosakos
these are usually latilobate, but in this species
they are variable but generally angustilobate. In
many specimens the lobe opening outward is more
elevated at the curve and is moderately excavated.
The median inlobe is also of interest. At its
posterior end, where the valve is flat, it is a high
and angular ridge, but it opens anteriorly with the
change of direction to form two closely spaced
ridges almost parallel to each other. In some specimens
these remain latilobate to the anterior, where
they disappear, but in one specimen the ridges join
and stop to appear again a little farther anteriorly
to form a narrow ellipse near the anterior margin.
In this same specimen some of the lateral ridges
join distally to close the lobe to the exterior.
Although the complete brachial valve has not
yet been found, fragments and the nature of the
visceral lobes give a clue to the form of this valve.
Generally the loops are moderately to strongly
oblique and extend anterolaterally. Usually three
oblique lobes may be counted, with a shorter one
extending anteriorly, to make four. The brachial
valves are slender and delicate. Another feature is
a right angle bend near the shell body. This is due
to the right angle bend between the place of attachment
and the upright shell.
One specimen (USNM 150715a) is worthy of
special mention because of its great elongation and
the effect this had on the brachial valve. The
specimen is 21 mm long, 7 mm wide at midvalve
and about 8 mm deep just anterior to the place
of geniculation. The septal ridges show no lobation,
and the brachial valve would have been two
long lobes separated by a narrow gash between
them.
As previously mentioned, the brachial valve of
this species was undoubtedly fragile. No complete
or perfect specimen has been found, but several
imperfect valves, mostly of the rear end or body
of the shell, have the eccentric and small cardinal
process observed in other species of Pseudoleptodus.
Another feature of interest in them is the
strong angle of geniculation at about the point
where lobation begins, a result of the upright living
position.
Pseudoleptodus lepidus, new species
PLATE 132: FIGURES 3-14
Medium size for genus, wider than long, transversely
elliptical in outline. Attached by posterior
half of surface, anterior and sides lifted at strong
NUMBER 15 399
angle from surface attachment. Elevated part of
shell thin.
Pedicle valve interior with narrow, straight
hinge; visceral region defined by strong anterior
and posterior vallar ridges, but lateral manifestation
of vallum not strongly thickened; lobes irregular,
2-3 per side, anterior one bifurcated. Median
ridge narrow to moderately wide, posteriorly excavated.
Diductor scar narrowly sheathed on each
side but not enclosed dorsally; outside wall of muscle
scar larger.
Brachial valve variable, lobes narrow to wide;
cardinal process small; surface marked by fine
granules.
MEASUREMENTS (in mm).—Holotype: length 13.0,
maximum width 20.0, hinge width 4.0, height 5.5?;
paratype (152623a): length 11.2, maximum width
16.0, hinge width 4.0, height?
STRATIGRAPHIC OCCURRENCE.—Word Formation
(Appel Ranch Member).
LOCALITY.—USNM 719z, 727j.
DIAGNOSIS.—Transversely elliptical Pseudoleptodus
with the anterior and lateral half elevated from
the surface at a large angle.
TYPES.—Holotype: USNM 152623f; figured paratypes:
152623a-c; measured paratype: 152623a; unfigured
paratypes: 152623d, e.
COMPARISON.—This species in its Poikilosakoslike
habit is different from most other species of
the genus. Pseudoleptodus getawayensis Stehli and
P. guadalupensis (Stehli) are larger, more conical,
and much more of the anterior part of the shell is
extended above the substrate. The new species
from the Word Formation, P. nodosus, is similar
in growth habit, but the lateral lobes are much
stronger. Pseudoleptodus granulosus, new species,
also has a similar habit, but more of the shell is
attached to the substrate and the shell surface between
the loops is strongly granulose.
DISCUSSION.—Six specimens of P lepidus are
known, no two of them alike. Two of the pedicle
valves are similar, but the third was aborted anteriorly
by the adherence of another oldhaminidine.
Two of the brachial valves have wide channels, but
the third has narrower interior channels and they
are thickened marginally, whereas the others are
not. It is possible that more than one species is
involved.
Pseudoleptodus nodosus, new species
PLATE 127: FIGURE 1
Known only from pedicle valve, small, wider
than long, transversely elliptical in outline; exterior
smooth. Interior with narrow hinge area;
diductor muscle sheathed and extending at almost
right angle from hinge; 2 lobes separated by latilobate
ridge, part of incomplete vallum, which is low
laterally and posteriorly. Median lobe septate posteriorly,
but latilobate anteriorly and fairly wide
at front. Posterior and extravallar areas marked
by nodes or pustules. No cowl.
MEASUREMENTS (in mm).—Length 11.6—|—, width
22 + . hinge width 4.6, height 6.0?
STRATIGRAPHIC OCCURRENCE.—Word Formation
(China Tank Member).
LOCALITY.—USNM 713.
DIAGNOSIS.—Transversely elliptical Pseudoleptodus
with fine pustules or nodes in the extravallar
areas.
TYPES.—Holotype: USNM 150707.
COMPARISON.—This species has the finest nodes
of all the nodose or granulose species.
Pseudoleptodus primitivus, new species
PLATE 130: FIGURES 2-4
Small for genus, subelliptical in outline, broad
surface attached to substrate, posterior and lateral
parts forming callus flap on substrate, then growing
upward away from substrate. Profile low or moderate
cone, depending on height of flap.
Visceral region of interior surrounded by strong
vallum forming fairly high wall and defining two
broad lobes; vallum medially indented and uniting
near midvalve to define deep indentation forming
anterior tube; hinge straight, narrow, and anteriorly
notched. Diductor scar large, subflabellate, not
laterally surrounded by shell tissue, but thickened
along anterior margin.
Brachial valve unknown.
MEASUREMENTS (in mm).—Holotype (USNM
150713a): length 6.2, maximum width 8.2, hinge
width 1.6, height?; paratype (USNM 150713b):
length 7.3, maximum width 9.8, hinge width 1.4,
height 3.0.
STRATIGRAPHIC OCCURRENCE.—Neal Ranch Formation
(top 15 feet of bed 2 of P. B. King).
400 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
LOCALITY.—USNM 701.
DIAGNOSIS.—Pseudoleptodus of small size, 2 lateral
lobes, and a tubular anterior median inlobe.
TYPES.—Holotype: USNM 150713a; figured paratype:
150713b; unfigured paratype: 150713c.
COMPARISON.—This species differs from all other
described forms in having a strongly tubular anterior
inlobe, two broad smooth lobes anterolaterally,
and a wide muscle scar.
DISCUSSION.—This is the simplest species of the
genus found in the Glass Mountains. In its bilobed
form it suggests a young specimen and also
suggests "Cardinocrania" Waagen. The three specimens
are distinctly conical and thus indicate a postinfantile
stage. They are unlike Cardinocrania in
the possession of the eccentric diductor muscle.
The muscle scar, however, is somewhat broader
distally than those seen in other species. The vallum
is thin and delicate but strongly elevated. Of
special note is the median lobe, which is roofed
over for at least half its length to form a tube.
Pseudoleptodus Indeterminate Species
PLATES 130, 131, 132, 139, 183
Some "species" are represented by too few specimens
to be identified as known species or to be described
as new species. Brachial valves are found
more commonly than pedicle valves because brachial
valves can be transported more easily than
the cemented pedicle valves. Consequently, the indeterminate
"species" are generally specimens of
brachial valves. These specimens are assigned tentatively
to Pseudoleptodus because it occurs more
frequently than Poikilosakos.
Pseudoleptodus? species 1
PLATE 139: FIGURES 12-14
This species has a narrow hinge and an extremely
short body. The lobes are stubby and wide.
Two lateral lobes appear on each side, and a short
anterior lobe is indicated. Internally a sharp, low
median ridge extends posteriorly from the proximal
end of the median indentation for slightly
more than half the distance to the hinge. The
cardinal process is eccentric but poorly formed. A
suggestion of adductor scars appears just posterior
to the proximal end of the median ridge. The
specimen is 14.2 mm long, 17.3 mm wide (but is
not complete in this direction), and has a hinge
4.6 mm wide. The specimen is from the lower Bone
Spring Formation at AMNH 46.
TYPES.—Figured specimen: USNM 153639.
Pseudoleptodus? species 2
PLATE 139: FIGURES 1, 2
This is a short-bodied form, but it contrasts with
the preceding in having two narrow lateral lobes
and a narrow anterior one. Internally a ridge appears
in the concave side of the lobes. The specimen
is 12.6 mm long and 14.4 mm wide, but it is
incomplete in this direction. The hinge is 4.5 mm
wide, but it appears incomplete. The specimen
comes from the Bone Spring Formation at AMNH
591.
TYPES.—Figured specimen: USNM 150710.
Pseudoleptodus? species 3
PLATE 130: FIGURES 13-17
This species is represented by several brachial
valves and four fragments of pedicle valves (USNM
150711a, b). It is not certain that these belong together,
but the combination is possible. The fragments
of the pedicle valve indicate a broadly
expanded shell with low concavity. The exterior is
marked by numerous fine concentric wrinkles. One
specimen shows part of a posterior irregular scar of
attachment, indicating that the species probably
was posteriorly attached and anteriorly free. Inside
the shell are broadly rounded lobes that are widely
spaced. Two lateral and one anterior lobes are indicated.
The vallum of the median lobe is well
separated and more strongly elevated than the lateral
ones. The hinge and muscle scar have not been
seen.
Six brachial valves are variable, but they indicate
a narrow-hinged form with short body. Two
lobes extend laterally and one anteriorly. The
lateral extent of the lobes is variable, but two
specimens indicate a long first lobe but shorter
lateral and anterior ones. In one specimen the
reverse is true, and in the others the lobes have
been damaged. Internally the cardinal process is eccentric
and minute and the median ridge is threadlike.
One specimen of the six has broader lobes
NUMBER 15 401
than the others. Satisfactory measurements cannot
be obtained, but the length of the brachial valve
as indicated by USNM 150711b is 12 mm and the
maximum width about 22 mm. The hinge of this
specimen is 3.6 mm wide. This lot is from the
Hegler Member of the Bell Canyon Formation at
USNM 731.
TYPES.—Figured specimens: USNM 15071 la,b;
unfigured, described specimens: 15071 l c - j.
Pseudoleptodus? species 4
PLATE 132: FIGURES 1, 2
This species is represented by four brachial valves
(USNM 150712a-d) having two lateral and one
anterior lobes, the lateral lobes separated by wide
reentrants. The shell body is moderately long, but
the hinge very narrow. The median reentrant or
slot is wide. The surface is smooth. Interior of
body and lobes is moderately deep, and no median
ridge is developed posterior to the reentrant. No
cardinal process was observed. The specimens are
from the lowest part of the Cathedral Mountain
Formation just above the conglomerate at USNM
708u.
TYPES.—Figured specimen: USNM 150712a.
Pseudoleptodus? species 5
PLATE 130: FIGURE 5; PLATE 131: FIGURES 43-45
This is a large species represented by three
specimens (USNM 152624a, b from USNM 721u
and a small one (USNM 152625) from USNM
703a1. The one complete specimen of the larger
group is transversely elliptical in outline, about 13
mm long by 21 mm wide. The shell is distorted,
but the lobes have a strongly elevated vallum. The
median lobe is narrow, low, and not strongly excavated.
The small specimen from 703a1 is 8 mm
long by 12 mm wide. It is thin shelled and the
left side forms a smear on the spiriferoid, to which
it is attached. The anterior margins of both specimens
are elevated above their substrate. All of the
lobes are rudimentary. The specimen is clearly a
young one.
TYPES.—Figured specimens: USNM 152624a,b;
152625.
Pseudoleptodus? species 6
PLATE 130: FIGURE 1
This is a very small specimen of indefinite outline
because the pedicle valve can scarcely be distinguished.
The brachial valve is in place, 6.6 mm
long and 9 mm wide. It is bilobed, one lobe extended
laterally and the other anteriorly. The anterior
of the pedicle valve is elevated above its
substrate. The specimen is from the Cathedral
Mountain Formation (Wedin Member) at USNM
714w.
TYPES.—Figured specimen: USNM 153641.
Pseudoleptodus? species 7
PLATE 139: FIGURES 15, 16
Two brachial valves, both probably immature
are all that are known of this species. They are
wide bilobed, the lobes short and stubby, one extending
laterally, the other anteriorly. A mere
trace of the cardinal process remains, but a threadlike
median septum is present in both. The specimens
are from the Road Canyon Formation,
USNM 724c.
TYPES.—Figured specimens: USNM 153640a,b.
Pseudoleptodus? species 8
PLATE 183: FIGURES 15-17
Known only from the pedicle valve, which is
a small cowled form, wider than long, with a small
base of attachment. Measurements in mm are:
length 13.4, width 15.0, hinge width 4.0, height 6.6,
cowl length 3.0. Diductor muscle slightly sheathed,
short, and confined to the attachment area. Vallum
incomplete, latilobate; median inlobe latilobate,
widely open anteriorly. 3 outlobes. Exterior wrinkled
and smooth. Word Formation at USNM 737b.
TYPES.—Figured specimen: USNM 153568.
Choanodus, new genus
[Greek choane (funnel) + odous (tooth) ]
Small to medium size for lyttoniids, irregularly
cowled with small to moderate-sized apical cicatrix
of attachment; anterior side longest but with generous
cowl over posterior side. Exterior surface
concentrically wrinkled.
402 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
Pedicle valve interior with toothlike commonly
corrugated projections on each side of, and just
anterior to, hinge, bearing lateral flanges of brachial
valve hinge. Diductor scar asymmetrical, large. Inlobes
thick, papillose, latilobate in young, but
angustilobate in adults; outlobes with thickened,
rounded ridge bounded by narrow channel; posterior
edge of earliest formed lobe undulated; early
lobes occasionally branched; lobes ranging from 3
to 8. Median lobe solidiseptate, strongly elevated,
and divided anteriorly into 2 narrow ridges.
Brachial valve irregular, with margin of first
lobes undulated posteriorly and commonly
branched on one side or other; hinge with lateral
flanges; interior with lobed but eccentric cardinal
process without shaft; median ridge prominent;
lobes with margins deflected in ventral direction.
TYPE-SPECIES.—Choanodus irregularis, new species.
DIAGNOSIS.—Cowled Poikilosakidae having shelflike
articulating processes in the pedicle valve and
articulating flanges in the brachial valve and thick
angustilobate lobes.
COMPARISON.—This genus suggests a conical
Poikilosakos, but it differs in having more elaborate
and advanced lobation. It also lacks the open
troughlike median lobe and has a larger, more
flabellate, unsheathed asymmetrical adductor scar.
The cardinal process of the brachial valve is more
prominent and shows myophore surfaces.
This genus also suggests Keyserlingina Tschernyschew
in the exterior form of its pedicle valve, but
the interior details appear to be different. The
brachial valve of Keyserlingina as figured by Fredericks
(1927a: 86) has posterior humps on the earliest
lobes and also branched lobes. The hinge region
of Keyserlingina is small, and no indication of
lateral flanges is given. Furthermore, views of the
pedicle valve given by Tschernyschew (1902, pi. 42:
figs. 14-17) and Licharew in (Sarycheva, 1960, pi.
42: fig. 8) indicate that it had an open latilobate
divided median lobe, not yet closed to form a solid
median ridge. The Russian Keyserlingina in this
respect is more like conical Poikilosakos than is
Choanodus.
This genus differs from Pseudoleptodus, which it
resembles in its conical form and robust solidiseptate
lobes, in the different type of hinge, the more
strongly anterolateral direction of the lobes, and
the narrow outlobe channels.
DISCUSSION.—This genus is recognized readily by
the stout shells and conical form, some of the cones
being almost symmetrical. The attachment area is
generally small, but it is substantial enough for
sure fixation. The initial stage is generally flat, but
the shell is soon deflected at a high angle from the
surface of the substrate. Choanodus is commonly
attached to Eolyttonia, but it is also attached to a
variety of other shells, including some of the smaller
productids such as Xenosteges.
The interior of the pedicle valve of this genus is
unusual for its hinge and the thick angustilobateto-
solidiseptate lateral vallum. The hinge is unique
and is an important element of the structure in
the pedicle valve. This consists of conical, toothlike
bodies on each side of, and just anterior to,
the lateral ends of the slitlike hinge. These bodies
suggest an articulate process, but they have their
posterior face flattened, and, in well-preserved
specimens, the process is minutely corrugated. This
face receives a flat surface of the lateral articular
nubs of the brachial valve. This makes for a more
rigid articulation than usually is found in the
Poikilosakidae.
The muscle scars are preserved clearly in all of
the specimens, but several individuals show a large
asymmetrical scar on the right side of the interior.
This is broad and subflabellate and usually thickened
strongly at the anterior ends.
The lobes of the pedicle valve are noteworthy
for the robustness of their development. The inlobes
of the younger valves are composed of two
ridges (angustilobate) moderately compressed but
forming a thick medially depressed ridge. With increasing
age the median depression is filled in and
the ridge becomes solidiseptate, a rounded and
thick partition bounding the outlobes. The interridge
channels are marked by a narrow, rounded
ridge separated from the side of the inlobes by
narrow channels. This creates a series of low ridges
bounded by higher ones. Most of the ridges are
directed anterolaterally rather than laterally and
convex anteriorly as is usual in most of the Lyttoniidae.
Some inlobes are so thick and strong that
they dominate the posterior half of the shell.
The brachial valves, as in other poikilosakids,
have the posterior margin of the posterior lobe,
NUMBER 15 403
which may be the longest one, marked by several
posteriorly directed lumps. This feature was seen
also in Pseudoleptodus. It is a common occurrence
for one or more of the lateral lobes to bifurcate,
especially the posteriormost one. Occasionally adjacent
lobes fuse.
Choanodus anomalus, new species
PLATE 183: FIGURES 11-14
Small, elongate oval in outline; conical but with
short cowl. Exterior with strong, concentric wrinkles.
Interior with Choanodus articulation consisting
of 2 articulating nubs bounding sockets;
median ridge thick, low posteriorly, highest in posterior
third. Posterior one-fourth of median ridge
solidiseptate but anterior three-fourths angustilobate;
anterior half of median ridge decreasing
in height but widening anteriorly. Each side of
median ridge with 6 wide inlobes, broadly angustilobate
and highest anteriorly, depressed area of inlobes
papillose. Grooves between lobes shallow but
marked medially by longitudinal adventitious
thickening.
MEASUREMENTS (in mm).—Holotype (USNM
153569a): length 18.3, maximum width 14.6, hinge
width?, height 6.8, cowl length 3.5.
STRATIGRAPHIC OCCURRENCE.—Cathedral Mountain
Formation.
LOCALITY.—USNM 72lu.
DIAGNOSIS.—Small, conical, elongate Choanodus
with thick and strongly papillose inlobes.
TYPES.—Holotype: USNM 153569a; unfigured
paratypes: 153569b,c.
COMPARISON.—This species differs from C. perfectus,
new species, in its smaller size and its imperfect
conical form. It is unlike C. irregularis,
new species, in its more elongate form, shorter
cowl, and wide, papillose inlobes.
Choandus irregularis, new species
PLATE 133: FIGURES 8-11; PLATE 134: FIGURES 6-12;
PLATE 135: FICURES 1-41; PLATE 162: FIGURES 8-10
Shell small, forming irregular cones attached at
apex by small to medium-sized cicatrix; cones
broadly open when viewed from dorsal side; cowl
usually short; valves circular to roundly elliptical
in outline. Exterior with concentric wrinkles and
with interseptal spaces strongly and coarsely
pustulose.
Pedicle valve interior with narrow hinge and
strong anterior, shelflike teeth; initial lobes usually
with 1 or more prominent posterior humps; 1 or
more lobes occasionally branched to produce asymmetrical
arrangement. Lobar channels consisting of
2 parallel grooves separated by narrowly rounded
median thickening; median lobe solidiseptate, not
reaching hinge region, usually thick in median region
but decreasing in height anterior to midvalve
and dividing into 2 weak ridges near front margin.
Diductor scar usually difficult to see, but, when
visible, usually broadly flabellate and with anterior
marginal thickened rim. Inside of cowl
strongly papillose.
Brachial valve with straight hinge and thin
lateral articulatory flanges; lobes thin, irregular,
posterior lobes with 1 or more humps on posterior
side; 1 or more lobes branched, branching not symmetrical.
Surface strongly pustulose.
Brachial valve interior with small, bulbous, eccentric
cardinal process; median ridge moderately
strong but low; lobes with thickened and elevated
margins; trough running parallel to margins at
base of elevations; trough bounded on inside by
low, thin, elevated line parallel to margin; area
between thin lines faintly pustulose. Adductor
scars indistinct.
MEASUREMENTS (in mm).—
maximum hinge cowl
length width width height length
USNM 702un
150832a
USNM 703b
150835a
150835b
150835c
150835d
150835e
150835f
USNM 714w
150840
USNM 702
150827a
150827b
150827c
150827d
150827e
150827f
150827g
150827h
14.1
10.8
12.0
13.8
15.4
15.1
19.7
19.0
12.3
13.1
19.0
18.4
22.4
11.5
17.2
24.0
18.8
12.6
17.0
16.0
16.7
18.9
21.3
21.8
17.5
19.0
17.6
25.4
28.7
15.0
17.9
25.7
3.3?
2.3
?.
2.9
3.3
2.7
3.1
3.9
3.0
?
?
2.6?
3.5
3.3
3.0
?
8.2
3.9
6.4
5.6
6.9
4.5
9.6
10.4
6.7
9.0
9.5
9.2
9.3
6.4
8.6?
14.0
6.2
1.4
4.6
3.5
4.2
3.0
4.1
11.0
5.6
6.1
8.8
6.7
4.2
4.4
4.8
8.3
404 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
STRATIGRAPHIC OCCURRENCE.—Cathedral Mountain
Formation, Cibolo Formation.
LOCALITIES.—Cathedral Mountain: USNM 702,
702a, 702a1, 702b, low, 702un; 703, 703a1, 703b,
703bs, 708, 712o, 714w; 717e, 721u, 726o, 726u, 726x,
733m, AMNH 500, 500H, 500L, 500X, 658; Cibolo:
USNM 725v.
DIAGNOSIS.—Choanodus of moderate size with
greatly thickened interlobar spaces.
TYPES.—Holotype: USNM 150838; figured paratypes:
150727, 150826a, c-e, 150827c,e,f,g; 150828a,
d, 150830, 150835b,e,f, 150840, 150842, 153604,
153605, 153606, 153645; measured paratypes:
150832a, 150835a-f, 150827b-h; unfigured paratypes:
150826b, 150827b,d,e, 150828b,c, 153835a,
c, d.
COMPARISON.—No other species of this genus is
closely comparable to C. irregularis. Fragments of
another species were taken from the Bone Spring
Formation in Black John Canyon in the Sierra
Diablo. This is larger, and the inloops are much
thicker and stronger than those of C. irregularis;
however, the form of the hinge and other details
of the shell are not known. Detailed comparison
with C. perfectus, new species, the only other species
known well enough to describe, is given under
that species.
DISCUSSION.—This species is best developed and
perhaps most abundant in the zone of Institella at
the base of the Cathedral Mountain Formation. It
ranges just above this zone, however, and is fairly
common in the Eolyttonia beds just above it in the
Split Tank area and in the vicinity of the Old
Word Ranch.
Choanodus perfectus, new species
PLATE 133: FICURES 20-24; PLATE 136: FIGURES 1-17;
PLATE 137: FIGURES 1-20
Large, irregularly conical in outline, cones tending
to become more regular with increase in size;
anterior side slightly longer than posterior one,
which extends as long cowl over posterior of pedicle
valve. Exterior marked with fine growth lines and
irregular concentric wrinkles.
Pedicle valve interior with 12 to 14 lobes in
largest specimens; articulatory processes small,
located on both sides of hinge. Initial lobes usually
small and convex toward anterior; lateral lobes
more direct. Septal ridges thickest in posterior,
decreasing in thickness and height anteriorly; interseptal
callosity low rounded ridge bounded on
each side by grooves running parallel to septal
ridges. Median ridge slender and moderately high
in posterior half, dividing into 2 low ridges at
midvalve in some specimens, but farther forward
in others.
Brachial valve externally granulose, with slender
lobes convex toward anterior or extending
nearly straight laterally. Axial region thick, reaching
to about midvalve, there deeply cleft. Articulating
flanges thick, not usually well preserved.
Interior with eccentric, short and thick cardinal
process and low median ridge. Interior of lobes
deep, with thickened margins bearing trough at
base and bounded by thin parallel line running
around lobe longitudinal lobes, bounding median
cleft deep and marked just inside of inner margin
by strong carinate ridge running from angle of
cleft to anterior extremity.
MEASUREMENTS (in mm).—
U S N M 702un
150846a
150846b (holotype)
150846c
150846d
150846e
150846f
150846g
length
58.7
40.0
34.0
42.8
38.5
44.0
22.3
maximum
width
49.1
41.2
40.5
39.4
55.0
40.6
25.0
hinge
width
?
?
4.0?
?
7.0
?
?
height
28.0
20.6
17.0
23.7
27.7
20.5
14.2
cowl
length
9.0
17.5
6.0
16.7
22.5
19.8
12.1
STRATIGRAPHIC OCCURRENCE.—Bone Spring Formation,
Cathedral Mountain Formation (Wedin
Member).
LOCALITIES.—Bone Spring: AMNH 504, 591;
Wedin: USNM 700-1, 700x, 714w, 727p; Cathedral
Mountain: USNM 702, 702b, 702un, 703a1, 703b,
708, 708u, 721u, 726u, 735b.
NUMBER 15 405
DIAGNOSIS.—Large Choanodus with numerous
lateral lobes.
TYPES.—Holotype: USNM 150846b; figured paratypes:
105845a-c, 150846a, d, e, 153607 a, b, 153608,
153609, 153610, 154647; measured paratypes:
150846a, c-g; unfigured paratypes: 150846c, f, g.
COMPARISON.—In general form this C. perfectus
is similar to some species of Eolyttonia such as E.
pocillata, new species, and E. diabloensis (Stehli).
Both of these differ from C. perfectus in having
thicker shells, wider and stouter lateral lobes in the
brachial valve, and a different type of hinge in the
pedicle valve. Choanodus irregularis, new species,
also has stouter shells than C. perfectus, and also it
has more posterolateral^ directed lobes and
stronger, thicker inlobes in the pedicle valve, but
it has a lesser number of lateral lobes and is a
smaller shell. It is also strongly papillose in surfaces
outside of, and between, the lateral lobes.
DISCUSSION.—Choanodus perfectus is a rare
species known only from the zone of Institella. It
forms nearly complete and often nearly perfect
cones attached by a small apical part to productids,
bryozoans, lyttoniids, and other substantial objects.
This is a much larger species than C. irregularis,
with more numerous lateral lobes but generally a
more delicate shell. The cowl in adults is wide and
flaring and may match the anterior side in length.
The hinge is like that of the genotype, the toothlike
projections often prominent and corrugated to
receive the articulating flanges of the brachial valve.
They are not visible clearly in all specimens, especially
those that were dead and waterworn when
buried and fossilized.
The development of the lobes is not entirely like
that of C. irregularis, and the posterior lobes are
seldom as massive; they form lobes with the convex
side anteriorly directed, whereas, in the other
species, the lobes extend anterolaterally. In the
young the lobes form a vallum that is closed anteriorly
in some specimens. With growth the inlobes
are compressed and narrowed, in some cases
becoming completely closed and solid in the proximal
part adjacent to the median channel, but
remaining open distally toward the lateral margins.
The lateral lobes of the brachial valve are very
closely crowded. In the posterior third the lobes
are fairly elevated and at least partly solid, but
anteriorly they are raised only slightly and the
appearance of fairly strong interseptal ridges complicates
the pattern.
The median or axial canal is narrow and, in the
adult, is unusually so. It is almost completely occupied
by the median ridge, which is fairly strong.
This extends nearly to the hinge, is thickest in the
midregion and is divided in the anterior third in
many specimens.
The hinge of this species appears to be exactly
like that of the type-species, but no unequivocal
example showing the asymmetrical adductor scar
was seen. This scar was difficult to see in the typespecies;
thus, it is not surprising that it was not
detected in a larger and thinner-shelled species. This
fact, however, does cast some doubt on the generic
affinities of the species. It was placed in Choanodus,
rather than in Eolyttonia, which it strongly resembles,
because of the nature of the hinge.
The brachial valve of this species is characterized
by its thick but short axial region, the strong
anterior cleft generally extending posteriorly beyond
midvalve, and the delicate, very slender lateral
lobes. It is also characterized by a very short initial
lateral lobe without the posterior undulating
margin. One specimen from USNM 714w, however,
has a moderately long initial lobe with several posterior
lumps characteristic of Choanodus.
Sceletonia, new genus
[Greek skeleton (mummy) ]
Medium size for Oldhaminidina, incompletely
conical, posterior with short cowl and small attachment
surface. Exterior with radial lobes corresponding
to lobation of interior.
Interior strongly ridged with median ridge
having 3 lateral, oblique ridges on each side. All
ridges granulose on crests. Troughs occupied by
lower median elevation. Musculature asymmetrical,
with well-defined muscle mark on (observer's)
right.
Brachial valve with subradial lobes ornamented
by strong concentric growth lines and strong pustules;
interior with narrow straight hinge having
small ears; visceral region moderately large, with
low, median ridge and obscure adductor scars.
Cardinal process uneven with myophore lobes, one
on observer's right being larger. Channels of lobes
deep, narrow, and with strong, elevated outer
border and lower inner one.
406 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
TYPE-SPECIES.—Sceletonia crassa, new species.
DIAGNOSIS.—Poikilosakidae with thick inner lobes
visible on the exterior and with an asymmetrically
bilobed cardinal process.
COMPARISON.—The thick internal ridges of this
genus set it apart from all others except Choanodus,
which also has fairly thick internal septa lobes;
however, Sceletonia differs in having a less conical
form, shorter cowl, and less laterally curving septa.
Furthermore, the brachial valves are quite different,
that of Sceletonia having very direct rays, a
stronger cardinal process, and much wider lateral
lobes.
DISCUSSION.—The few specimens of this genus
now known are unique among the Oldhaminidina
and are unusual for their exterior as well as interior
details. The exterior reflects the lobation of the
interior, the lobes of the exterior corresponding to
the troughs of the interior. The dichotomy of the
median lobes is well displayed. That this is not
a freak of preservation is shown by specimens from
the Sierra Diablo, as well as from the Glass Mountains,
having the same external lobation. The
troughs between the lobes are occupied by concentric
lamellae that undulate more or less strongly
over the whole exterior. Strong concentric undulations,
as well as fairly strong pustules, also appear
on the exterior of the brachial valve.
On the interior, two sets of ridges appear, one
thick, conspicuous, and strongly elevated set, and,
between these, a lower set that occupies the center
of the troughs. Longitudinally the center is marked
by a strong median ridge that runs from near the
apex to the front margin. It is undivided, not excavated.
This divides the median channel, from which
three strong ridges diverge at an angle of about 45°.
These create four oblique channels. Medially each
channel bears a low ridge that evidently is related
to the central channel of the brachial valve lobes.
The brachial valve is fairly solid, with a thick
shell having strong marginal rims. The cardinal
process is interesting because it is bilobed, although
the lobes are unequal in size. It does not have a
well-defined shaft. The visceral region has traces
of adductor muscles, but they are not separable into
their parts. The channels all extend from the
visceral region and are marked by the marginal
rim, a narrow submarginal channel separated from
the main channel by a low ridge. The median
channel undoubtedly corresponds to the medial
low ridges of the main channels of the pedicle valve.
The genus is assigned to the Poikilosakidae because
of the primitive character of the channels
and ridges and the asymmetric musculature.
This peculiar genus is known only from the
Skinner Ranch Formation in the Glass Mountains
and from the lower part of the Bone Spring Formation
of the Sierra Diablo. This rare occurrence is
a confirmation of our correlation of the Skinner
Ranch and the lower Bone Spring.
Sceletonia crassa, new species
PLATE 138: FIGURES 1-34; PLATE 139: FIGURES 3-10
Fairly large with thick shell and strong inner
ridges; transversely elliptical in outline, greatest
width near midvalve; sides narrowly rounded; anterior
broadly rounded. Attachment scar small;
cowl short. Exterior marked marginally by 4 lobes
on each side of median line; inner 2 lobes uniting
at about one-third length toward posterior, resulting
unified lobe uniting with third lobe at midvalve,
this one extending to apex. Fourth or outer
lobe extending direct from margin to beak. Exterior
with concentric, raised ridges unevenly distributed
but best developed anteriorly.
Interior as defined for genus.
MEASUREMENTS (in mm).—Paratype (USNM
151328d): length 24.0, maximum width 33.7, hinge
width 7.6, cowl length 6.8, depth 10.2; holotype
(USNM 151328h): length 24.3, maximum width
33.6, hinge width 12.6, cowl length 7.3, depth 9.0.
STRATIGRAPHIC OCCURRENCE.—Skinner Ranch
Formation (Dugout Mountain and Sullivan Peak
members), Bone Spring Formation.
LOCALITIES.—Dugout Mountain: USNM 732d,
732e, Sullivan Peak: 7221, 727a; Bone Spring:
AMNH 591, USNM 725c.
DIAGNOSIS.—Subconical, strongly ridged Sceletonia.
TYPES.—Holotype: USNM 151328h; figured paratypes:
151328a, d-g, i, j , 152626, 153587a, b,
153588a, b, 153589a, b; measured paratype:
151328d; unfigured paratypes: 151328b, c.
COMPARISON.—No other species of the genus is
known.
DISCUSSION.—Sixteen specimens of this species
were taken in the Glass Mountains, and nine occur
in the collections from the Sierra Diablo.
NUMBER 15 407
Family LYTTONIIDAE Waagen, 1883
Usually large, conical or subconical with numerous
lateral septa in pedicle valve and numerous
lobes in brachial valve. Lateral septa originating
from poikilosakid vallum: angustivallate to fragmentivallate.
Muscle marks symmetrical when
present; myophragm present in some genera. Brachial
valve pinnate to sievelike, usually with bilobed
or quadilobed cardinal process.
DISCUSSION.—The prevailing form assumed by
members of the Lyttoniidae is that of a cone, uncommonly
a complete and symmetrical cone, but,
nevertheless, usually some modification of a cone.
The symmetrical cone is best exemplified by the
genus Pirgulia Cooper and Muir-Wood from the
Sosio Limestone of Sicily. This is a long, slender
cone, pointed at the apex but narrowly elliptical at
the open end. These shells attain large size, having
a length of 135 mm, a width at the aperture of 75
mm and an apical angle of about 30°. They probably
lived attached by their apex for at least part
of their life, but such large shells could not have
retained vertical stability when they attained full
adulthood (Rudwick and Cowen, 1968).
Another completely conical form is Eolyttonia
gigantea, new species, from the Glass Mountains.
This is not a tapering cone like Pirgulia, but it has
a broadly rounded base with a fairly broad surface
of attachment. This could quite easily have been
attached throughout its life. Fairly complete cones
are produced by other species, and some forms of
Eolyttonia Fredericks form broad shallow cones.
Some genera that normally have broad, shallow,
or misshapen cones may produce deeply conical
specimens because of unfavorable growth conditions
in a cluster. This is true of a specimen of
Coscinophora Cooper and Stehli (see Plate 182:
figures 35, 36), which was so crowded that its only
direction of growth after a certain stage was aperturally.
The cowl, unable to grow laterally, expanded
toward the anterior and thus produced a
deep cone, suggesting that of Eolyttonia gigantea.
Specimens of Eolyttonia often form broad, open
cones, found in such species as E. circularis, new
species, which is in the form of a broad, shallow
dish. Others have misshapen cones in which the
anterior side has grown more rapidly than the cowl,
producing a broad and oblique aperture.
In contrast to the cones are the flattish shells of
Collemataria, new genus, Petasmaia Cooper and
Grant, and Leptodus Kayser, in which there is no
cowl, but a flap grows posteriorly, thus destroying
any resemblance to a cone. Exceptions occur in
these genera, however, in which the circumstances
of growth force the flap to become cowl-like and to
grow opposite to its normal direction. Such misshapen
cones are produced as an aberrancy. Petasmaia
commonly attached to crinoid stems or other
small, round objects to produce broad flat expansions
quite unlike the more normal conical genera.
Inside the pedicle valve the hinge of the various
genera seems not to show any exceptional characters,
and nothing like the hinge of Choanodus was
seen. Considerable variation occurs in the lip overhanging
the hinge in many species, but the pattern
in all of them seems the same.
The most interesting and important features of
the pedicle valve are the lateral loops and their development
into septal ridges. The septa are variable
with the age of the animal and within the same
specimen. Only rarely is it possible to generalize
on the type of septum. Genera such as Keyserlingina
and early Eolyttonia have the septa in the form
of in-and-out wide loops, forming a vallum that
may be complete around the entire visceral area or
may be incomplete anteriorly. With growth and
with geological age the loops are compressed in a
direction parallel to the long axis of the shell.
Therefore, in early youth some of the genera have
lateral septa that bear a groove down the middle
(latilobate to angustilobate). This is characteristic
of the type-species of Eolyttonia and its synonym
Paralyttonia. This was so prominent in some of
the Russian representatives of these genera that
lateral septa so grooved are said to be in the
Paralyttonia stage (pervivallate). With continued
age the median groove is eliminated and the lateral
septum becomes narrowly rounded (solidiseptate).
This type of septum is commonly seen in the larger
and geologically younger, more anterior or more
adult parts of many specimens (septivallate stage).
The final stage (terminivallate) is that seen in
Oldhamina, in which the lateral septa are thin and
delicate and have a knife-edge crest (anguliseptate).
This has been termed the "oldhaminoid" stage in
allusion to its common occurrence in the Pakistan
genus. As will be explained below, this character
does not always denote an evolutional end mem408
SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
ber, but that is also dependent on other features of
the shell, which culminate their development in
Oldhamina.
It is a common but exasperating occurrence to
find all of these stages of lateral septal development
in one and the same specimen, not only from certain
genera, but also from most of the genera that
have developed large shells. The type of lateral
septum definitely depends on age, but it also may
depend on shell shape. Specimens that have developed
unusual depth or convexity from youth to
old age develop lateral septa having the characteristics
of the oldhaminoid stage (anguliseptate).
Evidently Oldhamina produces a majority of lateral
septa in the anguliseptate condition, because the
shell is generally deeply concave in its normal
development.
Many lyttoniids are distorted considerably because
of their attached form of growth; consequently,
some are deeper than normal, while
others have become strongly concave in lateral
profile. Such a reversion of the normal inner
surface also produces profound effects on the lateral
septa. The normal lateral septum dips posteriorly
at a moderate angle and commonly overhangs the
interseptal trough in the front or in an anterior
direction. Shells that are convex inward may have
lateral septa that are vertical or overturned. In
such shells the posterior surface dips anteriorly and
overhangs the interseptal space behind, or posterior
to, it, and the lower surface dips anteriorly. This
condition is not frequent, but it does illustrate the
profound effect the curvature of the shell has on
the form and development of the lateral septa. The
dependency of the form of the lateral septum on
the shape of the shell severely limits the value of
these structures in classification and recognition of
genera.
Another variation seen in the septa is the transition
laterally along the same lateral septum from
the rounded solidi or anguliseptate condition
("Leptodus" stage) to the grooved angustilobate
condition ("Eolyttonia" stage). This too is rare in
occurrence, but it adds to the confusion.
Spasmodic branching occurs in the outlobes or
lateral septa of the various genera. In the Poikilosakidae
this is common and often leads to inequality
of the two sides of the brachiopod. This
has helped the view that the Poikilosakidae normally
have unequal valves. Inequality of the right
and left halves is abnormal for brachiopods, and
we believe that it is abnormal, even though frequent,
for the Poikilosakidae. Members of the
Lyttoniidae also produce branched lateral septa,
although the occurrence is less frequent than in
the more primitive family. The branching takes
place on either side of the axis or on one side only.
It usually results in distortion of the lateral septa
posterior and anterior to the branching one. Another
abnormality seen outside of Coscinophora is
the breaking up of a lateral septum into a row of
beads or dashed ridges (the moniliseptate condition).
This too may occur at any part of the shell.
Coscinophora is unique among the Lyttoniidae
in having most of the septal rows moniliseptate.
These generally behave like the septal ridges of
other genera in their variation. They may be long
or short, steep or gently inclined, and in the
younger or larger part of the shell, where there
seems to be some instability, they may have solidiseptate
lateral septa.
The anterior part of the lyttoniid shell appears
to be a place of instability. Here many aberrations
of the lateral septa take place. They often change
their direction from lateral to anterolateral or anterior
as the case may be. They are also known
to make sweeping curves that throw the normal
regularity into chaos. Beading of the lateral septa
may take place here, and so faintly are the septa
raised above shell floor level that it is common for
them almost to disappear.
The course of development of the lateral septa
was first worked out by Fredericks and, except for
minor details, appears to be as he stated. Later
observers have corroborated the general scheme,
which is also borne out by our study of the Texas
lyttoniids. The young of the Lyttoniidae and the
adults of the Poikilosakidae have in their earliest
stage a simple ringlike ridge bounding the visceral
region, herein called vallum. In the early stages of
both families the vallum is indented anteromedially.
With advancing age, indentations appear
on the sides in a number according to the genus
and species. These indentations produce inlobes
and outlobes of the vallum, which still retains its
continuity. The anteriomedian indentation produces
a strong and deep inlobe. The outlobes are
part of the visceral region, whereas the inlobes parNUMBER
15 409
take of the strong granulation of the lateral part
of the shell outside the visceral region. The vallum
thus defines the form of the brachial valve, which
fits snugly within the confining wall. Poikilosakos
represents the adult stage of this early condition.
It is a lobate wall, having an equal number of lateral
lobes indenting the visceral region and a long
median lobe indenting the anterior and all surrounded
by a continuous wall or vallum ("flange"
of Watson, 1917). Evolution affects the vallum in
two ways: (1) it disrupts its continuity by increasing
the number of lateral lobes anteriorly; and (2)
it gradually compresses the wall of the lateral lobes
into a single ridge and the median inlobe into a
median ridge. In the Poikilosakidae the vallum remains
fairly complete except for the anterior in
advanced genera, and, in the Lyttoniidae, it loses
its continuity except in extremely young stages, and
the number of lateral lobes or septa is increased
enormously.
The lateral septa retain a trace of the inlobe
condition well after they have been compressed
into a lateral septum. In many septa that are narrowly
grooved, the material in the groove, bounded
by ridges, is granulose, i.e., pseudopunctate, like
that of the side of the shell margining the ends of
the septa. This is clearly shown in thin sections
and is proof of the evolution of the lateral septum.
In septa distorted in position because of accidents
of attachment, the intervallar space, i.e., the space
or groove between the two ridges, is also distorted,
being narrowed or widened. Lateral septa tilted
abnormally forward have the intervallar groove
widened, the posterior side appearing as a ridge
well down the slope of the surface of the lateral
septum. Where lateral septa are tilted posteriorly,
the intervallar or grooved part appears on the anterior
side.
The modification of the lateral septa in conformity
with the varying contours of the pedicle
valve have been explained above. Other modifications
appear, but these seem to be common to all
genera and have no particular significance in taxonomy.
A noticeable modification that commonly
alters the interior appearance of the pedicle valve
is the interseptal callosity that appears as a prominent
ridge in the interseptal channels between the
lateral septa. These ridges may be low, or, in the
anterior region, they may equal or exceed the
height and strength of the lateral septa. The interseptal
ridges originate at the distal extremities
of the interseptal channels in the earliest formed
(oldest) part of the shell. With growth these appear
farther and farther anteriorly and penetrate
laterally toward the median channel. In the youngest
part of the shell toward the front margin they
commonly occupy the entire interseptal channel
from lateral margin to median channel. They create
a closely ridged or corrugated surface usually
occupying from one-fourth to one-third of the valve
length.
The interseptal ridges undoubtedly restrict the
interior because the lateral lobe of the brachial
valve overlies them closely. If the brachial valve
was immovable, as has been contended, the interior
of the anterior third would have been nonfunctional.
Another feature of the lateral septa and the adjacent
interseptal channels is the striation of the
septum on its posterior (and often anterior) face
and the concomitant striation or pitting of the interseptal
channel. The striation of these surfaces is
brought about in the adventitious deposit laid
down in the interseptal space on each surface of
the lateral septum. Generally the fluting of this
material is strongest and most regular on the posterior
face of the interseptal ridge. This results in
a serration or fluting of the anterior margin of the
lateral lobe of the brachial valve that is inserted
against the edge of the striated layer. In interseptal
thickening where a ridge is produced, the fluting
takes the form of a row of pits on the anterior side
of the posterior lateral septum bounding an interseptal
channel and the posterior side of the anterior
lateral septum. Long sloping lateral septa or
extremely elevated ones have the striation most
pronounced. The floor of interseptal areas is
marked also by irregular pits like those seen in a
variety of pseudopunctate shells such as many
Strophomenidina and Productidina. This fluting
may have accomodated setae along the lateral
grooves.
The median ridge divides the central or axial
channel into two parts. Its development is like
that of the lateral septa. It originates as an inlobe
or indentation of the middle of the front margin
of the vallum. Throughout the history of the
Poikilosakidae this median inlobe maintains its
410 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
open character and, in some cases, forms a median
chamber. In the Lyttoniidae, on the other hand,
lateral pressure originating posteriorly results in a
squeezing of the median vallum to form a narrowly
open or grooved ridge, then a ridge divided
and open anteriorly from midvalve, and finally a
completely closed, single ridge.
Variation of the median ridge within species and
individuals is common. It varies in height and
strength, in the location at which it divides anteriorly
to form an open lobe, and in its continuity.
Commonly in Collemataria, but more rarely in
other genera, the ridge may become anteriorly discontinuous,
moniliseptate, and form a row of beads
or dashes with a concomitant fenestration of the
median axial region of the brachial valve. This is
so prominent in some specimens that the Termiers
created the genus Gubleria for it. It is also common
in Leptodus (=Lyttonia) as remarked by
Huang (1932:89). It is in reality an evanescent
feature without generic value except in Coscinophora,
where all or nearly all of the lateral septa
and the median ridge are moniliseptate.
The median septum served to close the median
groove when the brachiopod was at rest or in alarm.
The slit of the anterior axial region of the brachial
valve fits snugly against, or over, the median
ridge—in many genera, just posterior to the point
where the ridge divides.
A SURVEY OF THE GENERA OF LYTTONIIDAE.—This
will help to crystalize the above remarks and the
characters used in the separation of the genera.
Adriana DeGregorio (1931:29). The poor
sketches of lyttoniids offered by DeGregorio do not
permit a proper assignment of this genus to either
family of the Lyttoniidae. It was mentioned above,
under the Poikilosakidae, that this genus cannot be
placed in that group because it is impossible to
see the family characters in it. This lack of family
character information makes it impossible to place
the genus in the Lyttoniidae as well. The conical
form of Adriana is more suggestive of lyttoniid
structure than it is of poikilosakid affinities, but
this is a tenuous argument for such placement. The
correct assignment of this genus will have to await
reexamination of DeGregorio's specimens or topotype
material if such can be identified.
The figures also suggest a possible relationship
of Adriana to algal forms such as Irma and Imperia
and not to the Brachiopoda. Williams', et al. (1965:
H520, figs. 3a, b) reconstruction is very doubtful.
Cardinocrania Waagen (1885:745). This genus
has not been adequately described or figured, and
the interior of the brachial valve is unknown. The
pedicle valve is provided with a hinge like that of
the Lyttoniidae or perhaps a very young Richthofenia.
Just in front of the hinge there is a broad
anteriorly excavated plate bearing muscle scars.
The anteromedian region is indented, and a short
median ridge extends posteriorly for a short distance.
The brachial valve according to Schuchert
(1939, pi. 1: fig. 1) fits over the hollow, surrounded
by the thickened margin, and is externally papillose.
This is all that is known of the valve.
The Salt Range specimens differ from those figured
by Wanner and Sieverts (1935:6, figs. 1, 2) in
having muscles on both sides of the muscle region,
whereas those from Timor have muscles only on
the right side. Wanner and Sieverts' specimens suggest
the young of Pseudoleptodus rather than
Cardinocrania. Schuchert (1939) thought that
Cardinocrania represented the young of Richthofenia,
which might be true of his specimen, but
Muir-Wood and Cooper (1960:137) believed that
this genus was the young of Leptodus rather than
that of Richthofenia. They pointed to the similarity
between the hinge arrangement of Cardinocrania
and Leptodus and to the bilobed form of
the latter. The hinge region of Cardinocrania is
unlike that of young Hercosia of the Glass Mountains.
Muir-Wood and Cooper (1960), having been
misled in this respect by the figures of Wanner and
Sieverts, were mistaken in their view that the musculature
of Cardinocrania was a single scar like that
of Poikilosakos. The proposition that Cardinocrania
is the young of Leptodus is more in accordance
with the structure of the two genera because
intermediate forms between the two are not known.
We regard Cardinocrania as a junior synonym of
Leptodus.
Chaoella Licharew (1931:161). This is a small
conical genus that Licharew (1932:103) placed in
the synonymy of Keyserlingina a short time after
he described it.
Collemataria, new genus. This name is applied
to Lyttoniidae that are generally flattish, expanding
anteriorly, have a posteriorly growing callus
flap, and the hinge and cowl margins coinciding
NUMBER 15 411
in the adult. No muscle scars have been seen in
the pedicle valve. This genus is similar to Leptodus,
but it lacks well-defined muscle scars and lateral
muscle ridges, and the lateral septa are mostly
in an advanced pervivallate to septivallate stage.
Coscinophora Cooper and Stehli (1955:469).
This genus is usually a broadly open cone, but it
varies in form to that of a small cup. It is unique
for the degeneration of the lateral septa and median
ridge into rows of beads or dashes (fragmentivallate).
The brachial valve is a perforated plate,
thickened medially.
Gubleria Termier and Termier (1959:241). This
genus is based on fragments of the anterior of a
lyttoniid in which the anterior cleft has been restricted
to a row of elliptical holes corresponding
to fragmentation of the median ridge into a moniliseptate
condition. This phenomenon occurs in individuals
of other genera such as Leptodus,
Collemataria, Pirgulia, and Eolyttonia. It is an individual,
rather than a generic, character. We regard
Gubleria, therefore, as a probable synonym of
Leptodus.
Keyserlingina Tschernyschew (1902:55, 473).
This is a rare and poorly understood genus because
only the pedicle valve is known. All illustrations
show it to be a primitive or an immature form,
because it has a nearly complete vallum (circumvallate
stage) and the median lobe is open from the
anterior margin nearly to the hinge area. We are
not able to corroborate Tschernyschew's description
of the hinge region with its delthyrial structure.
Nothing like this was seen in any of the
early lyttoniidae in North America. Keyserlingina
is most similar to Stehli's Pseudoleptodus in its
conical form and circumvallate condition, but an
eccentric muscle scar has not been described or figured
in Keyserlingina. Choanodus, new genus, is
similar in its conical form and internal structure,
but it has a solid, well-advanced median ridge in
the pedicle valve and a less deeply cleft brachial
valve. At any rate, Keyserlingina is a primitive
form, as it occurs in the "Schwagerina" Limestone
of the Urals and the Trogkofel beds of the Alps,
corresponding to part of the late Pennsylvanian or
Wolfcampian of North America.
Leptodus Kayser (in Richthofen, 1883:161 =
Lyttonia Waagen, 1883:395, 396) (Plate 191: figures
11-15). Examination of one of the type specimens
of Leptodus indicates the identity of this genus
with Lyttonia. The specimen is 31 mm long and
39 mm wide, evidently a fairly young individual.
It shows eight lateral lobes and a broad median
region. Most of the shell is exfoliated from the
specimen. The shell is strongly pseudopunctate
and shows a median ridge. No evidence of a cowl
could be seen, and the small apex suggests a broad,
spreading apical region like that of the Salt Range
"Lyttonia" (z=Leptodus). On the right side, just
anterior to the apex, crossing the second lateral
lobe, there is a calcareous ridge suggesting a septal
plate that bounds the muscle area. No evidence of
muscle scars was seen. Huang (1932:87, pi. 8: figs.
4a, b) described and figured a specimen referred to
this species. This clearly has affinities with the
Pakistan form.
This specimen, figured by Kayser (1883, 4:161,
pi. 21: figs. 11, 11a), is designated as the type of
the species. The specimen is in the collections of
the Geologischer-Palaontologischer Museum, Berlin,
East Germany. The specimen comes from the
Upper Permian in Loping, China.
Leptodus nobilis Waagen (Plate 191: figures 8,
9) is a species from Pakistan with numerous lobes.
Seldom silicified, it afforded an opportunity to figure
the nature of the lobes in relation to the secondary
or fibrous shell layer.
Loxophragmus, new genus. This name is proposed
for small transversely elliptical attached
shells in the terminivallate stage.
Oldhamina Waagen (1883:395, 403). This is
one of the best known and most distinctive of the
Lyttoniidae. It is characterized by a fairly strongly
convex lateral profile and deeply concave pedicle
valve. This odd shape helps to account for the
terminivallate stage of the lateral septa, which are
thin, strongly oblique, and knife-edged (anguliseptate).
The posterior attachment is folded posteriorly
and rounded in such a way that it suggests the
adult life of the shell was spent unattached from
the substrate.
Oldhaminella Wanner and Sieverts (1935:232).
Information on this genus is based wholly on the
discussion and figures given by Wanner and Sieverts.
The shells are strongly convex, attached,
wider than long, and consist of three to four lateral
septa, most of which appear to be in the
pervivallate stage. According to Wanner and Sie412
SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
verts, the outer half of the lateral septa are in the
state mentioned, but the inner half are Oldhaminalike
(anguliseptate). The ridgelike sides of the
lateral septa are separated by a fairly wide band of
secondary shell. Perhaps the most conspicuous feature
of the genus is its musculature and the presence
of two muscle ridges on each side of the
median ridge.
This genus is based on two pedicle valves that
are attached to crinoid stems and are engulfed
partly by tissue from the stems growing over them.
The specimens suggest to us immature forms, perhaps
the young of Lyttonia catenata described in
the same publication (Wanner and Sieverts, 1935).
This species is attached to crinoid stems, but its
musculature is not now known. The generic evaluation
of the muscle ridges is a problem that cannot
be settled here because only two specimens are
known that have them and a similar arrangement
has not been seen in other lyttoniids. This is a
probable synonym of Leptodus.
Paralyttonia Wanner and Sieverts (1935:207).
These are small shells attached by their entire ventral
surface like Poikilosakos. The septal ridges are
in the lativallate state, i.e., with broad, open lobes,
all directed anteriorly. The posterior lobe margin
is undulated as in the Poikilosakidae, but the muscle
scars in the pedicle valve, as indicated by Wanner
and Sieverts (1935, pi. 6: fig. 4b), are bounded
by lateral ridges and are separated by a median
myophragm, thus making them symmetrical. This
is contradicted by another specimen assigned to this
species and illustrated by figure 7b on the same
plate. The specimen is anomalous because it has
an eccentric muscle on the left side of the valve,
unlike any other poikilosakid or lyttoniid. This
may be due to imperfect preservation, but it is
difficult to be sure from an illustration. The brachial
valves are anteriorly digitate and granulose
exteriorly, but their interior is not known.
The probable symmetrical nature of the muscle
scars, in spite of the Poikilosakos-like appearance of
the shells, indicates relationship to the Lyttoniidae.
The minute size and primitive character of the septal
lobes again suggests a possible immature stage
of Leptodus. If this is an adult form, it must be
ranged with Rigbyella in the Lyttoniidae.
Petasmaia Cooper and Grant (1969:10). This
name is applied to large, circumvallate to septivallate,
rapidly expanding, and generally flattish lyttoniids
that have strong lateral ridges bounding the
muscle area and lateral septa predominantly in the
latilobate to solidiseptate states. These shells commonly
attached to crinoid stems or to other narrow
objects, but they are not confined to this type of
substrate.
Pirgulia Cooper and Muir-Wood (1951:195).
This name is used for elongate and narrowly conical
Lyttoniidae having lateral septa in the pervivallate
to septivallate stages. The slender, nearly
symmetrically conical form is unique in the family.
Rigbyella Stehli (1956a:310). This genus is similar
to Paralyttonia; its type-species originally was
placed there. It differs from Paralyttonia in having
a cuplike form. Its musculature is symmetrical,
and it is, therefore, referable to the Lyttoniidae.
Uralina Schuchert and LeVene (1929:127 =
Uralia Licharew, 1925:4). A synonym of Eolyttonia.
Vincia De Gregorio (1930:31). The members of
this genus form misshapen cones composed of a
long ventral side and a shorter dorsal side in the
form of a cowl. The scar of attachment is fairly
large, and the lateral septa are in the pervivallate
to septivallate stages. The genus strongly resembles
Eolyttonia, which has priority over Vincia and
probably is a senior synonym.
Ecology of the Lyttoniidae
The Lyttoniidae were, for the most part, cemented
animals. That some of them lived loose on
the sea bottom seems evident from the conditions
under which they are collected and from their shell
anatomy. Oldhamina and Pirgulia probably lived
for a considerable part of their adult life free on the
sea bottom, but most of the other genera lived attached.
All of the Poikilosakidae were attached throughout
life, and Poikilosakos was fixed by its entire
ventral surface. The later poikilosakids, such as
Pseudoleptodus and Choanodus, geniculated in a
dorsal direction along the lateral and anterior margins
to produce a cuplike form. These little cups
were fixed strongly to a host, a fact that accounts
for the rarity of their shells in the residues. No
preference of host by any of the Poikilosakidae was
noted.
NUMBER 15 413
The conical Lyttoniidae were less strongly cemented
to the substrate than the broad, expanding
forms such as Collemataria and Petasmaia. The
former, with their large callus flaps, make clusters
and small banks like oysters, but the conical forms
are often stripped by storms or currents from their
moorings. Banks of the conical forms are also
made under stable conditions, but they break up
more readily than the more tightly cemented species.
The latter also are often found loose, tightly
cemented to a fragment of their host.
None of the lyttoniid genera seems to have been
selective in the type of host to which an individual
anchored. Petasmaia appeared to thrive on crinoid
columns, but this may not have been a matter of
selection of substrate. Many specimens were attached
to the carinate edge of pelecypods such as
Leiopteria Hall, a surface that approximates a
crinoid stem, but they were also attached to flatter
objects. Wanner and Sieverts (1935:248) illustrate
their species Lyttonia catenata attached to a crinoid
stem with the posterior of the Lyttonia oriented
in an upper position. We believe that Petasmaia
probably also attached to living crinoid stems but
that the orientation on the stem should be opposite
to that figured by Wanner and Sieverts. The
posterior of the brachiopod should be down, i.e.,
toward the sea bottom, with the anterior margin
facing the crinoid crown. The widely expanded
form of these shells, growing rapidly all around
the edge of the shell except at the point of attachment,
can be explained only by the fact that they
must have been free.
Attachment of the lyttoniid spat was so random
for most genera that it is no wonder they have such
a wide range of form and distortion. Coscinophora
had broadly open cones, but some, such as specimens
USNM 153655c, f, formed complete cones
because they were unable to expand normally. The
anterior tube of Collemataria batilliformis, new
species, appears to have been induced by extreme
crowding. A small fraction of specimens of all sizes
and ages shows this anterior channeling phenomenon.
It is thus not an old age character, but it must
have been caused by crowding at the anterior end
of the shells.
The shape of a shell may be controlled by its
host. This is especially confusing in such genera as
Collemataria, which does not normally have a cowl.
The larva settles on the concave side of a small productid.
The valve grows in all directions, but, because
of the curvature of the host, the posterior part
is forced to grow in an anterior direction. This
produces a cowl over the hinge region and a shell
form like that of Eolyttonia.
In the Glass Mountains, lyttoniids occur in few
places in countless numbers. They are most conspicuous
in the Split Tank area just above the
Institella zone at the base of the Cathedral Mountain
Formation. Here layers three to four feet thick
abound in specimens (Plate 20: figure 3). These
suggest that a large colony lived and was partially
destroyed at this place. Many specimens are loose
and must have been detached from the main mass.
A few small clusters can be obtained. In the etching
process, it is difficult to hold the larger pieces together;
consequently, it is not possible to tell how
much of a decalcified piece originally consisted of
attached specimens. The field evidence suggests,
however, that masses of considerable size, including
many individuals, existed on the sea bottom in
many places.
The same is true of Coscinophora, which forms
large colonies or banks in the Road Canyon Formation
(Plate 17: figures 3, 4). These occur scattered
throughout the formation, but most frequently near
the base. Generally the specimens are not connected
and appear to have been broken from a
large mass. Decalcification of blocks of this material
yields some connected clusters that can be
held together with care. Generally the clusters collapse
when the supporting rock is removed. Evidence
points to the fact that loose clusters and
masses existed on the sea bottom to form bioherms.
An excellent example from the Skinner Ranch Formation
is shown on Plate 129: figures 20, 21.
Some biohermal development of lyttoniids exists
in the Wolfcampian Neal Ranch Formation.
One locality (USNM 722x) produced a small patch
of Eolyttonia cemented by encrusting algae. These
lime-secreting plants are also present in some of
the bioherms high in the Cathedral Mountain Formation.
Wolfcampian bioherms with lyttoniids are
fairly common and, in our experience, occur in the
Neal Ranch and Skinner Ranch formations. The
Cibolo Formation (Brecciated Zone of Udden) in
the Chinati Mountains (USNM 728-1 contains bioherms
notable for the large size of the Eolyttonia
414 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
making up much of their mass. The Word Formation,
on the other hand, has not yet revealed bioherms
in the Glass Mountains. The lyttoniid occurrences
there are usually isolated loose specimens
or clusters of two or three individuals. These may
have made patches, but they were broken and distributed
over the sea bottom to contribute their
share to the numerous death assemblages.
The above remarks appear to be true of the
lyttoniid occurrences in the Guadalupe Mountains
and in the Sierra Diablo as well. No large patches
of lyttoniids suggesting bioherms were seen in
either area. All of the lyttoniids were taken from
death assemblage associations. These regions have
been studied only casually, from a paleontological
point of view; consequently, more exhaustive exploration
may yield some lyttoniid bioherms.
Rudwick and Cowen (1968) discussed the feeding
mechanisms of the lyttoniids, suggesting two possibilities.
One method suggested is that they fed by
bringing in water currents through the slits and
out the anterior; the other method is that, by a
gentle pulsation of the brachial valve, they produced
the entrance of streams of food-bearing
water. The feeble cardinal process and musculature,
together with the median channel of the pedicle
valve, suggest to us the former, rather than the
latter, method. The musculature of these animals—
what can be seen of it—was not very powerful. In
many of the genera with large individuals, the
brachial valve, even with the numerous openings in
it, would have been fairly heavy.
Genus Eolyttonia Fredericks, 1924
Eolyttonia Fredericks, 1924a:25; 1925:63.
Conical to semiconical circumvallate, to septivallate
pedicle valves having short to long cowl enclosing
hinge area; attachment at apex small to
large; surface marked by concentric lines and
wrinkles.
Pedicle valve, interior with narrow hinge having
thickened overhanging lip and lateral articulating
pits; lateral lobes numerous, convex anteriorly,
early species and young specimens with well-defined
vallum laterally; later species and old specimens
with vallum compressed into latilobate to solidiseptate
ridges, but with anterior septa ungrooved; in
later species grooved septa confined to young, or
sporadically developed in adults. Median ridge
variable partially septivallate, usually open anteriorly
from midvalve depending on species. Interseptal
spaces, especially anteriorly, marked by thickened
ridge and commonly strongly pitted.
Brachial valve with lobes convex anteriorly;
hinge straight, with small articulating nubs. Cardinal
process single shafted, shaft short, and bilobed
myophore generally spreading. Median ridge low;
valve commonly deeply cleft anteriorly.
TYPE-SPECIES.—Oldhamina (Lyttonia) mira Fredericks
(1916:74, pi. 2: figs. 8, 9).
DIAGNOSIS.—Conical Lyttoniidae with latilobate
vallum in young stages or early adult species, but
with grooved angustilobate or ungrooved (solidiseptate)
septa in adult forms or late species; brachial
valve with single shafted cardinal process.
COMPARISONS.—Eolyttonia has the form of Keyserlingina
Tschernyschew and Parakeyserlingina
Fredericks. The former genus is usually small and
has only a few lateral lobes, which are defined by
a well-formed vallum. Furthermore, it does not
have a single median septum, but rather a central
posteriorly directed lobe of the vallum, as in the
Poikilosakidae. From all that can be gathered from
the literature and the illustration of Parakeyserlingina
darvasica (Tschernyschew), the type-species
of Parakeyserlingina, the same is true for that genus.
Corroboratory evidence is seen in the hypothetical
constructions of the brachial valve of Parakeyserlingina,
which are shown with a median cleft extending
almost to the hinge, suggesting that the
cleft surrounded an open posteriorly directed median
loop of a vallum. If this supposition is true,
Parakeyserlingina is closer to Keyserlingina than to
Eolyttonia, as stated by King. This supposition is
also supported by the synonymizing of Parakeyserlingina
with Keyserlingina, as indicated in Sarycheva
(1960:238) and Williams, et al., (1965:H518).
Eolyttonia differs from Collemataria in the form
of the shell and the type of attachment, the latter
being fixed at the posterior with a reenforcement
of callus and without a cowl. Furthermore, the
lateral septa of the pedicle valve of Collemataria
seldom are grooved medially, and, if they are, it is
only in the juvenile stages or sporadically in the
adult.
Choanodus is strongly conical like Keyserlingina,
NUMBER 15 415
but it differs from Eolyttonia in having an elaborate
articulation.
Eolyttonia differs from Leptodus in the form of
the shell and in the lack of muscle marks at the
posterior. The method of attachment is dissimilar
in the two genera, Leptodus being flatter and more
expanded anteriorly. Oldhamina is much more
convex than Eolyttonia, is attached differently, and
generally has oblique and sharply angular lateral
septa (anguliseptate).
DISCUSSION.—Eolyttonia is an early name that
may be useful for a number of species of Lyttoniidae
that hitherto have not been satisfactorily placed.
The interpretation given here may not prove satisfactory
when the various species are better known
from larger collections. The latitude given the
name here includes the form of the shell and the
interpretation of the development of lateral septa.
The type-species, E. mira (Fredericks), appears
to be a low, asymmetrical cone, the shell having a
long ventral side, but the cowl short. The American
species assigned to Eolyttonia have shell shapes
ranging from like that of the type-species to ones
that are complete and almost symmetrical cones.
Eolyttonia fredericksi (R. E. King) is a species with
considerable variation in the form of the shell. The
species having the most symmetrical shells is E.
gigantea, new species, which formed deep cones
with a broadly rounded apex and broad openings
at the other end. Some of these approach the proportions
of a teacup.
The hinge of Eolyttonia is like that of Leptodus,
an overhanging posterior lip that may be strongly
swollen. It also has lateral depressions to receive
small articulating points on the brachial valve.
The most important feature of Eolyttonia that
makes it distinctive is the development of the lateral
septa. In the young a well-formed and complete
vallum can be detected. With growth the
anterior walls of the outloops are pressed toegther
to produce narrow latilobate lobes with subparallel
walls. But advancing age may compress the lobes
still farther until the outlobe becomes angustilobate
to solidiseptate, usually with a narrow median
depression. This is the condition of the septa
in E. mira and is the usual condition of the septa
in many young forms, although, with growth, the
depression along the crest of the ridge may be filled
and the septal ridge may have a narrowly rounded
crest. Later species have a majority of the septa
with narrowly rounded crest—the most advanced
stage for this genus.
Eolyttonia fredericksi (R. E. King) is a large species,
unique for having a fair portion of its first
formed lobes in the young stage in the augustilobate
condition. In this species, however, later and
more anterior lobes are low, but often fairly widely
grooved. In deeper parts of some specimens that
are more curved than normal, some septa may approximate
the stage seen in Oldhamina (anguliseptate),
but generally the septa are not so sharply
carinate, but they are strongly inclined.
All species of Eolyttonia from the Glass Mountains
have the septal lobes descending anteriorly in
height and widening with the expanding cone. Generally
the last few lobes are low, and the ones
nearest the front are commonly difficult to discern.
Beginning posteriorly and along the distal extremity
of the lobes, a low rounded ridge appears
between the vallum walls and parallel to them.
These ridges extend in successive lobes inward toward
the median trough. In the lobes nearest the
front they extend from end to end and are often
as strongly elevated as the vallum wall. When this
takes place, the anterior part of the shell appears
to be made of nearly equally spaced, narrow ridges
like corduroy. This development is not uniform,
but it seems to occur spasmodically within a species.
In addition to the transverse parallel ridges,
rows of pits appear in the depressions on either side
of the adventitious ridges. This feature also is
developed spasmodically in the genus, but it appears
conspicuously in other genera such as Collemataria.
The median ridge is not uniformly developed in
all species. In some it is medianly grooved posteriorly
and anteriorly, but in most of them it is
grooved or open only anteriorly, usually beyond
midvalve. The median ridge usually extends to
the hinge, but at the posterior it is generally thin
and delicate. At the front, after it has divided, the
ridges become low and may be difficult to see.
The brachial valve normally is unsymmetrical
and anteriorly cleft for varying distances, depending
on the condition of the median ridge of the pedicle
valve. The hinge is straight and narrow, usually
with small points or alae laterally. Internally the
hinge is marked laterally by a small triangular area
416 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
on each side separated by a low, oblique ridge.
The cardinal process has a single shaft of varying
length that frequently is distorted, in one valve
almost parallel to the hinge. The myophore is bilobed
and usually small, but it may be expanded
laterally. The cardinal process is usually near the
center of the hinge, but many appear slightly off
center.
The midline of the brachial valve is generally
marked by a median elevation, not developed, or
only poorly developed in the young, but more
strongly marked to prominent in adult and old
shells. At the cleft and anterior to it, a ridge extends
parallel to the margin of the cleft. This gives
the appearance of two ridges margining the longitudinal
lobe anterior to the cleft. The lateral lobes
are usually deep, but they may be thickened medially
by adventitious shell, beaded on the margins
or forming a low ridge. This ridge is parallel to
the lobe margins and also to the proximal ends of
the lobes at the median trough. Many of the lobes
have scalloped margins where the shell is in contact
with the pitted interior of a pedicle valve lobal
trough.
Eolyttonia appears to be characteristic of the
Lower Permian. It is common in the Wolfcampian
of the Glass Mountains, but rarer in the Leonardian
and rare in the Guadalupian. It appears to
be commonest in biohermal associations.
Eolyttonia catilla, new species
PLATE 145: FIGURES 1-4; PLATE 157: FIGURES 1, 2
Large for genus, broadly conical in profile with
large cowl; broadly elliptical in outline, but variable;
cicatrix variable but substantial; surface
marked by numerous concentric wrinkles. Known
from pedicle valve only.
Interior with about 13 lateral lobes; latilobate
to angustilobate; lobes dying out anteriorly, anterior
third broad and smooth. Median ridge solidiseptate
to beyond midvalve, but angustilobate
anteriorly; median ridge low and inconspicuous;
hinge narrow.
MEASUREMENTS (in mm).—Holotype (USNM
153584): length 83.0-f, width 104.6, hinge width
13.5, cowl length 42.0, height 34.0; paratype
(USNM 153583): length 83.0, width 80.7, hinge
width ?, cowl length 46.8, height 47.3.
STRATIGRAPHIC OCCURRENCE.—Neal Ranch Formation
(bed 9 of Cooper = bed 12 of P. B. King).
LOCALITY.—USNM 701c.
DIAGNOSIS.—Gigantic Eolyttonia wth broad open
cones and septa mostly latilobate to angustilobate.
TYPES.—Holotype: USNM 153584; figured paratype:
153583.
COMPARISON.—This species ranks in size with E.
gigantea, new species, of the Skinner Ranch Formation
(Decie Ranch Member), but it differs markedly
in having a broad, open cone with the anterior
side longer than the posterior. The specimens are
like a small, oddly-shaped dish.
DISCUSSION.—These specimens were taken from
the same bioherm that produced specimens of
Eolyttonia fredericksi (R. E. King), but they have
an entirely different shape. They do, however,
have a very similar stage of development of the
lateral lobes to that of King's species.
To have attained such a large size without notable
deformation, these forms must have been solitary
dwellers.
Eolyttonia chaotica, new species
PLATE 141: FIGURES 1-17; PLATE 142: FIGURES 1-17
Moderate to large, irregular, varying from shallow
expansions to moderately deep bowl-like shells,
deepest posteriorly, but becoming shallow to flat
anteriorly; attachment moderately large, usually
with considerable callus in one or more layers;
sides strongly curved and elevated in dorsal direction
posteriorly, but descending anteriorly; sides
and anterior usually well rounded. Surface marked
by strong but fine concentric wrinkles.
Pedicle valve interior with about 16 lateral septa
in adults, posterior 7 of which are generally fairly
elevated and inclined forward, deeply undercut and
single-edged (solidiseptate) or grooved (angustilobate)
on crest. Septa descending in height anteriorly
and strongly ridged or pitted on anterior and posterior
surfaces. Interseptal callosities originating on
outside of early lobes and growing inward anteriorly
and strongly ridged or pitted on anterior and
posterior surfaces. Callosities moderately thick and
narrowly rounded. Median trough narrow, marked
by low median ridge, usually less conspicuous in
posterior half, strong medially but becoming flattened
toward front end, some specimens with meNUMBER
15 417
dian groove or dividing to form 2 low, threadlike
septa. Hinge narrow with strong posterior lip and
with lateral articulating grooves.
Brachial valve with narrow median axis marked
by shallow median, longitudinal groove; lateral
lobes narrow, about 2.5 mm in anterior-posterior
direction; loops not connected distally. Exterior
with strong, scattered granules.
Brachial valve interior with small to moderately
large eccentric cardinal process; median ridge
strong and extending from cardinal process to anterior
cleft; lobes shallow and marked by a deep
groove and low ridge parallel to all margins; interridge
areas roughened and papillose.
MEASUREMENTS (in mm).—
maximum hinge cowl
length width width height length
USNM 721-o
150649a
150649b
150649c
(holotype)
150649d
150649e
150649£
150649g
150649h
USNM 702c
150645
49.0
49.9
49.0
59.0
51.1
61.0
53.6
27.0
63.7
49.6 ?
53.5 ?
58.0 9.6
62.0
39.6?
51.0
56.5
34.0
60.0
?
?
10.0
8.0
5.0
?
22.0
7.0
24.7
30.6
23.0
21.6?
18.0
6.0
20.0?
10.6
11.0
20.0
18.4
15.2
11.0
9.5
5.0
13.5?
STRATIGRAPHIC OCCURRENCE.—Cathedral Mountain
Formation, Road Canyon Formation.
LOCALITIES.—Cathedral Mountain: USNM 702,
702b, 702 low, 702un, 703b, 712o, 726o; Road Canyon:
702c, 703a, 703d, 707e, 719x, 721j, 721o, 721s,
721x, 721y, 723u, 726d, 726z.
DIAGNOSIS.—Advanced Eolyttonia with short
cowl, 16 lateral, oblique septa, usually obliquely
grooved.
TYPES.—Holotype: USNM 150649c; figured paratypes:
150644a, 150649a, b, e, g, i, j , 153619a-e,
153621a, b, 153620, 153622; measured paratypes:
150645, 150649a, b, d-h; unfigured paratypes:
150649d, f, h.
COMPARISONS.—This species is like E. pocillata,
new species, in profile, outline, and the degree of
conical development, but it differs in having a
larger adult size and a generally stronger septal
development. The septa of E. chaotica are usually
more strongly fluted.
This species is not as strongly conical as E.
fredericksi (R. E. King) and the septa are in a more
advanced stage, generally having the median grooving
of the posterior septa obscure or strongly
oblique (angustilobate to solidiseptate).
DISCUSSION.—The strongly developed vallum of
young forms of this species indicates clear relationship
to Eolyttonia, but the species shows definite
advancement in the development of its lateral septa
in the adult form. The exterior shape of the shell
is not unique or unusual, but some variation of
the attachment surface leads to confusion in generic
assignment. Shells growing on a flat surface tend
to be broadly open, but their conical form is generally
clear. Others in less favorable positions may
have the development of the cowl aborted at an
early stage so that the posterior may strongly resemble
that of Collemataria with its posteriorly
spreading callus flap.
Although the exterior of these shells is seldom
distinctive, the interior offers more possibilities in
detail for separation of species; and although the
form and development of the hinge offer no possibilities
in this direction, the vallum and septa do.
Young specimens ranging up to 25 mm in length
have a well-defined vallum with good continuity
except at the front, where its course is not clear.
Whether or not the formation of the vallum is a
function only of youth in shells of this size is not
altogether clear because one of the specimens is
flat. Another is moderately curved, but its vallum
is not well-formed anteriorly. In E. chaotica, adult
lateral septa tend to be strongly oblique to the
inner surface with the dip toward the back. In
such septa the two original septa may be obscured,
or the anterior one may appear at or near the
crest of the lateral septum and the other near the
base on the posterior side. This broad obliquity
of the septal groove is a common feature of this
species. In late-formed septa, a groove at the crest
or spread along the sloping surface is not easily detected.
The posterior lateral septa, to a point near
the midvalve or slightly beyond, are the most likely
parts for the preservation of the septal groove. The
anteriormost septa seldom, if ever, show this feature.
The lateral septa commonly are fluted strongly
on both sides. The fluting of the broad dipping
surface or an oblique septum is strongly striated
longitudinally, but on the shorter anterior surface
it suggests a strong pitting. The edge of the bra418
SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
chial valve lobes are fluted and wavy to correspond
to the undulations of the septa.
The development of the median ridge in E.
chaotica is of interest. In the posterior part of the
shell it is thin and, in some cases, not clearly
shown. Furthermore, in the rear third it may bear
a median groove. In the anterior third or half, the
ridge becomes stronger, more elevated, and substantially
solid. It is probably at this point that the
brachial valve is cleft to fit snugly on both sides of
the median ridge. In the anterior third or less, the
ridge again lessens in height and strength and may
divide into two narrow threadlike ridges with a
flattened space between.
Another feature of the interior is the modification
of the lateral grooves. These are commonly
occupied by fairly strong, rounded ridges, often
fluted on both sides. These interseptal ridges originate
at the distal side of the grooves in the old
parts of the shell and increase in length proximally
in the later-formed shell stages.
The brachial valve of this species is strongly
granulose on the exterior and the granules are well
separated. The hinge is provided with well-formed
ears for articulation. Furthermore, at the apex
appears a small, triangular, smooth area that represents
the surface over which the protruding posterior
lip rubbed in the movement of the brachial
valve when the animal gaped (Williams', 1953,
"primary shell layer").
The cardinal process is variable and is always
irregular, seldom in direct line with the median
ridge. The myophores usually are small, but some
are laterally expanded. The lateral lobes are generally
narrow and moderately convex toward the
anterior in the posterior part of the shell, but they
tend to straighten anteriorly. The lobes are also
less oblique to the shell axis at the apical region
than near the midvalve, where the shell is generally
deepest. At deep parts the lobes may be at a
strong angle to the axis to accommodate to the
obliquity of the lateral septa. Generally the posterior
edge of the lateral lobes is somewhat flattened
where it rests against the sloping edge of the lateral
septum, but it is thin and sharp along the anterior
margin, where it is articulated at the base of the
lateral septum. In many specimens the margins
of both sides of the lobes are strongly waved or
fluted to fit the striations of the lateral septa.
Inside the lobes the floor usually is thickened
by adventitious shell with pseudopunctae. The
thickening is demarcated clearly by a groove parallel
to the lobe edge and a somewhat thickened line
inside the lobe edge. The line is continuous along
the lobe margins, and also around the margin of
the groove between the lobes.
The median axis is marked medially by a ridge
of variable height in different specimens that extends
from the cardinal process shaft to the median
cleft. At the median cleft a low ridge extends anteriorly
along the inner margin of the cleft.
Eolyttonia chaotica is best developed in the
Cathedral Mountain and Road Canyon formations,
especially at USNM 702c. It occurs lower in the
former formation in the eastern part of the Glass
Mountains, but the specimens are not always typical
of the species at this level. The best development
is at the base of the Road Canyon Formation at
USNM 719x, where it is abundant. The national
collection contains about 100 specimens of different
sizes and varying stages of preservation from excellent
to poor. The silicification is not uniform and,
in some, has gone so far as to alter or mar details.
The species lived in clusters and also singly, with
a number of species utilized as substrate.
Eolyttonia circular is, new species
PLATE 143: FIGURES 1-16; PLATE 144: FIGURES 6-14;
PLATE 145: FIGURE 5
(Lyttonia nobilis americanus R. E. King (not Girty),
1931:103, pi. 32: fig. 6.
Broad, subcircular, and shallow cones, generally
deepest near midvalve; attachment scar small, generally
puckered; cowl variable, usually large and
folded posteriorly, but seldom overhanging the
hinge. Sides and anterior margins well rounded.
Surface marked by concentric lines and wrinkles.
Pedicle valve interior with narrow hinge having
rounded swollen, posterior lip. Cowl in some specimens
sharing in attachment. Lateral septa generally
strongly convex anteriorly; lateral septa grooved
(latilobate to angustilobate) in young and often in
adults, but many adults with more advanced solidiseptate
septa. Interseptal ridges increasingly strong
and wide anteriorly; interseptal slots pitted. Median
ridge low and inconspicuous.
Brachial valve with short visceral region, variable
NUMBER 15 419
hinge and anterior cleft from one-half to one-third
valve length from front margin. Median depression
moderately deep; surface finely granulose. Lateral
lobes narrow and curved, convex anteriorly. Hinge
with narrow articulating processes. Lobes anteriorly
serrate.
Brachial valve interior with deformed eccentric
cardinal process; median ridge strong and moderately
elevated. Loops with fairly strong adventitious
thickening.
MEASUREMENTS (in mm).—
maximum hinge cowl
length width width height length
USNM 702un
150727 46.0 52.0 12.0 28.0 23.0
(holotype)
USNM 702a1
150723a 45.5 49.0 10.3 19.0? 16.0
150723b 48.0 49.0 11.9 14.0? 10.0
150723c 42.0 53.0 7.0 15.0 15.0
150723e 40.0 42.0 12.0 17.0 17.0
1507231 35.0 45.0 7.5 21.0 11.0
USNM 702
150721d 60.0? 67.0 12.0 15.7 15.6
STRATIGRAPHIC OCCURRENCE.—Cathedral Mountain
Formation, Road Canyon Formation.
LOCALITIES.—Cathedral Mountain: AMNH 500c,
500H, 504, 591, USNM 702, 702a, 702a1, 702b,
702 (low), 702un, 703b, 703bs, 726y; Road Canyon:
USNM 703a.
DIAGNOSIS.—Large, shallow, conical Eolyttonia
with broad cowl extended posteriorly and with
maximum depth at midvalve.
TYPES.—Holotype: USNM 150727; figured paratypes:
150650, 150721d, 150723e-g, 153616a-c,
153585, 154530; measured paratypes: 150721d,
150723a-c; unfigured paratypes: I50721a-c,
150721a-c 150723a-d.
COMPARISON.—The broad, open, shallow conical
form of these shells is distinctive and separates them
from all of the deeply conical species. Eolyttonia
circularis is similar in appearance to E. chaotica,
but that species has its greatest depth in the posterior
part and its cowl is many-layered and ragged
in appearance, whereas the cowl of E. circularis is
quite smooth.
Eolyttonia diabloensis (Stehli) has similarities to
E. circularis, but it is a strongly papillose species
with a more irregular cowl.
DISCUSSION.—The cowl and hinge are the most
distinctive parts of this species. The cowl is variable
in length, but it forms a flattish posterior expansion
that may or may not assist in the attachment of the
shell. In some specimens the attachment scar is an
irregular patch in the position of the beak, but the
cowl extends above it and is entirely free. In others
the cowl extends posteriorly as a flap over the attachment
surface, often welding the specimen
tightly to its host, and often so neatly that contact
of the callus and shell is not visible. The hinge
is also distinctive as a narrow slit with a strong
overhanging lip that is almost bulbous in some
specimens.
Most pedicle valves of adult specimens have a
fair number of the lateral septa angustilobate. In
the posteriormost septa the groove is narrow and
occupies the crest of the ridge, but in the more
anterior septa the groove is distorted and spread
onto the sloping or oblique face of the septum.
Many specimens have the interseptal parts occupied
by low, pitted interseptal ridges. These originate
early and are increasingly long anteriorly.
This species is uncommon and appears to be
restricted to the lower and middle parts of the
Cathedral Mountain Formation, where it occurs
with Collemataria elongata, new species.
Eolyttonia cornucopia, new species
PLATE 146: FIGURES 1-6
Large and variable but forming well-defined and
nearly complete cones having fairly acute apex;
length and width variable, usually longer than
wide; cicatrix of attachment small; cowl long, almost
equaling length of ventral side. Surface
marked by concentric lines and wrinkles.
Pedicle valve interior with at least 15 lateral
septa, posterior ones generally in angustilobate to
solidiseptate stages of development. Posteroproximal
parts of lateral septa most elevated, decreasing
in height anteriorly; all lateral septa low anteriorly
and with moderate development of interseptal
ridges. Median ridge low and continuous nearly
to hinge.
Brachial valve not seen.
MEASUREMENTS (in mm).—
maximum hinge cowl
length width width height length
150627a 89.0 61.0 ? 45.0 45 +
150627b 68.0 61.0 ? 45.0 61.0
150627c 70.0 66.0 ? 41.0 36.0
(holotype)
420 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
STRATIGRAPHIC OCCURRENCE.—Skinner Ranch
Formation (base).
LOCALITIES—USNM 720e.
DIAGNOSIS.—Large, strongly conical Eolyttonia
having a fairly acute apex.
TYPES.—Holotype: USNM 150627c; figured paratype:
150627b; unfigured paratype: 150627a; measured
paratypes: 150627a, b.
COMPARISON.—This species was seen only at
USNM 720e, and there in only one biohermal
patch. Unfortunately the specimens are not well
preserved and are very ragged; nevertheless, the
strong and sharply pointed conical form is well
shown. No brachial valves were found with the
specimens or in place within the cones. Many of
the cones were crusted inside and out by a brownish
laminated material, now silicious, that strongly indicates
encrusting algae.
Eolyttonia diabloensis (Stehli)
PLATE 140: FIGURES 1-25; PLATE 162: FIGURES 11-18
Leptodus? diabloensis Stehli, 1954:307, pi. 18: figs. 12-14.
Lyttonia nobilis americanus (Girty) R. E. King, 1931:103,
pi. 32: figs, la, b.
This is a variable species defined by its author
as having "simple lateral ridges and median ridge;
without dental plates (or) a true median septum;
growth habit conical." Stehli failed to designate
a type specimen from the two illustrated. We,
therefore, choose the specimen illustrated on his
plate 18: figure 14 as lectotype (AMNH 27290/1:2).
This specimen, which is only a pedicle valve, is
selected rather than that shown by figures 12 and
13 because it shows important generic details that
cannot be seen in the other more complete specimen.
The form of this species is important in its definition.
It is said to be conical, but a wide range of
forms occurs. The lectotype forms an open cone
with a broad cowl moderately deflected toward the
anterior. The paratype is somewhat more conical,
but it has a shorter cowl that is arched more
abruptly over the hinge. The prevailing form seems
to be like that of the lectotype, with a broad cowl
variably deflected. The species thus ranges from
nearly completely flat to a fairly well-formed cone.
This broad range of form is owing to the host
to which it is attached and to the nature of the
attachment. Usually it is attached at the apex, but,
if the host is flat, the cowl will extend posterodorsally,
rather than anterodorsally, and the shell will
form a wide cone. In some the cowl remains partly
attached to the host and is unable to be reflected
toward the hinge. This happens in specimens that
resemble the lectotype specimen of E. americana
(Girty). Few specimens are strongly conical, but
the few that are have the same strongly papillose
cowl as the more open and more typical cones.
Assignment to Eolyttonia is based on the nature
of the lateral septa and median ridge in the pedicle
valve and on the character of the brachial valve.
Young specimens still attached to the host have a
well-marked vallum and a fairly open median ridge.
They thus suggest specimens of Poikilosakos, but
they do not have the eccentric diductor muscle
characteristic of that genus. In youthful flat specimens
the vallum is still discernible, but the lobes
are latilobate to angustilobate. Fairly large adults
have many of the lateral septa distinctly and occasionally
deeply grooved (angustilobate), but the
grooving is generally restricted to the posterior half
or less of the lateral septa. Some have lateral septa
in which the proximal part near the median trough
is deeply trenched, but the depression is pinched
shut at the distal end of the later septum (solidiseptate).
The median ridge is generally low and inconspicuous,
extending almost to the hinge. In the
posterior of some specimens it has a depression in
it or it consists of two thin parallel ridges. In others
the ridge is a single moderately elevated plate.
At midvalve in nearly all specimens the ridge is
single and strong. Variably at the anterior, the
ridge bears a groove or is divided and becomes
much lower until it disappears.
The brachial valve is extremely variable in several
respects. Young specimens are strongly cleft
anteriorly, but this becomes filled during growth.
The filling may take place at several points along
the cleft, resulting in a number of holes along the
anterior midline, as in the dubious genus "Gubleria."
The filled track of the cleft appears as a
moderately deeply impressed sulcus along the midline
of the valve. The exterior, like the cowl and
interseptal areas of the pedicle valve, are strongly
papillose. In some young shells the papillae are
much elongated and could be described as small
spines.
NUMBER 15 421
The hinge region is variable, but usually it has
small articulating nubs and a small triangular area
representing the range of movement between the
brachial valve and the pedicle valve hinge.
Inside the brachial valve the cardinal process is
variable from small to large, asymmetrical to fairly
regular, and usually has four myophore surfaces.
The median ridge is not well developed in the
visceral region, but strong and thick anterior to it.
Lateral lobes are moderately deep, but not strongly
thickened with adventitious shell. The inner margins
along the median cleft are strongly thickened.
MEASUREMENTS (in mm).—
maximum hinge cowl
length width width height length
USNM 728e
153586f
153586h
153586-1
29.4 38.0 6.6
36.0 42.0 ?
58.0 61.4 10.0
11.0 9.0
25.0 24.0
25.0? 12.0
STRATIGRAPHIC OCCURRENCE.—Lower Bone Spring
Formation.
LOCALITIES.—AMNH 625, 628, 629, 631, 632, 696,
USNM 725c, 728e, 728f, 728h.
TYPES.—Lectotype:" AMNH 27290/1:2; figured
paratypes: AMNH 27290/1:1; figured hypotypes:
USNM 153586a-L, 150620a, 153648, 153649.
Eolyttonia fredericksi (R. E. King)
PLATE 144: FIGURES 1-5; PLATE 147: FIGURES 1-14;
PLATE 148: FIGURES 1-6
Parakeyserlingina fredericksi R. E. King, 1931:102, pi. 31:
figs. 7-8 (not fig. 9 —?).
Leptodus species Huang, 1936:489, 490, pi. 1: figs. 1, la.
Variable shape, generally in form of irregular
cup, anterior side generally more elongated than
posterior side with cowl over hinge region. Attachment
area generally small, puckered about attachment
surface; exterior marked by strong
concentric wrinkles. Hinge narrow, with swollen
posterior margin. Septal lobes numbering 15 in
large specimen (latilobate to angustilobate). Posterior
half of lobes generally strongly elevated, inclined
forward in concave specimens and decreasing
in height anteriorly. Interseptal callosity developing
with third or fourth lobe on outside and progressively
approaching midline in anteriorly
succeeding lobes. Median ridge moderately elevated
extending from near hinge to anterior margin,
usually grooved medially posteriorly and also anteriorly
in many specimens.
Brachial valve exterior smooth, with narrow
lobes, with long median depression and median slit
decreasing in length with age. Interior with thickened
lobe margins and double ridge running anteriorly
along margins of median slit.
MEASUREMENTS (in mm).—
maximum hinge cowl
length width width height length
USNM 701c
150670a
150670b
150670c
USNM 701h
150673a
150673b
150673c
150673d
60.5
61.0
40.0
35.6
35.0
71.0
50.0
67.0
46.7
57.2
43.5
40.6
35.0
54.0
7.0
?
10.0?
7.0
8.0
?
8.0
19.0?
36.5
20.0
17.3
25.5
46.5
38.0
20.4
20.0
9.3
9.0
16.0
28.0
41.6
STRATIGRAPHIC OCCURRENCE.—Neal Ranch Formation
(beds 2-14 of P. B. King), Lenox Hills Formation,
Cibolo Formation.
LOCALITIES.—Neal Ranch: USNM 701, 701a,
701a3, 701c, 701d, 701h, 701k, 701-1, 706x, 721g;
Lenox Hills: 705K, 705m, 707ja; Cibolo: 728-1.
DIAGNOSIS.—Large variable cones, the posterolateral
septa generally with wide to narrow depressions
in their crest (latilobate to angustilobate) and
the anterolateral septa becoming low and indistinct.
TYPES.—Holotype: T10671a; figured paratypes:
T10671b; figured hypotypes: USNM 150669a-c,
150670c, 150673, 153617a, 153618a, b; measured hypotypes:
150670a-c.
COMPARISON.—This species differs from E. phialiforma,
new species, in attaining a greater size, a
more enclosed cone, larger lip on the posterior side
of the hinge, and less advanced lateral septa and
median ridge. The lateral septa in the posterior
part usually have the median groove filled up or
nearly so, making the edge of the septa appear flat
(solidiseptate). The median ridge in the adult does
not have either the anterior or the posterior depressions
in its crest.
Eolyttonia fredericksi is much larger and more
conical than either of the Russian species assignable
to this genus: Keyserlingina darvasica Tschernyschew,
the type-species of Paralyttonia, and Lyttonia
mira Fredericks, the type-species of Eolyttonia.
422 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
DISCUSSION.—Eolyttonia fredericksi is not common
in the Wolfcampian, but it inhabited bioherms
at USNM 701c and 701h. It is seen only
sporadically at USNM 701d, but more prospecting
in that area might bring to light some communities
of this species. A few lyttoniids from the Lenox
Hills Formation in Leonard Mountain and in the
Lenox Hills are assigned to E. fredericksi. These
specimens are not silicified, but they do show internal
parts that suggest this species; the exterior
conical form is like that of specimens from the
Neal Ranch Formation.
King (1931:102) mentioned the strong inclination
to the axis, 50°, of the first five lobes of his
species. Our normal specimens do not show this
inclination, as all of the lobes extend laterally at
about a right angle. Specimens long and narrow
from crowding, however, do show a strong inclination
of the early formed lobes.
Eolyttonia gigantea, new species
PLATE 148: FIGURES 7-12; PLATE 149: FIGURES 1-9;
PLATE 150: FIGURES 1-4; PLATE 151: FIGURES 1-6;
PLATE 152: FIGURES 1-4; PLATE 153: FIGURES 1-5;
PLATE 154: FIGURES 1-4; PLATE 155: FIGURES 1-6, 8;
PLATE 156: FICURES 1-10.
Large, forming almost complete cone with wide
elliptical anterior opening and narrow but rounded
apex; usually longer than wide, maximum width
near anterior margin. Shell thick, attachment cicatrix
proportionately small for large cone. Aperture
obliquely elliptical. Surface marked by strong
but irregular concentric wrinkles.
Pedicle valve interior with straight but narrow
hinge; lateral septa numbering about 22 in larger
specimens, variable, ranging from narrow crested
(anguliseptate) to wide crested (solidiseptate) and
grooved latiseptate; septa not strongly elevated except
in posterior part near median groove. Median
ridge most elevated in apical region, becoming
lower and broader anteriorly and dividing toward
front, anterior to midvalve. Interseptal callosities
not strongly developed.
Brachial valve with narrow axial region; lobes
extending laterally from axis nearly at right angles,
slightly bowed in anterior direction in posterior
lobes, but extending directly laterally or sloping
slightly in anterior direction in front part of shell;
lobes narrow, measuring about 2.7 mm in anteriorposterior
direction. Surface with coarse granules.
Brachial valve lobes shallow, with thickened margins;
marginal grooves narrow and deep and bordered
inside by strongly beaded line. Cardinal
process not seen.
MEASUREMENTS (in mm).—
maximum hinge cowl
length width width height length
USNM 707a
150633
USNM 714t
150640a
150640b
150640c
150640d
(holotype)
59.2
50.0
110.0
123.0
92.0
66.0
55.0
70.0
64.0
90.0
14.0?
?
?
?
?
41.5
43.0
51.0?
65.0?
80.0?
39.0
44.0
70.0
78.0
74.0
STRATIGRAPHIC OCCURRENCE.—Skinner Ranch Formation
(Decie Ranch and Sullivan Peak members).
Cibolo Formation (Breccia Zone of Udden).
LOCALITIES.—Decie Ranch: USNM 707a, 708q,
714t, 732b; Sullivan Peak: 707, 707g, 710r; Skinner
Ranch (base): 705b, 71 Id, 714p, 720e; Cibolo:
728-1.
DIAGNOSIS.—Eolyttonia forming large deep cups
with fairly complete conical form but well-rounded
apex with moderately large attachment surface.
Lateral lobes numerous.
TYPES.—Holotype: USNM 150640d; figured paratypes:
150632a, b, 150633, 150634, 150640b, 150641a,
150642, 153615a-h, 153571, 153578, 153579a-e,
153580; measured paratypes: 150640a-c, 150633;
unfigured paratypes: 150640a, c, d, I50641b-e.
COMPARISON.—This species can be distinguished
from all others in the Glass Mountains and North
America by its enormous size and almost completely
conical form. No other Eolyttonia has a cowl so
elongated that the shell becomes an almost complete
and symmetrical cone.
In the completeness and large size of the cone
the American species E. gigantea suggests Pirgulia
Cooper and Muir-Wood from the Sosio Limestone
of Sicily, but important differences may be seen.
The Sicilian genus has completely conical shells,
but they have an acutely pointed apex that may be
long and tapering. The lateral septa of Pirgulia appear
to be more advanced than those of E. gigantea
because they are strongly elevated, ungrooved, and
stout (solidiseptate).
DISCUSSION.—It is difficult to find first-rate speciNUMBER
15 423
mens of this species because they are generally not
well silicified. For the shape to be studied, the
specimens must be taken out of the rock by breaking,
which is often disastrous. The silicification is
so patchy in the Decie Ranch Member that one
can find completely silicified specimens only on
the rock surfaces. Most specimens are silicified in
spots, making extraction by acid impossible. Despite
these difficulties, the pedicle valve is fairly well
known, although important details of the brachial
valve remain to be determined. Fairly good silicified
specimens occur in the Cibolo Formation in the
Chinati Mountains.
Perhaps the most interesting features of this species
are its size and fairly symmetrical conical form.
It has the most nearly complete cone of any species
of Eolyttonia, but the cone does not taper to a
point; rather it is narrowly truncated. Thus the
attachment surface is fairly large, about one-third
the width. In one fairly large specimen (USNM
150633), it is 35 mm in a length of 68 mm. In another
(USNM 150641a), it is about 18 mm in a
length of 55 mm. T h e . widest specimen with a
length of 92 mm has an attachment surface estimated
to be about 25-30 mm. The form of the cone
is variable, depending on age, and it is complete,
or nearly so, in large adults.
As might be suspected in such large shells, the
nature of the lateral septa is extremely variable.
Young specimens show a fairly complete vallum, but
the lobes are fairly closely compressed (angustilobate).
In young adults the lobes are like those of
the type-species of Eolyttonia, fully formed septa
with moderately deep grooves (angustilobate).
Grooved septa occur also in fully grown specimens;
some specimens have all or most of the lateral
septa grooved. In addition to the grooving, most
lateral septa are striated or pitted on anterior and
posterior surfaces. Interseptal ridges are developed
in many of the specimens. These are generally not
strong but low and narrow.
An odd development appears in some specimens.
A lateral lobe may develop far beyond its normal
limits. In one shell the last formed lobe on one
side cuts across the next one posterior to it, terminating
its growth but aligning it precisely with the
second lobe posterior to it. In another the distal
end of a lobe near midvalve curves sharply posteriorly
to occupy the side of the valve at the distal
ends of the next three lobes posterior to it. Similar
aberrations are reported by Rudwick (1968:44) and
Rudwick and Cowen (1968:159).
The median ridge is not strongly developed for
such large shells. Generally the posterior fourth or
third of the ridge is slender and delicate, but the
median part is fairly strong and moderately elevated.
In the anterior fourth or third the ridge is
somewhat flattened and medially grooved. It is
thus similar to that of other species.
The brachial valve of this species is poorly
known, and the cardinal process has not been seen.
One specimen preserving the axial region and part
of the lateral lobes indicates considerable thickening
of the inside of the lobes, but with a marked
depression parallel to all margins of the lobes, between
the edge of the lobe and the inner thickening
that extends along the lobe axis.
This species is best known from the west side
of the Glass Mountain and occurs where bioherms
or brachiopod patches are developed in the Decie
Ranch and Poplar Tank members. On the north
side of the Hess Ranch Horst it is fairly rare. It
appears in some abundance in the Skinner Ranch
Formation bioherms on the north slope of Leonard
Mountain, but it does not attain the large size that
is reached in the Decie Ranch Member. It is also
present in clusters or patches in the Chinati
Mountains.
Eolyttonia parviconica, new species
PLATE 160: FIGURES 3-10
Small for genus with long cowl and deeply conical
form. Apical attachment small. Usually longer
than wide and with concentrically wrinkled anterior.
Pedicle valve with 6 septal lobes fairly
widely separated. Septa variable, angustilobate to
anguliseptate. Median ridge strong, posteriorly
solidiseptate but anteriorly from about midvalve,
angustilobate. Posterior slopes of septa fluted.
Brachial valve unknown.
MEASUREMENTS (in mm).—Holotype (USNM
153626a): Length 23.0, width 18.4, height 13.0,
cowl length 19.6; paratype (USNM 153626b):
length 21.5, width 25.0, height 11.4, cowl length
15.4.
STRATIGRAPHIC OCCURRENCE.—Road Canyon Formation.
424 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
LOCALITY.—USNM 726d.
DIAGNOSIS.—Small, narrow cones with 6 lobes.
TYPES.—Holotype: USNM 153626a; figured paratype:
153626b; unfigured paratypes: 153626c-h.
COMPARISON.—This, the smallest of the conical
species, can be recognized by the posterior to ventral
flattening of the cone. It most resembles an
unnamed conical form from the Lamar Member
of the Bell Canyon Formation (Plate 191: figures
4-7) in its flattened form, but the latter has more
septa and almost rectangular and wider aperture.
DISCUSSION.—These must have been solitary
forms to have produced such a strongly conical
shape.
Eolyttonia phialiforma, new species
PLATE 180: FIGURES 16-21
Medium size for genus, subcircular in outline,
formed broad shallow eccentric cup attached at
posterior third or fourth; exterior with strong concentric
wrinkles and growth lines. Cowl broad,
generally expanded posteriorly.
Interior with narrow, straight hinge bulging
medially and with 2 notches at each end. Septal
ridges about 13 on each side, highest and strongest
posteriorly, but diminishing in height anteriorly,
there becoming very low; septal ridges broad and
with low median depression (latilobate to angustilobate).
Interseptal thickening at fourth or fifth
ridge on outside and proceeding inward in anterior
direction. Septal ridges bowed anteriorly to
about midvalve, then gradually extending directly
laterally. Median ridge fairly strongly elevated
in posterior half, but descending anteriorly to become
about same height as depressed septal ridges.
MEASUREMENTS (in mm).—
maximum hinge cowl
length width width height length
USNM 721x
150666a
(holotype)
150666b
150666c
47.4?
48.0?
47.0?
56.0
50.0?*
47.0
5.0
7.0
9.0
21.0
11.0
14.0?
17.0
15.5
11.0
STRATIGRAPHIC OCCURRENCE.—Neal Ranch Formation
(top of Gray Limestone Member of P. B.
King.)
LOCALITIES.—USNM 701, 722x.
DIAGNOSIS.—Eolyttonia forming broad, shallow
cups with thick septal ridges.
TYPES.—Holotype: USNM 150666a; figured paratype:
150666b.
COMPARISON.—This species occurs earlier than
E. fredericksi (R. E. King), but it seems to share
more advanced characters on the interior. It is
generally flatter and has a less well-defined conical
form and is shallower. Its hinge has a somewhat
bulbous posterior lip in contrast to the small one
of E. fredericksi. Inside the pedicle valve the lateral
septa are thick, and few of them show the characteristic
median depression, because it has been
filled in. The median ridge is likewise thick and
rounded and only rarely shows a median depression.
DISCUSSION.—In some specimens of this species
the rounded ridge commonly occurring between
the lateral septa in the anterior part is very well
developed. It is low and rounded and has about
the same height as the lateral septal ridge. Anteriorly
these adventitious lateral ridges extend
from the median trough to the distal end of the
lobe, but posteriorly they originate farther and
farther toward the lateral shell margin. The
brachial valve of this species has not yet been
found.
Another feature of interest is the occurrence of
this species, which occupied a small patch near
the top of the Gray Limestone Member of P. B.
King. In this patch most of the lyttoniids are partially
or completely covered by a layer of laminated
lime, probably of algal origin. This is one
of the few bioherms that shows definite evidence
of algal deposits.
Eolyttonia pocillata, new species
PLATE 158: FIGURES 1-25
Moderately large, elongated, crudely cup-shaped
or bowl-shaped, anterior side elongated and posterior
side forming elevated but seldom elongated
cowl, sides rounded and fairly strongly curved in
dorsal direction; anterior usually flattened. Surface
strongly marked by fine, concentric wrinkles.
Interior with narrow hinge having moderately
overhanging ledge and lateral articulating notches.
Lateral septa numbering maximum of 14, strongly
to moderately bowed anteriorly, posterior 4-6
being grooved (angustiseptate) and strongly to
moderately elevated, those anterior to these lower
and becoming indistinct near anterior margin. InNUMBER
15 425
terseptal callosity strongly developed, appearing
early in shell development in first formed lobes and
extending from outside inward, and strongly developed
anteriorly; septa and callosities pitted or
longitudinally striated; median ridge low, best
developed posteriorly, poorly developed and occasionally
obsolete anteriorly.
Brachial valve hinge variable but narrow,
straight, with short, broadly triangular smooth area
at posterior representing area in contact with pedicle
valve hinge. Articulating flange small; exterior
marked by prominent longitudinal depression;
anterior cleft open in young forms but closed in
adults; lobes narrow, measuring 2 mm or less in
longitudinal direction; lobes not connected. Surface
smooth.
Brachial valve interior with small eccentric cardinal
process; lobes moderately deep with adventitious
ridge paralleling them; median ridge low,
extending full length of shell to median split.
MEASUREMENTS (in mm).—
USNM 702b
150653a
150653b
USNM 702un
150658a
150658b
150658c
150658d
150658e
150656f
150656g
I50658h
150658i
150658J
150654
USNM 702
150651a
150651b
(holotype)
length
30.3
27.0
46.2
34.6
30.2
27.0
29.8
39.7
34.4
38.8
19.5
33.7
41.1
39.7
29.2
maximum
width
28.0?
24.2
42.6
25.0
24.1
31.6
30.0
34.0
28.2
48.0
22.0
35.6?
38.2
43.7
32.3
hinge
width
7.3
6.6
8.3
6.0
6.0?
6.0?
6.4
7.3
7.3
8.5
4.6
9.3
6.5?
9.6
7.0?
height
13.7
18.0
16.8
27.0
14.1
10.1
10.1
10.3
14.2
16.7
6.9
8.0
14.0
18.3
10.8
cowl
length
?
7.5
5.7?
5.0
4.0
8.0?
3.5
3.2
5.0
7.8
7.3
6.6
9.4
13.0?
7.9
STRATIGRAPHIC OCCURRENCE.—Bone Spring Formation,
Cathedral Mountain Formation.
LOCALITIES.—Bone Spring: AMNH 497, 591;
Cathedral Mountain: AMNH 500F, 500K, 500L,
500N, 500X, USNM 702, 702a, 702b, 702 (low),
702un, 703b, 703bs, 708, 732u.
DIAGNOSIS.—Eolyttonia of medium size, with a
short cowl having few lateral septa in the pedicle
valve (about 10-14), generally grooved (angustilobate),
and with interseptal ridges well developed.
TYPES.—Holotype: USNM 150651b; figured paratypes:
150651a, 150653b,k,o,q-s, 150654, 150658b,
150623, 150624; measured paratypes: 150651a,
150653a,b, 150658a-j, 150654; unfigured paratypes:
150651a, 150653a, c-j, m, n, p.
COMPARISON.—This species is most like E. chaotica,
new species, but it differs in being smaller
with about 14 or fewer lateral septa, in having a
poorly developed cowl, and generally in having
more septa in the angustilobate condition. The
median ridge is poorly developed compared to that
of E. chaotica. The brachial valve interior of the
lobes is covered by thicker adventitious deposits
that nearly fill the lobe except for the narrow
groove just inside the lobe edge.
Eolyttonia diabloensis (Stehli) is similar but generally
larger, with less crowded lateral septa having
a much lesser development of interseptal
ridges. Furthermore, the lobes of the brachial valve
do not have the thickening deposits in them.
DISCUSSION.—This species is definitely conical,
but the cowl generally is aborted and often somewhat
thickened. The most interesting feature of
the species is the development of the lateral septa,
which give the appearance of close crowding because
of the interseptal ridge development. The
septal development is extremely variable, but generally
the posterior lobes are in the angustilobate
stage, which becomes modified anteriorly to low
but fairly simple solidiseptate. Interseptal ridges
develop at an early stage and normally are elaborately
formed through the entire cone. The
interseptal ridge generally is crowded against
the posterior walls of the lateral septum, complicating
the appearance and confusing its origin
and type. Both sides of the lateral ridge are pitted
or striated, and the interseptal ridge becomes
pitted when formed against a pitted lateral septum.
The median ridge of E. pocillata is poorly developed,
a feature that distinguishes this species
from several others. It is best developed in the
posterior half, but it is low in the anterior part of
most specimens and often is obscurely divided.
The brachial valve hinge is straight and usually
there is a smooth area where the shell slides
against the hinge. It is also provided with articulating
processes. The cardinal process is small and
asymmetrical when well preserved, but this feature
is seldom seen. The anterior margin of the lobes
426 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
commonly is serrated strongly to accommodate the
fluting or striation of the lateral septa. The inner
parts of the lobes are heavily filled with adventitious
material, leaving a narrow groove inside the
lobe margins and the inner thickening.
The median cleft of the brachial valve is short
in adults. As the cleft is eliminated anteriorly by
deposition of shell material at the proximal end,
the effect on the interior is to produce a broad,
carinate median ridge. This is strongly developed
along the axis but less so in the hinge region.
Eolyttonia progressa, new species
PLATE 159: FIGURES 1-10; PLATE 160: FIGURES 11-19;
PLATE 161: FIGURES 1-11
Lyttonia nobilis americanus R. E. King (not Girty), 1931:103
(part), pi. 32: fig. 7 (only).
Large, variable, generally broadly triangular in
outline with rounded front margin and irregular
sides; posterior narrowed and overhanging hinge in
form of fairly broad cowl, attachment usually small,
with callus flap behind it; generally flatly convex
in lateral profile but broadly convex in cross section.
Surface marked by irregular concentric
wrinkles.
Pedicle valve interior with narrow hinge having
strong rounded lip above it; lateral septa numbering
about 18 in large adults, 8 septa in 25 mm usually
fairly strongly elevated at least in posterior
three-fourths; septa with fairly broad, flattened
(solidiseptate) or in some cases distally grooved
(angustilobate) crests. Lateral septal lobes low;
interseptal callosities generally not strongly developed
and usually best established by anterior
third, where septa are low. Median ridge low,
rounded, strongest in median region, widening,
flattening or dividing at anterior as insert to
brachial valve cleft.
Brachial valve generally irregular in shape, narrow
visceral body bearing median depression; lobes
narrow measuring about 2.4 mm in longitudinal
direction, not distally united.
Brachial valve interior with quadrilobed, symmetrical
cardinal process becoming greatly swollen
in adults; shaft grooved; median ridge flattened and
divided or grooved just anterior to cardinal process,
moderately elevated anteriorly; lobes moderately
deep, with beaded marginal ridge parallel to
their sides; proximal ends of posterior interlobe
spaces partially filled by webs of adventitious shell;
valve anteriorly cleft in anterior third.
MEASUREMENTS (in mm).—
maximum hinge cowl
length width width height length
USNM 728
150749a 67.0+ 72.0 ? 49.7 33.0
150749b 59.6 79.4 12.0 15.0 19.0
150749c 54.0+ 57.4* 13.0 21.0 13.0
150749d 41.0+ 51.5 12.6 12.4 22.4
USNM 716v
150740a 81.0 81.0 ? 21.0? 18.0?
USNM 7l5i
150739a 57.0 51.0 10.0 14.0? 5.0?
150739b 77.0 87.0 ? 21.0? 23.0?
USNM 714o
150738 48.0 68.0 ? 21.0? 23.0?
USNM 719z
151311a 67.5 46.0 ? 30.0 33.7
(holotype)
STRATIGRAPHIC OCCURRENCE.—Cherry Canyon Formation
(Getaway Member), Word Formation (Appel
Ranch Member).
LOCALITIES.—Getaway: AMNH 21, 496, 512, 519,
600, Moore 31, USNM 728, 730, 732; Appel Ranch:
USNM 704, 714o, 715i, 716v, 719z, 722t, 727j.
DIAGNOSIS.—Large Eolyttonia with the width
equal to, or greater than, the length and with
strongly elevated lateral septa in the pedicle valve.
TYPES.—Holotype: USNM 151311a; figured
paratypes: 150739c, 150746a, 150749a,d-i 15131 lb-d,
153625; measured paratypes: 150738, 150739a,b,
150740a, 150749a-d; unfigured paratypes: 150739a,b,
150749c.
COMPARISON.—This species is easily distinguished
from all others of the genus by its extremely wide
conical form and the strength and elevation of the
lateral septa in the pedicle valve.
DISCUSSION.—The species is represented by a fair
number of specimens, but they are not well preserved
and many are fragmentary. It is identified in
the Guadalupe Mountains as well as in the Glass
Mountains. Naturally, with such a wide geographical
gap between them, the specimens from the
two places show some differences, but they do share
in common the strongly elevated lateral septa, the
number of the septa in 25 mm, and other details.
The specimens from the Guadalupes are thickshelled
and robust. The Glass Mountains specimens
are not as stout, but they are, nevertheless,
large, strong shells.
Too few of the specimens are complete enough
NUMBER 15 427
to show the cowl in undamaged condition, but the
Glass Mountains specimens generally have it extending
over the hinge to make a cone. Growth of
the cowl in a posterior direction is unusual, but
some small specimens have this feature, thus producing
broad open cones. The Guadalupe Mountains
shells are generally cones with the cowl extending
over the hinge, but apparently a larger
proportion of specimens also has the cowl growing
more posteriorly than posterodorsally. Consequently,
some large specimens that are open cones
appear in the collection.
Small specimens of this species have the lateral
septa grooved latilobate to angustilobate, and the
very young have a well-marked but anteriorly incomplete
vallum. Many adult specimens display
grooving along the crest of the lateral septa in
their distal parts, the septa along the axial channel
being rounded. Many septa are strongly oblique,
especially in convex individuals, and the dip of the
septa is toward the posterior. Specimens nearly
flat or slightly concave have the septa nearly perpendicular
to the valve floor.
The median ridge is fairly strongly developed,
but it is not greatly elevated in any of them. It is
generally low arid threadlike at the posterior of
many specimens, and, in others, its anterior part
is grooved for some distance, but this feature is
not uniform.
The brachial valves have no noteworthy differences.
In both geographic regions they seem to have
about the same amount of internal callus deposit.
The median ridge generally is developed strongly
in specimens from both areas.
The smallest specimen of this species comes from
USNM 716v in the Glass Mountains. It is about
16 mm in diameter and is in the 4-lobe stage, having
strongly grooved lateral septa and a straight
narrow hinge. The specimen is nearly flat, having
been attached on a fenestellid frond. The direction
of the branches of the fenestellid have been impressed
on the interior of the thin shell and have
produced an oblique striation of the interior. The
collection is not sufficiently rich in young specimens
to trace the ontogeny of the species.
Eolyttonia species
PLATES 160, 162, 191
Several species of Eolyttonia are represented by
specimens too poor to describe as separate species.
These specimens are from a number of stratigraphic
levels and are best discussed on the basis of their
geological appearance.
Eolyttonia from Sullivan Peak Member
Six lots are from this level; four are unsilicified
and were taken from matrix by splitting the rock.
The specimens are large, all are fragmentary, and
none shows the complete shape. The large size
suggests relationship to E. gigantea, but the completely
conical form of that species cannot be
proved, nor can any other significant details.
LOCALITIES.—USNM 708e (USNM 150791), 71 Id
(USNM 150793), 715h (USNM 150794).
Eolyttonia species 1 from Taylor Ranch Member
PLATE 160: FIGURES 1, 2
The specimens from this horizon come from
several localities, but two types of facies are represented:
specimens from a sponge bioherm (702d)
and from a muddy bottom.
LOCALITIES.—USNM 702d, 702m (USNM 150788),
716n (USNM 151310), 716o (USNM 150796), and
716c.
Specimens from the sponge bioherm are extremely
variable, some being widely triangular, but
others somewhat elongate. The lateral septa, however,
suggest mutual relationship because these are
of fairly advanced type without grooves (solidiseptate)
or with the grooves, shallow (angustilobate),
and oblique or confined to the oldest shell
part. Many of the lateral septa are anguliseptate,
with some deeply excavated anteriorly and with
sharp crests. Furthermore, in the widest specimen
the lateral septa are strongly elevated, very broad,
and are strongly striated in a longitudinal direction.
Brachial valves preserving the posterior half can
be removed from two of the specimens to show a
broad, deeply cleft cardinal process and a prominent
median ridge. Both of these valves have the
lateral lobe bifurcated.
The sponge bioherm is surrounded by finegrained,
brittle, somewhat siliceous limestone that
weathers into nodules or cobbles. Fossils, mostly
brachiopods, are enclosed partially by the nodules
428 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
and are frequently well preserved and fairly abundant.
They include the large productoid Peniculauris
imitata, which is the distinctive species of
this level. Lyttoniids are rare in the nodular beds
and are seldom well preserved. Several pedicle
valves are in the USNM collection along with a
few brachial valves completely isolated from their
companion valves. The pedicle valves are normal,
gently convex to slightly concave in lateral profile,
but gently convex in anterior profile or cross-section.
Several specimens are concave medially, but
the best interior in the collection is a large pedicle
valve (USNM 150788) nestled against one ear of a
large Peniculauris. This specimen is deeply concave,
and its shape is controlled by the curvature of
the brachial valve of the productid. As a result,
the lateral septa of this specimen are mainly in the
anguliseptate stage. The hinge, however, is clearly
visible and the cowl is smeared out over the ear and
hinge region of its host. The lateral septa of the
more normal, nearly flat pedicle valves are less elevated,
less oblique, and with well-marked grooves
along their crests (angustilobate) in the older parts
of the shell. The lateral septa of the anterior parts
are low and inconspicuous and have strongly developed
interseptal ridges. Striation of the septa is
not strong in any specimen.
Brachial valves are notable for the slenderness
of the axial region and the lateral lobes. They are
also deeply but narrowly cleft to about the midvalve
and have a coarsely, pustulose exterior.
The preservation of these two groups of lyttoniids,
the one from the bioherm and the other
from a muddy bottom, are so different that it is difficult
to relate them. They may be the same species,
but the material at hand does not permit a decision
in the matter. Furthermore, it is not possible
to relate the specimens from the nodules to any
of the species named herein. The specimens from
the bioherm are somewhat similar to E. circularis,
but they are narrower posteriorly and not so deep.
TYPES.—Figured specimens: USNM 150788,
153627.
Eolyttonia from Cathedral Mountain Formation
Two lots of a lyttoniid different from the abundant
specimens in the Split Tank area need special
mention.
Eolyttonia species 2 from USNM 702un
PLATE 162: FIGURES 1-7
The specimens from this locality differ from E.
pocillata in being more elongate, deeper, with a
smaller cowl, and highly advanced lateral septa in
the pedicle valve. The best-preserved specimen is
•15 mm long and about the same width at the
anterior. It is conical in form, moderately convex
in lateral and anterior profiles, but with a strongly
truncated apex where it attached. Its living position
must have been fairly erect. The cowl is moderately
long and commonly overhangs the hinge
for 10 or more millimeters. Inside the pedicle
valve the lateral septa are mostly anguliseptate, delicate
and thin, and deeply excavated. They descend
in height anteriorly, where the anteriormost two
or three out of the 12 maximum are low and inconspicuous.
Their posterior slope is generally striated.
In the young the lateral septa are angustilobate,
but high at the posterior. The interior of
the brachial valve is unknown.
TYPES.—Figured specimens: USNM 150769a-c.
Eolyttonia species 3 from Lamar Limestone
Member
PLATE 191: FIGURES 4-7
Two specimens from the Lamar Limestone indicate
an undescribed species. These are completely
conical pedicle valves. One specimen has two individuals
adhering to each other by the long cowl,
which makes a complete cone, the posterior and
anterior sides being almost equal. The lateral septa
are moderately elevated, about 9 in number and
are slightly over 2 mm. In this respect, these specimens
internally resemble Collemataria spatulata
from the same horizon. The median ridge is low
and rounded. The hinge is at the base of the cowl.
LOCALITY.—USNM 738b.
TYPPS.—Figured specimen: USNM 150774.
Eolyttonia species 4 from Capitan Limestone
One specimen from the Capitan Limestone
(USNM 725-1; USNM 151317), is a strongly conical
form with closely spaced septa and a long cowl.
The specimen suggests the conical form from the
Lamar Limestone noted above.
NUMBER 15 429
Genus Petasmaia Cooper and Grant, 1969
[Greek petasma (spread out) ]
Petasmaia Cooper and Grant, 1969:10.
Usually large, broadly expanded anteriorly, but
commonly narrow posteriorly where attached to
crinoid stem or to other narrow object; profile flat
to gently convex; surface marked by concentric
growth lines and wrinkles.
Pedicle valve interior with narrow hinge with
strong posterior lip, muscle region bounded by
strong, thin, slightly divergent plates; lateral septa
numerous, usually latilobate to angustilobate in
young, but generally thin and oblique in adult
(solidiseptate to anguliseptate) median ridge low,
thin, and delicate, open or split only at extreme
distal end.
Brachial valve consisting of numerous lobes
convex anteriorly, median axis grooved longitudinally
and cleft narrowly at anterior; axial region
commonly narrowly convex; surface smooth; hinge
narrow and with small, deflected articulating
points.
Brachial valve interior with double but bifurcated,
short-shafted cardinal process with 4 myophore
surfaces. Median ridge moderately well developed;
lobes moderately deep.
TYPE-SPECIES.—Petasmaia £xpansa Cooper and
Grant (1969:10, pi. 2: 15-18).
DIAGNOSIS.—Large expanded Lyttoniidae having
strong, divergent plates bounding muscle region
and well-developed complete cardinal process.
COMPARISON.—This genus at present need be
compared only to Oldhaminella Wanner and Sieverts
(1935) and to Leptodus Kayser (1883), which
have elevated plates bounding the muscle region.
Oldhaminella, however, is a much smaller creature
and is strongly convex, a fact that led to its name—
derived from convex Oldhamina. Petasmaia is
generally not .strongly convex, but it varies from
nearly flat to moderately curved. Furthermore,
Petasmaia has many more lateral septa and lobes
than Oldhaminella. Another important difference
is the fact that the Timor genus has two strong
muscle ridges on each side of the muscle region,
the inner pair running parallel to the median ridge
for some distance. Wanner and Sieverts (1935)
described the lateral septa as in the "Eolyttonia"
(latilobate to solidiseptate) stage in the outer half,
but in the Oldhamina stage (anguliseptate) in the
inner half. In the Glass Mountains genus these
stages can be recognized, the "Eolyttonia" stage in
the young and the "Oldhamina" stage in the adults,
especially in the more convex individuals.
Oldhaminella is not a well-known genus because
only two ventral valves were described and the
brachial valve is not known. The two described
specimens were attached to crinoid stems, which so
irritated the stem that the crinoid deposited additional
lime, some of it concealing part of the brachiopod.
No such phenomenon was seen in connection
with Petasmaia, which also has an affinity for crinoid
stems.
Petasmaia is similar to Leptodus, as that genus
is now conceived, in its expanded form and in the
presence of lateral plates in the apical region. It
differs, however, in having much stronger lateral
plates, which are subparallel, and it seldom shows
the musculature as the Pakistan shells do. Its lobes
in the posterior are somewhat less advanced than
those in Leptodus in the same place. The lateral
lobes of Petasmaia are usually oblique to the inner
surface and are usually strongly carinate or almost
knife-edge sharp (anguliseptate). Those of Leptodus
are blunt and usually nearly erect.
DISCUSSION.—Petasmaia, like other members of
the Lyttoniidae, is variable in outline and profile.
The variability is mainly owing to the kind of host
on which it started life. Most specimens in the collection
are attached to crinoid stems or other narrow
objects, such as the curved posterior of the
pelecypod Leiopteria, and to narrow brachiopods.
The favorite attachment site is the crinoid stem,
which affects the form of the shell. Specimens thus
attached generally have narrow posterior regions
and strongly narrowly convex median areas in the
brachial valve. The brachiopod generally wraps a
strong sheath of shell material around the crinoid
stem to form an attachment tube. Convexity develops
as the anterior of the shell grows away from
the crinoid stem. We suppose that the Petasmaia
lived with its posterior down and the anterior
margin up when attached to a crinoid stem, but
it is possible, as Grant (1963) has shown with spat
of Linoproductus, that direction of growth is entirely
an accident of the position of settling.
Although Petasmaia appears to have preferred
narrow objects on which to grow, a healthy animal
430 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
was not deterred if it settled on a flat object. On
such substrate the pedicle valve may form a veneer
over the surface for as much as 25 mm. Such individuals
usually are broadly rounded in outline
without any posterior attenuation and the shell may
range from flat to moderately convex, depending on
age and the congeniality of its surroundings.
The hinge of the pedicle valve of Petasmaia is
like that of Collemataria in having a strong posterior
lip over the slit and lateral notches. The
horizontal slit is deep and the lateral notches strong,
with the anterior shelf serving to receive the articulatory
processes of the brachial valve. The deep
notches and overhanging lip serve as articulating
joints and for holding the brachial valve in place.
The strong lateral plates diverging from the inner
ends of the articulating notches of the hinge
have been interpreted as dental plates or the remnants
of these structures. Actually no articulating
processes or teeth occur in the pedicle valve, and
this interpretation is therefore doubtful. These lateral
plates are herein regarded as bounding plates
of the muscle area, similar to, but more elaborate
than, the sheath surrounding the single muscle in
Poikilosakos and Pseudoleptodus. In most specimens
these plates or lateral myophragms are simple,
thin, erect septa originating at the inner ends of
the articulating notches and extending with slight
divergence anteriorly to the second or third lateral
septum. In one specimen (USNM 151343g) the
plates are not erect but are curved inwardly,
strongly suggesting the muscle sheath of the Poikilosakidae.
The lateral septa are variable in adults as well
as in the young. In immature specimens a close
resemblance to the vallum of Poikilosakos or Pseudoleptodus
is shown by the fact that the wall is
continuous and produces inlobes and outlobes, the
latter usually the wider. The vallum of the young,
however, is not continuous with the median loop
anteriorly, as in the more primitive genera.
With advancing age and increasing size, the lateral
lobes are crowded anteriorly, some of the
posterior lobes in large specimens becoming angustilobate
proximally, but solidiseptate to anguliseptate
distally. In adults generally the lateral lobes
have become anguliseptate and are sharp-edged
septa lying at a low angle to the inner surface.
Minor fluting of the septa at right angles to the
edge is clear in some specimens, but this development
is not as strong as in later genera.
The median lobe of the smallest specimens, as
well as of the largest adults, has been laterally compressed
into a single ridge divided or open only at
the extreme distal extremity, and this for a short
distance only. The ridge extends from the horizontal
hinge groove anteriorly almost to the anterior
margin. Near the margin its height decreases, and
in some specimens a division into two faint ridges
may be seen.
The hinge region of the brachial valve seen from
the exterior is characterized by two small points
that are deflected in a dorsal direction and serve
to articulate the valve to the lateral notches of the
pedicle valve. Also present is a small, smooth triangular
area having a widely obtuse angle and two
small lateral angles. This area (Williams' "primary
shell") represents the surface of movement of
the posterior of the brachial valve in the horizontal
groove against the posterior articulating lip of the
pedicle valve hinge.
The cardinal process consists of twin myophores
joined to a shaft, the whole consisting of two shafts
and four myophore surfaces. The two shafts and
twin myophores are separated by a deep groove.
The whole structure lies at approximately the middle
of the hinge, but it does not always terminate
or lie in the path of the median ridge. This cardinal
process contrasts strongly with that of the Poikilosakidae.
The brachial valve of Petasmaia is cleft anteriorly
for about one-third its length. The cleft is
filled proximally as the shell grows, leaving a fairly
strong longitudinal sulcus behind it.
OCCURRENCE.—Petasmaia is not a common genus
and has been found only in the Glass Mountains,
normally in the Cathedral Mountain Formation at
the level of Institella, with a single fragment having
been found in the Road Canyon Formation. Furthermore,
it has been found mostly at Split Tank
and westward as far as the Old Word Ranch. It
was not seen in the residues from the Wedin Member
of the Cathedral Mountain Formation in which
Institella is so common.
Petasmaia expansa Cooper and Grant
PLATE 163: FIGURES 1-8; PLATE 164: FIGURES 1-16;
PLATE 165: FICURES 1-23; PLATE 169: FIGURES 11-16
NUMBER 15 431
Petasmaia expansa Cooper and Grant, 1969:10, pi. 2: figs.
15-18.
Pedicle valve large, variable in shape and convexity,
generally narrow posteriorly and expanding
widely anteriorly, greatest width forward of midvalve;
more rarely widely subcircular; usually gently
concavoconvex but varying from nearly flat to moderately
curved longitudinally. Exterior surface with
growth lines only, but commonly with uneven surface
from impinging against neighbors. Attachment
commonly to narrow round objects such as crinoid
stems or bryozoa, resulting in forms with narrow
posterior and scalloped posterolateral margins;
more rarely attached by part of posterior to flat
objects, resulting in more circular form. Attachment
callus or posterior flap moderately large, frequently
folded completely around object of attachment
and along posterolateral margins. Lateral
nonseptate areas flat to moderately folded in dorsal
direction on posterolateral margins, usually flat to
slightly deflected in anterior half to third.
Pedicle valve interior with narrow, straight hinge
slightly produced and moderately elevated; hinge
margins of both valves in contact; lateral sockets
deep; interarea (?) flat and triangular. Muscle field
elongate, subtriangular in outline and bounded by
strong, erect plates tangential to first 1-3 septal
lobes and bounding median, trough. Lateral septa
variable, numbering 20 in largest specimens, strongest
posteriorly and decreasing in strength laterally
and anteriorly. Young septa in some specimens
latilobate to angustilobate, but in others solidiseptate
to anguliseptate; young septa nearly vertical
but later ones medianly situated in old shells steeply
inclined, dipping posteriorly at low angle to valve
surface. Septa strongly convex anteriorly in posterior
but gently convex toward anterior in anterior
half. Crests of lateral septa ranging from 4
to 6 mm apart. Posterior surfaces of septa generally
faintly grooved in direction of long axis of young
shells but beaded in old ones; interseptal spaces
generally smooth but in old shells coarsely pitted
in rows adjacent to anterior side of septum. Median
longitudinal septum, low, carinate, and continuous
from hinge nearly to anterior margin.
Brachial valve conforming to curvature of pedicle
valve; exterior finely pustulose. Hinge narrow and
nearly straight with strong pointed and slightly
deflected lateral articulating processes; posterolateral
lobes narrow but widening progressively to midvalve.
Posterior body moderately convex and fairly
deep, marked centrally by narrow, shallow depression
extending to median cleft at anterior; median
cleft variable in length depending on age. Lateral
lobes strongly rounded in cross section. Median
trough moderately deep; median ridge strongest at
midvalve, vestigial or absent posteriorly. Cardinal
process small, without buttress.
MEASUREMENTS (in mm).—
USNM 702b
151341a
151341b
151341c
151341d
151341e
15134H
151341g
USNM 702un
151343
(holotype)
153601a
length
85.9
66.0
55.0
23.0
25.0
19.0
10.5
71.0
75.0
maximum
width
85.9
76.0
62.0
24.0
23.5
19.0
11.5
65.4
85.0
hinge
width
11.0
8.0
7.0
5.0
4.5
4.0
3.0
10.6
11.0
midwidth
83.0
63.0
54.0
24.0
23.5
19.0
11.5
65.4
80.0
STRATIGRAPHIC OCCURRENCE.—Cathedral Mountain
Formation (Institella beds).
LOCALITIES.—AMNH 500E, 500F, 500H, 500L,
504, USNM 702, 702a, 702b, 702-low, 702un, 703b,
726u, 726x.
DIAGNOSIS.—Petasmaia generally with narrow
posterior but broadly expanded anterior region.
TYPES.—Holotype: USNM 151343; figured paratypes:
151441a, d-g; unfigured paratypes: 151341b,
c; measured paratypes: 151341a-g; figured hypotypes:
151339, 151345, 153598, 153599a, b, 153600,
153601a, b, 155128b-h, 155129a-e.
COMPARISON.—When seen from the inside, this
species is readily distinguished by its lateral myophragms.
When only the exterior is visible, it is
generally distinguishable from Eolyttonia Fredericks,
with which it occurs, by the narrowed posterior
but expanded anterior and shallow convexity.
The brachial valve also is generally deeper posteriorly
than those of the other genera.
DISCUSSION.—This species is rare in the Split
Tank area and just west of there. It is best developed
at USNM 702un, where it occurs in its maximum
size. At USNM 702b it is seldom found in
living position because that deposit consists chiefly
of shell debris in a thanatocoenose; nevertheless,
432 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
the best immature specimens were taken from this
locality. The species is extremely rare at USNM
703b.
Bain (1971:134) illustrated and described an inverted
specimen of P. expansa that is attached to a
crinoid stem by the pedicle valve beak; the specimen
provides the substrate for attachment of an
individual of Hercosia uddeni (Bose), whose spines
and much of the surface of the P. expansa are covered
by an encrusting fistuliporid bryozoan. The
pedicle valve of P. expansa was identified (Bain,
1971) as the brachial valve of a species of Derbyia,
incredibly suggesting that Derbyia could have lived
and grown to large size while the function of the
articulating apparatus, including the cardinal process,
was defeated by direct impingement of a crinoid
stem. The upright position of the H. uddeni indicates
that, if the crinoid was living when P. expansa
attached to it, the orientation of P expansa had
the pedicle valve up and the brachial valve facing
the sea floor. Such orientation would have protected
the openly pinnate brachial valve from settling
sediment by providing a rooflike pedicle
valve. The single example, however, with its obvious
ambiguities, does not prove that this was the
preferred orientation of P. expansa.
Petasmaia species 1
Fragments of a large Petasmaia were taken from
the Road Canyon Formation at USNM 720d and
736x, showing still another link of this formation
to the Leonardian. The specimens were attached to
a crinoid stem in life, as usual with the genus, and
the lateral septa are well preserved. Only four of
the lateral lobes are preserved, and the median
region is keeled. The size and shape of the species
represented are problematical.
TYPES.—Described specimens: USNM 151345,
154922.
Loxophragmus, new genus
[Greek loxos (slanting) + phragmos (wall) ]
Small, transversely elliptical in outline and conical
in profile; cowl short but strongly overhanging
hinge region; attachment at apex small; surface
marked by concentric lines and wrinkles.
Pedicle valve interior with straight hinge line
having lateral grooves for articulating but without
projecting posterior lip. Vallum developed in
young but adult shells with broad, 6-7, oblique,
low, lateral septal ridges usually strongly fluted or
striated and descending in elevation anteriorly;
median ridge low posteriorly but strong and thick
near midvalve, becoming divided anteriorly.
Brachial valve with 6-7 narrow lateral loops;
shell body short; shell cleft anteriorly from one-half
to two-thirds length from anterior end; cleft narrow.
Exterior granular.
Brachial valve interior with small eccentric cardinal
process; median ridge low; lobes moderately
concave.
TYPE-SPECIES.—Loxophragmus ellipticus, new
species.
DIAGNOSIS.—Small Lyttoniidae with strongly
oblique lateral septa (terminivallate).
COMPARISON.—This genus suggests Keyserlingina
Tschernyschew in its form and profile, but it has a
strong median ridge and the lobes of the vallum
modified to strongly oblique, single-crested lateral
septa (solidiseptate to anguliseptate).
DISCUSSION.—This genus is unusual in producing
advanced Oldhamina-like lateral septa (anguliseptate)
in a shell with otherwise primitive
characters, such as the deeply cleft brachial valve
and the dual median ridge.
Loxophragmus ellipticus, new species
PLATE 137: FIGURES 21-22; PLATE 152: FIGURES 5-8;
PLATE 166: FIGURES 1-37
Small, incomplete cone; width generally greater
than length; greatest width near midvalve; profile
gently to moderately convex. Cicatrix of attachment
small, attachment flap variable, cowl short.
Surface with strong concentric wrinkles and fine
lines of growth.
Pedicle valve interior with narrow hinge having
lateral articulating sockets; lobes numbering 9 in
fully grown adult; initial loops narrow; posterior
4 lobes generally bowed strongly in anterior direction,
tilted strongly anteriorly and deeply undercut;
crests of early loops usually with single crest (solidiseptate
to anguliseptate), but occasionally doublecrested
(angustilobate) lobes strongly striated
longitudinally, measuring 2.5 to 3 mm from crest
to crest; anterior 2-4 lobes slightly elevated, elevation
decreasing anteriorly, last lobe sometimes diffiNUMBER
15 433
cult to determine. Median ridge generally thick
and moderately elevated, with single crest on posterior
but anteriorly decreasing in height, flattened
to grooved along crest and, when grooved, suggesting
division into 2 ridges. Interseptal lateral callosities,
low, developed only anteriorly in last 2-3
lobes.
Brachial valve with narrow lobes and short body;
hinge straight with lateral articulating flanges; cardinal
process consisting of 1 slightly eccentric lobe
with 2 muscle scars; median ridge low; concave
side of lobes with trough and elevated line parallel
to lobe margins, which are thickened. Median cleft
extending for about three-fourths valve length.
MEASUREMENTS (in mm).—
USNM 702b
150683a
150683b
150683c
150683d
150683e
150683f
150683g
150683h
150683i
150683J
150683k
USNM 702 (low)
150685
(holotype)
length
24.2
19.6
20.8
18.2
15.4
20.6
15.9
15.0
15.0
16.2
14.0
19.6
maximum
width
27.0
22.3
22.4?
22.0
24.1
23.2
23.0
22.3?
19.6
19.6
18.5
27.3
hinge
width
5.2
3.7
5.4
4.3
3.3
5.1
3.7
5.5
4.2
3.9
4.0
?
height
9.6
7.6
6.7
8.1
5.9
5.5
6.8
6.2
6.0
6.8
5.6
8.2
cowl
length
5.3
3.3
4.0
1.0
2.8
4.4
3.0
4.4
3.6
5.3
3.0
5.8
STRATIGRAPHIC OCCURRENCE.—Cathedral Mountain
Formation (Institella Zone), and upper Cathedral
Mountain.
LOCALITIES.—AMNH 500, 500D, 500L, 500N,
USNM 702, 702b, 702ent, 702 (low), 702un, 703b,
703bs, 726x, 735b.
DIAGNOSIS.—Small, laterally expanded Loxophragmus
with early lobes of the pedicle valve
strongly inclined forward and anteriorly excavated.
TYPES.—Holotype: USNM 150685; figured paratypes:
150681 c, d, 150682a-c, 150683b, g, 150686a,
153611, 153612a, b, 153613, 153614a-d; measured
paratypes: 150683a-k; unfigured paratypes:
150681a, b, 150683a, c-f, 150686b.
COMPARISON.—The small size and generally elliptical
form separate this species from all others
of the genus. The species, which resembles some
forms of Keyserlingina Tschernyschew, has a more
advanced type of median ridge and lateral septa.
Furthermore, Keyserlingina has a more symmetrically
conical form than species of Loxophragmus.
DISCUSSION.—This is an anomalous species because
it has primitive features in the deeply cleft
brachial valve and advanced characters in the nature
of the lateral septa. The conical form is unusual
with only a small development of the cowl.
The earlier genus, Keyserlingina, is more strongly
conical. Relationships to Eolyttonia Fredericks
seem clear in that the young have a fairly welldeveloped
vallum. In later stages the shell is unusually
advanced in the character of its lateral
septa, which are similar to Oldhamina (anguliseptate)
except that the septa are usually nearly prone.
This species has few septa, only up to about
seven or eight. Nearly all lateral septa are broad
and flat, the posterior three or four strongly oblique
to the valve floor, but the more anterior ones
usually are only slightly elevated. The surface of
the septa are broad and flat and usually striated.
The broad, flat surface represents the groove along
the septal edge so characteristic of Eolyttonia. Usually
the slight ridge forming the posterior side of
the groove can be seen at the posterior base of
the septum. These septal ridges, thus, are very
oblique, resulting in a widening of the distance
between segments of the vallum.
The median ridge is generally fairly thick, originating
at the hinge where it is low but strengthening
and heightening anteriorly to midvalve or
beyond. Near midvalve it flattens and widens and
usually is grooved to form two low ridges.
The brachial valve is unusual for the deep cleft
that extends posteriorly for more than half the
valve length. The loops are narrow and moderately
to strongly convex toward the anterior. The
surface is granular as usual in the Lyttoniidae. The
hinge region bears small ears to fit into the articulating
slots of the pedicle valve.
Internally the cardinal process is small and offcenter.
The axial region is strengthened by ridges
extending from the beginning of the cleft and running
parallel to the inside wall to the anterior end.
Collemataria, new genus
[Greek kolla (cement) ]
Lyttonia (part) R. E. King, 1931:102.
434 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
Variable, usually scoop-shaped, large, with subtriangular
outline, apex narrow, anterior expanding;
attached at beak or apex by posteriorly growing
callus and usually further cemented by broad
flap over attachment and part of host; sides posteriorly
somewhat narrowly folded in dorsal direction.
Surface marked by concentric lines and
wrinkles.
Pedicle valve interior usually with numerous lateral
septa, generally oblique and ungrooved (solidiseptate)
in adults, but may be grooved in young
(angustilobate); median ridge moderately well developed,
reaching to hinge; margin of cowl forming
upper lip of hinge.
Brachial valve with slightly deflected ears but
without articulating processes; hinge usually narrow;
valve anteriorly cleft, slit healed from posterior
toward anterior or at numerous points
between; median depression strong.
Brachial valve interior with variable cardinal
process having divided shaft and 4 myophore surfaces.
Median ridge low and thick.
TYPE-SPECIES.—Collemataria elongata, new species.
DIAGNOSIS.—Usually large Lyttoniidae with
progressive lateral septa, posterior callus flap for
attachment, and hinge forming margin of cowl.
COMPARISON.—Collemataria in its outline and
profile is most like Leptodus Kayser, from which it
differs in not having signs of any musculature or
bounding plates in the apical region of the pedicle
valve. Although the attachment area of Leptodus
is like that of Collemataria, the hinge of the former
is revealed as a narrow slit with a posterior lip and,
thus, is unlike that of Collemataria in which the
anterior margin of the cowl serves as the lip of the
hinge. We were unable to find any clear distinction
between the lateral septa of the two genera,
thus making it necessary to have complete specimens
for identification.
Collemataria differs from Eolyttonia Fredericks
in form and outline, but especially in the relationship
of the hinge to the cowl. In Collemataria the
cowl is outside the hinge, which appears as a slit
with overhanging lip; the lip, in some species, is
thick and often bulbous. The lateral septa of Collemataria
are somewhat more advanced (solidiseptate)
than those of Eolyttonia, which often has the
majority of the septa deeply grooved medially (angustilobate).
Petasmaia Cooper and Grant and Coscinophora
Cooper and Stehli are the only other large American
Lyttoniidae, but they are so unlike Collemataria
that close comparison is unnecessary. The
former is usually narrow at the hinge and has wellmarked
plates bounding the muscles. Coscinophora
is unique in being fragmentivallate, all septa modified
to rows of beads and the brachial valve a solid
plate with perforations matching the beads.
Collemataria americana (Girty)
PLATE 157: FIGURES 3-6; PLATE 181: FIGURE 12
Leptodus americanus Girty, 1909:212, pi. 25: figs. l-3a.
This species has been identified widely throughout
the Permian areas of this country from many
different stratigraphic levels. Obviously a variety
of species, probably also genera, have been thus
misidentified. One of Girty's specimens has also
been assigned to the genus Rigbyella, after Wanner
and Sieverts (1935) had indicated that it did
not belong to Leptodus. The true relationships of
this species largely depend on determining the locality
from which Girty's specimens came. This
is now almost impossible, but it seems certain that
they came from the Sierra Diablo, although the
exact level is not known definitely. According to
Girty (1909:512) the specimens come from USGS
3764, a locality mentioned in Von Streeruwitz's
report (1893:170), which is said to be "along the
cliffs on the east side of the Sierra Diablo, about 8
miles north of Hazel Mine." This would locate
the section approximately opposite the north end
of the Baylor Mountains and about 2.5 miles south
of Victorio Peak. This also puts the locality into
close proximity with those collected by F. G. Stehli
and ourselves, near the mouth of Victorio Canyon.
Not only does the geographic location suggest
Stehli's material, but also the preservation and color
of Girty's types are like those of Stehli's specimens.
Girty's specimens are well silicified, stout but brittle,
the color a yellowish brown like some of the
Stehli material preserved at the American Museum
of Natural History and some specimens at the
United States National Museum. It is possible,
therefore, to suggest that the level from which
NUMBER 15 435
"Leptodus" americanus was taken is the lower part
of the Bone Spring Limestone.
Although all of the evidence points to the location
and horizon of Stehli, to prove that this species
belongs to either of Stehli's described species
from the Sierra Diablo is more difficult. Stehli
(1954:307, 308) described Leptodus} diabloensis
and Leptodus? marshalli and distinguished them
mostly on the type of attachment and the general
form of the shell. The former is definitely conical
and was attached without a callus flap, whereas
the latter had a narrow posterior attachment with
strong callus. Collemataria americana appears to
be most like Leptodus? marshalli in having an expanded
callus flap and elevated lateral septa with an
obscure groove along the crest of several of them
(angustilobate to solidiseptate). Collemataria marshalli,
however, is differently shaped and not
strongly granulose.
Leptodus americanus is herein assigned to Collemataria
because of its posterior flap, cowl, and the
angustilobate nature of the lateral septa. Several
of the lateral septa have a fairly well-marked groove
along the crest, as is characteristic of at least the
early formed lateral septa of Collemataria. The
median ridge is fairly strong and, in the paratype
(USNM 118513a), is divided at the anterior. A
fragmentary brachial valve (USNM 118513b) has a
small eccentric cardinal process, a strong median
ridge with median depression, and an anterior cleft.
It is not possible to say whether or not these interior
characters, based on one specimen, are a mark
of the species rather than the details of the specimen.
Girty did not designate a type for his species. We,
therefore, select the largest and most nearly complete
specimen, USNM 118513, as lectotype. The
other two specimens, an incomplete pedicle valve
(USNM 118513a) and an incomplete brachial valve
(USNM 118513b), are paratypes.
TYPES.—Lectotype: USNM 118513; paratypes:
118513a, b; figured hypotypes: 153582.
Collemataria batilliformis, new species
PLATE 167: FIGURES 1-40; PLATE 168: FIGURES 1-45;
PLATE 169: FIGURES 1-10
Small, usually elongate, length commonly about
twice width; sides converging anteriorly to form
narrow groove or, rarely, a tube; sides more usually
strongly folded in dorsal direction to form deep
trough; attachment cicatrix usually small but commonly
with large callus flap; cowl usually short,
often not formed; surface marked by irregular concentric
wrinkles or fairly smooth.
Pedicle valve interior with 9 lateral septa, posterior
6 fairly well raised, single (solidiseptate) or
double crested (angustilobate) posterior septa usually
sloping posteriorly and undercut on anterior
side; septal ridges fluted, strongly in some specimens,
moderately in others; median ridge narrow
and moderately raised posteriorly, variable, widening,
flattening or noticeably dividing anteriorly at
variable distance from visceral cavity, becoming
row of beads or dots (moniliseptate) at anterior in
some. Interseptal callosities developed in old or
large adults.
Brachial valve generally with deep cleft; lateral
lobes irregular, occasionally branched or intergrown;
shell body short, moderately deep. Exterior
marked by fairly strongly scattered pustules.
Brachial valve interior with small, eccentric
cardinal process commonly with swollen myophore;
median ridge low; lobe margins scalloped, strongly
curved toward pedicle valve to form fairly deep
channels; ridges parallel to lobe margins strong and
inter-ridge areas thickened and granulose.
436 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
MEASUREMENTS
USNM 721j
150815a
150815b
150815c
150815d
150815e
150815f
150815g
150815h
150815i
150815J
150815k
1508151
150815m
USNM 726d
153603s (holotype)
(in mm).—
length
27.0
22.6
14.5
28.0
18.0
25.0
27.0
15.8
25.6?
26.7
30.0
11.6
20.7
27.4
maximum
width
18.2
13.5
7.8
13.5
15.0
13.2
11.8
9.5
16.0
17.0
16.3
12.0
13.0
18.7
width at
front margin
10.5
4.3
3.9
6.0
6.0
6.4
6.7
3.4
5.6
4.0
13.6
5.6
7.0
5.0
hinge
width
4.0?
?
?
4.3?
?
?
}
?
4.8
?
4.7
?
4.0
?
height
7.0
9.4
8.5
9.5
10.0?
13.4
13.0
6.0
6.4
9.0?
8.5
10.3
9.3
12.0
cowl
length
2.8
3.3
4.6
10.0?
5.7
3.7
13.0?
3.2
8.0
5.0
3.5
5.0
9.3
11.0
STRATIGRAPHIC OCCURRENCE.—Road Canyon Formation.
LOCALITIES.—USNM 721j, 721z, 722v, 724c, 726d,
732j.
DIAGNOSIS.—Small, elongate Collemataria with
narrowed anterior ends producing a narrow trough,
or, in some specimens, a tube.
TYPES.—Holotype: USNM 153603s; figured paratypes:
150815c, 1, 153602a-j, 153603b, c, e-i, 1-q,
t-z; measured paratypes: 150815a—1; unfigured paratypes:
150815a, b, d-k, 153603a, d, j , k, r.
COMPARISON.—The small size, elongate form,
and tubular anterior end make this species unique
for the genus and not closely comparable to any
other species.
DISCUSSION.—This unusual little species is abundant
about 25 feet below the top of the Road Canyon
Formation. There it occurs in a layer about
one foot thick, which is a coquina of fusulinid
shells and other fossil debris. The specimens all
show evidence of transportation in partly broken
brachiopod tests and well-rounded fragments of
fusulinids. Collemataria batilliformis is scattered
throughout the debris. Most specimens appear as
single valves rather than as clusters, suggesting that
masses were broken or that the specimens lived
singly or in small groups but were ripped off their
moorings. A fair number of this species occur
broken in the rock and probably were not broken
in the solution process.
The exterior form of this species is extremely
variable, ranging from shallow open specimens to
ones that are almost complete tubes. The latter
have strongly curved sides, and some have the sides
united at the anterior to form a tube. The tubular
anterior is generally an adult feature, but some
small specimens not half the length of the normal
adult occur with the anterior formed into a complete
tube. These may be old but stunted forms,
"geromorphs" in the jargon. On the other hand,
many of the largest specimens have not produced
a tubular anterior. They are, however, usually
narrowed into a restricted channel at the front, but
they remain open on the dorsal side. It is possible
that the formation of a tube is a fortuitous occurrence
induced by crowding. The feature does
not seem universal enough or sufficiently regular
to be regarded as more than evanescent.
As usual with this type of shell, the attachment
and cowl are variable. The cowl may grow almost
wholly posteriorly, leaving the hinge completely
revealed, or else it may grow forward sufficiently to
hide the hinge, producing a broad flap over the
object of attachment. Many specimens attach to
round objects, while others spread out on flat surfaces
to produce obvious aberrancies.
Inside the pedicle valve the usual variations in
the form and development of the lateral septa may
be observed. Young specimens have a welldeveloped
vallum except at the anterior. Growth
squeezes the ridges forming the lobes together in
an anterior-posterior direction to become angustilobate
and finally to produce narrowly rounded septal
ridges (solidiseptate). Grooved ridges occur in
NUMBER 15 437
specimens of any size, but the advanced, sharp,
strongly oblique ridges (anguliseptate), deeply undercut,
are generally found in the adults and in
shells of considerable depth.
The median ridge is low, but conspicuous and
solid, thinnest near the beak but stout a short distance
anterior to it. The ridge is commonly grooved
(angustilobate) for two-thirds of its length, and the
grooved part is exposed between the long cleft in
the brachial valve. In at least one specimen the
median ridge is moniliseptate.
In an environment as rough as that in which C.
batilliformis must have lived or to which it was
transported, it is only natural that the brachial
valves were detached and often destroyed. This
valve is, therefore, rare compared to the more resistant
pedicle valve. The brachial valve, like the
pedicle valve, also shows infinite variation. Usually
it is slender and delicate, cleft medially for one-half
to two-thirds of its length from the anterior. This
naturally makes the valve weaker in its resistance
to transportation. The lateral lobation is also variable,
some lobes are branched, and others coalesce
with adjacent ones. In one the lateral axial
branches have joined to produce an almost solid
plate except for a short central slit and a few slits
and holes on the sides (Plate 167: figures 3, 4). The
interior, unlike the outside, presents no novel features.
Collemataria elongata, new species
PLATE 139: FIGURES 11, 17-20;
PLATE 170: FIGURES 1-16; PLATE 171: FICURES 1-18;
PLATE 172: FIGURES 1-16; PLATE 173: FIGURES 1-40;
PLATE 181: FIGURES 12-15; PLATE 183: FIGURES 22-23;
PLATE 191: FIGURES 10
Lyttonia nobilis americanus R. E. King (not G i r t y ) , 1931:103,
pi. 32: figs. 2, 3, 9.
Pedicle valve large, variable, scoop-shaped, generally
narrow and elongate, expanding gradually
anteriorly to attain maximum width anterior to
midvalve; pedicle valve forming shallow elliptical
dish, flat to strongly convex in lateral profile but
gently convex in anterior profile, sides abruptly reflected
in dorsal direction. Exterior surface usually
irregular without ornament other than concentric
lines and wrinkles of growth. Attachment callus
(posterior flap) generally small, but occasionally
large over substrate, occasionally folded part way
along sides and rarely forming cowl reminiscent of
Eolyttonia. Nonseptate lateral areas forming narrow
marginal band.
Pedicle valve interior with narrow but variable
hinge; lateral sockets nearly obsolete; brachial valve
held in place by socket formed by posterior fold of
pedicle valve; interarea obsolete (?). Articulating
nubs small, not present or not seen in all specimens.
Muscle field and bounding ridges obsolete or obscure.
Lateral septa numerous 8 in 25 mm, having
maximum of 27 extending close to margin, highest
in posterior and median regions, decreasing in
height anteriorly and barely visible at margin of
many specimens. Septal crests variable; in some
specimens younger crests grooved (angustilobate)
but at midvalve generally narrowly rounded to
sharply carinate (solidiseptate to anguliseptate).
Granulose interseptal ridges appearing between
septa laterally in older parts of shell, gradually
lengthening toward midline in younger and wider
parts, septal crests 3 to 3.5 mm. apart. Old septa
pitted, striated, or beaded on both sides in old
specimens; interseptal spaces pitted variably in
strength depending on age. Median ridge continuous
from apical region nearly to margin, generally
low, usually narrowly rounded.
Brachial valve exterior finely papillose; apical
callosity triangular, small. Body usually slightly
convex. Hinge irregular, variable, seldom straight.
Articulating processes rudimentary or obsolete. Lateral
lobes narrow, strongly convex in section,
slightly arcuate toward the posterior not in contact
laterally.
Brachial valve interior with long, low, rounded
median ridge extending anteriorly from cardinal
process to front margin. Median trough about 4
mm wide. Lobes deep, with minute row of beads
running parallel to walls and around curve, there
lobe meeting median trough. Cardinal process
small, buttressed by median ridge in many specimens,
and with myophores divergent.
MEASUREMENTS (in mm).—
maximum hinge
length width width midwidth height
USNM 706e
150821a
150821b
150821c
150821d
150821e
104.3
82.3
79.8
64.4
67.4
41.5
45.0?
38.4
54.4
40.0
9.0?
14.0?
15.0?
15.7
11.2?
32.5
44.5
32.0
33.6
33.0
18.8
9.7
8.2
15.7
15.0
438 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
15082H
150821g
150821h
15082U
150821]
150821k
150821-1
150821m
150821n
150821O
150821p
150821r
150821s
(holotype)
15082U
150820a
150820b
length
55.7
44.0
37.5
42.8
37.4
23.7
18.4
19.8
18.8
18.4
11.0
3.3
70.0
14.6
7.8
8.8
maximum
width
29.7
32.4
30.0
29.0
22.4
20.0
20.5
17.8
13.8
13.8
9.3
4.7
30.0
9.9
11.1
8.5
h inge
width
11.0
10.9
7.4
6.8
5.2
5.2
4.3
4.0
3.9
3.4
2.8
1.3
5.0?
2.6
3.0
2.7
midwidth
29.0
27.4
26.0
25.7
20.0
14.8
19.0
15.6
12.0
11.0
8.3
4.4
27.0
9.6
10.0
8.5
height
11.7
17.9
9.6
10.5
8.0
8.3
5.8
6.4
5.8
4.0
3.7
1.3
12.0
2.8
2.0?
4.0?
STRATIGRAPHIC OCCURRENCE.—Word Formation
(China Tank, Willis Ranch, and Appel Ranch
members and lenses between the last two).
LOCALITY.—China Tank: USNM 706c, 706z,
726r, 733q; Willis Ranch: 706, 706e, 718d, 723t,
734u, 732s; lenses: 706b, 732c; Appel Ranch: 704,
710, 714o, 715i, 716v.
DIAGNOSIS.—Large Collemataria, elongate and expanding
moderately anteriorly but with strongly
elevated lateral septa in the pedicle valve.
TYPES.—Holotype: USNM 1050821s; figured
paratypes: 150817a, b, 150819a, b, 150820c-n,
150821a, e, 153628b, d-w, 153629, 153630, 153631a,
b, 153632a-g, 153633, 153634a-i, 153638a-d, and
153566; measured paratypes: 150821a-p, r, t,
150820a, b; unfigured paratypes: 150820a, b, 150821
b-d, f-r, 153628a, c.
COMPARISON.—Collemataria elongata is comparable
to C. gregaria, new species, but important differences
may be noted, some of which require a
number of specimens for determination. The outline
of C. elongata is usually more elongated than
that of the Cathedral Mountain species and is usually
less expanded anteriorly. This is an overall
picture of the material. Individual specimens of
either species may be short and expanded, depending
on conditions, but, in general, the Word species
is less expanded anteriorly than C. gregaria.
Another distinction between the two is the height
of the lateral septa in the pedicle valve, those of
C. elongata having the greater height. The median
ridge is also unlike, that of C. gregaria being
low and inconspicuous compared to that of C.
elongata.
Two differences may be observed in the brachial
valves of these two species. The lateral lobes of
some specimens of C. gregaria are joined at their
distal ends, a feature that has not been observed in
the Word species. The blister-like expansions along
the axial region of the exterior of C. elongata have
not been observed in the Cathedral Mountain species.
A difference was noted in the development of the
young of these two similar species. Young specimens
of C. gregaria less than 25 mm long seldom
show a smooth hinge line because in most of them
the margin of the cowl forms the hinge line. In
C. elongata, on the other hand, many of the young
have the hinge smooth, as in Eolyttonia, but others
of the same size have it and the cowl corresponding,
as in the adult condition.
DISCUSSION.—Collemataria elongata undoubtedly
lived in small clusters, probably smaller than those
of C. gregaria. Evidence is extant that, among the
larger number of specimens making up the collection
of C. elongata, few large clusters have been
found. The few usually show a large individual
with a few smaller ones clustered on it. This may
not represent the true conditions because C. elongata
normally is found in a death assemblage with
no specimens in place except the small or tiny attaching
forms. Collemataria gregaria, on the other
hand, is found in larger masses and in blocks in
which the only visible specimens are this species, as
at USNM 702a1- Collemataria elongata commonly
occurs in accumulations of dead shells; specimens
are usually attached to small productids or other
small holdfasts that are not particularly stable.
The type of attachment alluded to above is common
with C. elongata. The spat are commonly
found attached to shells of all sizes and frequently
to small shells. The ultimate form of Collemataria
may depend on the holdfast. Spat that settles inside
a dead productid shell may develop a deeply
concave interior at the beginning that may affect
the lateral septa, producing high and oblique plates
(anguliseptate) in the young. A shell attaching to
a flat pelecypod may develop a flat form with wellformed
vallum. A shell that attaches tangentially
to a curved surface may develop a free anterior
margin early in its life.
NUMBER 15 439
Development of a cowl over the hinge may occur
in this Word species if the spat settles in a deep
hollow requiring the shell to expand anteriorly.
The lateral septa are variable in this species, but
generally they are well elevated in the adult, highest
in the posterior one-half or two-thirds and lowest
at the anterior. In a few adults some of the
septa are grooved (latilobate to angustilobate), but
this is unusual. They are commonly sharp-crested
(solidiseptate to anguliseptate) and range from
strongly oblique, with the slope in a posterior direction,
to erect and less commonly oblique, with
the slope anterior and the anterior face up. These
variations are generally due to changes in curvature,
the more concave specimens have the septa
oblique and sloping posteriorly, but the few specimens
that are arched and convex dorsally have the
lateral septa sloping in the opposite direction. Normally
grooved septa are generally in the posterior.
Oblique septa are frequently grooved, but the
groove is spread along the sloping face. In young
specimens and fairly large flat ones, grooved septa
appear to be the rule and the grooves may be so
wide that a vallum, incomplete anteriorly, is
formed.
Irregularities in the lateral septa are common
especially at the anterior, where all semblance to
regularity may cease. Specimens subjected to distortion
in growth frequently have skewed septa
that may point anterolaterally or anteriorly, or they
may be curved or bent proximally; distally
branched lateral septa also appear in parts of the
shell, and no reason is apparent for the irregularity.
Anteriorly most of the septa are pitted or striated.
Interseptal ridges are developed in most adults.
These appear on the distal sides of the interseptal
spaces as short ridges in the posterior and lengthened
inward as the shell grows. The interseptal
ridges when normally developed are usually lower
than the lateral septa, but they may approach them
in strength. In one large shell the interseptal ridges
have the appearance of the normal septal ridge, an
oblique plate undercut anteriorly. This is exceptional,
however, and the usual development is more
toward the anterior. Some large specimens develop
no interseptal ridges.
The median ridge of C. elongata generally is
large and strongly elevated, continuous from posterior
to anterior margins. Posteriorly it is usually
lower than medially or anteriorly. In some specimens
the ridge is continuous for part of its length,
but anteriorly it becomes broken into a string of
beads (moniliseptate). In at least one it appears as
a string of elongate beads for the entire length.
Where it appears as beads the anterior cleft of the
brachial valve is welded between the beads to produce
a median row of holes—the feature used to
distinguish the "genus" Gubleria by Termier and
Termier (1960).
The brachial valve presents one exceptional feature,
but otherwise it is similar to that of other
species in this genus. The exterior, when well preserved,
is finely papillose as usual, and the median
region is marked by a long depression that indicates
the elimination of the median cleft with growth.
The unusual exterior character is the presence of
large blisters of shell that are revealed when
broken. They show the presence of more than one
layer. The blisters range in size from two or three
mm to ones extending for half the valve length.
Indications are that the blisters were broken before
the shell was entombed in the rock, because
recesses in them are commonly filled with sediment
and, in a few of them, attaching forms such as
young Collemataria are cemented across the layers
of the broken blister onto the layers below. This
fact, together with the occurrence of sediment in a
slightly cracked blister, indicates that they were
hollow. What induced them is not known. They
were probably not hollow in the living animal, but
perhaps they were filled with liquid produced by
the mantle of the brachiopod. The blisters may
have been generated because of irritation to, or
under, the mantle.
DEVELOPMENT.—A good series of young valves
was obtained from USNM 706e, which permits a
fair idea of the development of C. elongata. The
smallest specimen has a diameter of 3 mm (USNM
153632c). It has no lateral lobes but a strong fold
at the anteromedian part of the shell. The hinge
appears as a straight line with lateral notches.
Three specimens with a length of about 4-6 mm
(USNM 150821r, 153632g, 153632e) are more advanced,
having the broad median fold and one lateral
lobe that defines two lobes of the brachial
valve. The inlobe is not strongly developed and a
vallum is not formed, the median ridge suggesting
a fold rather than a ridgelike plate and not com440
SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
posed of two septa uniting with inlobes and outlobes,
as in the Poikilosakidae. Another specimen,
8 mm wide (USNM 153632a), has essentially the
same structure, but the anterior sloping face of the
fold and the interseptal part of the inlobe are
strongly granulose. Furthermore, this specimen has
a well-marked cowl. From this stage on, considerable
variation exists in the formation of the cowl,
in the development of the lateral septa, and in the
formation of the median ridge.
A specimen, 9 mm long and 8 mm wide, has
two inlobes, a fairly high median ridge that is
papillose from about midvalve to the margin, and
the cowl joined with the hinge, as in adults. Some
specimens of comparable development have not
formed a cowl but have the straight line of the
hinge slightly elevated and laterally notched, as in
the primitive lyttoniids.
The third inlobe appears in specimens having
a length of 10 to 11 mm (USNM 150821p). Again
considerable variation may be seen, but the inlobes
are fairly wide and the median ridge is flattened
or grooved from about midvalve anteriorly. In one,
the cowl and hinge coincide, but, in another, the
hinge is in the primitive condition. At 14 to 16 mm
(USNM 150821) the growing shell attains five inlobes
and the median ridge has a mature appearance,
being slender for most of its length and anteriorly
grooved for a short distance. At about 20
mm (USNM 150821o) a sixth inlobe is added and
the shell has essentially mature character. It must
be emphasized that, at this size and before, a large
amount of variation exists in all features. One
specimen of 14 mm length with four inlobes, the
last somewhat poorly developed, has some lateral
septa that are oblique and slope to the posterior,
and also it has interseptal ridges. To be sure, the
lateral septa are also grooved (angustilobate), but
they are undercut anteriorly. Nevertheless, this
little specimen exhibits well-advanced characters.
The smallest brachial valve in the collection is
6.5 mm (USNM 153632b) long and is in the twolobe
stage. The lateral lobes are direct, and the
exterior is finely pustulose. The anterior slit extends
dorsally for about one-third valve length. The lobes
are shallow and not strongly rimmed, and the
median ridge is not yet formed. The cardinal process
is a small rounded mass not distinguishable
into any recognizable features.
A specimen with three lobes measures 7.5 mm
(USNM 154923a) and shows some advanced characters.
Although the cardinal process is not welldeveloped,
the margins of the lobes are thickened
and a median ridge has formed. Its median cleft
is about one-third the valve length. A specimen
with four lobes is 9.5 mm long (USNM 154923b)
and has a cardinal process with low shaft, the lobes
are marginally thickened, the median ridge is
broad and low, but the median cleft is equal in
length to about half the valve length. Thus, at
about 10 mm the brachial valve has attained essentially
adult characters.
Collemataria gregaria, new species
PLATE 133: FIGURE 7; PLATE 174: FIGURES 1-15;
PLATE 175: FIGURES 1-12; PLATE 176: FICURES 1-14;
PLATE 177: FICURES 1-4
Lyttonia nobilis americanus R. E. King (not Girty), 1931:103,
pi. 31: figs. 10a, b, pi. 32: figs. 5, 6, 8.
Pedicle valve large, variable in outline and convexity,
forming crude triangle, maximum width
well anterior to midvalve. Usually gently concavoconvex
with convexity low, some valves nearly flat,
some moderately convex but rare specimens moderately
to strongly concave. Exterior with growth
lines and concentric wrinkles. Valve in cross section
moderately deep, with upturned lateral margins
except at front. Attachment surface varying from
nearly entire valve to small apical cicatrix; attachment
callus (posterior flap) usually not greatly
thickened and with moderate expansion; exceptional
specimens with small cowl developed under
unusual conditions.
Pedicle valve interior with variable hinge and
with brachial valve inserted in deep pit. Lateral
sockets rarely preserved. Interarea obsolete. Lateral
septa numerous, numbering 24 in largest specimen,
variable, not strongly elevated and descending in
height anteriorly, last 4 or 5 very low and often
obscure and irregular. Septal crests usually well
rounded (solidiseptate). Development of interseptal
ridges variable, usually located in anterior half.
Septa grooved (angustilobate) and beaded (moniliseptate)
in anterior half; interseptal ridges commonly
pitted or grooved. Median ridge appearing
at apex, low and narrow posteriorly, becoming
wider and more elevated anteriorly but never very
NUMBER 15 441
strong. Anterior part of median septum beaded in
some old individuals.
Brachial valve exterior finely papillose; apical
flattened area not well preserved; hinge line irregular
and usually narrow and articulating processes
remnantal or lacking. Lateral lobes, narrow, nearly
straight posteriorly but becoming gently arcuate anteriorly;
lobes commonly fused at distal ends in old
parts of large specimens.
Brachial valve interior with long, low median
ridge, narrowly rounded to slightly grooved on crest
and extending from cardinal process shaft to anterior
margin. Median trough shallow, about 5 mm
wide, lobes moderately deep, with thin ridge parallel
to elevated edges and running along floor. Cardinal
process small, tetralobed, and well buttressed.
Spaces between lobes filled in posteriorly to form
solid plate at posterior of large specimens.
MEASUREMENTS (in mm).—
USNM 702a1
150802a
150802b
150802c
150802d
150802e
150802f
(holotype)
150802g
150802h
150802i
length
85.0
92.0
72.0
71.0
76.6
52.0
37.4
26.7
10.0
maximum
width
80.0
53.0
56.0
54.6
65.0
36.0
26.9
24.4
9.5
hinge
width
10.0
13.8
11.4
12.5
9.5
10.0
6.2
4.0
2.5
midwidth
65.0
47.7
53.0
44.7
51.0
33.6
26.9
23.0
8.5
height
15.0?
18.7?
17.0?
16.6
12.0?
18.2
10.0?
5.3
1.9
STRATIGRAPHIC OCCURRENCE.—Cathedral Mountain
Formation.
LOCALITIES.—AMNH 500, 504, USNM 702, 702a,
702a1, 702b, ?702ent, 702-low, 702un, 703a1, 703b,
711q, 726u, 726y, 732u.
DIAGNOSIS.—Large scoop-shaped Collemataria,
fairly widely expanded anteriorly and with lateral
lobes of brachial valve frequently joined distally.
TYPES.—Holotype: USNM 150802f; figured paratypes:
150800a, h, 150801a, b, 150802a-c, j-1,
150806a, d, e, 153573a-d, 153574a, b, 153575,
153576, 153577a, b, 153644; measured paratypes:
150802a-e, g-i; unfigured paratypes: 150800b-g,
150802d-i, 150806b, c.
COMPARISON.—-This species is best compared to
C. elongata, new species, to which it has considerable
resemblance. The Cathedral Mountain species
attains a greater size and wider anterior spread
than the Word species, but these details are seen
only in the fully grown adults, which are rare.
Another distinction is in the lesser number of lateral
septa on the interior of the pedicle valve in
the Cathedral Mountain species. The young of
C. gregaria generally are more anteriorly expanded
than the young of C. elongata. The brachial valves
of the larger specimens of C. gregaria have an
unusual feature in the joining of some of the distal
ends of the lateral lobes in the adult, a feature not
seen in C. elongata.
These details of comparison may seem nebulous
when applied to a collection of a few specimens,
but they are real in the large collections from the
Glass Mountains.
DISCUSSION.—As mentioned above, C. gregaria
appears to have lived in larger aggregates than the
Word species, or else the clusters were not so effectively
and completely broken up as they were in
the Word. Some large clusters of C. gregaria survived
the etching process, but it is probable that
even larger ones might be obtained if some method
could be found to prevent collapse of the clusters
with the removal of the supporting limestone. This
is not true of the Word occurrence because the
specimens are not in their original position of
growth.
All of the remarks pertaining to the interior of
the pedicle valve of C. elongata are applicable to
that of C. gregaria. The lateral septa usually are
fairly advanced (solidiseptate) in showing no grooving
or very little grooving of the lateral septa except
at the posterior or oldest part of the shell.
Variations of the lateral septa and branching are
also noted. The anterior of the shell is commonly
a place of scrambled or much disordered lateral
septa. Specimens in which the shell is bowed toward
the brachial valve and thus have a concave
pedicle valve have the lateral septa oblique and,
with their inclined surface extending anteriorly,
thus exposing the opposite side of the lateral septum
from normal specimens.
The median septum in C. gregaria is not strongly
developed, usually less so than in C. elongata. It
also shows variations like that of the Word species.
In some specimens it is not direct, but it is twisted
or curved to the side. It is also, but rarely, beaded
anteriorly, in which case the axis is opposed by a
series of holes in the axis of the brachial valve.
Interseptal spaces commonly are pitted deeply or
442 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
striated, resulting in serration of the margin of the
lateral loops of the brachial valve. Interseptal
ridges usually are not strongly developed and appear
chiefly in the anterior part of the shell.
The brachial valve, when symmetrically developed,
is triangular in outline, tapering gradually
and symmetrically toward the hinge. The median
axis is marked by a moderately deep and narrow
depression that meets the cleft near midvalve or
anterior to that point. In many specimens anterior
to midvalve, a row of holes, usually elliptical
in outline, follows the axis and partially
closes the cleft. This is the feature on which Termier
and Termier (1960) based the genus Gubleria.
Inside the brachial valve of C. gregaria the cardinal
process is moderately large, generally well
formed and with a well-defined shaft. The median
ridge is low, moderately thick, and continuous from
the shaft of the cardinal proces to the cleft. The
spaces between the lobes in the posterior part are
filled partly by webs of shell material to widen and
strengthen the posterior axis. The lobes are unthickened
internally in most specimens. Perhaps
the most unusual feature of the brachial valve is
the joining of the lateral lobes distally near the
midvalve where they are widest. This appears to
be a specific character for this species.
Very young specimens of C. gregaria are rare in
the collection. The smallest specimen is imperfect,
but it was about 6 mm in diameter. The
hinge is not preserved, but a low, thin median ridge
is present. The specimen has one inlobe on each
side, indicating a brachial valve of two lateral
lobes. The next largest specimen is about 7.5 mm
long and slightly wider. It has a grooved median
septum and one inlobe, which is granulose. A third,
still larger specimen with a diameter of 9 mm has
the hinge visible, a broad, grooved median ridge
and two inlobes, indicating a brachial valve that
has three lateral lobes. The interior is granulose
and the inlobes are fairly wide. A specimen of 11
mm diameter is essentially the same as the preceding,
with the same number of lobes and a strongly
granulose interior. A specimen with length of 11.5
mm has three inlobes and a brachial valve of four
lateral lobes. The 4-inlobe stage of the pedicle
valve is reached at 14 to 15 mm. Interseptal ridges
are developed early, at least at the 2-inlobe stage
of the pedicle valve.
Collemataria irregularis, new species
PLATE 129: FICURES 22-28; PLATE 133: FIGURES 4-6, 8-11;
PLATE 178: FIGURES 1-16
Moderately large when undistorted, usually
elongate oval, variably conical, cowl short, sides
strongly developed to form deep scoop; longitudinally
moderately convex in lateral profile. Posterior
flap for attachment; surface marked by
concentric lines and wrinkles; attachment area
usually small.
Pedicle valve interior with narrow and straight
hinge having moderately swollen posterior lip;
hinge edge and cowl merging in few specimens;
lateral septa numbering 14 to 15 in large adults,
8 occupying length of 25 mm; posteriormost half
of septa strongest elevated; anterior half low and
anteriorly obscure. Older septa commonly grooved
(angustilobate) and those of young specimens usually
grooved widely (latilobate) and forming vallum;
some lateral septa strongly inclined and
sharp-edged (anguliseptate) but showing evidence
of longitudinal groove. Median ridge posteriorly
indistinct, medially moderately strong and anteriorly
flattened or grooved and less distinct. Interseptal
ridges early formed; lateral septa and
interseptal ridges in median and anterior half commonly
striated to pitted.
Brachial valve externally granulose, with anterior
cleft reaching posteriorly for one-fourth valve
length; lateral lobes moderately oblique to horizontal,
joined distally at widest part in old shells;
median groove narrow and shallow; surface granulose.
Brachial valve interior with small triangular articulatory
wings set off by oblique ridges; cardinal
process small, with short shaft; median ridge moderately
strong, medially grooved. Lateral lobes moderately
thickened and with thickened and bevelled
posterior margins.
MEASUREMENTS (in mm).—
maximum hinge
length width width height length
USNM 714w
150752a
150752b
150752c
150752d
150752e
USNM 721u
153635a
(holotype)
52.0
46.0
36.0
34.0
34.0
35.0
32.0
34.0
33.0
19.0
?
?
5.0?
7.0?
?
16.0
15.0
11.0
16.0
11.0
12.0
21.0
10.0
6.0
12.0
51.2 37.3 8.0 14.0 11.5
NUMBER 15 443
STRATIGRAPHIC OCCURRENCE.—Cathedral Mountain
Formation (Wedin Member at base).
LOCALITIES.—Wedin: USNM 700-1, 714w, 717e,
723v; Cathedral Mountain: 703b, 721u, 723u.
DIAGNOSIS.—Deep, oval to triangular shells, with
slightly developed cowl.
TYPES.—Holotype USNM 153635a; figured paratypes:
150752a, b, e-g, 153635b-f, 153636, 153643,
153645, 153657a-d; measured paratypes: 150752a-e;
unfigured paratypes: 150752c, d, 153635a.
COMPARISON.—Two species are available for comparison
with C. irregularis. It differs from Eolyttonia
pocillata, new species, which occurs at the
same stratigraphic level, in being generally larger
in the adult form, more elongate oval to subtriangular
in outline, and in having a less welldeveloped
cowl. The adult of this species suggests
Collemataria gregaria, new species, in the lack of
development of the cowl of some specimens. Generally
it is less triangular and smaller than that
species.
DISCUSSION.—This, not a common species, has
been found mostly in the Wedin Member of the
Cathedral Mountain Formation, where it is usually
found attached to Institella. The latter is not the
only host form, however, because the species attached
to Neospirifer, to a variety of bryozoans, to
Enteletes, and to its own brethren. The variety of
hosts and the irregular nature of the surface of
Institella make the early form of attached C. irregularis
unpredictable. The collection does not
include many adults because it is possible that the
unstable attachment of Institella, which apparently
was often ripped from its moorings, made life
equally precarious for C. irregularis. Many of the
young failed to reach maturity, which was only
attained by specimens moored to substantial hosts.
The region of the cowl of this species is variable,
some specimens having it extended posteriorly
rather than over the hinge. These types are not
common; occasionally the cowl is moderately well
developed and the hinge is visible beneath it. The
lateral septa are variable. In the young they are
mostly in the form of a moderately compressed but
incomplete vallum. Young adults of six or eight
inlobes generally have the lateral septa deeply
grooved (angustilobate). In a few specimens, however,
the lateral septa are so oblique that the groove
is flattened and spread over the septal surface. A
few specimens have lateral septa as in Oldhamina
(anguliseptate). Interseptal ridges appear early in
the life of this species and are best developed in
the anterior half, where they generally extend from
the distal extremity of the interseptal grooves to
the median trough. The median ridge is only moderately
well developed and is not a conspicuous
feature of the interior.
The brachial valve in the young is cleft medially
to about midvalve. The cleft becomes proportionately
less with growth and is gradually eliminated
in the usual manner. The cardinal process is small
and inconspicuous with little or no shaft. The
median ridge is moderately strong, and some thickening
takes place in the lateral lobes.
The holotype affords some interesting details
connected with crowded living. At its anterior the
specimen grew against a fenestellid bryozoan. This
caused the anterior to be diverted from its normal
growth into a more dorsal direction. The result
was the diverting of the median trough to the left
and a skewing to the left of the median cleft and,
presumably, the median ridge underneath. The
valve then grew back to its normal position, and
the anteriormost lateral lobes on the right side became
abnormally long. This sort of "injury" or
distortion is fairly common in lyttoniids, but an
example with both valves preserved is not commonly
found.
Collemataria marshalli (Stehli)
PLATE 133: FIGURES 1-3; PLATE 179: FIGURES 1-21
Leptodus} marshalli Stehli, 1954:308, pi. 19: figs. 1-3.
Stehli distinguished this species from Eolyttonia
diabloensis (Stehli) on the character of its attachment,
claiming that Collemataria marshalli (Stehli)
lived suspended above the bottom. We believe that
the two species are different, but not for the same
reason, because a fairly large suite of specimens
shows no uniformity or preference in the form of
attachment. This seems to be as haphazard as that
of E. diabloensis. The smaller species is E. diabloensis,
which does not produce any specimens
attaining the size of C. marshalli. Furthermore,
the lateral septa of the latter species are stronger
and more distant than those of E. diabloensis,
which has seven or eight in 20 mm, whereas C.
marshalli has only five or six in the same distance.
444 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
The lateral septa of C. marshalli are thicker and
higher than those of the other species, and more
of them are grooved (angustilobate). They thus
appear to be in a less advanced state of development
than those of E. diabloensis. Other differences
are seen in the smooth exterior and in the
larger cardinal process of C. marshalli, the broader
axial region, and broader lateral lobes.
Collemataria marshalli does not seem to have
favored attachment to crinoid stems as Stehli avers,
to judge from the collection of this species in the
National Museum of Natural History. Some specimens
were attached thusly and formed a tubular
posterior with the attachment callus wrapped
around the crinoid stem. Some attached to cylindrical
bryozoans in a similar manner. But the majority
of specimens attached to a variety of hosts
having widely different form. Stehli mentions attachment
to platycerid gastropods. Other hosts are:
Isogramma, Kozlowskia, Eolyttonia, flat massive
bryozoa, Teguliferina, corals, and small Derbyia.
In many specimens it is not possible to say what
host had supported the shell because the attachment
lamellae are thin and puckered as though
they had attached over an irregular surface or on
one that was not completely consolidated. Later
the material playing host had been washed out
from between the layers. We have the impression
that C. marshalli, by necessity, settled on any surface
close by when the urge to settle came on the
larva.
Development of the cowl is as variable in this
species as in most others of this genus. In many
it is folded posteriorly and ventrally, and thus it
may grow over the posterior margin and actually
attach to its surface. Specimens situated differently
at the beginning may have the cowl deflected anteroventrally,
in which case the shell tends to become
conical. The cowl in C. marshalli, however,
is seldom sufficiently developed to produce a
well-formed cone.
Young and adult specimens have grooved lateral
septa (latilobate to angustilobate). Some grooves
occupy the full length of the septum, but in others
the groove is pinched off distally or dies out by
obliquity of the septum in the same direction. In
one fully grown adult of more than 60 mm length,
all of the lateral septa are grooved, and the more
anterior septa are widely grooved. On the other
hand, in another specimen, more convex than usual,
the lateral septa are not grooved, but the
position of the considerably widened groove can
be seen on the oblique ridges. Interseptal ridges
and interseptal pitting or striation are not strongly
developed in this species.
The median ridge is inconspicuous for such a
large shell. In most specimens it is threadlike in
the posterior, but, in the posteromedian region, it
may be grooved by an extremely narrow slit. Near
midvalve the ridge is generally solid and moderately
strong, but anterior to midvalve it widens
somewhat and again is grooved or divided.
Few good specimens of the brachial valve have
been found, but these indicate a wide visceral and
axial region and a narrow hinge. Articulating processes
generally are badly worn. Internally the
median ridge is low but strong and extends in
attenuated form to the cardinal process. The lobes
are moderately convex and moderately deep with
little development of adventitious shell. Growth
webs between the lobes, which tend to widen the
axial part, are strong and are exhibited at the
posterior in most of the specimens. The cardinal
process is moderately large, very irregular and
with four thin myophores.
MEASUREMENTS (in mm).—Hypotype (USNM
150767a): length 66.7, maximum width 59.0, hinge
width 11.0, height 16.0.
STRATIGRAPHIC OCCURRENCE.—Lower Bone Spring
Formation, Skinner Ranch Formation.
LOCALITIES.— Bone Spring: AMNH 625, USNM
725c, 728e; Skinner Ranch: USNM 720e.
TYPES.—Lectotype: AMNH 27291/1:2; figured
paratype: AMNH 27291/1:1, 27291/1:3; figured
hypotypes: USNM 150764, 150766a, b, 150767a-e,
g-j; measured hypotype: 150767a; unfigured hypotype:
150767f.
DISCUSSION.—Stehli failed to designate a type for
this species. We, therefore, select the specimen illustrated
on Plate 19: figure 2 (AMNH 27291/1:2)
as lectotype. This seems best to typify the more
abundant material from the same locality in the
National Museum of Natural History.
Collemataria platys, new species
PLATE 180: FIGURES 1-15
Moderately large, flat to gently concave and irNUMBER
15 445
regular; attachment surface moderately large to
nearly entire ventral surface; cowl broad, spreading
posteriorly, seldom overhanging hinge; surface
with strong concentric wrinkles.
Pedicle valve interior with narrow hinge having
thin but conspicuous posterior lip; median ridge
moderately strong, grooved or ungrooved and usually
divided anteriorly; lateral septa strongly and
widely grooved (latilobate to angustilobate) in
young, retaining grooved surfaces posteriorly in
adults; interseptal ridges strong, occupying most
of lateral grooves in adults; interseptal areas
strongly pitted.
Brachial valve finely papillose and with narrow,
short visceral region. Anterior cleft wide in young,
usually not reaching midvalve.
Brachial valve interior with strong oblique ridges
setting off articulating wings at hinge; cardinal
process with short, cleft shaft; myophore surface
moderately broad; median ridge low, broad and
stout; lateral lobe edges strongly serrated; lobes
slightly thickened by adventitious shell; elimination
of lobes moderately developed posteriorly.
MEASUREMENTS (in mm).—
USNM 705a
150734a
(holotype)
150734b
150734c
length
49.0
43.0
48.0
maximum
width
50.0
47.0+
44.0 +
hinge
width
7.0
7.0
7.0
height
14.0
3.5?
7.0?
cowl
length
7.0+
10.0
9.0+
STRATIGRAPHIC OCCURRENCE.—Skinner Ranch
Formation.
LOCALITIES.—USNM 705a, 715v, 722-1.
DIAGNOSIS.—Collemataria with nearly flat to
gently concave valves and with most of lateral
septa grooved (latilobate to angustilobate) at all
ages.
TYPES.—Holotype: USNM 150734a; figured paratypes:
150734b-h; measured paratypes: 150734b, c.
COMPARISON.—This species suggests Eolyttonia
diabloensis (Stehli) or Collemataria americana
(Girty), but it differs in its generally flatter form,
more strongly papillose or granulose surface, larger
size, less strongly elevated lateral lobes in the posterior.
This species is not likely to be confused
with any other in the Glass Mountains.
DISCUSSION.—Although the collection includes a
fair number of specimens, they are not well preserved.
Most of the fossils at USNM 705a have
suffered from rolling about on the sea bottom and
from compression after lithification of the sediment.
This species occurs in the interbiohermal
shell debris and, consequently, has suffered from
current damage. Nevertheless, sufficient material
is at hand to give a good idea of the species.
This is a variable species and, like others of its
ilk, varies in shape according to the host. A fair
number of specimens attached to fairly flat shells,
such as a huge Pmna-like pelecypod, and, therefore,
they produced nearly flat shells. Specimens free to
grow and develop a normal shape produced shells
of low convexity. This can, therefore, be regarded
as a characteristic of the species.
Another characteristic of this species is the primitive
nature of the lateral septa. In the young these
have a well-defined vallum and widely open median
ridge strongly suggesting the Poikilosakidae,
but the vallum is not continuous anteriorly, although
it is continuous laterally. In adult shells
nearly all of the lateral septa show the result of
compression, but all retain a well-marked groove.
This is true also of old specimens, which have a
fairly well-defined groove, although the anterior
septa may be oblique or ill defined. Strongly pitted
interseptal areas are the rule, and, in the older
shells, an interseptal ridge is well developed from
near the hinge to the anterior margin.
The median ridge in young shells is primitive
because it divides far posteriorly and continues as
two slightly diverging ridges to the anterior margin.
In adults and old shells the ridge is fairly
strong and is divided posteriorly and anteriorly
in some individuals.
The brachial valve presents no features of unusual
character and is not strongly thickened internally.
Collemataria spatulata, new species
PLATE 154: FIGURE 5; PLATE 181: FIGURES 1-11
Long and narrow, generally spatulate in form,
expanding gently anteriorly; posterolateral regions
strongly folded and high, descending anteriorly.
Sides slightly divergent. Attachment surface moderately
large, commonly flattened, shell of many
specimens at right angles to cicatrix. Cowl small,
usually growing posteriorly. Surface marked by
concentric lines and wrinkles.
446 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
Pedicle valve interior with narrow hinge, usually
independent of cowl; lateral septa numerous, nearly
straight, usually not grooved (solidiseptate), generally
low and fairly uniform in height, septa in
posterior half, however, somewhat stronger than
in anterior half. Interseptal ridges well developed,
usually pitted especially in anterior half. Lateral
septa measuring 11 in 25 mm and numbering about
16 in long specimens. Median ridge low and thin.
Brachial valve with narrow median axis and
small triangular smooth areas at apex; median
depression shallow; lobes measuring 1.4 mm in
anterior-posterior direction.
Brachial valve interior with small bilobed cardinal
process, long double median ridge and shallow
lobes marked by beaded ridge parallel to margins.
MEASUREMENTS (in mm).—
maximum hinge cowl
length width width height length
USNM 738b
150757a
150757b
(holotype)
150757c
AMNH 430
150762
USNM 725e
152628
35.0
28.0
42.0
20.6
63.8
21.8
31.0
25.0
18.0
30.5
7.0
6.0
6.0
4.4
6.0
10.5
6.0
8.8
7.0
9.0
12.0
?
7.0
3.5
8.9
STRATIGRAPHIC OCCURRENCE.—Bell Canyon Formation
(Lamar and McCombs members), Capitan
Formation.
LOCALITIES.—Lamar: AMNH L-2, L-3, 38, 40,
401, 430, USNM 725e, 720i, 728p, 738, 738b; McCombs:
AMNH 409; Capitan: USNM 737a.
DIAGNOSIS.—Small elongate and spatulate Collemataria
with narrow lateral lobes.
TYPES.—Holotype: USNM 150757b; figured paratypes:
150757a, c, 152628, 153570; measured paratypes:
150757a, c, 150762, 152628.
COMPARISON.—This species is readily distinguished
from all others of Collemataria by its
elongate form, nearly parallel sides, fairly uniform,
narrow, and numerous lateral lobes.
DISCUSSION.—The species is uncommon and difficult
to obtain in good condition. The result is
that the full range of variation and distinction
from "Leptodus" guadalupensis Girty is uncertain
(see "Discussion" in that species below). The form
of its cowl and manner of attachment are fairly
distinctive.
The form of attachment consists of a fairly broad
surface that is commonly at a large angle to the
main body of the shell, as much as 90°. The brachial
valve also shares in this angular relation and
may have a strong angular bend in it near the
posterior. The attachment varies from a simple
posterior flap to an elaborate flap of several layers
at several levels.
Young specimens of 8 to 10 mm length are usually
flat or nearly so and adhere by their entire
surface. They have a well-marked vallum, incomplete
at the anterior, but with wide inlobes. The
median ridge is solid to about midvalve, where it
is divided by a narrow groove. Generally adult
specimens have few grooved lateral septa, but some
have them, and, in others, the grooves are shallow
and spread over the oblique surface of the septum.
Most of the lateral lobes in most of the specimens
are fairly low, thick, and broadly rounded on their
crests. The lateral septa in a large specimen are
remarkably uniform in height, those of the anterior
half, although slightly lower, are nevertheless fairly
uniform. This is a distinction from most other
species of the genus.
The brachial valve presents few unusual features.
The lateral lobes are narrow and thickrimmed.
Webs of callus appear in the interspaces
on each side of the median trough for a considerable
distance. The cardinal process is broad and
has a wide depression in the shaft.
Collemataria from Road Canyon Formation
The specimens from this level may be discussed
on a locality basis because all of the localities have
what appear to be different species.
AMNH 503 (=USNM 703).—This locality is represented
best by two specimens, a pedicle and dorsal
valve, both fairly well preserved. The pedicle
valve (USNM 151228) has a diameter of about 43
mm, is crudely circular, and has the maximum
width at about midvalve. It is moderately deep
medially, probably deeper than it appears, as a
slight crushing of the specimen is evident. The
cowl is folded back, but the hinge is not visible.
The lateral septa number 10, are fairly strongly
convex anteriorly, and are angustilobate. The posterior
six septa are strongest and are moderately
elevated, but the anterior four are low, and the last
NUMBER 15 447
is barely visible. The posterior side of the grooved
septa is minutely wavy. The median ridge is low,
strong, and flattened medially except at the anterior
fourth, where it is grooved.
The brachial valve (USNM 151228b) has fairly
strongly curved lateral lobes that are convex toward
the anterior. The lobes have a longitudinal
distance of 2.4 mm, and the interspaces are about
1 mm in the same direction. The lobes are serrated
on the anterior side and are slightly oblique
to the median plane, dipping anteriorly. The cardinal
process is broad, flattened but indistinct, and
the median ridge is low. The lateral lobes are
occupied by a median ridge separated from the
margins by a narrow trough that leaves little room
on the interior.
USNM 703c.—A few scraps from this locality are
similar to the above except for one elongate specimen
(USNM 150771). The specimens are mostly
young ones.
USNM 707e.-—Lyttoniidae from this locality are
rare. This is, perhaps, a reflection of the type of
bottom indicated by the black, muddy limestone.
The few specimens indicate a fairly small species
with short, wide shell, about 36 mm long and the
same distance wide. The posterior flap is folded
back, spreading over the host. The lateral septa
are grooved or oblique and the crests are about 4
mm apart. The median ridge is strong and anteriorly
grooved. The lateral lobes of the brachial
valve have a longitudinal dimension of about 3
mm, but other details are not visible.
One specimen (USNM 150772) is instructive as
to manner of growth. It is attached to branching
round bryozoans, and the posterior flap has engulfed
three of the branches. In its anterior growth
the front has butted medially against another
branch of the bryozoan, split at this place. Part
of the shell has grown dorsad and formed a sheath
around the bryozoan. After completing the closure
around the stem, the anterior had started to heal
the breach when the animal died.
USNM 710u.—Lyttoniids are rare at this locality,
and two species are indicated by four specimens.
A single specimen (USNM 150792a), 29 mm long
and probably 25 mm wide, has deeply and widely
grooved lateral septa (latilobate to angustilobate)
and cleft median ridge. The hinge is visible, and
the posterior flap extends posteriorly, but it is
small. The specimen is obviously a young one.
The other three specimens (USNM 150792b-d)
are incomplete, but they suggest a small, deeply
concave form about 25 mm long, 19 mm wide, and
14 mm deep. The lateral septa are anguliseptate
proximally but strongly grooved angustilobate
along the lateral margins. The cowl is strong with
part extended posteriorly and part in a dorsad
direction. These are compact, thick shells, suggesting
a stunted growth.
USNM 720d.—A few specimens of a broadly
conical species were taken in lenses just above
limestone of the Road Canyon Formation at this
place. The specimens are broad, shallow cones
with an elaborate and extensive posterior flap over
the attachment host. The true length of the septate
portion is not known; the specimen (USNM
150798) with the largest posterior flap has a septate
portion of 20 mm, but the cowl extends posteriorly
for the same length and is more than twice
as wide. The lateral septa in this specimen are low
and simple, with the crests about 3 mm apart. The
second large specimen has the lateral septa deeply
and widely grooved (angustilobate). The septate
part is 27 mm anterior to the hinge. The median
ridge is low and inconspicuous. The lateral lobes
of the brachial valve are moderately convex toward
the anterior and are serrated on the anterior side.
They measure 2.5 mm in the longitudinal direction
of the shell axis. The cardinal process is small,
and the inside of the lobes are slightly thickened.
These specimens suggest Collemataria platys, new
species, rather than Eolyttonia circularis, new species,
because of their generally flattened form. The
extent of the posterior flap and low lateral septa
do not conform to either of the other species.
USNM 721 j.—Collemataria of uncertain character
occurs with Collemataria batilliformis, new species,
and is rare. Only two good specimens (USNM
150799a, b) have been found, but many fragments
may have derived from this species. The two good
specimens may be the same, the more delicate one
being younger. This delicate specimen is thinshelled
and about 35 mm in length and width. It
is fairly deep, about 15 mm, the posterior flap is
small and extends posteriorly, but it partly engulfs
the hinge, which is unusually wide, 10 mm. The
sides are fairly strongly incurved and extend as an
448 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
elevation to the front margin. The lateral septa
are anguliseptate, but they are slender, delicate,
and deeply undercut, numbering 12 and measuring
about 3 mm from crest to crest. The anterior
two are very indistinct. The median ridge is fairly
elevated and slender. The second good specimen
was larger, but it is too imperfect to measure; it
has the same wide hinge. The lateral septa are
thicker, stronger, more elevated than those of the
other specimens, and their true number cannot be
determined because of breakage at the front. In
spite of all the differences, the crests of the lateral
septa of both specimens are 3 mm apart.
Fragments of immature specimens and young
specimens, all pedicle valves, also appear in the
collection. These have some grooved septa, as
might be expected in the young, but it is difficult
to link them with assurance to the two specimens
described above.
Fragments of brachial valves having a size sufficient
to link them to the two large specimens described
above have a flattened cardinal process
with cleft shaft. The lateral lobes are 2.5 mm in
the longitudinal dimension of the shell, and internally
they are strongly thickened by axial deposits.
Similar specimens occur at USNM 702c,
703a, 706f, 712q, 716x, 716xa, 721z, 722e, 723w,
724c, 724j.
Genus Leptodus Kayser, 1883
"Leptodus" guadalupensis Girty
Leptodus guadalupensis Girty, 1909:213, pi. 4: figs. 6, 6a, 6b.
The type specimen of this species is a poorly preserved
impression of the pedicle valve interior and
its partially preserved cowl. The apical region is
flattened, but it is not clear whether this condition
is owing to erosion or if it represents the cicatrix
of attachment. It may be both, and, if so, it indicates
a specimen that lived fairly erect. One side
shows the actual pseudopunctate shell, indicating
a fairly high and smooth lateral margin, but it cannot
be clearly distinguished whether the margin
extended into a long cowl or not. A band of concentrated
growth marks at the very posterior suggests
not, but, in the absence of a complete shell,
it is not possible to be sure. The specimen measures
(in mm): length 44, width 35.5.
The septate impression is so poorly preserved
that a positive count of the lateral septa is not
possible. Taken from a cast of this specimen, 12
septa can be counted on the left side, but three
or four more must have existed opposite the cicatrix,
now weathered away, making a total of 15
or perhaps 16 for the species. The cast also indicates
a strong development of interseptal ridges,
which tend to subordinate the lateral septa and
make the count difficult. The spaces between the
septa and interseptal ridges are pitted, and the posterior
slopes of the lateral septa are striated. The
median ridge is low and indistinct.
STRATIGRAPHIC OCCURRENCE.—Capitan Formation.
LOCALITY.—USGS 2926 (green).
TYPES.—Holotype: USNM 118515.
DISCUSSION.—The stratigraphic level of this species
is stated to be in the middle of the Capitan
Limestone (Girty 1909:215). Other specimens
found with it are said to be even more poorly preserved.
It is thus almost impossible to characterize
the species. Collemataria spatulata, new species,
has some features that are similar, but the general
form is different; that species is more elongate,
more spatulate, and not expanded anteriorly. Furthermore,
the lateral septa of Girty's species are
more distant from each other than those of C.
spatulata. Add to these facts the probability that
the two species are widely separated stratigraphically,
and it seems unlikely that they are the same.
Girty's species must await clarification, therefore,
on the basis of additional material in better quality
from the type-locality.
Genus Rigbyella Stehli, 1956
Rigbyella Stehli, 1956:310.
Paralyttonia (part) Wanner and Sieverts, 1935:209, 210.
Small, attached posteriorly but anterior free and
making strong angle to attached part; cowl short
when present; surface without ornament but with
broad gentle folds corresponding to interior troughs
between ridges.
Pedicle valve with strong, thick median ridge;
lateral septa usually 1 or 2 on each side of median
ridge and directed anteriorly or anterolaterally;
lateral wall next to outermost groove forming several
lobes. Hinge narrow, deeply inset. Muscle
scars not clearly defined.
NUMBER 15 449
Brachial valve with 2 branched lateral lobes directed
anterolaterally, outermost lobe with several
rounded projections along outer margin. Interior
not known.
TYPE-SPECIES.—Paralyttonia girtyi Wanner and
Sieverts (1935:210).
COMPARISON.—This genus is similar to Paralyttonia
Wanner and Sieverts (1935:207) for which it
was mistaken. It differs from that genus in having
a different growth form and a different septal arrangement.
Rigbyella is attached only at the beak
end, and its anterior grows at about right angles
to the attachment surface. Paralyttonia, on the
other hand, is attached by its entire surface.
DISCUSSION.—Rigbyella is a rare genus in the
Permian of West Texas and New Mexico. It has
not yet been found in the residues from the Glass
Mountains. The interior lobation of the shell suggests
relationship to the Poikilosakidae, rather than
to the Lyttoniidae, but the muscle area of all the
pedicle valves fails to reveal the unpaired muscle
characteristic of the former group. Until more is
known of this genus, it will have to be regarded as
an aberrant lyttoniid with atavistic features suggestive
of the Poikilosakidae.
The only known species of this genus is a small
shell attached by most of the posterior end. The
attachment may be made on flat or rounded surfaces.
In any case, some callus developed around
the attachment area to assist in making the hold
on the host as secure as possible. The fact that
many loose specimens have a hole between the
hinge and the median ridge, approximating the
surface of the muscle area, indicates that attachment
in the beak area was thin. It was, however,
thickened peripherally.
The anterior cuplike part of the shell extends
at about right angles from the attachment surface
and is thus erect. Such attachment habit is like
that of other lyttoniids that occur in the Lamar
Limestone Member with Rigbyella. A cowl does
seem to be a common feature of this genus, and
it was seen in one specimen, arching over the hinge
as is usual in lyttoniids.
Based on the position of one specimen attached
to Stenoscisma, Stehli postulated that Rigbyella
probably lived with the brachial valve horizontal.
Stehli (1956:311) believed that Stenoscisma lived
with the pedicle valve down, a reasonable assumption
for free-living Stenoscisma. If it remained attached
by the pedicle, however, it may have lived
with the brachial valve down, and the little Rigbyella
occupied the sheltered underside. Furthermore,
no evidence was presented that the Stenoscisma
was alive when the Rigbyella attached. It
is likely that the Rigbyella on the Stenoscisma survived
because it had found firm substrate in a
sheltered spot, where it could thrive regardless of
its position.
The hinge of this genus is like that of other
lyttoniids, a narrow slit with callus shell above it
worn into a flat surface, usually triangular, by the
vertical movements of the brachial valve. The
brachial valve fits into this snugly. Well-preserved
hinges reveal small notches on each side to receive
articular nubs of the brachial valve. One specimen
(USNM 147719) shows a callus development
in the muscle region, but it was not possible to
resolve this into definite scars. Stehli's largest specimen
(AMNH 27933:1) shows the median ridge extending
posteriorly as a myophragm. On each side
of it are two elongate scars, which may be adductor
scars because of their close proximity to the myophragm.
The septal ridges of the pedicle valve are of considerable
interest because they are so different from
those of any other genus. In the first place they
are directed anteriorly or anterolaterally. Furthermore,
although most of the specimens have a symmetrical
development of the interior, this is not
always true. The median ridge is the strongest and
the longest and extends from the muscle region
almost to the anterior margin. On each side of this
median ridge appears another ridge of about the
same strength but directed anterolaterally. Additional
but shorter ridges may be intercalated inside
the primary three or outside them. One specimen
has a ridge intercalated between the median ridge
and the next primary one on the right side, but,
on the opposite side, the intercalated rib appears
between the outer margin and the outside primary
ridge. The presence of the intercalated ridges
makes the lobation of the brachial valve complicated
and unsymmetrical.
Of considerable interest is the lobation of the
outer channel between the outside ridge and the
side of the shell. In specimen USNM 147719 this is
marked by a posterior depression that is followed
450 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
by three others set off by small folds of the shell.
These lateral depressions produce small lobes or
protuberances on the outside lobe of the brachial
valve. This minor lobation is suggestive of the
waves seen on the posterior lateral lobes of some
Poikilosakidae, such as Pseudoleptodus Stehli and
Choanodus, new genus. Similar lobation is illustrated
in Paralyttonia Wanner and Sieverts.
The ridging of the interior is reflected on the
outside of the shell. The ridges of the interior
create gentle longitudinal troughs on the exterior,
while the inner troughs between the ridges create
gentle folds. This suggests that the ridges are
formed by gentle folding of the shell. Whether or
not this is initiated by a fold of the primary lamellar
layer of the shell is not known. This is probably
the case, as in other lyttoniids, but unsilicified
material will be needed to demonstrate this.
The brachial valve is, unfortunately, poorly
known and has been seen in one specimen only
(Stehli, 1956a, pi. 41: fig. 10). This valve is very
delicate and fragile and, because of its branching
nature, may not be readily recognized. Its fragility,
amorphous quality, and great rarity have all combined
to prevent discovery of a loose valve. The
specimen figured by Stehli and also herein shows
well the lobation of the outer branches and the
bifurcation of the main lobes. Undoubtedly young
specimens of Rigbyella had a bilobed stage in
which the brachial valve was cleft medially by the
median ridge. With continued growth and the appearance
of the lateral ridges, the two primary
lobes bifurcated to form the basic adult pattern of
four lobes.
Rigbyella girtyi (Wanner and Sieverts)
PLATE 182: FIGURES 1-30
Leptodus americanus Girty, 1909: pi. 4: figs. 8, a, b.
Paralyttonia girtyi Wanner and Sieverts, 1935:210.
Rigbyella girtyi (Wanner and Sieverts) Stehli, 1956a:310.
Inasmuch as only one species of this genus is
known, the important anatomical features have
been amply discussed under the generic heading.
Girty's specimen, the holotype (USNM 118512), is
a more immature form than the ones figured by
Stehli. It shows the original bilobation well and
the cleft produced to accommodate the median
ridge. It also shows the early stages of bifurcation
of the two primary lobes. Unfortunately, the specimen
yields no details of the interior, and the brachial
valve cannot be removed because it is tightly
cemented to the pedicle valve.
STRATIGRAPHIC OCCURRENCE.—Bell Canyon Formation
(Pinery and Lamar members), Capitan Formation.
LOCALITIES.—Pinery: USNM 725h; Lamar:
AMNH 38, 430; USNM 725e, 728p, 738, 738b;
Capitan?: USGS 2906 (green).
TYPES.—Holotype: USNM 118512; figured hypotypes:
AMNH 27933/1-3, USNM 147719a-c.
DISCUSSION.—Stehli (1956:311) has rightly
pointed out the uncertainty of the stratigraphic
level of Girty's specimen. USGS 2906 is in a faulted
area with uncertain stratigraphic levels. The Lamar
Limestone is thought to represent deposits at
the base of the great Capitan reef, including slide
material from the reef. It is not known definitely,
therefore, whether Rigbyella girtyi lived on the
reef or in the waters 1500 to 2000 feet below it
at its base.
Genus Coscinophora Cooper and Stehli, 1955
Coscinophora Cooper and Stehli, 1955:469.—Termier and
Termier, 1959:237.
DIAGNOSIS.—Large Lyttoniidae with well-formed
muscle scars bounded by lateral plates and separated
by myophragm; median and lateral ridges
broken into series of beads (moniliseptate); terminivallate;
brachial valve with lateral lobes connected
by dissepiments to produce series of holes
corresponding to beads of pedicle valve; cardinal
process broad, thick.
TYPE-SPECIES.—Coscinophora nodosa Cooper and
Stehli (1955:470, pi. 52: figs. 17-20).
DISCUSSION.—Cooper and Stehli established this
genus on a species from the Split Tank area in
the Hess Canyon Quadrangle, AMNH 500H. Their
specimens showed most of the details to perfection.
In describing the genus, they felt forced to
abandon R. E. King's species Lyttonia hortoni,
which is definitely a Coscinophora. The action was
taken because of the poor quality of the King
specimen. This individual has been examined further
by us, during the preparation of this monograph,
and has been considerably cleaned. It clearly
shows all of the characters of the genus, especially
NUMBER 15 451
on the reverse side to that figured by King. In view
of the fact that this holotype is so badly worn,
without good specific characters and without a
brachial valve, we cannot be sure that L. hortoni
King and C. nodosa Cooper and Stehli are the
same species. The two come from essentially the
same stratigraphic level but on opposite sides of
the mountains. It seems best, therefore, not to
create a synonymy that cannot be defended.
The exterior of Coscinophora is very similar to
that of other lyttoniids, with the exception that
the species have a tendency to be subcircular or
elliptical rather than spatulate, as in Collemataria,
Eolyttonia, and Leptodus. The attachment surface
is, naturally, variable, but it is generally moderately
large in small specimens, but, in proportion,
it is small in the largest ones. It is usually somewhat
transverse. The specimens commonly lived
in large clusters, with every conceivable position
being occupied, to create a maximum of conflicts
among the growing individuals. This leads to
stunting, distortion, and internal maldevelopments.
The majority of specimens that develop in a
reasonably normal form are broadly and flatly conical,
but the cone is greatly distorted, so that one
side is much shorter than the other. This is brought
about by the development of a short cowl. In the
very young the form may be a well-developed cone,
but, as growth continues, the anterior side grows
faster than the posterior, leaving a short cowl that
may be directed anteriorly or posteriorly, depending
on conditions of attachment. The usual seems
to be a fairly erect cowl, but many are tilted more
or less strongly anteriorly.
As usual, broad surfaces such as those presented
by either side of Coscinophora are favorable sites
of residence for a variety of sessile animals. Coscinophora
is, therefore, a place of attachment for
sponges, corals, brachiopods, and bryozoans—the
hangers-on, when vigorous, resulting in the death
of the host. Clusters of Coscinophora from USNM
709c and 710u usually are richly coated with a variety
of species.
The hinge of Coscinophora is like that of Eolyttonia.
In the young it is narrow and straight, consisting
of an elevated ridge against which the edge
of the brachial valve is fitted. In adults it may
occupy a position under the cowl and not be easily
visible. In these it is again a transverse slit bordered
posteriorly by a lip that is usually somewhat
thickened and may be almost bulbous. The lip
bounds a small triangular flat area that represents
the zone of movement of the brachial valve while
gaping. This also seems to give additional evidence
that the valve was movable.
The muscle region of this genus is of unusual
interest because of its fairly good development and
the trace of the scars left on the valve. The muscle
region is generally triangular, bounded by thin
laterally divergent plates that suggest dental lamellae
and might be atavistic remnants of them. At
any rate, these delicate plates extend anterolaterally
for a considerable distance, often to the third
lateral row of beads, and commonly include some
of the beads within their confines. Elongate, narrow
diductor scars appear at the base of the lateral
bounding ridges. Median and slightly anterior to
them are larger patches of less definite shape, but
of marked dendritic pattern, representing the adductor
scars (Stehli, 1956a: 309, pi. 42: figs. 2, 7).
It is important to note that the scars indicate a
symmetrical development of muscles of considerable
size and strength. This is another clear evidence
that Coscinophora could move its brachial
valve to open and close the shell.
A characteristic feature of this genus is the myophragm
that divides the muscles of the pedicle
valve. This stands as a thin, bladelike septum, generally
with the highest part toward the anterior.
Its thin, bladelike character appears in the smallest
specimens. The myophragm is not always connected
with the median ridge or row of beads that
serves as the median ridge in the genus. In many
specimens the myophragm lies at a small angle to
the median bead row.
The most distinctive feature of the genus is the
curved rows of beads that serve in the place of the
lateral septa of other Lyttoniidae. In a few specimens,
especially young or youthful ones, the distal
parts of the beaded rows are solid (solidiseptate),
like Eolyttonia or Leptodus. In general the beads
are flat plates of varying length and degree of
inclination to the valve surface. In deep specimens
the beads are longer and more elevated than in
the flatter specimens, a situation corresponding to
that in Eolyttonia, where deeper specimens have
strongly projecting and oblique lateral septa. The
beads appear to be laminar shell material protrud452
SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
ing from a layer of fibrous, pseudopunctate shell
that completely surrounds them. Interseptal ridges
and longitudinal striations are developed in the
older stages of some specimens. In many specimens
the inner fibrous layer almost completely submerges
the beads and only their distal extremities protrude.
In some specimens from USNM 709c, the
shell is very thick, attaining 10 mm in some individuals.
The median row of beads is constructed like
that of the lateral rows, except that the beads are
oriented longitudinally instead of transversely, as
in the lateral rows. Unexpectedly, the elevated
myophragm of the muscle area is not always in line
with the median bead row, but often it extends at
an angle to it, destroying the usual interior symmetry.
The brachial valve of this genus is not well
known. It is a single perforated plate and is usually
much more delicate than the attached valve,
except for its posteromedian region. Consequently,
no perfect and complete specimen of the brachial
valve appears in the collection.
Few specimens preserving the cardinal process
have been seen. The best-preserved specimen (paratype,
USNM 124121a) has a broad, thickened but
somewhat flattened boss. It is not possible to resolve
this into myophores and shafts. The median
ridge of the brachial valve is low and broad and is
indistinct just anterior to the cardinal process. In
this specimen four indistinct adductor scars appear
on each side of the ridge on a flattened area just
anterior to the cardinal process. In the holotype of
C. nodosa the median ridge consists of two elevated
parallel ridges with a median groove between
them to about midvalve. Anterior to this point it
is composed of two elevated lines, but, between
them, there is a series of holes corresponding to
the beaded median line of the pedicle valve.
The lateral lobes of the brachial valve are shallow,
gently curved, and not complicated by internal
thickening. They are connected by narrow dissepiments.
In the holotype mentioned above the proximal
part of the space between the lateral lobes has
been filled in to form a solid posterior plate.
DEVELOPMENT.—Young specimens from USNM
709c give a clue as to how the species grew. As
usual, the shape is variable; some specimens have
a cowl, but those that grew on flat surfaces have
the cowl reflected posteriorly.
The smallest specimen (USNM 153591c) is 8 mm
long by 11 mm wide. It has a fairly well-developed
vallum laterally, a strong median septum apically,
and has two outlobes separated by a marginal indentation
and a single bead inside that. The median
ridge anterior to the septum is fairly slender
and consists of a long bead and an angustilobate
ridge near the anterior margin. The hinge is
straight on the anterior side of an arch, the sides
of which form part of the attachment surface of
the specimen.
A second specimen (USNM 154924a) is 14 mm
in diameter and has a well-formed vallum marginally
consisting of three outlobes and one bead
at the first inlobe, one bead at the second inlobe,
and two beads at the base of the third outlobe.
This is the arrangement on the left (observer's)
side of the shell. On the right side the septa are
represented by single beads. The- median septum
is strong at the apex with two beads anterior to it.
The third bead is angustilobate and occurs at the
margin.
A specimen (USNM 154924b), ~t9 mm long by
17 mm wide, has a small cowl and a strong median
septum at the apex. The median ridge consists of
two elongated and thick beads. The septa on the
left side consist of three beads only, representing
that many septa. On the right side this specimen
is abberant in having three, possibly four, septa in
the solidiseptate condition and, with this, interseptal
adventitious ridges.
A third specimen, about 20 mm in diameter
(USNM 154924c), is very irregular in its development.
The median septum is present, and the median
ridge is represented by three beads, the anterior
one in the angustilobate stage. On the left
side the first septal row consists of two beads, the
second one is a ridge in the angustilobate stage,
the third consists of two beads, and the fourth is a
low septum in the angustilobate stage. Some interseptal
thickening occurs at the margins.
A specimen, 17 mm long and 22 mm wide, forms
a crude cone with posteriorly directed cowl
(USNM 154924d). The median septum is well
formed, and the median ridge consists of two long
beads. The left side has three rows consisting, in
order from the posterior, of one, two, and three
NUMBER 15 453
beads. The bead of the first row is strongly inclined
toward the anterior. On the right side the
rows in the same order are two in the first, three
and an incipient fourth in the second. The latter
is angustilobate and is part of the vallum, which
is marginally low and inconspicuous. The third
row has four beads and the fourth row has three
and a short angustilobate extension of the vallum.
A specimen (USNM 154924e), 25 mm long and
32 mm wide, is more normally developed. The
first septal row on each side consists of an inner
bead and an angustilobate extension of the vallum
that is indistinct. The second row is of three beads,
the outermost one a part of the vallum. The third
row has six beads on the left side and three on the
right. The fourth row has five beads on the left,
three on the right. An indistinct fifth row of three
beads appears at the anterior of the right side. The
median septum is well developed and, anterior to
it, is a row of four elongated beads. Most of the
beads of the septal rows dip posteriorly.
It is possible to conclude from the above descriptions
'that the young Coscinophora has an incomplete
vallum and that its septal walls are in the
angustilobate stage. As growth continues, the inner
parts of the septal wall are pinched off as beads.
The Septum is as strong a feature of the young as
it is of the adult. It is also clear that the young
Coscinophora is affected in its development by its
habitat situation and that it seldom develops uniformly.
The collection also contains four young brachial
valves, the smallest about 6 mm long (USNM
154924f). This small specimen has two lateral
lobes, and, on the left side, the lobes are joined by
a dissepiment that bounds one hole. On the opposite
side the hole is partially formed, and the
dissepiment on the outside is not formed. The
median region is moderately broad, and the shell
is cleft medially for about one-third the length. On
the inside the median ridge is indistinct, but adductor
scars appear to be visible on each side of it.
The cardinal process is not distinguishable.
STRATIGRAPHIC DISTRIBUTION.—This, genus appears
first in the Decie Ranch Member of the
Skinner Ranch Formation, where it forms small
clusters and patches. It is also present in the Sullivan
Peak Member of the Skinner Ranch Formation.
It is present in the Wedin Member, low in the
Cathedral Mountain Formation. It is rare in the
Split Tank area, where it occurs in the Institella
Zone of the Cathedral Mountain Formation. The
most abundant occurrence of the genus is in the
Road Canyon Formation. From Sullivan Peak east
to the Hess Ranch house it forms bioherms and
patches, some of considerable thickness. It has not
been found above the Road Canyon Formation.
Coscinophora hortoni (R. E. King)
PLATE 134: FIGURES 1-5; PLATE 191: FIGURES 1-3
Lyttonia hortoni R. E. King, 1931:104, pi. 33: fig. 18.
The specimen designated as type in King's (1931)
plate legend to this species was illustrated from one
side only. The side figured is badly worn and shows
moderately sized beads, about 6 or 7 in 25 mm
worn down almost level with the surface between
the rows. The row along the axis consists of
elongate beads numbering 7 in 25 mm. Other than
these facts, this side of the specimen gives little
information.
On the reverse side of the holotype two individuals
are attached, a large one attached by most
of its surface and an immature one. The large
specimen preserves somewhat more than half and
thus exhibits the axis and part of the muscle region.
The lateral plates and myophragm are visible
but badly worn. The latter is not in line with the
median row of beads. Seven beads appear in 25
mm in the anterior two rows. A remnant of the
posterior flap shows this to have been directed posteriorly
as usual in broadly cemented forms.
The immature specimen exhibits a median longitudinal
row of beads, although the two sides are
different. The right side has one continuous lateral
septum and a second ridge of only one bead.
The left side shows two continuous ridges and an
anterior row of two beads. The surface of both
specimens on this side are crusted and worn.
The holotype and the specimens attached to its
reverse indicate a species of large size, more than
55 mm long and more than twice that in width.
We are unable to prophesy the true form of the
holotype; but it must have been somewhat elliptical
for it to have had a large attachment surface
and to have been fairly flat.
STRATIGRAPHIC OccuRRENCE.-^Cathedral Mountain
Formation (section 14, bed 16 of P.B. King;
454 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
according to R. E. King, 1931:71, bed 16 contains
Institella leonardensis), Cathedral Mountain Formation
(Wedin Member).
LOCALITY.—Cathedral Mountain (Wedin Member):
King 7, USNM 714w.
TYPES.—Holotype: YPM 12062; figured hypotypes:
USNM 150860a, b.
DISCUSSION.—We have assigned to this species a
few specimens from USNM 714w, probably the
same level from which King's type came.
Coscinophora magnifica, new species
PLATE 182: FIGURES 35, 36; PLATE 184: FIGURES 1-8;
PLATE 185: FIGURES 1-17; PLATE 186: FIGURES 1-13;
PLATE 187: FIGURES 1-11; PLATE 188: FIGURES 15-22, 24
Large, broad, shallow cones having variable outline,
usually subcircular to broadly subelliptical but
elongate when distorted. Attachment surface generally
small. Cowl usually short, generally erect,
more rarely curved over hinge. Shell thick and
strong; surface marked by concentric lines and
wrinkles.
Pedicle valve interior with broad hinge; lateral
plates of muscle area not well developed; myophragm
thin, delicate, high anteriorly; muscle region
deep, scars indistinct. Bead rows numbering
about 20, strong in anterior two-thirds but becoming
obscure at anterior and generally consisting of
continuous ridges in terminal rows of old specimens.
Beads ranging in number from 6 to 9 in 25
mm. Bead rows moderately convex anteriorly. Interseptal
ridges strong in anterior third.
Brachial valve with small, thickened posterior
region; lateral lobes thin and delicate; dissepiments
narrow and delicate. Cardinal process not developed;
median ridge consisting of 2 low ridges
bounding row of holes.
MEASUREMENTS (in mm).—
maximum hinge cowl
length width width height length
USNM 710u
150858a
150858b
150858c
USNM 709c
150856a
150856b
USNM 72It
151331c
151331d
(holotype)
88.6
94.0
52.0
71.0
47.0
77.5
69.2
91.3
77.5
50.0
76.0
52.0?
88.7
69.6
19.6
16.0
?
16.5
8.0
9.0
12.0
20.0?
28.0
23.5
35.0?
28.0
32.0?
39.7
14.0
19.0
15.0
24.0
8.0
24.0
26.5
STRATIGRAPHIC OCCURRENCE.—Road Canyon Formation.
LOCALITIES.—USNM 706f, 709c, 710u, 716x, 720d,
72Ij, 721t, 721w, 721z, 722e, 724a, 724c, 724d, 726d,
726e, 732j, 732t, 732w, 733a, 733n.
DIAGNOSIS.—Large thick-shelled Coscinophora
with beads small • and generally numerous, with
broadly rounded form, and thin, delicate brachial
valve.
TYPES.—Holotype: USNM 151331d; figured paratypes:
150856a, 153655c, 150858b, c, 150859,
151330a, b, e-k, 151331a-c, e, f, 153591a-g,
153592a-c, 153593a-f,> 153594, 153655c, 154924c;
measured paratypes: 150856a, b, 150858a-c, 151331c;
unfigured paratypes: 150858a, 151330c, d, 15133Id,
154924a-f.
COMPARISON.—Variability in attached forms
makes it difficult to compare species of this genus.
Coscinophora magnifica usually can be recognized
by its thick shell and generally rounded to transversely
elliptical form, together with the great
number and small size of the beads in the lateral
rows. Coscinophora nodosa Cooper and Stehli is a
somewhat smaller species with larger and flatter
beads in the rows and a stouter and thicker brachial
valve. Coscinophora magnifica differs from
C. monilifera, new species, in the smaller size of
the beads and their lesser height above the inner
surface.
DISCUSSION.—This species is based on the large
and fairly well-preserved specimens that come from
the Road Canyon Formation just east of Sullivan
Peak (USNM 709c and 710u).
When favorable circumstances permitted this
species to grow unconfined, it developed a nearly
circular to roundly and transversely elliptical form
with short cowl and broadly conical profile. Few
specimens had as favorable conditions of life as
the holotype of this species. Most are distorted in
some direction to produce elongate forms or exaggeratedly
transverse specimens. Many specimens
were not able to develop the gentle convexity of
the normal specimen, but they were distorted ventrally
or dorsally or both. Such distortions involved
the beads of the rows in types of abnormality. General
deepening of the pedicle valve led to elongation
of the beads to a slatlike form, the proximal
part being buried in the fibrous shell tissue. Dorsal
bulging led to an opposite effect.
NUMBER 15 455
The cowl of this species from the Road Canyon
Formation generally was short, but some specimens
have the cowl unusually long. One specimen
(USNM 151330), which must have been a nearly
perfect cone, had a cowl 38 mm long. The surface
of the cowl is marked by numerous, closely crowded
pits representing pseudopunctae. About 10 layers
of shell can be counted at the edge of the cowl.
The beads in the rows of this species are not as
strongly protuberant as those of C. monilifera.
This is due apparently to the great thickening of
the valve floor. The shell of the holotype is about
6 mm thick near the anterior margin, but some
specimens are still thicker. The beads can be seen
along broken edges as laths or rods buried deep
within this tissue with their rounded distal ends
protruding. Toward the anterior ends of large
specimens the lateral rows of beads are complicated
by the interseptal ridges of Eolyttonia and of other
lyttoniid genera. In many specimens these ridges
are equal in height to the bead rows bounding
them. In some specimens the ridges between the
bead rows are striated parallel to the long axis of
the shell, as in Eolyttonia and other oldhaminidine
genera. The median row of beads, corresponding
to the axial ridge of other lyttoniids, is seldom direct,
but it is usually sinuous and the beads vary
considerably in size.
The muscle scars are not usually well preserved
in this species, but their details may be determined
from study of a large number of specimens. Generally
the lateral ridges bounding the muscle region
are strongly defined. The lateral margins may be
defined by a ridge or abrupt change of slope,
rather than an elevated plate as in C. nodosa. The
lateral plate in some specimens, although present,
appears to have been eliminated by the deposition
of adventitious shell in the depressions on its outer
side. The myophragm is also variable, but it is
generally so poorly preserved, because of its delicacy,
that its true form is not known. It appears to
rise to a sharp crest near its anterior and then
taper away anteriorly.
The muscle scars are not clearly visible in many
specimens of this species, but the peculiar dendritic
pattern of the adductor scars illustrated by Stehli
(1956a, pi. 42: figs. 2, 7) has been confirmed. The
scars, however, are not elevated on a callus as in
Stehli's specimens.
The brachial valve of this species is characterized
by a very thick postero-axial region and very delicate
lateral lobes with thin dissepiments tying
them together. This is a feature strongly contrasting
to the stout nature of the brachial valve of
C. nodosa. No specimen of the brachial valve of
this species showed a cardinal process. The diductor
muscles must have been attached to the posterior
margin or posterior edge, but no scars of
attachment have been detected.
ECOLOGY.—Coscinophora magnifica is abundant
in the Road Canyon Formation, where it occurs in
bioherms composed almost wholly of this species.
Specimens are abundant in the rock, but they are
not usually compacted. They are loosely but fairly
densely disposed, suggesting the breaking up of
large patches. Few other species occur with them,
at least as far as can be seen from the outcrop itself.
Brachial valves are extremely rare in these
deposits, suggesting some pounding by currents.
These bioherms are common from the east side of
Sullivan Peak to the hill north of Leonard Mountain.
Many of these bioherms occur in the band
of Road Canyon limestone on the west, south, and
east sides of this mountain north of Leonard Mountain,
which are excellent places to collect or study
the species. The species was not found in the exposures
of the Road Canyon Formation in the vicinity
of Old Word Ranch, but a few specimens
have been taken from the Sierra del Norte west of
Dugout Mountain.
Coscinophora monilifera, new species
PLATE 129: FIGURES 20, 21; PLATE 183: FIGURE 1;
PLATE 188: FIGURES 1-3, 23; PLATE 189: FIGURES 1-5;
PLATE 190: FIGURE 1
Fairly large, forming broad, shallow cone with
moderately developed cowl and subcircular to subelliptical
outline. Lateral profile moderately convex;
attachment surface generally small; cowl usually
overhanging hinge; shell moderately thick, exterior
marked by concentric lines and wrinkles.
Pedicle valve interior with narrow hinge having
broad triangular surface on cowl; lateral plates
bounding muscle area obscure or not formed; myophragm
low and thin, highest anteriorly; muscle
marks obscure. Bead rows numbering about 17 in
largest specimens; beads narrow, flattened, strongly
456 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
oblique and strongly elevated in posterior half, becoming
lower anteriorly; beads variable in lateral
extent, well individualized. Septal ridges between
bead rows strong, variable, present mostly in anterior
half. Median bead row prominent.
Brachial valve poorly known from fragments,
which indicate stout platelike valve.
MEASUREMENTS (in mm).—
maximum hinge cowl
length width width height length
USNM 707a
150865a
150865b
150865c
USNM 733j
153590d
(holotype)
153590b
153590c
53.0
66.0
38.0
53.0
58.7
54.5
52.0
70.0
44.0
47.3
63.0?
68.3
7.0
?
6.0
9.6
9.4
8.7
19.0
27.0
15.0
25.0
22.0
?
12.0
17.5
10.0
15.0?
22.0
13.0
STRATIGRAPHIC OCCURRENCE.—Skinner Ranch
Formation (Decie Ranch, Poplar Tank, and Sullivan
Peak members).
LOCALITIES.—Decie Ranch: USNM 707a, 714t;
Poplar Tank: 707h, 708a; Sullivan Peak: 707d, 707g,
714y, 715j, 722-1, 733j; Skinner Ranch (base): 711d,
712p.
DIAGNOSIS.—Moderately large Coscinophora of
moderate depth with strongly elevated beads in
posterior half.
TYPES.—Holotype: USNM 153590d; figured paratypes:
153656, 153564, 153590a-c, e, f, 153595,
153597.
COMPARISON.—Individuals of this species are difficult
to separate from individuals of C. magnifica,
new species, but in the mass this species has
stronger and less numerous but more elevated
beads than C. magnifica. Lateral plates and muscle
areas are less well developed, the specimens attain
a smaller size, have a stronger development of the
cowl, and generally tend toward deeper cups. To
distinguish the two, large numbers of specimens are
necessary.
This species differs from C. nodosa Cooper and
Stehli in its greater size, lesser development of the
muscle area, less prominent myophragm, and generally
greater elevation of the beads.
DISCUSSION.—Coscinophora monilifera is not a
common species and generally is confined to the
Lenox Hills and Dugout Mountain, where it occurs
in small clusters. Its most noteworthy features
are the strong development of the beads, whicl
stand up strongly and obliquely above the valve
floor. Adventitious shell is not as strongly developed
about them as in C. hortoni (King) or C.
magnifica, in which the beads are nearly buried in
some specimens.
The exterior form of C. monilifera is variable.
Some specimens develop a fairly deep conical form
with a good development of the cowl. Some of
these individuals also have the anterior margin
bent in a dorsal direction, further emphasizing the
depth and conical form. Other specimens, however,
do not have any deflection of the anterior and
are nearly flat in this part of the shell.
The large cluster shown on Plate 129: figures 20
and 21 is of interest because the only evidence of
this species on the block from which it was etched
was a few specimens. There was no hint that the
bulk of the rock was composed almost wholly of
this species. In addition, numerous specimens of
Geyerella and Tropidelasma were intimately cemented
within the mass. (See Plate 5: figure 1 for
view of outcrop from which the Coscinophora mass
was taken.)
Coscinophora nodosa Cooper and Stehli
PLATE 182: FICURES 31-34
Coscinophora nodosa Cooper and Stehli, 1955:470, pi. 52B:
figs. 17-20.
This is a rare species; only four specimens are
presently known. Cooper and Stehli described it
from a holotype and paratype, both of which are
adults. Two additional specimens from the Split
Tank area and a small individual adhering to the
paratype permit some further remarks on the species.
The additional specimens are all immature,
but two of them exhibit the muscle scars in some
detail.
The smallest of the specimens (USNM 154926)
measures 14 mm long by 22 mm wide and has three
bead rows, the first of one bead or short septum,
the other two of two beads each on the left side
but only one bead each on the right side. A fourth
incipient row appears at the anterior of the right
side . The median axial row consists of three beads.
Lateral plates are not developed, but the myophragm
is strong and is highest near its midlength
and tapers to the median bead row. Diductor scars
NUMBER 15 457
are indistinct, but longitudinal striation just anterior
to their ends indicates the position of the
adductor scars. The anterior margin of this specimen
is broad and sloping and is marked by numerous
pustules representing pseudopunctae.
The second specimen (USNM 154925) measures
36 mm long and 32 mm wide, but neither dimension
is correct because the right side and part of
the anterior are broken away. Five bead rows appear
on the left side, the first being partly buried
in shell tissue. Five rows appear on the right side,
but the fifth or anteriormost row is opposite the
fifth row of the left side. This suggests that the
right side is occupied by six rows. The axial bead
row is sinuous, and the five beads visible are all
bent toward the right side. The beads of all rows
are elongate, flat, strongly oblique to the shell floor,
and well separated. The muscle field is well developed
and has a low lateral plate on the left side
but none on the right. The diductor scars are narrow
and elongate and lie at the base of the lateral
ridge or the change of slope where this ridge would
be. The adductor scars are small, rounded, somewhat
thickened, and strongly dendritic, the one on
the right side overlying a partly buried bead of the
first or oldest row. The myophragm is high and
thin, highest posteriorly and tapering fairly
abruptly near midlength to form a low ridge between
the adductor scars at the anterior end of
which it terminates. The myophragm in this specimen
has a broad curve to the right and terminates
on the proximal bead of the second bead row on
the right side. It is thus not in line with the axial
median bead row.
The small specimen attached to the paratype is
incomplete, but it preserves to perfection the posterior
cowl, which is short and thick, and the muscle
region. In this specimen the elongate diductor
scars are well formed. On the left side the distal
end of the diductor scar overlies the second bead
of the first bead row. The myophragm is high and
delicate, the adductors are not thickened, but the
dendritic markings are present, although not
strongly marked.
It is an odd fact that only the smallest specimen
of this species has the myophragm continuous with
the axial longitudinal bead row. The beads of all
rows of the holotype and paratype are flattened
and somewhat lathlike, strongly oblique, with
sharp edges, and strongly protruding from the
floor. These characters of the beads and the nature
of the muscle area are among the features distinguishing
this species from the others.
Another characteristic of C. nodosa that separates
it from C. magnifica, new species, is the solid character
of the brachial valve, which is strong and
platelike. The lateral lobes and dissepiments are
strong and thick, contrasting strongly to the delicate
nature of the brachial valve of C. magnifica.
This valve has not been seen in its entirety in
C. monilifera, new species, but the traces of it that
have been encountered suggest that it is intermediate
between C. magnifica and C. nodosa. Clearcut
evidences of a cardinal process do not appear in
any specimens or species of Coscinophora, but C.
nodosa has a boss at the posterior apex that suggests
this structure. It has not been possible, however,
to resolve this small mass into myophores
and shaft. Possibly Coscinophora had eliminated
its cardinal process.
STRATICRAPHIC OCCURRENCE.—Cathedral Mountain
Formation.
LOCALITIES.—AMNH 500H, 500L.
TYPES.—Holotype: USNM 124121b; paratype:
124121a; described hypotypes: 154925. 154926.
458 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
Literature Cited
(addition to list in volume I)
Fischer de Waldheim, G.
1850. Orthotetes genre de la famile des brachiopodes.
Societe Imperial des Naturalistes de Moscou Bulletin,
23 (2) : 491-494.
Grant, R. E.
1972. The Lophophore and Feeding Mechanism of the
Productidina (Brachiopoda). Journal of Paleontology,^
46:213-248, 12 figures, 9 plates.
Gray, J. E.
1840. Synopsis of the Contents of the British Museum. 42nd
edition, 370 pages. London.
Huxley, T. H.
1869. An Introduction to the Classification of Animals.
147 pages, 47 figures. London: John Churchill &: Sons.
Licharew, B. K.
1934c. Pages 458-552, figures 707-843, in Zittel, Grundzuge
der Palaontologie: I, Invertebrata. Leningrad-Moscow.
[Russian edition.]
McKee, E. D.
1941. Derbyia arizonensis, New Name for D. regularis
McKee. Journal of Paleontology, 15 (1) :91.
Ruiz, C.
1933. In Fabiani and Ruiz, Sui Giacimenti Permianti del
Sosio (Palermo) e sugli Strofomenidi in essi trovati.
Societa Geologica Italiana Memorie, 1: 22 pages.
Schuchert, Charles
1897. A Synopsis of American Fossil Brachiopoda. United
States Geological Survey Bulletin, 87: 464 pages.
Streeruwitz, W. H. von
1893. Trans-Pecos Texas. Pages 139-175 in Geological Survey
of Texas, 4th Annual Report, for 1892.
Stuckenberg, A. A.
1905. Die Fauna der obercarbonischen Suite des Wolgadurchbruches
bei Samara. Geologischeskii Komitet
Trudy (Comite Geologique Memoires), new series,
23: 144 pages, 13 plates.
White, C. A.
1862. Description of New Species of Fossils from the
Devonian and Carboniferous Rocks of the Mississippi
Valley. Boston Society of Natural History Proceedings,
9:8-33.
Williams, Alwyn
1953c. North American and European Stropheodontids:
Their Morphology and Systematics. Geological Society
of America Memoir, 56: vii + 67 pages, 13 plates.
PLATE 24
Isogramma and Roemerella
Isogramma lobatum, new species: 1, Interior of a very well-preserved brachial valve, showing
cardinal process with its excavated shaft and median septum and "brachial ridges," X 1»
holotype USNM 151384; 2, dorsal view of cardinal process of same specimen, X 2 [Cathedral
Mountain Formation (lower), locality USNM 702b].
3, 4, Interior and exterior views of another large specimen, x •> paratype USNM 151383
[Cathedral Mountain Formation (lower), locality USNM 702].
Isogramma species: 5, 6, Exterior and interior of a small brachial valve, X 3, figured specimen
USNM 152570 [Skinner Ranch Formation (Sullivan Peak Member), locality USNM 722-1].
Roemerella gigantissima, new species: 7, 8, Rubber replica of the exterior of an imperfect
specimen and the cast from which it was made, x *> holotype USNM 151393a [Road Canyon
Formation, locality USNM 703].
NUMBER 15 459
PLATE 24.— Isogramma and Roemerella.
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460 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 25
Isogramma
Isogramma species: 1, 2, Exterior and interior views of a fragment of the pedicle valve,
showing interarea, delthyrium, and trace of the muscle region, x 3, figured specimen USNM
151388 [Cherry Canyon Formation (Getaway Member), locality USNM 728].
Isogramma cf. /. lobatum, new species: 3, 4, Interior and exterior views of a dorsal valve,
showing the elongated cardinal process, x 1. figured specimen USNM 153187a; 5, 6, interior
and exterior of another brachial valve, showing excavated cardinal process shaft and median
septum, x 1» figured specimen LISNM 153187e; 7, 8, interior and exterior views of a fragmentary
dorsal valve, showing expanding cardinal process myophore and excavated shaft,
X 1, figured specimen USNM 153187c; 9, 10, posterior parts of two brachial valves in interior
view, showing cardinal process and blister-like shaft, x I> figured specimens USNM 153187f
and d [Cathedral Mountain Formation (lower) , locality USNM 72lu].
Isogramma species: 11, 12, Exterior and interior views of the posterior parts of an imperfect
pedicle valve, showing short interarea, wide delthyrium, diductor scars, and pedicle track,
X 1, figured specimen USNM 152566 [Road Canyon Formation, locality AMNH 503 = USNM
703].
Isogramma vidriense, new species: 13, 14, Pedicle valve, showing long, narrow pedicle track,
X 1. X 2, holotype YPM 10837 [Gaptank Formation, locality King 203].
Isogramma diabloense, new species: 15, Exterior of a fragment, showing the ornament, X 3,
paratype USNM 151382p [Bone Spring Formation, locality USNM 725y].
Isogramma concavum, new species: 16, 17, Exterior and interior views of a deeply concave
brachial valve, x 1. holotype USNM 153188 [Neal Ranch Formation (bed 4 of P. B. King),
locality USNM 727e].
NT'MBER 15 461
PLATE 25.—Isogramma.
4 6 2 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 26
Derbyoides and Isogramma
Derbyoides nebrascensis Dunbar and Condra: 1, Interior of the pedicle valve, showing secondary
median septum, muscle area, and pseudodeltidium, x '. hypotype USNM 150427c;
2, 3, interior and posterior views of the brachial valve, showing dendritic muscle field, cuplike
sockets, and median ridge, X 1. hypotype USNM 150427c; 4, cardinalia of the preceding specimen
enlarged, x 3 [shale just below the Cass Limestone, locality USNM 519].
Isogramma diabloense, new species: 5, 6, Exterior and interior of a fragment of a pedicle
valve, showing featureless interior and traces of pedicle region on the exterior, x 6, paratype
USNM 151382a; 7, exterior of a small brachial valve, x 1. holotype USNM 151382b; 8, 9,
posterior and interior of the preceding specimen, x 3; 10-12, posterior, exterior, and interior
of a fragmentary brachial valve, showing break at junction of septum and cardinal process
shaft, x 3, paratype USNM 151382c; 13-15, posterior, exterior, and interior of another brachial
valve, showing the same features, x 3, paratype USNM 151382d [Lower Bone Spring Limestone,
locality USNM 725y].
NUMBER 15 463
PLATE 26.—Derbyoides and Isogramma.
4 6 4 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 27
Lepidocrania and Acanthocrania
Lepidocrania tardispinosa, new species: 1. Dorsal view of a strongly lamellose specimen, x "•
paratype USNM 151395a [Road Canyon Formation (base), locality USNM 702c].
Acanthocrania alts,-new-species: 2, 3; Dorsal and side-views of a minutely spinose, elevated
cone, x 4, holotype USNM 152571 [Skinner Ranch Formation (Decie Ranch Member), locality
USNM 720g].
Acanthocrania intermedia, new species: 4-6, Side, dorsal and interior views of a somewhat
sparsely spinose specimen, x 4, holotype USNM 151440c; 7, exterior of another brachial valve,
X 4, paratype USNM 151440a; 8-10, dorsal, side, and interior views of a lamellose and
sparsely spinose specimen, x 4, paratvpe USNM 151440b [Word Formation (Willis Ranch
Member), locality USNM 706].
Acanlhocrania species: 11, Dorsal view of a small, minutely spinose individual, X 6, figured
specimen USNM 153046a [Cathedral Mountain Formation (top), locality USNM 726o].
Acantliocrania densispina, new species: 12, Dorsal view of a densely spinose cone, X 4, paratype
USNM 151434a; 13-15, interior, side, and exterior views, x 4. holotype USNM 151434b
[Road Canyon Formation (base) , locality USNM 702c].
Acantliocrania densispina, new species: 16-18, Interior, side, and dorsal views of a distorted
and much thickened specimen, x 4. paratype USNM 151434c [same stratigraphy and locality
as above].
Acanthocrania species: 19-21, Dorsal, side, and interior views of a highly conical and coarsely
spinose specimen, x 4, figured specimen USNM 153047a [Road Canyon Formation, locality
USNM 726x].
Acanthocrania conferta, new species: 22, 23, Dorsal and side views of a strongly spinose specimen,
x 6, paratype USNM 151429a [Cherry Canyon Formation (Getaway Member) , locality
AMNH 512 z= USNM 728]. 24-26, Dorsal, side and interior views of the holotype with
strongly marked interior, x 4, USNM 151430b [Cherry Canyon Formation (Getaway Member),
locality USNM 732].
Lepidocrania species: 27-29, Interior, side, and dorsal views, X 4, figured specimen USNM
151421a [Bone Spring Formation (lower), locality USNM 728f|.
Lepidocrania species: 30, 31, Side and dorsal views of a distorted specimen, x 4, figured
specimen USNM 151445 [Bone Spring Formation (lower) , locality USNM 728h].
NUMBER 15 465
PLATE 27.—Lepidocrania and Acanthocrania.
466 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 28
Lepidocrania, Acanthocrania, and Petrocrania
Lepidocrania sparsispinosa, new species: 1, Exterior of a young brachial valve attached to
productid shell, x 3, paratype USNM 151402 [Neal Ranch Formation, locality USNM 721g].
2-4, Dorsal, side, and interior veiws of an average specimen, x 4, holotype USNM 151401
[Neal Ranch Formation, locality USNM 701c].
5, 6, Dorsal and side views, x '> paratype USNM 151438a; 7, 8, interior and side views of
the same specimen, x 4; 9, 10, dorsal and interior views of another paratype, x l> USNM
151438b; 11-13, the same specimen, showing lamellae and sparsely scattered coarse spines,
X 4 [Neal Ranch Formation, locality USNM 721g].
Acanthocrania platys, new species: 14-16, Interior, dorsal, and side views, showing fine spines,
muscle scars, and sponge or barnacle borings, x 4, holotype USNM 151456 [Bone Spring
Formation (lower), locality USNM 728F).
Petrocrania teretis, new species: 17-19, Interior, side, and dorsal views of a paratype, x 4,
USNM 151404c; 20-22, interior, side, and dorsal views of another paratype, x 4, USNM
151404a [Word Formation (lens between Willis Ranch and Appel Ranch Members), locality
USNM 706b].
23-25, Dorsal, side, and interior views of the holotype, x 4, USNM 151405a [Word Formation
(Willis Ranch Member, top), locality USNM 706e].
Petrocrania species: 26-28, Interior, side, and dorsal views, showing well impressed muscle
scars, x 4, figured specimen USNM 152579a [Cathedral Mountain Formation (lower), locality
USNM 721 u].
Petrocrania diabloensis, new species: 29-31, Dorsal, side, and interior views of a large specimen,
x 1. paratype USNM 152577; 32, interior of brachial valve showing muscle scars of paratype,
x 6; 33, 34, side and dorsal views of the exterior, x 4 [Bone Spring Formation, locality
AMNH 625].
Petrocrania exasperata, new species: 35, 36, Side and dorsal views of the holotype, x h USNM
152578a; 37, side view, x 2; 38, interior, showing muscle scars, x 3 [Bell Canyon Formation
(Hegler Member), locality USNM 731].
Petrocrania septifera, new species: 39, 40, Interior and dorsal views of the holotype, X 1>
USNM 151422; 41-43, interior, side, and dorsal views, showing anterior septum, X 4 [same
stratigraphy and locality as above].
Acanthocrania minutispinosa, new species: 44, Dorsal view, showing mat of minute spines,
X 6, holotype USNM 151447 [Bell Canyon Formation (Hegler Member), locality AMNH 635].
NUMBER 15 467
PLATE 28.—Lepidocrania, Acanthocrania, and Petrocrania.
468 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 29
Lepidocrania
Lepidocrania tardispinosa, new species: 1, Exterior view of the brachial valve, x 4, paratype
USNM 151427 [Road Canyon Formation, locality USNM 706f].
2, 3, Side and dorsal views, x 1. paratype USNM 152582c: 4-6, interior, dorsal, and side
views of the same specimen, x 4; 7-9, side, dorsal, and interior views of the holotype, X 4,
USNM 152582a; 10-12. same views of the holotype, X l [Road Canvon Formation, locality
USNM 721 z].
IS, A very young specimen, x ''• paratvpc USNM 151395o [Road Canvon Formation (base) ,
locality USNM 702c].
14-16, Interior, side, and dorsal views of a distorted and strongly lamellose specimen, x 4,
paratype USNM 152581 [Cathedral Mountain Formation, locality USNM 721u].
17-19, Dorsal, interior, and side views of a large brachial valve, x 4, paratype USNM 152583
[Road Canyon Formation, locality USNM 724c].
Lepidocrania sublamellosa, new species: 20-22, Dorsal, side, and interior of a large specimen,
x 4, paratype USNM ]5140fie: 23-25, interior, dorsal, and side views of a thickened specimen,
x 4, paratype USNM 151406f; 26-30, interior and dorsal views, X l> a n d interior, side,
and dorsal views of a large somewhat worn specimen, X 4, paratype USNM 151406c; 31-34,
side, interior, and dorsal views, x 4, and side view, x '> OI another paratype, USNM 151406b;
35-37, side, interior, and dorsal views of the holotype, x 1. USNM 151406a; 38^10, the same
views of the holotype, showing the muscle scars of the brachial valve, x 4 [Word Formation
(Willis Ranch Member, top), locality USNM 706e].
NUMBER 15 469
PLATE 29.-Lepidocrania.
4 7 0 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 30
Niviconia, Derbyia, Tropidelasma, Diplanus, Acanthocrania, and Lepidocrania
Niviconia globosa (R. E. King): 1, View of the interarea of a large pedicle valve, showing
the narrow, elevated fold on the pseudodeltidium, x L hypotype USNM 153048 [Cathedral
Mountain Formation (lower) , locality USNM 702b],
Derbyia carteri, new species: 2-6, Ventral, posterior, dorsal, anterior, and side views, x '•
paratype USNM 151020b [Neal Ranch Formation (bed 4), locality USNM 701d].
Tropidelasma species 4: 7, 8, Exterior and side views of the brachial valve, x •> figured
specimen 152603a; 9, 10, side and interior views of another brachial valve, showing the long
cardinal process, X 1. figured specimen USNM 152603b [Cathedral Mountain Formation
(lower), locality USNM 721 u].
Diplanus cf. D. rarus, new species: 11, Dorsal view of a large specimen attached to a lyttoniid
shell, x 1. figured specimen 153049a; 12, side view of another specimen similarly attached,
X 1. figured specimen USNM 153049b [Skinner Ranch Formation (Sullivan Peak Member) ,
locality USNM 733j].
Acanthocrania vasta, new species: 13-15, Interior, dorsal, and side views of a large dorsal
valve, x 1> holotype USNM 152573; 16-18, side, interior, and dorsal views of the holotype,
showing the small muscle scars, x - [Bell Canyon Formation (Hegler Member) , locality
USNM 731].
Lepidocrania tardispinosa, new species: 19, Immature brachial valve in dorsal view, showing
beginnings of lamellae, x 6, paratype USNM 151395J [Road Canyon Formation (base) , locality
USNM 702c].
Acanthocrania regularis, new species: 20-22, Dorsal, interior, and side views, showing thickened
muscle scars, x 4, holotype USNM 152572c; 23, dorsal view of another specimen, showing
the coarsely spinose surface, x 4, paratype USNM 152572a; 24, dorsal view of another paratype
from which most of the spines have been stripped, x 4, USNM 152572b [Bell Canyon Formation
(Rader Member), locality USNM 725f].
Acantliocrania intermedia, new species: 25-27, Dorsal, side, and interior views of a paratype,
X 4, USNM 151442a [Word Formation (China Tank Member), locality USNM 702c].
NUMBER 15 471
PLATE 30.—Niviconia, Derbyia, Tropidelasma, Diplanus, Acanthocrania, and Lepidocrania.
472 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 31
Hypopsia
Hypopsia versuta, new species: I, 2, Interior and exterior of a pedicle valve, x l> paratype
USNM 152587d; 17, interior of the preceding specimen, showing spondylium, x 2; 3, cardinalia
of the brachial valve, x 5, paratype USNM 152587k; 4, 5, interior and posterior of a large
pedicle valve with spondylium attached to floor, x J. paratype USNM 152587a; 6-9, anterior,
side, posterior, and dorsal views of a small, complete individual, x l> holotype USNM I52587i;
10-14, anterior, side, posterior, ventral, and dorsal views of the holotype, X 3; 15, 16, posterior
and interior of a long, narrow pedicle valve, x 3, paratype USNM 152587J; 18, 19, exterior
and interior of a brachial valve, X 1» paratype 152587f; 20-22, posterior, exterior, and interior
of the preceding, x 2 [Neal Ranch Formation (bed 2 of P. B. King), locality USNM 701].
NUMBER 15 473
PLATE 31.-Hypopsia.
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4 7 4 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 32
Schuchertella and Hypopsia
Schuchertella subvexa, new species: 1, Interior of a brachial valve, x 1> paratype USNM
152589i; 3, exterior of the same, x 1-5; 2, interior of the same, showing cardinalia, X 2; 4,
posterior of same showing chilidium, x 3; 5, exterior of a well-preserved pedicle valve, x 2,
paratype USNM 152589e [Neal Ranch Formation (bed 2 of P. B. King), locality USNM 701].
Hypopsia versuta, new species: 6, 7, Exterior of the pedicle valve, x 1> X 2, paratype
USNM 152587-1; 8, 9, partial side and interior views of a pedicle valve, showing spondylium,
X 1. paratype USNM 152587b; 10, 11, same views as preceding, but X 2; 12, 13, exterior of a
brachial valve, x 1> X 2, paratype USNM 152587m; 14, posterior of same, showing cardinal
process and chilidium, x 4; 15, exterior of a pedicle valve, x 2, paratype USNM 152587c;
16, 17, interior and posterior views of a pedicle valve, x 2, paratype USNM 152587e; 18,
posterior of a brachial valve, showing cardinal process, x 3, paratype USNM 152587k; 19,
cardinalia of an obese brachial valve; x 4, paratype USNM 152587n [Neal Ranch Formation
(bed 2 of P. B. King), locality USNM 701].
NUMBER 15 475
PLATE Vl.-Schuchertella and Hypopsia.
4 7 6 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 33
Schuchertella
Schuchertella subvexa, new species: 1, 2, Exterior and posterior of a brachial valve, X 1-5.
paratype USNM 152589J; 3, 4, same specimen enlarged to show the cardinalia, X 2 and X 4;
5, 6, exterior and interior of another brachial valve, X 2, paratype USNM 152589k; 7-9,
exterior, posterior, and interior of the same specimen, x 3; 10, cardinalia of the preceding,
showing laterally extended supporting plates, x 4; 11-13, side, ventral, and dorsal views of an
immature, complete specimen, x 4, paratype USNM 152589b; 14, 15, exterior and interior of a
pedicle valve, x '> paratype USNM 152589f; 16, 17, same views of same specimen, X 2; 18,
interior of same specimen, tilted to show absence of dental plates, x 1-5; 19, interarea of preceding
specimen, showing pseudodeltidium, x 4; 20, 21, interior and exterior of another pedicle
valve, x '> paratype USNM 152589g; 22, 23, exterior and interior of a large pedicle valve, X J>
holotype USNM 152589h; 24, 25, same views of holotype, X 2; 26, interarea of the holotype in
full view, x 2 [Neal Ranch Formation (bed 2 of P. B. King) locality USNM 701].
NUMBER 15 477
PLATE 33.-Schuchertella.
4 7 8 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 34
Derbyoides
Derbyoides nebrascensis Dunbar and Condra: 1, 2, Interior and exterior of a pedicle valve,
showing the secondary median ridge, x 2, hypotype USNM 150427a; 3, view of the pseudodeltidium
and secondary median ridge of another pedicle valve, x 3, hypotype USNM 150427c;
4, 5, interior and posterior views of the cardinalia of a brachial valve, showing strong chilidium,
indistinct median ridge, sockets, and dentifers, x 3, hypotype USNM 150427f; 6, interior view
of the cardinalia, x 3, hypotype USNM 150427g; 7, 8, posterior and interior views of another
specimen, showing cardinalia and the dendritic pattern of the muscle scars, X 3, hypotype
USNM 150427h [shale just below the Cass limestone, locality USNM 519].
NUMBER 15 479
PLATE ^.-Derbyoides.
4 8 0 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 35
Ombonia and Derbyoides
Ombonia invecta, new species: I, 2, Exterior and side views of a young pedicle valve, X I»
paratype USNM I50995d; 3-5, side, interior, and exterior views of a large pedicle valve, X l<
holotype USNM 150995a; 6, 7, posterior and side views of a smaller pedicle valve, x l> paratype
USNM 150995i; 8, 9, exterior of a small brachial valve, x 2, X l paratype USNM 150995J;
10, II, interior of a brachial valve, X 2, x 3, paratype USNM 150995k; 12, posterior of another
brachial valve interior, showing the long, widely divergent erismata supporting the cardinal
process, x 4, paratype USNM 150995-1; 13, 14, exterior of a small brachial valve, X J> X 2,
paratype USNM 150995m; 15-17, interior side and exterior views of a large brachial valve, X 1>
paratype USNM 150995c [Road Canyon Formation, locality USNM 702d].
Derbyoides nebrascensis Dunbar and Condra: 18, Interior of the pedicle valve, showing
muscle field and strong, secondary median ridge, X 1. hypotype USNM 150427b [shale just
below the Cass Limestone, locality USNM 519, 2 mi NW Nehawka, Nebraska].
Derbyoides marathonensis, new species: 19, 20, Interior and exterior of a brachial valve, X 2,
paratype USNM 150425c; 21-23, interior, exterior, and posterior views of a ventral valve, x 2,
holotype USNM 150425a; 24, interior of another pedicle valve, showing a thick median ridge,
X 2, paratype USNM 150425d; 25, 26, exterior and interior of another brachial valve, x 2,
paratype USNM 150425c [Neal Ranch Formation (Gray Limestone of P. B. King), locality
USNM 701].
Derbyoides dunbari, new species: 27, 28, Interior and exterior of the brachial valve, X L
paratype USNM 150424b; 29, 30, exterior and interior of the pedicle valve, showing secondary
median ridge, x 1. holotype USNM 150424a [same stratigraphy and locality as above].
NUMBER 15 481
PLATE 35.—Ombonia and Derbyoides.
4 8 2 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 36
Goniarina
Goniarina permiana (Stehli): 1-3, specimen attached by its beak to a Composita valve; posterior,
side and interior views, x 1> hypotype USNM 153514a; 4, one individual attached to
the inside of the pedicle valve of another individual, x 3, hypotype USNM 153514b; 5, 6,
pedicle valve with two others attached, x 1. X 2, hypotype USNM 153514d; 7, pedicle valve attached
to the brachial valve of Elliottella, x 3, hypotype USNM 153514c; 8, 9, side and posterior
views of pedicle valve with elongated beak and well-developed pseudodeltidium, x 3,
hypotype USNM 153514e; 10, 11, posterior and interior of another pedicle valve of more normal
proportions, x 3, hypotype USNM 153514f; 12, posterior of same, x 1; 13-17, ventral, side,
posterior, dorsal, and anterior views of a complete specimen, x 1> hypotype USNM 150405t;
18-20, ventral, posterior, and dorsal views of the preceding, x 2; 21, 22, interior and tilted
views of a pedicle valve, x 1. hypotype USNM 150405q; 23, interior of the same, X 3; 24, 25,
interior and exterior of a brachial valve having a cyst and boring, x 4, hypotype USNM
153514g; 26-28, posterior, exterior, and interior of a large brachial valve, X 4, hypotype USNM
150405a; 29-31, side, posterior, and interior views of a small brachial valve, showing welldeveloped
cardinalia, x 4, hypotype USNM 153514h; 32-34, posterior, x 1. ana" interior and
posterior, x 2, of a pedicle valve, hypotype USNM 153514J; 35, interior of dorsal valve, showing
cardinalia, x 4, hypotype USNM 150514i [Bone Spring Formation, locality USNM 728f].
NUMBER 15 483
PLATE 36.—Goniarina.
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484 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 37
Goniarina
Goniarina permiana (Stehli) : 1, Interior of a large brachial valve, showing cardinalia and
thickened median ridge, x 4, hypotype USNM 153514k; 9-11, posterior, interior, and side
views of a thickened brachial valve, showing cardinalia and great development of taleolae,
X 4, hypotype USNM 153514-1; 12-14, posterior, ventral, and interior views of a pedicle
valve, x I> hypotype USNM 153514m; 15-17, tilted interior, posterior, and ventral views of
the preceding, x 2 [Bone Spring Formation, locality USNM 728f].
2, 3. Interior and exterior of an immature brachial valve, x *>> hypotype USNM 153515a;
4, 5, exterior and interior of a smaller specimen than the preceding, x 6, hypotype USNM
153515b; 6, 7, a still smaller specimen, x 6, hypotype USNM 153515c; 8, exterior of the smallest
specimen, x 6, hypotype USNM 153515d; 18, 19, interior and exterior of a well-preserved
brachial valve, x 4, hypotype USNM 153515e; 20-22, posterior, tilted and interior views of a
thickened brachial valve, x 4, hypotype USNM 153515f [Bone Spring Formation, locality
USNM 728h].
23-27, Dorsal, anterior, side, posterior, and ventral views of a complete specimen, x 2,
hypotype USNM 153516 [Bone Spring Formation, locality USNM 725c].
NUMBER 15 485
PLATE 37.-Goniarina.
2* -3t486
SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 38
Goniarina
Goniarina pyelodes, new species: 1-5, Dorsal, side, anterior, ventral, and posterior views, x 4,
holotype USNM 15041 lg; 6-9, dorsal, side, posterior, and ventral views of the holotype, x 1;
10-13, side, dorsal, anterior, and posterior views of a large adult, x '> paratype USNM 15041 If;
14-18, side, dorsal, ventral, posterior, and anterior news of the same specimen, x 4; 19-23,
dorsal, posterior, side, anterior, and ventral views of a small specimen, x 4, paratype USNM
15041 Id; 24-26, posterior, tilted interior and interior views of the pedicle valve, X 4,
paratype USNM 15041 li; 27-30, exterior, interior, posterior, and side views of a brachial valve,
X 4, paratype USNM 15041 l j ; 31, 32, posterior and exterior of a pedicle valve, x 4, paratype
USNM 150411k; 33, interior of a brachial valve, x 4, paratype USNM 150411-1; 34, 35,
posterior and interior of another brachial valve, x ''- showing cardinalia, paratype USNM
150411m; 36, valve of Teguliferina with attached Goniarina pyelodes, x 3, paratype USNM
150410; 37-39, interior, ventral, and side \iews of a large pedicle valve, showing teeth and
pseudodeltidium, x 4, paratype USNM 15041 In [Neal Ranch Formation, locality USNM 701k].
NUMBER 15 487
PLATE 38.—Goniarina.
488 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 39
Goniarina
Goniarina diabloensis, new species: 1-3, Interior, exterior, and posterior of the pedicle valve,
X 1-5, paratype USNM 150390a; 4, posterior of same, x 1; 5, 6, exterior and interior of the
brachial valve, x 1> holotype USNM 150390b; 7, 8, interior and exterior of the holotype,
showing cardinalia and median ridge, x 2 [Bone Spring Formation (lower) locality USNM
728f].
Goniarina futilis, new species: 9-13, Ventral, anterior, posterior, dorsal, and side views of
a small individual, x 4, paratype USNM 150393f; 14-17, ventral, posterior, anterior, and
side views of another but still smaller specimen, x 4, paratype USNM 150393c; 18-21, anterior,
posterior, dorsal, and side views of an adult, x 4, paratype USNM 150393h; 22-26, posterior,
dorsal, anterior, ventral, and side views of a large adult, x 4, paratype USNM 150393; 27-29,
ventral, side, and anterior views, x ' > paratype USNM 150393i; 30-34, posterior, side, ventral,
dorsal, and anterior views of the same specimen, x 4; 35-37, anterior, ventral, and side views
of a large specimen, x ' 4 , holotype USNM 150393J; 38-42, anterior, dorsal, side, ventral, and
posterior views of the holotype, x 4 [Cathedral Mountain, locality USNM 702].
NUMBER 15 489
PLATE 39.-Goniarina.
490 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 40
Streptorhynchus and Goniarina
Streptorhynchus pelargonatum (Schlotheim) : 1, Posterior view of an internal mold of a
complete specimen, showing the slots produced by the supporting plates (erismata) of the
cardinal process, X 4, figured specimen YPM 27901 [Zechstein (middle), Posneck, Thuringia,
Germany].
Goniarina striata, new species: 2, Fragmentary specimen of Coscinophora with attached G.
striata, x 1> paratype USNM 150413; 3, the same specimen enlarged, x 3 [Road Canyon
Formation, locality USNM 710u].
4-8, Side, anterior, posterior, ventral, and dorsal views of a young adult, X 4, holotype
USNM 153550a; 16, 17, posterior and interior of a large pedicle valve, X 3, paratype USNM
150417b; 25, interior of another dorsal valve, x 4, paratype USNM 150417c [Road Canyon
Formation, locality USNM 721j].
9-12, Side, anterior, ventral, and dorsal views of a complete specimen, x 3, paratype
USNM 153551a; 13-15, side, posterior, and ventral views of a large pedicle valve with twisted
beak, x 3, paratype USNM 153551b; 22, exterior of a brachial valve, x 6, paratype USNM
153551c; 23, 24, posterior and interior of another brachial valve, showing cardinalia, x 6,
paratype USNM 15355Id [Road Canyon Formation, locality USNM 721z].
18, 19, Posterior and interior views of a thickened pedicle valve, X 3, paratype USNM
150415c; 20, 21, tilted and interior views of a brachial valve, showing cardinalia, x 4, paratype
USNM 150415e [Road Canyon Formation, locality USNM 702d].
NUMBER 15 491
PLATE 40.—Streptorhynchus and Goniarina.
4 9 2 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 41
Goniarina
Goniarina species 5: 1,2, Interior and exterior of an almost fully grown brachial valve, X 3,
figured specimen USNM 152562a; 3, 4, posterior and exterior of another nearly adult brachial
valve, x 1» figured specimen USNM 152562b; 5, interior of the same specimen, showing median
ridge and cardinalia, x 2; 6, another immature brachial valve, x '• figured specimen USNM
152562e; 7, the same enlarged, x 2; 8, 9, exterior and interior of a small brachial valve, x 1»
figured specimen USNM 152562f; 10, exterior of an imperfect but large brachial valve, X 2,
figured specimen USNM 152562c; 11, 12, interior and exterior of a small pedicle valve, X 1»
figured specimen USNM 152562g; 13, 14, exterior and interior of another, smaller pedicle valve,
X 1. figured specimen USNM 152562h; 15, exterior of a pedicle valve, X U5; figured specimen
USNM 152652i; 16, interior of the preceding, showing interarea, x 2; 17, exterior of an immature
pedicle valve, X 1. figured specimen USNM 152562d [Cathedral Mountain Formation (lower),
locality USNM 721u].
Goniarina species 1: 18, 19, Interior and exterior of a medium-sized brachial valve, x 3,
figured specimen USNM 150420 [Cathedral Mountain Formation (base), locality USNM 708u].
NUMBER 15 493
PLATE 41.—Goniarina.
494 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 42
Goniarina, Strigirhynchia, and Dyoros (Dyoros)
Goniarina appeli, new species: 1-5, Ventral, anterior, side, posterior, and dorsal views of a
complete specimen, x 3, holotype USNM 150395 [Hess Formation (Taylor Ranch Member) ,
locality 702d].
Goniarina species 7: 6, 7, Interior and exterior of a brachial valve, x 3, figured specimen
USNM 152564a; 8, posterior of the same, x 4 [Cathedral Mountain, locality USNM 726x].
Goniarina species 3: 9-11, Interior, posterior, and exterior views of a small pedicle valve,
X 1, figured specimen USNM 153513a; 12-14, exterior, interior and posterior views of another,
larger pedicle valve, x 1. figured specimen USNM 153513b [Skinner Ranch Formation (Sullivan
Peak Member), locality USNM 722-1].
Strigirhynchia indentata (Shumard) : 15, Interior of a brachial valve showing cardinalia and
median septum, x 3, hypotype USNM 155108 [Bell Canyon Formation (Lamar Member) ,
locality USNM 728p].
Dyoros (Dyoros) vulgaris, new species: 16, Interior of the pedicle valve, showing spiny septum
and endospines (taleolae), X 2, paratype USNM 153750g [Road Canyon Formation,
locality USNM 732j] (for additional views, see Plate 502: figures 46-62).
Goniarina species 3: 17-19, Posterior and exterior of a brachial valve, x l> figured specimen
USNM 150423a; 19, interior of the same brachial valve, showing characteristic muscle scars
and cardinalia, x 2 [Skinner Ranch Formation (Sullivan Peak Member), locality USNM 722-1].
Goniarina magniextensa, new species: 20, 21, Interior and exterior of the brachial valve, X J>
holotype USNM 150402b; 22, exterior of another less extended, brachial valve, x 1» paratype
USNM 150402g; 23, 24, exterior and interior of the pedicle valve, X 1. paratype USNM 150402a;
25, 26, exterior and interior of the same specimen, showing incipient myophragm x 2 [Skinner
Ranch Formation (base = Decie Ranch Member) , locality USNM 720e].
NUMBER 15 495
PLATE 42.—Goniarina, Strigirhynchia, and Dyoros (Dyoros).
9mm
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496 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 43
Hypopsia, Derbyoides, and Goniarina
Hypopsia versuta, new species: 1, Cardinalia of the brachial valve, x 6> paratype USNM
152587k [Neal Ranch Formation (bed 2 of P. B. King) , locality USNM 701].
Derbyoides nebrascensis Dunbar and Condra: 2, Interior of the pedicle valve, showing the
secondary median ridge simulating the septum of Derbyia, x 2, hypotype USNM 150427d
[shale just below the Cass Limestone, locality USNM 519].
Goniarina species 6: 3, 4, Exterior views of the brachial valve, x l> figured specimen
USNM 153541a; 5, 6, posterior and interior of the same specimen, showing cardinalia, X 4;
7, 8, exterior and interior of a larger brachial valve, x ' > figured specimen USNM 153541b;
9, cardinalia of the preceding, x 4; 10, 11, interior and exterior of a small brachial valve,
X 1. figured specimen 153541c; 12-14, ventral, side, and interior views of a small pedicle
valve with twisted beak, x 1. figured specimen USNM 153541d; 15, 16, posterior and exterior
of the preceding specimen enlarged, x 2; 17-19, interior, exterior, and side views of another
pedicle valve, x 1. figured specimen USNM 153541e; 20, 21, posterior and exterior views of
the same specimen, x 2; 22-24, side, exterior, and interior of another pedicle valve, x 1>
figured specimen USNM 153541 f; 25, 26, posterior and exterior of the same specimen, x 2
[Neal Ranch Formation (bed 4 of P. B. King) , locality USNM 727e].
Goniarina diabloensis, new species: 27, Interior of the brachial valve showing the cardinalia,
X 6, paratype USNM 150390k [Bone Spring Formation (lower) , locality USNM 728f].
NUMBER 15 497
PLATE 43.—Hypopsia, Derbyoides, and Goniarina.
498 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 44
Diplanus
Diplanus catatonus, new species: 1-3, Anterior, posterior, and dorsal views of a small specimen,
x 3, paratype USNM 150432i; 4-8, side, dorsal, posterior, ventral, and anterior views
of an adult, x 1. paratype USNM 153496k; 9-11, posterior, anterior, and side views of a large
specimen, x 1> paratype USNM 153496-1; 16, small specimen attached to a bryozoan, x 4,
paratype USNM 153496m; 17-19, posterior, side, and anterior views of a large specimen, x 2,
paratype USNM 153496n; 20-24, anterior, dorsal, posterior, side and ventral views of a small
specimen distorted by attachment, x 4, paratype USNM 150432k [Neal Ranch Formation,
locality USNM 701d].
12, 13, Dorsal and side views of specimen bored by barnacles, x 1, paratype USNM 150433b;
14, 15, posterior and dorsal views, x 2, of the same specimen; 25, dorsal view of same [Neal
Ranch Formation, locality USNM 701h].
Diplanus apochordus, new species: 26-29, anterior, posterior, dorsal, and side views of a small
specimen, x 1. paratype USNM 150440a; 30, 31, posterior and side views of the same specimen,
showing interareas, x 2; 32-35, dorsal, anterior, posterior, and side views of a large specimen,
X 1, holotype USNM 150440b; 36, posterior of the holotype, x 2; 37-40, posterior, side, interior,
and anteriorly tilted views of a brachial valve, x 3, paratype USNM 150440c [Skinner Ranch
Formation (Decie Ranch Member) , locality USNM 707a].
NUMBER 15 499
PLATE 44.-Diplanus.
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500 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 45
Diplanus
Diplanus catatonus, new species: 1, Interior of the dorsal valve with part of pedicle valve
attached, showing teeth and thick, long cardinal process, x 4, paratype USNM 153496o; 10,
posterior of the brachial valve, showing the large cardinal process, X 4, paratype USNM
153496p; 11, interior of another brachial valve, showing the large sockets, x 4, paratype USNM
153496q; 12-14, interior, posterior, and laterally tilted views of the pedicle valve, showing the
large teeth, x 4, paratype USNM 153496r; 15-17, interior of the pedicle valve in anteriorly
tilted, direct, and laterally tilted views, showing the huge teeth, x 4, paratype USNM 153496s;
19-21, interior, lateral, and posterolateral views of another large pedicle valve, x 4, paratype
USNM 153496t [Neal Ranch Formation, locality USNM 701d].
2-5, Posterior, anteriorly tilted, laterally tilted, and interior views of a brachial valve, X li
paratype USNM 150434a; 6-9, posterior, laterally tilted, anteriorly tilted, and interior views
of the same specimen, showing deep sockets and cardinal process, x 3 [Neal Ranch Formation,
locality USNM 701k].
18, Exterior of a complete specimen, x 2, paratype USNM 150433c [Neal Ranch Formation,
locality USNM 701h].
NUMBER 15 501
PLATE 45.-Diplanus.
502 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 46
Diplanus
Diplanus catatonus, new species: 1, Several specimens attached to Eolyttonia and associated
with Teguliferina, x 2, paratype USNM 150431a [Neal Ranch Formation, locality USNM 701c].
2, Two individuals attached to a brachial valve of Limbella, x 1. paratype USNM 153496a;
3, another individual attached to the apertural side of a fenestellid colony, x 3, paratype USNM
153496b; 4-7, side, ventral, posterior, and dorsal views, X 1. holotype USNM 150432a; 8, 9,
dorsal view of an immature specimen x '» X 5, paratype USNM 153496c; 10, 11, views of
two attached specimens, x 1> paratype USNM 153496d; 12-16, ventral, dorsal, posterior, anterior,
and side views of an average specimen, x 1. paratype USNM 150432e; 17, immature
specimen attached to a bryozoan stem, x 6> paratype USNM 153496e; 18, 19, small specimen
attached to a sponge, x 1> X 2, paratype USNM 153496f; 20, 21, dorsal view of two immature
specimens, x 5, paratypes USNM 153496g, h; 23, cluster of specimens showing mode of attachment,
x 3, paratype USNM 153496i; 24, numerous small individuals attached to the cellular face
of a fenestellid colony, x 3, paratype USNM 153496J [Neal Ranch Formation, locality USNM
701d].
22 Bryozoan frond with attached Diplanus and Geyerella x 1. paratype USNM 150433a
[Neal Ranch Formation, locality USNM 701h].
NUMBER 15 503
PLATE 46.-Diplanus.
504 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 47
Diplanus
Diplanus lamellatus (R. E. King) : 1, 2, Specimen attached to the pedicle valve of Institella,
X 1. hypotype USNM 150462a; 13-17, dorsal, side, anterior, ventral, and posterior views of
a specimen with twisted beak, x 2, hypotype USNM 150462b [Cathedral Mountain Formation
(Wedin Member), locality USNM 714w].
3, Dorsal view of rounded specimen attached to Eolyttonia, X 1. hypotype USNM 150446c;
24-27, anterior, posterior, ventral, and side views of a complete specimen, X 2, hypotype
USNM 150446d [Hess Formation (Taylor Ranch Member), locality USNM 702d].
4-6, Three views of a small specimen attached to a bryozoan colony, x 3, hypotype USNM
150470a [Bone Spring Formation (base), locality USNM 728f].
7, Dorsal view of a small attached specimen, x 3, hypotype USNM 153505 [Cathedral Mountain
Formation (Wedin Member), locality USNM 700-1].
8-10, Anterior, posterior, and side views of an elongated specimen, x 2, hypotype USNM
150454a [Skinner Ranch Formation ( — Taylor Ranch Member), locality USNM 705r].
11, 12, Side view of another greatly elongated specimen, x 1. X 2, hypotype USNM 150541a
[Cathedral Mountain Formation (base), locality USNM 703bs].
18-22, Posterior, ventral, dorsal, side, and anterior views of a small stout individual, X 2,
hypotype USNM 150444a; 23, ventral view of a complete specimen, x 2, hypotype USNM
153502b [Cathedral Mountain Formation (lower), locality AMNH 500—USNM 702] (for additional
views, see Plate 48: figures 9-12) .
28-32, Side, dorsal, anterior, ventral, and posterior views, X 2, hypotype USNM 153506
[Bone Spring Formation, locality AMNH 660].
33-37, Side, posterior, anterior, dorsal, and ventral views of a complete specimen, x l> hypotype
USNM 153507; 38-42, dorsal, posterior, anterior, ventral, and side views of the same
specimen, x 3 [Bone Spring Formation (middle), locality AMNH 658].
NUMBER 15 505
PLATE 47.-Diplanus.
506 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 48
Diplanus
Diplanus lamellatus (R. E. King): 1-3, Interior, posterior, and tilted views of the pedicle
valve, x 2, hypotype USNM 153501 [Bone Spring Formation (base), locality AMNH 625].
4-8, Ventral, dorsal, posterior, anterior, and side views of a complete specimen, x 2, hypotype
USNM 153502a; 9-12, posterior, anterior, side, and dorsal views of another complete specimen,
X 2, hypotype USNM 153502b [Cathedral Mountain Formation, locality AMNH 500= USNM
702] (for additional view, see Plate 47; figure 23) .
13-17, Ventral, posterior, anterior, dorsal, and side views, X 2, hypotype USNM 153503a; 18-21,
anterior, side, posterior, and dorsal views of a rotund individual, x 1. hypotype USNM 153503b;
22, dorsal view of the preceding, x 2 [Skinner Ranch Formation, (Decie Ranch Member),
locality USNM 707a].
23-25, Side, posterior, and anterior views, x 2, hypotype USNM 150446a; 26-28, side, anterior,
and posterior views of another specimen, x 2, hypotype USNM 150446b [Hess Formation
(Taylor Ranch Member), locality USNM 702d].
29, 30, Interior and exterior of a brachial valve, x 2, hypotype USNM 153498a; 31, 32,
posterior and interior of the same specimen, showing cardinal process and sockets, x 4; 33,
exterior of another brachial valve with finer costae, x 2, hypotype USNM 153498b; 34, 35,
interior tilted posteriorly and posterior, showing cardinalia and small median ridge, x 4
[Cathedral Mountain Formation, (lower) , locality USNM 721u].
36-39, Brachial valve tilted posteriorly, in full view, posterior view, and tilted laterally to
show cardinalia and long cardinal process, X 3, hypotype USNM 153504 [Skinner Ranch Formation
(lower = Decie Ranch), locality USNM 705a].
NUMBER 15 507
PLATE 4S.-Diplanus.
508 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 49
Diplanus
Diplanus lamellatus (R. E. King) : 1-3, Posterior view, x 2, X ' . ana" side view, x •» holotype
YPM 11399 [Leonard = Cathedral Mountain Formation, King locality 245].
4, 5, Exterior of two brachial valves, x '. X 2, paratypes YPM 11398a, b [Hess Formation •=.
Skinner Ranch Formation (base?), King locality 105].
Diplanus lamellatus (R. E. King) . 6-8, Exterior, interior, and posterior views of pedicle
valve, x 2, hypotype USNM 153498f [Cathedral Mountain Formation (lower), locality USNM
721u].
9-12, Laterally tilted, x 3, posterior, x 4, and interior and posteriorly tilted, x 3, views
of a well-preserved brachial valve, hypotype USNM 153499a [Bone Spring Formation (lower),
locality USNM 728e].
Diplanus catatonus, new species: 13-16, Ventral, posterior, anterior, and side views of a specimen
with elongated and twisted beak, x 1. paratype USNM 150432h; 17-20, posterior, anterior,
side, and ventral views of the same specimen, x 4; 21, 22, side and posterior views of another
complete specimen, X 1, paratype USNM 150432g; 23-26, posterior, side, anterior, and dorsal
views of the same specimen, x 4; 30, part of an Eolyttonia with adhering Diplanus, x 1>
paratype USNM 153496u [Neal Ranch Formation, locality USNM 701d].
27, 28, Side and dorsal views of an adherent specimen, x 2, paratype USNM 153500 [Neal
Ranch Formation (bed 4 of P. B. King) , locality USNM 701-1].
29, Interior of a pedicle valve, showing costae extending beyond shell margin, x 1. paratype
USNM 150434c [Neal Ranch Formation, locality USNM 701k].
NUMBER 15 509
PLATE 49.-Diplanus.
510 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 50
Diplanus
Diplanus rarus, new species: 1-5, Dorsal, side, ventral, anterior, and posterior views of a complete
specimen, x 2, paratype USNM 153497a; 6-10, posterior, dorsal, anterior, side, and
ventral views of a fine ribbed specimen, x 1. paratype, USNM 153497b; 11-14, dorsal, posterior,
anterior, and side views of the same specimen, x 2 [Skinner Ranch Formation (Decie Ranch
Member) , locality USNM 707a].
Diplanus lamellatus (R. E. King): 15, 16, Dorsal and posterior views, X J. hypotype, USNM
150459a; 17-20, dorsal, side, posterior, and ventral views of the same specimen, x 3 [Cathedral
Mountain (base), locality USNM 708].
Diplanus rarus, new species: 21-25, Dorsal, anterior, ventral, posterior, and side views of a
complete specimen, x 1. holotype USNM 150472a; 26-30, dorsal, anterior, ventral, side, and
posterior views of the holotype, x 2; 31, another specimen attached in living position, x 1»
paratype USNM 150472b [Skinner Ranch Formation (Decie Ranch Member), locality USNM
714p].
Diplanus redactus, new species: 32-36, Dorsal, side, ventral, posterior, and anterior views of a
small specimen, x 2, paratype USNM 150474a [Gaptank Formation (bed 10 of P. B. King),
locality USNM 700a].
37—40, Side, ventral, dorsal, and posterior views of another small specimen, x 2, paratype
USNM 150475b; 41-45, posterior, anterior, ventral, side, and dorsal views of the holotype,
USNM 150475a [Gaptank Formation (Uddenites-bearing Shale Member) locality USNM 701e].
Diplanus catatonus, new species: 46, Specimen attached to the ventral surface of a Limbella,
X 2, paratype USNM 150434b [Neal Ranch Formation, locality USNM 701k].
NUMBER 15 511
PLATE 50.-Diplanus.
512 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 51
Tropidelasma
Tropidelasma culmenatum Cooper and Grant: 1, Dorsal view of an immature specimen, x 1>
paratype USNM 147829i; 2-5, anterior, side, posterior, and dorsal views of the preceding specimen,
x 4; 6-8, dorsal, side and anterior views of another larger immature individual, x 1«
paratype USNM 147829h; 9-13, posterior, dorsal, anterior, side, and ventral views of the preceding
specimen, x 4; 14-17, side, posterior, dorsal, and ventral views of a small adult, X 1» paratype
USNM 147829e; 18, 19, posterior and side views of the preceding specimen, x 2; 20-24,
anterior, side, posterior, dorsal, and ventral views of a young adult, x 1> paratype USNM
147829c; 25-28, side, anterior, ventral, and posterior views of a specimen larger than the preceding,
x 1« paratype USNM 147829k; 29-32, ventral, posterior, dorsal, and side views of a
large, greatly elongated adult, x '. holotype USNM 147829b; 33-36, ventral, posterior, side,
and anterior views of a large adult, x l> paratype USNM 147829a [Neal Ranch Formation,
locality USNM 701h].
NUMBER 15 513
PLATE 51.—Tropidelasma.
514 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 52
Tropidelasma
Tropidelasma culmenatum Cooper and Grant: 1-4, Posterior, ventral, anterior, and side views,
of a young adult, x I. paratype USNM 153559a; 31, young adult attached within the pedicle
valve of another specimen, x 1> paratype USNM 153559b; 32, young specimen attached to a
large bryozoan colony, x 0.5, paratype USNM 147873 [Neal Ranch Formation, locality USNM
701k].
5-9, Posterior, anterior, ventral, side, and dorsal views of a greatly elongated young specimen,
x 1. paratype USNM 147838; 10-12, posterior, side, and dorsal views of the preceding
specimen, x 2; 13-17, posterior, ventral, dorsal, anterior, and side views of a young specimen
attached to a fragment of sponge (and free of the sponge), x 1> paratype USNM 153560a;
18, 19, enlargement of the posterior and side views of the preceding specimen, x 2; 23, posterior
view of a pedicle valve, showing teeth and monticulus on the pseudodeltidium, x 1'
paratype USNM 153560b; 24-27, anterior, side, posterior, and partial side views of a fragmentary
brachial valve, showing one aborted prong of the cardinal process, x j> paratype USNM
147829-1; 28, posterior of the preceding specimen, showing also the chilidial structures, x 3
(for additional views, see Plate 53); 29, 30, small adult attached to part of a bryozoan colony,
X 1, paratype USNM 153560c [Neal Ranch Formation, locality USNM 701h].
20-22, Posterior, side, and anterior views of a brachial valve, showing the large cardinal
process, x 1> paratype USNM 147875 [Neal Ranch Formation (Gray Limestone of P. B. King),
locality USNM 701].
NUMBER 15 515
PLATE 52.—Tropidelasma.
5 1 6 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 53
Tropidelasma
Tropidelasma furcillatum, new species; 1, 2, Dorsal and ventral views of an imperfect pedicle
valve, x 1> holotype USNM 153561a; 3-5, ventral, dorsal, and side views of the holotype, X 2;
6-8, side, interior, and exterior views of a brachial valve, X 1> paratype USNM 153561b; 9-11,
side, interior, and exterior views of the preceding specimen, x 2 [Cherry Canyon Formation
(Getaway Member), locality USNM 732].
Tropidelasma culmenatum Cooper and Grant: 12-14, Posterior, interior, and partial side views
of a small brachial valve, X 1> paratype 147865a; 15, 16, anterior and partial side views of the
cardinal process of the preceding specimen, x 4; 19-22, partial side, posterior, interior, and
side views of another brachial valve, x 1. paratype 147865b; 23-25, partial side, posterior and
side views of the preceding specimen, showing the long shaft, small myophore, and the
chilidial structures at the base of the cardinal process, X 4; 26, posterior and anterior margins
of the preceding specimen, showing the beaded elevations along the inner anterior margin,
X 4 [Neal Ranch Formation, locality USNM 701k].
17, Side view of the cardinal process of another specimen, showing an aborted prong, x 4
(for the posterior view of this specimen, see Plate 52: figure 28), paratype USNM 147829-1;
18, interarea of a pedicle valve with elongated beak, x I. paratype USNM 153560d; 27, side
view, showing barnacle borings, X 2, part of a paratype USNM 147829a [Neal Ranch Format
tion, locality USNM 701h].
NUMBER 15 517
PLATE 53.—Tropidelasma.
wz>--
518 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 54
Tropidelasma
Tropidelasma rhamphodes, new species: 1-5, Ventral, anterior, side, dorsal, and posterior
views of a young adult, x I. paratype USNM 147882h; 6-10, anterior, ventral, posterior, side,
and dorsal views of another young adult, x I» paratype USNM 147882k; 11-13, side, posterior,
and anterior views of a large, unusually regular specimen, x *> holotype USNM 147882b; 14-17,
dorsal, side, dorsal tilted, and posterior views of a large, fairly regular specimen, x 1« paratype
USNM 147882a; 18-21, side, anterior, dorsal, and posterior views of a large specimen, X 1*
paratype USNM 147882d; 22, posterior view of a small adult, x 1. paratype USNM I47882J;
23-25, side, dorsal, and ventral views of an immature individual, X 1> paratype USNM
147882m; 26-29, side, anterior, ventral, and dorsal views of the preceding specimen, x 3; 30, 31,
dorsal and side views of a very young specimen, x 1> paratype USNM 147882p; 32-34, dorsal,
side, and ventral views of the preceding specimen, x 6; 35-38, side, posterior, anterior, and
ventral views of a small adult, x 1> paratype USNM 147882f [Skinner Ranch Formation,
(Decie Ranch Member), locality USNM 707a].
39, Specimen broken to show long-shafted cardinal process, X 1> paratype USNM 147809
[Skinner Ranch Formation (Sullivan Peak Member), locality USNM 714y].
NUMBER 15 519
PLATE 54.—Tropidelasma.
520 SMITHSONIAN.CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 55
Tropidelasma
Tropidelasma rhamphodes, new species: 1, 2, Ventral and dorsal views of a cluster of three
specimens, X 1> paratype USNM 147902; 3-5, side, anterior, and posterior views of a misshapen
specimen with unusually high brachial valve umbone, x '» paratype USNM 153554a; 6, 7,
small broken specimen, showing long-shafted cardinal process, x 1> paratype USNM 153554b;
8, 9, interior and posteriorly tilted views of a pedicle valve, X 1> paratype USNM 153554c; 10,
11, posterior and partial side view of another broken specimen, showing the cardinal process,
X 1, paratype USNM 153554d; 12-14, partial side, dorsal, and posterior views of a cluster of
several individuals, showing a young one growing inside a pedicle valve, x 1» paratype USNM
153554e [Skinner Ranch Formation (Decie Ranch Member), locality USNM 707a].
NUMBER 15 521
PLATE 55.—Tropidelasma.
522 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 56
Tropidelasma
Tropidelasma robertsi, new species: 1-3. Immature specimen attached to a fragment of
Coscinophora, x 1> paratype USNM 153558a; 4-7, dorsal, posterior, ventral, and side views of
another immature specimen, x I. paratype USNM 153558b; 8-11, dorsal, posterior, side, and
ventral views of a larger, immature specimen, x 1> paratype USNM 153558c; 12-15, anterior,
posterior, side, and dorsal views of a specimen with very attenuated beak, x 1» paratype
USNM 153558d; 16, anterior view of the interior, showing the long-shafted cardinal process,
X 1. paratype USNM 153558e; 17, posterior view of another brachial valve, showing the
myophore, X 1. paratype USNM 153588f; 18-22, ventral side, posterior, dorsal, and anterior
views of a large adult, x 1. holotype USNM 153558g; 23-26, posterior, dorsal, side, and ventral
views of a narrow, young adult, x 1» paratype USNM 153558h; 27, exterior of a large dorsal
valve, riddled by boring barnacles, x 1. paratype USNM 153558i [Skinner Ranch Formation
(Sullivan Peak Member), locality USNM 733j].
NUMBER 15 523
PLATE 56.—Tropidelasma.
*l mf
23
*•'• *1* *•>
24
• * ** V
tWmr
25
524 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 57
Tropidelasma
Tropidelasma strobilum, new species: 1-4, Side, ventral, dorsal, and posterior views of a
greatly elongated specimen, X 1. paratype USNM 147780c; 5-9, ventral, posterior, anterior,
side, and dorsal views of a more triangular specimen, x U holotype USNM 147780b; 14-17,
ventral, anterior, side, and posterior views of another small individual, x 1> paratype USNM
147780g; 18-20, side, ventral, and posterior views of a large specimen with long narrow beak,
X 1, paratype USNM 147780a [Lenox Hills Formation, locality USNM 705k].
10-13, Ventral, anterior, side, and dorsal views of a young specimen, x 1> paratype USNM
147793 [Lenox Hills Formation, locality USNM 705s].
Tropidelasma species 2: 21, 22, Posterior and ventral views of an unusually large and wide
species, X 1. figured specimen 147888 [Gaptank Formation (Uddenites-bearing Shale Member),
locality USNM 702q].
NUMBER 15 525
PLATE 57.—Tropidelasma.
526 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 58
Tropidelasma
Tropidelasma curtum, new species: 1-3, Dorsal, ventral, and side views of a pedicle valve,
X If holotype USNM 152590b; 4-6, side, ventral, and interior views of the holotype, x 2; 7-10,
side, interior tilted, exterior, and interior views of a brachial view, X 1» paratype USNM
152590d; 11-14, tilted, exterior, interior, and side views of the preceding paratype, x 2 [San
Andres Formation, locality AMNH B188-8].
Tropidelasma culmenatum Cooper and Grant: 15, Side view of a large adult attached by its
beak to a bryozoan colony, x 1. paratype USNM 147842 [Neal Ranch Formation, locality
USNM 701h].
Tropidelasma costellatum, new species: 16-19, Ventral, side, posterior, and anterior views,
X If holotype USNM 147823a; 20-23, ventral, posterior, side, and anterior views of the holotype,
X 2; 24-26, side, exterior, and posterior views of the brachial valve, x 1> paratype USNM
147823d; 27, posterior of the preceding specimen enlarged, x 2 [Hess Formation (Taylor
Ranch Member), locality USNM 702d].
Tropidelasma corniculum, new species: 28-31, Exterior, posterior, interior, and partial side
views of the brachial valve, x 1> paratype USNM 152593 [Road Canyon Formation, locality
USNM 721z].
32, 33, Posterior and side views of a pedicle valve, x '< paratype USNM 152592m [Road
Canyon Formation, locality USNM 720d].
34-36, Side, posterior, and ventral views of a large specimen, x li holoytpe USNM 153562
[Road Canyon Formation, locality USNM 724d].
Tropidelasma culmenatum Cooper and Grant: 37, 38, Posterior and side views of the brachial
valve belonging to the pedicle valve in figures 41 and 42, X l> paratype USNM 147839; 39,
posterior of the preceding specimen, x 2; 40, interior of the pedicle valve, x 1> paratype
USNM 147839; 41, posterior view of the pedicle valve, showing the strong teeth, x 2; 42, 43,
the complete specimen, x 1. X 2, paratype USNM 147839 [Neal Ranch Formation, locality
USNM 701h]
NUMBER 15 527
PLATE 58.—Tropidelasma.
528 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 59
Tropidelasma
Tropidelasma anthicum, new species: 1-3, Dorsal, side, and interior views of a small brachial
valve, x 1> paratype USNM 153555a; 4-6, exterior, interior tilted, and interior views of the
preceding specimen showing the cardinalia and ornament, x 2; 7, 8, exterior and interior
views of another small brachial valve, x 1. paratype USNM 153555b; 9, 10, interior and
exterior views of the preceding specimen, x - [Word Formation (Willis Ranch Member),
locality USNM 706e]
11-16, Ventral, anterior, posterior, side, dorsal, and posteriorly tilted views, X If holotype,
USNM 147861a; 17-21, ventral, anterior, posterior, and side and dorsal views of the holotype,
X 1.5; 22, interior of the pedicle valve of the holotype, x h 23-26, posterior tilted, interior, side,
and posterior views of the brachial valve of the holotype, showing the cardinalia, X L'> 28-32,
exterior, interior, posterior, interior tilted posteriorly, and side views of a brachial valve,
X 1, paratype USNM 147861d; 33, 34, interior and exterior of the preceding specimen, x 2;
35, 36, posterior and interior views of the same specimen as preceding, showing the cardinalia,
X 3 [Word Formation (lens between the Willis Ranch and Appel Ranch Members), locality
USNM 706b].
27, Young individual attached inside Neospirifer, x 1. paratype USNM 153556 [Word
Formation (China Tank Member) , locality USNM 706c].
NUMBER 15 529
PLATE 59.—Tropidelasma.
* «.*iacrr
„ ' / ' ' • ' • •
5 3 0 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 60
Tropidelasma
Tropidelasma anthicum, new species: 1-3, Ventral, posterior, and side views of a pedicle
valve, x I. paratype USNM 153557a; 26-29, side, interior, posterior and posteriorly tilted
views of a brachial valve, x 1. paratype USNM 153557b; 30-34, side, posteriorly tilted, interior,
exterior, and posterior views of a smaller brachial valve, x l> paratype USNM 153557c;
35-39, posterior, interior posteriorly tilted, exterior, side, and interior views of the preceding
specimen, x 2 [Word Formation (China Tank Member), locality USNM 726r].
4-7, Interior, posterior, side, and ventral views of a small, narrowly conical pedicle valve,
X 1, paratype USNM 147861g, 8-11, side, ventral, interior, and posterior views of the preceding
specimen, x 2; 12-15, posteriorly tilted, posterior, side, and interior views of a thick brachial
valve, x 1» paratype USNM 147861e; 16, 17, the preceding specimen posteriorly tilted to show
the cardinalia and posterior, x 2; 18-21, posterior, ventral, side, and interior views of a
pedicle valve, x 1. paratype USNM 147861b; 22-25, side, ventral, posterior and interior views
of the preceding, x 1-5 [Word Formation (lens between the Willis Ranch and Appel Ranch
Members), locality USNM 706b].
NUMBER 15 531
PLATE 60.—Tropidelasma.
532 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 61
Tropidelasma
Tropidelasma gregarium (Girty): 1, 2, Dorsal and ventral views of a pedicle valve, x 1»
hypotype USNM 152591d; 3-5, dorsal, side, and ventral views of the preceding specimen, x 2;
6, ventral view of another fairly symmetrical pedicle valve, x 1. hypotype USNM 152591e;
7-9, ventral, side, and posterior views of the preceding specimen, x 2; 10-13, interior, exterior,
anterior, and side views of a brachial valve, x 1. hypotype USNM 152591-1; 14-17, anterior,
exterior, side, and interior views of the preceding specimen, x 2; 18-21, anterior, side, exterior,
and interior views of another brachial valve, x 1. hypotype USNM 152591n; 22-25, anterior,
side, exterior, and interior views of the preceding specimen, X 2; 26-29, anterior, side, dorsal,
and ventral views of a complete specimen, x 2, hypotype USNM 152591a; 30-33, side, anterior,
dorsal, and ventral views of the preceding specimen, x 3; 34, 35, posterior and side views,
showing slender cardinal process, X 4, hypotype USNM 152591o; 36, pedicle valve attached
to another brachiopod shell, x 2, hypotype USNM 15259lp; 37, posterior view of a pedicle
valve with greatly elongated beak, x 3, hypotype USNM 152591q [Bell Canyon Formation
(Lamar Member), locality USNM 738b].
Tropidelasma species 4: 38-40, Posterior, interior, and side views of a fragmentary pedicle
valve, x li figured specimen USNM 152601a; 41-43, side, posterior, and interior views of a
brachial valve, x If figured specimen, USNM 152601b [Cathedral Mountain Formation, locality
USNM 721u].
NUMBER 15 533
PLATE 61.—Tropidelasma.
36 33 37
534 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 62
Derbyoides, Ombonia, Bothrostegium, and Dielasma
Derbyoides species 1: 1, 2. Dorsal and ventral views of a nearly complete specimen, x I>
figured specimen USNM 153801 [Gaptank Formation, locality USNM 701y].
Ombonia invecta, new species: 3, 4, Laterally tilted and interior views of a small brachial
valve, showing cardinalia, x 3, paratype USNM 150995-1 [Road Canyon Formation, locality
USNM 720d].
Bothrostegium derbyoideum, new species: 5-9, Posterior, anterior, side, dorsal and ventral
views, x 1. paratype USNM 153338; 10-14, ventral, side, posterior, dorsal, and anterior views
of the same specimen, x 3 [Road Canyon Formation, locality USNM 721t].
Dielasma compactum, new species: 15-19, Ventral view of the interior of five young specimens,
showing loop in centronelliform stage, the first three and the fifth X 4, the fourth
X 3, paratypes USNM 154527d, c, i, f, and b; 20, 21, interior of two specimens, showing early
development of the median fold in the transverse band, x 3, paratypes USNM 154527h and j
[Word Formation (Willis Ranch Member), locality USNM 706].
Bothrostegium compactum, new species: 22, 25, Exterior of a pedicle valve, X If X 4,
holotype USNM 152599b; 24, 26, interior, exterior of same specimen, x 4, X 1; 23, 27,
exterior and interior of another pedicle valve, X 4, paratype USNM 152599a; 28, posterior of
another pedicle valve, showing ponderous teeth and thick pseudodeltidium, x 6, paratype
USNM 1525991; 29, 30, exterior and interior of a brachial valve, x 1. paratype USNM 152599e;
31, interior of same specimen, x 4; 32, posterior of same, showing myophore, x 3; 33, exterior
of another brachial valve, x 3, paratype USNM 152599J; 34, interior of same, showing deep
muscle impressions and thickened cardinalia, x 4; 35, 36, laterally tilted and interior views
of the same specimen showing the cardinalia, x 6 [Road Canyon Formation, locality USNM
703c].
NUMBER 15 535
PLATE 62.—Derbyoides, Ombonia, Bothrostegium, and Dielasma.
536 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 63
Bothrostegium
Bothrostegium derbyoideum, new species: 1-3, Interior, x 3, and side and posterior views
of a pedicle valve, x 2, showing sulcate pseudodeltidium, paratype USNM 147891a; 4-7,
posterior, ventral, side, and anterior views, x 1» paratype USNM 152595b; 8-11, side, anterior,
and posterior views, x 1-5, and dorsal view x 2, of the paratype; 12-15, posterior, side, anterior,
and dorsal views of a small specimen; x If paratype USNM 152595d; 16-19, ventral,
posterior, anterior, and side views of the preceding, x 3; 20, dorsal view of the preceding,
X 4; 21-24, anterior, dorsal, posterior, and side views of a large specimen, x 3, paratype
USNM 152595a; 25-29, anterior, side, posterior, dorsal, and ventral views of the holotype,
USNM 152596a; 30-34, ventral, anterior, posterior, and side views, x 3, and dorsal view,
X 4, of the holotype; 35, specimen adhering to the inside of a Meekella shell in its attached
growth position, x 3, paratype USNM 147891c; 36-38, interior, x 4, and two posterior
positions, X 3, of the brachial valve, showing the cardinal process, paratype USNM 152596c;
39, exterior of a brachial valve, x 4; paratype 152596d; 40, same tilted sideways to show deep
socket, x 3; 41, 42, interior and exterior of a pedicle valve, showing strong teeth, x 3, paratype
USNM 152597a; 43, brachial valve laterally tilted to show sockets and cardinalia, x 4,
paratype USNM 147891b; 44, posterior of same, x 3; 45, 46, posterior views of the cardinalia,
X 3, x 4, paratype USNM 152598b [Road Canyon Formation, localities: figures 1-3, 35, 43,
44 — USNM 710u; 4-24 = USNM 721y; 25-34, 36-40 — USNM 721t; 41, 42 = USNM
724b; 45, 46 — USNM 721w].
NUMBER 15 537
PLATE 63.—Bothrostegium.
538 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 64
Derbyia
Derbyia bella, new species: 1-5, Ventral, anterior, side, posterior, and dorsal views of an
immature specimen, x 1. paratype USNM 153189a; 6-10, same views of a larger specimen,
X If paratype USNM 151025h; 11-15, dorsal, anterior, side, posterior, and ventral views of a
still larger specimen, x 1. paratype USNM 153189b; 16-20, dorsal, ventral, posterior, anterior,
and side views, x 1. holotype USNM 151025c; 21-25, ventral, posterior, side, dorsal, and
anterior views, showing median depression in pseudodeltidium, x •• paratype USNM 151025e;
26-29, dorsal, side, anterior, and ventral views of a small obese specimen, showing much anterior
growth, x 1» paratype USNM 153189c; 30, dorsal view of a small specimen with exceptional
broad interarea, x 1. paratype USNM 153189d; 31, posterior of a distorted specimen, showing
pseudeltidium with median groove toward the apex, x 1, paratype USNM 153189e; 32-34,
side, posterior, and dorsal views of a large specimen, x 1> paratype USNM 151025b; 35, 36,
views of two immature specimens attached to an adult, x '. X 2, paratype USNM 153285b;
37, cluster of immature specimens attached to one another, x !> paratype USNM 153279a;
38, 39, views of a small pedicle valve attached to another young specimen, x 1. X 2, paratype
USNM 153279b; 42, a cluster of larger specimens, x 1. paratype USNM 153279c; 43, another
cluster of attached specimens of assorted sizes, x 1> paratype USNM 153279d; 44, 45, views
of a pedicle valve interior, showing median septum and strong teeth, x 1> X 2, paratype
USNM 153189f [Neal Ranch Formation (bed 4 of P. B. King), USNM 701-1].
40, Pedicle valve of Derbyia carteri with several small specimens of D. bella cemented to
it, x 1. paratype USNM 153285a; 41, exterior of same pedicle valve, x 1 showing other
attached specimens and the attachment of the host D. carteri to a small D. bella [Neal Ranch
Formation (bed 4 of P. B. King), USNM 727e].
NUMBER 15 539
PLATE 64.-Derbyia.
540 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 65
Derbyia
Derbyia carteri, new species: 1, 2, Ventral and anterior views of a specimen deformed by
growing against a bryozoan, x 1. paratype USNM 153281a; 3, interior of the pedicle valve
slightly tilted to the side to show the thickened anterior rim around the muscle scars, x l>
paratype USNM 153281b; 4, 5, another pedicle valve interior in full view and slightly tilted
to show thickened muscle region, x 1> paratype USNM 153281c; 6, posterior of the interior
of a complete specimen, showing the relationship of the median septum to the cardinal process,
X 1. paratype USNM 153281d; 7, 8, views of the posterior of a brachial valve, showing the
cardinal process, its myophores, and the remnant of a chilidium, x l> X 3, paratype USNM
153281e; 9-12, posterior, interior tilted, full view, and side views of an adult brachial valve,
X 1, paratype USNM 153281f; 13, 14, full and posteriorly tilted views of a small brachial valve,
showing cardinal process and supporting plates, x l> paratype USNM 153281g; 15, posterior of
the preceding specimen, x 2 [Neal Ranch Formation (bed 4), USNM 701d].
Derbyia bella, new species: 16, 17, full and tilted views of a pedicle valve interior, x If
paratype USNM 153280a; 18, full view of the pedicle valve interior, x I* paratype USNM
153280b; 19-21, the same specimen in tilted and full views to show the septum, teeth, and
long interarea, X 2; 22, full view of the interior of a misshapen brachial valve, X 1- paratype
USNM 153280c; 23-25, anteriorly tilted, laterally tilted, and posterior views of the same
specimen, x 2; 26, 27, posterior and lateral views of the cardinal process of the same specimen,
showing chilidium, myophore, and socket, x 4; 28, full view of another brachial valve with
much thickened cardinal process, x *> paratype USNM 153280d; 29-31, same specimen in
laterally tilted, posteriorly tilted, and posterior views, showing the myophore slits and chilidium,
X 2; 32-34, posterior, posteriorly tilted, and full views of another brachial valve, showing
chilidium, supporting plates, and adductor myophragm, x 2, paratype USNM 153280e [Neal
Ranch Formation (bed 4 of P. B. King), USNM 701-1].
NUMBER 15 541
PLATE 65.-Derbyia.
1
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ft '
mi jj^Y^ySIF'?
1 $&fai:$X£-*p*
34
5 4 2 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 66
Derbyia
Derbyia carteri, new species: 1, Posterior, dorsal, side, ventral, and anterior views of an immature
specimen, x If paratype USNM 153282a; 2-6, posterior, side, anterior, dorsal, and ventral
views of the same specimen, x 2; 7-11, ventral, anterior, posterior, side, and dorsal views
of a larger specimen, x 1. paratype USNM 153282b; 12-16, ventral, side, anterior, posterior,
and dorsal views of the preceding, x 2; 17-21, side, ventral, anterior, posterior, and dorsal
views of a still larger specimen, x 1. paratype USNM 153282c; 22-26, anterior, ventral, posterior,
dorsal, and side views of the preceding, x 2; 46, 47, cluster of attached adults,
X 1, paratype USNM 153283 [Neal Ranch Formation (equivalent of bed 4 of P. B. King),
USNM 701d].
27-31, Dorsal, side, ventral, posterior, and anterior views of a nearly adult specimen, x 1>
paratype USNM 151020f; 32-36, dorsal, posterior, anterior, ventral, and side views of a mediumsized
adult, x ^ paratype USNM 151020c; 37-41, anterior, posterior, side, dorsal, and ventral
views of the holotype, showing effects of impingement against a branch of bryozoan, X If
USNM 151020a; 42-45, posterior, dorsal, anterior, and side views of a small specimen, X If
151020J [Neal Ranch Formation (bed 12) USNM 701k].
NUMBER 15 543
PLATE 66.-Derbyia.
544 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 67
Derbyia
Derbyia profunda, new species: 1-5, Posterior, side, dorsal, anterior, and ventral views of an
immature specimen, x 1> paratype USNM 151015c; 6-10, dorsal, anterior, posterior side and
ventral views of a larger paratype, X 1> USNM 151015e; 11-15, dorsal, ventral, posterior,
anterior, and side views, x 1, of a still larger paratype, USNM 151015g; 16-20, posterior, anterior,
dorsal, ventral, and side views of a nearly full grown paratype, x l» 151015J; 21-25,
side, posterior, ventral, anterior, and dorsal views of a fully grown adult, x 1> holotype USNM
153348; 27, broken specimen, showing cardinal process, median septum, and dental ridges,
X 1. paratype USNM 153347a [Neal Ranch Formation (beds 12-14 of P. B. King), USNM
701k].
26, Young specimen nestled in a niche of a bryozoan, x 1. paratype USNM 153349 (note
associated Teguliferina and Diplanus) [Neal Ranch Formation (beds 12-14 of P. B. King),
USNM 701h].
NUMBER 15 545
PLATE 67,-Derbyia.
546 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 68
Derbyia
Derbyia pannucia, new species: 1-3, Posteriorly tilted, laterally tilted, and posterior views of
a brachial valve, showing supporting plates and long prongs of the cardinal process, X 1>
paratype USNM 151122r [Word Formation (Willis Ranch Member, upper), USNM 706e].
Derbyia profunda, new species: 4, Imperfect specimen, showing cardinal process and dental
ridges, x 2, paratype USNM 153347c; 5, 6, pedicle valve interior and tilted laterally to show
median septum, x 1> paratype USNM 153347b; 7-9, brachial valve tilted laterally, in posterior
view and interior view, showing the cardinal process, x 1. paratype USNM 153847a; 10, 11,
lateral and posterior views of the cardinal process of the preceding specimen, showing the
vestigial chilidium and the forked myophore, X 2 [Neal Ranch Formation (beds 12-14 of
P. B. King), USNM 701k].
NUMBER 15 547
PLATE 68.-Derbyia.
v -'
548 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 69
Derbyia and Meekella
Derbyia strophomenoidea, new species: 1, 2, Ventral and dorsal views of a broken specimen,
showing the exterior and the cardinal process of the interior, X l> paratype USNM 151213a;
3-5, large specimen encrusted by specimens of Derbyia bella, X If holotype USNM 151213b;
6-9, posterior, anterior, dorsal, and ventral views of the holotype from which the encrusting
forms have fallen, x 1 [Neal Ranch Formation (bed 4 of P. B. King), USNM 701-1].
Meekella enormis, new species: 10-12, Interior, posterior, and laterally tilted views of a
young brachial valve, showing the massive cardinal process, X 1» paratype USNM 153448b
[Skinner Ranch Formation (— Decie Ranch Member), USNM 705a].
NUMBER 15 549
PLATE 69.-Derbyia and Meekella.
550 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 70
Derbyia
Derbyia nasuta Girty: 1-4, Posterior, ventral, dorsal, and side views of a small individual,
X If hypotype USNM 151038a; 5, 6, posterior and side views of another small specimen with
elongated beak, x 1> hypotype USNM 151038c [Skinner Ranch Formation (Decie Ranch Member),
USNM 707e].
7-11, Anterior, side, ventral, posterior, and dorsal views of an unusually large specimen,
X 1, hypotype USNM 151O30h [Skinner Ranch Formation (Decie Ranch Member), USNM
707a].
NUMBER 15 551
PLATE 70.-Derbyia.
Jr..^-.j6ift*-.t.
•••^iM 10 %•'»
552 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 71
Derbyia
Derbyia nasuta Girty: 1, Large specimen with elongated beak, x 1. hypotype USNM 151030e;
2-4, posterior, ventral, and side views of another specimen with exceptionally long beak developed
because of crowded conditions, where it was cemented in life, x If hypotype USNM
15IO30i; 5, large specimen with brachial valve removed to show cardinal process, median septum,
and enormous muscle field, x 1. hypotype USNM 151029 [Skinner Ranch Formation (Decie
Ranch Member), USNM 707a].
6, 7, Ventral and posterior views of a large specimen partially encrusted by bryozoans,
X 1, hypotype USNM 153297a; 8, interior of an incomplete pedicle valve, showing long median
septum, x 1. hypotype USNM 153297b [Bone Spring Formation (lower), USNM 428e].
9, Interior of a brachial valve, showing cardinal process, and adductor field surrounded
laterally by supporting plates of the cardinal process, X If hypotype USNM 15103d [Skinner
Ranch Formation (— Decie Ranch Member), USNM 720e].
NUMBER 15 553
PLATE 7l.-Derbyia.
. jfcV"' f'P'%" ' '^fP^f-ir5
5 4 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 72
Derbyia
Derbyia nasuta Girty: 1-4, Posterior, dorsal, side, and ventral views of a medium-sized specimen,
x 1> hypotype USNM 151038e; 5-8, side, ventral, dorsal, and posterior views of a fairly
large specimen with narrowed and elongated beak, x 1. hypotype USNM 151038f [Skinner
Ranch Formation ( = Decie Ranch Member), USNM 720e].
9, 10, Posterior and interior views of a medium-sized brachial valve, X If hypotype USNM
153298 [Bone Spring Formation (lower), AMNH 625].
11, 12, Interior and exterior views of a large pedicle valve, x If hypotype USNM 153299
[Bone Spring Formation (lower), USNM 725c].
NUMBER 15 555
PLATE 7Z-Derbyia.
- l^^r&M': 11
556 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 73
Derbyia
Derbyia nasuta Girty: 1-5, Side, anterior, ventral, posterior, and dorsal views of a very small
individual, x 1. hypotype USNM 151038i; 6-10, dorsal, anterior, posterior, side, and ventral
views of a larger specimen than the preceding, x 1» hypotype USNM 151038J; 11-15, dorsal,
ventral, posterior, side, and anterior views of a medium-sized specimen, x 1> hypotype USNM
151038g; 16-18, side, anterior, and dorsal views of a large specimen, x If hypotype USNM
151038h [Skinner Ranch (— Decie Ranch Member), USNM 720e].
Derbyia scitula, new species: 19-23, Anterior, posterior, side, ventral, and dorsal views of a
small paratype, x 1. USNM I51202d; 24-27, dorsal, posterior, anterior, and ventral views of a
larger specimen, x 1> paratype USNM 153345; 28-31, ventral, posterior, dorsal, and side views,
X 1, holotype USNM 151202a; 32, pedicle valve with young specimens attached, x If paratype
USNM 151202h [Neal Ranch Formation (Bed 2 = Gray Limestone of P. B. King), USNM 701].
NUMBER 15 557
PLATE 73.-Derbyia.
558 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 74
Derbyia
Derbyia laqueata, new species: 1-4, Dorsal, side, posterior, and anterior views of an average
specimen, x 1. paratype USNM 153293 [Road Canyon Formation, USNM 719x].
5-9, Dorsal, ventral, posterior, side, and anterior views of a small specimen, X It paratype
USNM 153294a; 10-14, ventral, dorsal, posterior, anterior, and side views of the holotype,
USNM 151090c; 15-19, posterior, anterior, side, dorsal, and ventral views of a small, distorted
specimen, x 1. paratype USNM 153294b; 24, adult attached inside Edriosteges, x 1» paratype
USNM 153294c; 26, dorsal view of another complete specimen with somewhat finer ornament,
X 1. paratype USNM 153295 [Road Canyon Formation (base), USNM 703a].
20-23, Dorsal, posterior, side, and ventral views of a very large specimen, X If paratype
USNM 151087 [Cathedral Mountain Formation (lower), USNM 702un].
25, Small individual cemented to a branching bryozoan, x 1> paratype USNM 153296 [Road
Canyon Formation, USNM 716x].
NUMBER 15 559
PLATE 74.-Derbyia.
5 6 0 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 75
Derbyia
Derbyia laqueata, new species: 1-4, Anterior, posterior, dorsal, and side views of a large
adult, x 1. paratype USNM 151086a; 8, interior of a small brachial valve, showing thickened
adductor, field, x 1, paratype USNM 151086b [Cathedral Mountain Formation (lower), USNM
702un].
5, 6, Full and posteriorly tilted views of the brachial valve interior, showing cardinalia,
X 1. paratype USNM 151080J; 7, posterior of the preceding, showing myophore and chilidium,
X 2; 9, pedicle valve interior, x 1» paratype USNM 151080k [Road Canyon Formation (base),
USNM 702c].
Derbyia crenulata Girty: 10-14, Dorsal, posterior, side, anterior, and ventral views of the
holotype, x 1. USNM 118499 [Bone Spring Formation, USGS 3764 (green)].
15, Interior of a misshapen and stunted brachial valve, x 2, hypotype USNM 153287; 21,
interior view of an average brachial valve, x 1. hypotype USNM 151045c; 22, posterior view
of preceding specimen, showing short cardinal process, X 2; 23-25, exterior, interior, and side
views of another brachial valve, x 1. hypotype USNM 151045d [Skinner Ranch Formation
(base = Decie Ranch Member), USNM 705a].
16-18, Pedicle valve, tilted laterally, exterior and full view, showing ornament and median
septum, X It hypotype USNM 151047a; 19, 20, interior and exterior views of a brachial valve,
X 1, hypotype USNM 151047b [Bone Spring Formation (lower), USNM 728e].
26-28, Exterior, posterior, and interior views of a large pedicle valve, x l> hypotype USNM
151048 [Bone Spring Formation (lower), AMNH 625].
NUMBER 15 561
PLATE 75.-Derbyia.
~^?
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6 :
is^»
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21
iiu
^ I 28
562 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 76
Derbyia
Derbyia informis, new species: 1-4, Views of the brachial valve interior: posteriorly tilted,
posterior, laterally tilted, and full, showing fairly short supporting plates and relatively small
cardinal process, x If paratype USNM 151055a [Cathedral Mountain Formation (lower),
USNM 702].
5-8, Ventral, posterior, side, and dorsal views of a very large specimen, x 1> holotype
USNM 152606c [Road Canyon Formation (base), USNM 703a].
NUMBER 15 563
PLATE 76.-Derbyia.
<;^ <vilttli
564 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 77
Derbyia
Derbyia informis, new species: 1-4, Dorsal, posterior, ventral, and side views of a large but
narrow specimen, x 1> paratype USNM 151056e [Cathedral Mountain Formation (lower),
USNM 702].
5-9, Anterior, side, dorsal, posterior, and ventral views of a medium-sized specimen, x 1.
paratype USNM 153292 (see Plate 78 for interiors of this specimen); 12, interior view of
pedicle valve tilted to the side to show the greatly thickened muscle field, x 1> paratype USNM
151073a [Road Canyon Formation, USNM 721t].
10, Posterior view of the interarea of a large pedicle valve, X 1. paratype USNM 153286a
(see-'Plate 81, figures 1-3 for additional views); II, posterior of a complete specimen showing
cardinal process, supporting plates, and median septum, x 1> paratype USNM 153286b [Road
Canyon Formation (base), USNM 703a].
NUMBER 15 565
PLATE 77.-Derbyia.
• i
566 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 78
Derbyia
Derbyia informis, new species: 1-5, Ventral, posterior, dorsal, side, and anterior views of a
small, compact specimen, x 1> paratype USNM 151059d; 6, dorsal view of a small individual,
X If paratype USNM 151059b [Road Canyon Formation (base), locality USNM 702c].
7-11, Ventral, posterior, anterior, side, and dorsal views, x 1. paratype USNM 152607a
[Road Canyon Formation (base), locality USNM 703a].
12-16, Ventral, side, anterior, posterior, and dorsal views of a large, compact specimen,
X If paratype USNM 151073c; 17, side view of a medium-sized specimen, showing an elongate
beak region, x If paratype USNM 151055b [Cathedral Mountain (lower), locality USNM
J«f 7J>f~r
18, Interior of the pedicle valve, showing the septum and thickened muscle region, x If paratype
USNM 153292; 19, 20, interior and posterior views of the brachial valve of the same
specimen, showing the cardinal process (see Plate 77 for exterior views of this specimen) [Road
Canyon Formation, locality USNM 721t].
NUMBER 15 567
PLATE 7S.-Derbyia.
4i ' ^
568 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 79
Derbyia
Derbyia cincinnata, new species: 1-4, Ventral, dorsal, side, and anterior views of an immature
specimen, showing development of wrinkling from a costellate stage, x l> paratype USNM
151136c; 5-9, side, ventral, anterior, posterior, and dorsal views of a young but strongly
wrinkled specimen, x 1. holotype USNM 151136e [Road Canyon Member (base), USNM 702c].
10-14, Side, dorsal, ventral, anterior, and posterior views of a narrow but deep specimen,
X 1, paratype USNM 153284 [Road Canyon Formation, USNM 724b].
15-19, Anterior, posterior, ventral, side, and dorsal views of a medium-sized specimen, X If
paratype USNM 151139a [Road Canyon Formation, USNM 710u].
20, Exterior of a medium-sized pedicle valve, showing strong and irregular wrinkles, X 1>
paratype USNM 151135a [Road Canyon Formation, USNM 703d].
21, Exterior of a large and strongly wrinkled specimen, x J> paratype USNM 151150a
[Road Canyon Formation, AMNH 503].
NUMBER 15 569
PLATE 79.-Derbyia.
:i^ 16 .,i$.\rf$2
!^4%*.; . Mil ' *p»Vr
18 21
570 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 80
Derbyia
Derbyia cincinnata, new species: 1-3, Dorsal, side, and posterior views of a large brachial
valve, X 1. paratype USNM 151141a [Road Canyon Formation (lower), USNM 7l9x].
4-7, Posterior, interior, posteriorly tilted, and side views of fragmentary specimen, showing
cardinal process, supporting plates, and adductor myophragm, x 1> paratype USNM 151137a
[Road Canyon Formation (lower), USNM 709c].
8, 9, Side and interior views of a smaller brachial valve, x 1. paratype USNM 151131a
[Road Canyon Formation (base), USNM 702c].
10-12, Interior, posterior, and side views of another fragmentary brachial valve, showing
the cardinalia, x 1. paratype USNM 151150b [Road Canyon (lower), AMNH 503].
13, 14, Exterior view, x 1> and posterior view, x 2, of another brachial valve, showing
wrinkles and cardinal process, USNM 151134a [Road Canyon Formation (lower), USNM 703d].
15, 16, Interior and exterior views of a medium-sized pedicle valve, showing muscle scars
and median septum, x 1» paratype USNM 151143a; 17, interior of another, larger pedicle
valve, x 1. paratype USNM 151143b [Road Canyon Formation, USNM 721 j].
NUMBER 15 571
PLATE 80.-Derbyia.
• * * * &
**^. 'if*. ,M~S ''i'' ' / *•' ** 'v*""'"•* -• v
572 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 81
Derbyia
Derbyia informis, new species: 1-3, Views of a specimen tilted posteriorly, in full view, and
tilted laterally to show thickening around the muscle scars, median septum, and its junction
with the pseudodeltidium, x 1> paratype USNM 153286a [Road Canyon Formation, locality
USNM 703a].
Derbyia complicata, new species: 4-8, Ventral, dorsal, anterior, posterior, and side views of
a small, strongly plicated paratype, X 1. USNM 151198j; 9-13, dorsal, side ventral, anterior,
and posterior views of a larger specimen, x 1» paratype USNM 151198d; 14-18, posterior,
dorsal, anterior, ventral, and side views of the holotype, x 1. USNM 151198h; 24-27, ventral,
side, posterior, and anterior views of a strongly plicated paratype, X 1. USNM 151198i; 29-31,
posterior, laterally tilted, and full views of a brachial valve, showing cardinal process and
long supporting plates, x 2, paratype USNM 151198m; 32, 33, posterior and interior views of
an encrusted brachial valve, x 1-5, paratype USNM 151198n; 34-36, full, laterally tilted, and
posteriorly tilted views of a pedicle valve, X 1. paratype USNM 151198-o; 37, pedicle valve
cemented to Institella, x 1> paratype USNM 151198p; 38, interior of a large pedicle valve
with small individuals cemented to it, x 2, paratype USNM 151198q [Cathedral Mountain
Formation (Wedin Member), USNM 714w].
19-23, Side, anterior, posterior, dorsal, and ventral views of a fairly strongly plicated adult,
X If paratype USNM 151192; 28, interior of a large pedicle valve, x 1. paratype USNM
151190a [Cathedral Mountain Formation (low), USNM 702].
NUMBER 15 573
PLATE SI.-Derbyia.
574 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 82
Derbyia
Derbyia cf. D. filosa, new species: 1, 2, Exterior and interior views of a small specimen,
showing barnacle borings and the internal blisters they produce, x 1> figured specimen USNM
153288 [Word Formation (lens between Willis Ranch and Appel Ranch Members), USNM
706b].
Derbyia scitula, new species: 3, Interior of a small brachial valve, X If paratype USNM
153289a; 4, 5, tilted and posterior views of the same specimen, showing myophore and chilidium,
X 3; 6, interior of another brachial valve, x 1. paratype USNM 153289c; 7, 8, tilted and
posterior views of the cardinal process of the preceding, showing one aborted prong (left) and
the large chilidium, x 4; 9, 10, full and laterally tilted views of the pedicle valve interior,
X 1, paratype USNM 153289d [Neal Ranch Formation (bed 2 = Gray Limestone of P. B.
King) , USNM 701].
Derbyia filosa, new species: 11-15, Ventral, posterior, anterior, dorsal, and side views of a
small specimen, x 1. paratype USNM I51154f; 16, young specimen cemented on a brachial
valve of Paucispinifera, x If paratype USNM 151154-1; 17, another young one attached to
the brachial valve of Rhamnaria, x 1, paratype USNM 151154m; 22, 23, full view and laterally
tilted view of a pedicle valve interior, showing delicate septum and thickened rim of the
adductor field, x 1» paratype USNM 151154-o; 28-30, interior, exterior, and side views of the
brachial valve, x 1> paratype USNM 151I54J; 31, posterior view of the preceding, showing the
short cardinal process, X 2 [Word Formation (lens between Willis Ranch and Appel Ranch
Members), USNM 706b].
18-21, Posterior, side, ventral, and dorsal views of a complete but damaged specimen, X If
paratype USNM 153291 [Word Formation (Willis Ranch Member), USNM 723w].
24-27, Exterior, full, posteriorly tilted, and laterally tilted views of a large pedicle valve,
X 1, holotype USNM 153290c [Word Formation (Willis Ranch Member), USNM 706e].
32, 33, Interior and exterior views of a pedicle valve, X If paratype USNM 151165a; 34,
35, exterior and interior views of a brachial valve, x '. paratype USNM 151165b; 36, posterior
of the preceding specimen, showing cardinal process and chilidium, x 2 [Cherry Canyon
Formation (Getaway Member) , locality AMNH 512 = USNM 728].
NUMBER 15 575
PLATE SZ-Derbyia.
576 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 83
Derbyia
Derbyia pannucia, new species: 1-3, Posterior, side, and dorsal views of a small specimen
with an immature one attached, x 1. paratype USNM 151115 [Word Formation (Willis Ranch
Member, lower) , USNM 706].
4-6, Interior, posterior, and laterally tilted views of an obese brachial valve, showing the
cardinal process, x 1> paratype USNM 151119b; 7, exterior of a medium-sized pedicle valve,
X 1. paratype USNM 151121f [Word Formation (Willis Ranch Member, upper), USNM 706e].
8-12, Side, anterior, posterior, ventral, and dorsal views of a large, much wrinkled and
distorted specimen, x 1. paratype USNM 151117 [Word Formation (lens between Willis
Ranch and Appel Ranch Members), USNM 706b].
NUMBER 15 577
PLATE S3.-Derbyia.
578 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 84
Derbyia
Derbyia pannucia, new species: 1, Exterior of a large and much wrinkled pedicle valve,
X If paratype USNM 151122n; 2, exterior of a small brachial valve, x l> paratype USNM
151121a; 3, exterior of another brachial valve, showing surface irregularity, x If paratype
USNM 151121b; 4, a still larger brachial valve in exterior view, x 1. paratype USNM 151121c
(for interior view, see Plate 85: figure 6) ; 5, exterior of an intricately wrinkled brachial
valve, X If paratype USNM 151121d; 6-8, posterior, interior, and exterior views of a large
pedicle valve, x 1> paratype USNM 151121e [Word Formation (Willis Ranch Member, upper),
USNM 706e].
NUMBER 15 579
PLATE 84.-Derbyia.
1
L i . -
k £ -,.• ••>'
\7
* -
xJIS
«Y;
4
. .ti
/" . sal * ^
8
f^ - * ; ^ jF
580 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 85
Derbyia
Derbyia pannucia, new species: 1, 2, Interior and exterior of a finely wrinkled pedicle valve,
showing thickening on anterior margin of muscle scars and long septum, x 1> paratype USNM
151122k; 3-5, interior, posterior, and exterior of a large brachial valve, showing cardinal
process and wrinkles, x 1> paratype USNM 151122p; 6, interior of another brachial valve,
showing well-developed brachiophores, x 1. paratype USNM 151121c (for exterior of this
specimen, see Plate 84: figure 4) ; 7, interior of a very large pedicle valve, x If paratype USNM
151122m [Word Formation (Willis Ranch Member, upper), USNM 706e].
NUMBER 15
PLATE 85.-Derbyia.
581
&J&&
tj') *>
\
>>,)•> > ? / > ; # \ . - V ,
^ • J
•
6
, 5 .-•.•
582 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 86
Derbyia
Derbyia pannucia, new species: 1, Interior of a small pedicle valve, x If paratype USNM
151122e; 2-4, ventral, interior, and posterior views of a larger specimen, x l> paratype USNM
151122g; 5, 6, posterior and posteriorly tilted views of an obese brachial valve, showing the
cardinal process, X li paratype USNM I51122q [Word Formation (Willis Ranch Member,
upper), USNM 706e].
7-11, Dorsal, side, posterior, ventral, and anterior views of a very large individual, x l>
holotype USNM 153346 [Word Formation (lens between Willis Ranch and Appel Ranch
Members), USNM 706b].
NUMBER 15 583
PLATE 86.-Derbyia.
< i i '' -^ '•..'•• •'••' ' ' " : ' ^ ^ . . ^
11
5 8 4 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 87
Derbyia
Derbyia texta, new species: 1, 2, Interior and exterior views of a brachial valve, bored by
barnacles and showing the blisters developed on the interior, x *• paratype USNM 151176
[Word Formation (lens between the Willis Ranch and Appel Ranch Members), USNM 706b].
3-7, Ventral, side, dorsal, posterior, and anterior views of a fully grown specimen, x If
paratype USNM 151184 [Word Formation (Appel Ranch Member), USNM 715i].
8-11, Ventral, dorsal, side, and posterior views of a complete specimen, x If paratype
USNM 153449a; 12, dorsal view of the same specimen, x 2; 21, dorsal view of a complete
specimen, x 1J holotype USNM 153449b; 22-26, dorsal, posterior, anterior, side, and ventral
views, X 2, of the preceding specimen; 32, 33, exterior of a brachial valve, X If X 2, paratype
USNM 153449f; 34, 35, interior of the brachial valve and process in greater detail, X If X 2,
paratype USNM 153449e; 42, posterior of the same specimen, showing the cardinal process in
greater detail, x 3; 36, 37, interior and laterally tilted views of a pedicle valve, X 2, paratype
USNM 153449c; 38, 39, interior of a brachial valve, x 1. X 2, paratype USNM 153449d; 40,
41, same specimen in posterior and tilted views, x 3 [Word Formation (Willis Ranch Member)
, locality USNM 706e].
13-15, Anterior, ventral, and dorsal views of a complete specimen, x *> paratype USNM
151186; 16-20, dorsal, anterior, side, posterior, and ventral views of the same specimen, x 2
[Cherry Canyon Formation (Getaway Member), AMNH 600].
27-31, Anterior, ventral, dorsal, posterior, and side views of a small, complete specimen,
X 1, paratype USNM 151179e [Word Formation (China Tank Member), USNM 706c].
NUMBER 15 585
PLATE 87.-Derbyia.
586 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 88
Derbyia
Derbyia complicata, new species: 1, 2, Exterior and interior of a large strongly plicated pedicle
valve, x It paratype USNM 153450a; 3, 4, interior and exterior of fragmentary specimen,
showing slits produced by boring organisms and the aberrations produced on the interior,
X It paratype USNM 153450c; 5, 6, exterior and interior of another small but strongly plicated
pedicle valve, x 1. paratype USNM 153450b [Cathedral Mountain Formation, locality USNM
721u].
Derbyia species 1: 7-10, anterior, dorsal, ventral, and side views of a small individual, X If
figured specimen 153465a; 26, 27, interior and exterior views of an elongated specimen, x If
figured specimen USNM 153465b [Bell Canyon Fbrmation (Pinery Member), AMNH 398].
11-15, Side, posterior, anterior, ventral, and dorsal views of a complete specimen, x 1«
figured specimen USNM 153466a; 16, 17, interiors of the pedicle and dorsal valves of the
preceding specimen, x 1; 24, 25, exterior and interior of an incomplete brachial valve, x If
figured specimen USNM 153466b [Bell Canyon Formation (Lamar Member) , USNM 728p].
18, 19, Interior and exterior of an imperfect pedicle valve, x Y> figured specimen USNM
153467c; 20, 21, interior and exterior of a smaller pedicle valve with attached Rigbyella, x If
figured specimen USNM 153467b; 22, 23, ventral and dorsal views of a small, complete specimen,
x If figured specimen USNM 153467a [Bell Canyon Formation (Lamar Member), AMNH
430],
28, 29, Interior and exterior of a brachial valve, x If figured specimen USNM 151205c; 30,
enlargement of the previous interior view, showing flaring supporting plates and short cardinal
process, x 2; 31, exterior of a large, much worn brachial valve, x 1> figured specimen USNM
151205b [Bell Canyon Formation (Lamar Member), USNM 738b].
NUMBER 15 587
PLATE 88.-Derbyia.
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588 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
PLATE 89
Geyerella, Tropidelasma, Meekella, Derbyia, Collumatus, and Teguliferina
Geyerella americana Girty: 1, Posterior view of the enormous cardinal process, x 1. hypotype
USNM 153543 [Bell Canyon Formation (Lamar Member), locality USNM 728p].
Geyerella hessi, new species: 2, Posterior view of an imperfect pedicle valve, x If figured
specimen USNM 153544a; 3, 4, posterior and exterior of the brachial valve, x 1> figured specimen
USNM 153544b [Cibolo Formation (breccia bed), locality USNM 738r].
Tropidelasma gregarium (Girt