Tertiary and Mesozoic Echinoids of Saudi Arabia SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY NUMBER 10 SERIAL PUBLICATIONS OF THE SMITHSONIAN INSTITUTION The emphasis upon publications as a means of diffusing knowledge was expressed by the first Secretary of the Smithsonian Institution. In his formal plan for the Insti- tution, Joseph Henry articulated a program that included the following statement: "It is proposed to publish a series of reports, giving an account of the new discoveries in science, and of the changes made from year to year in all branches of knowledge. This keynote of basic research has been adhered to over the years in the issuance of thousands of titles in serial publications under the Smithsonian imprint, com- mencing with Smithsonian Contributions to Knowledge in 1848 and continuing with the following active series: Smithsonian Annals of Flight Smithsonian Contributions to Anthropology Smithsonian Contributions to Astrophysics Smithsonian Contributions to Botany Smithsonian Contributions to the Earth Sciences Smithsonian Contributions to Paleobiology Smithsonian Contributions to Zoology Smithsonian Studies in History and Technology In these series, the Institution publishes original articles and monographs dealing with the research and collections of its several museums and offices and of professional colleagues at other institutions of learning. These papers report newly acquired facts, synoptic interpretations of data, or original theory in specialized fields. These pub- lications are distributed by mailing lists to libraries, laboratories, and other interested institutions and specialists throughout the world. Individual copies may be obtained from the Smithsonian Institution Press as long as stocks are available. S. DILLON RIPLEY Secretary Smithsonian Institution INTERNATIONAL BOOK YEAR ■ 1972 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY NUMBER 10 Porter M. Kier Tertiary and Mesozoic Echinoids of Saudi Arabia I5S0er JUN 14 197? SMITHSONIAN INSTITUTION PRESS CITY OF WASHINGTON 1972 ABSTRACT Kier, Porter M. Tertiary and Mesozoic Echinoids of Saudi Arabia. Smithsonian Contributions to Paleobiology, number 10, 242 pages, 50 figures, 67 plates, 1972.— The Mesozoic and Tertiary echinoids are described from Saudi Arabia. Fifty-one species, thirty-four of them new, occur in beds ranging from the Lower Jurassic to the Miocene. Two species are present in the Lower Jurassic (Toarcian) Marrat Formation, one is new: Acrosalenia marratensis. The Middle Jurassic (Bajocian- Bathonian) middle Dhruma Formation yielded eleven species, all new: Acrosalenia arabica, Acrosalenia dhrumaensis, Heterosalenia dhrumaensis, Pseudocidaris de- pressa, Polycyphus arabicus, Pseudosalenia magniprocta, Farquharsonia crenulata, Leioechinus namus (type species of new genus of the family Stomechinidae), Ple- siechinus altus, Bothryopneustes arabica, and Bothryopneustes dhrumaensis. Thirteen species are described from the Late Jurassic (Gallovian) upper Dhruma Formation, including twelve new species: Acrosalenia bower si, Pseudocidaris romani, Pseudo- cidaris raratuberculata, Hypodi'adema nanituberculata, Heterosalenia brocki, Hetero- salenia ornata, Leioechinus amplus, Polycyphus parvituberculatus, Holectypus phe- lani, Pygurus (Pygurus) arabicus, Bothryopneustes kauffmani, and Bothryopneustes inflata. One species, Bothryopneustes orientalis Fourtau, occurs in the Callovian Tuwaiq Mountain Limestone. Eleven species are reported from the Late Cretaceous (Campanian or Maestrichtian) Aruma Formation, five of which are new. Rhyn- chopygus arumaensis, Proraster granti, Iraniaster bowersi, Iraniaster affinimorgani, and Iraniaster affinidouvillei. The sympatric pairing of two species of Iraniaster corresponds to a pairing of another two species of this genus in the Senonian of Iran. This pairing has been reported in living spatangoids. The Early Cretaceous Yamama Formation yielded the new species Pygurus (Pygurus) yamamaensis. Beds of Eocene or Oligocene age yielded three echinoid species, one of them new: Agassizia arabica. Nine species occur in the Miocene Dam Formation, three are new: Schizechinus pentagonus, Fibularia damensis, and Agassizia powersi. These Miocene echinoids are quite similar to species now living in the littoral zone. The distribution and affinities of the echinoid species indicate faunal provinces in the Jurassic largely confined to Saudi Arabia, and in the Cretaceous confined to Saudi Arabia and Iran with some connections to North Africa but not to India. The Miocene distribution differs in being a part of a fauna occurring along the present borders of the Persian Gulf and the Arabian Sea of Saudi Arabia, Iran, West Pakistan, and northwestern India. Official publication date is handstamped in a limited number of initial copies and is recorded in the Institution's annual report, Smithsonian Year. UNITED STATES GOVERNMENT PRINTING OFFICE WASHINGTON ■ 1972 For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 - Price $3.00 (paper cover) Stock Number 4700-0178 Contents Page Abstract ii Introduction 1 Previous work 1 Methods 1 Acknowledgments 2 Stratigraphy and echinoid faunas 2 Lower Jurassic—Marrat Formation 2 Middle, Upper Jurassic—Dhruma Formation 5 Middle Dhruma Formation 5 Upper Dhruma Formation 8 Relationship between Middle and Upper Dhruma Echinoid Faunas 8 Upper Jurassic—Tuwaiq Mountain Limestone 9 Lower Cretaceous—Yamama Formation 9 Upper Cretaceous—Aruma Formation 10 Tertiary 10 Eocene—Oligocene? 10 Miocene—Dam Formation 11 Paleography 13 Comparison with living species 13 Paleoecology 13 Comparison of echinoid faunas of Saudi Arabia with those of North Africa, Iran, and India 14 Fossil Echinoid Localities in Saudi Arabia (by H. A. McClure) 15 Systematica 19 Jurassic Species 19 Cretaceous Species 68 Tertiary Species 87 Literature Cited 102 Explanation of Plates 107 Index 242 in Porter M. Kier Tertiary and Mesozoic Echinoids of Saudi Arabia Introduction For many years I heard of remarkable echinoid faunas in Saudi Arabia. When I received a few specimens for identification from the Arabian- American Oil Company (Aramco) in 1961, I be- came very anxious to go to Saudi Arabia to collect. Mr. S. D. Bowers of Aramco initiated the correspond- ence and Mr. O. A. Seager made the necessary arrangements. In 1962 an expedition led by Dr. R. W. Powers was undertaken. This Smithsonian-Aramco expedition consisted of Dr. Erie G. Kauffman and myself from the Smithsonian Institution and Dr. R. W. Powers, Mr. C. D. Redmond, and Mr. H. A. McClure from Aramco. The Smithsonian members were flown into central Saudi Arabia in an Aramco aircraft where they joined the oil company party of geologists, and support personnel. We visited the classic Jurassic outcrops of the Jabal Tuwayq region and collected extensively from measured sections. Large collections were made of mollusks, brachiopods, sponges, corals, and echinoids, and with the guidance of the Aramco geologists, the stratigraphic positions of these collections were noted relative to prominent marker beds. Our party moved by truck convoy east- ward and collected from sites in the Cretaceous and finally in the Tertiary. Dr. Kauffman made an ex- tensive collection of mollusks which he is now study- ing, and it is hoped that the rest of the fauna will be studied soon. The ammonites from this expedition have been described by Imlay (1970). This report is based on the echinoids collected on this expedition and all those collected earlier and Porter M. Kier, Department of Paleobiology, National Mu- seum of Natural History, Smithsonian Institution, Washing- ton, D. C. 20560. later by the Aramco geologists. The echinoids from the Yamama had been tentatively identified by Dr. Jean Roger. Previous Work With the exception of the ammonites, the Saudi Arabian megafossil fauna is largely unknown. The Jurassic ammonites have been described by Arkell (1952) and Imlay (1970) and one echinoid species has been described by R. V. Melville (1955). Aramco geologists and various consultants have tentatively identified many of the fossils, and these identifications are in Powers, Ramirez, Redmond, and Elberg (1966). Methods Generally, descriptions and illustrations of echinoid species are inadequate. It is nearly always necessary to borrow the type specimen in order to decide whether new material is conspecific. Thanks to mod- ern computers some of these problems can now be overcome. Chesher (1968) has explained superbly why it is necessary to provide more statistical infor- mation on echinoid specimens. Where possible in this paper I have made the measurements of the spatangoids that he recommends. The value of making measurements and statistically examining them was clearly demonstrated to me in my study herein of Moira adamthi Clegg and Laga- num tumidum Duncan and Sladen. These Miocene- Pliocene species are very similar to living species, and L. tumidum has been considered by two previous workers to be conspecific with the living L. depressum L. Agassiz. However, the results of the student t-test 1 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY showed clearly that the species were distinct and that the chances that they could be the same were less than one in a thousand. Without this statistical sup- port, I had intended to consider L. tumidum a synonym of L. depressum, and Moira adamthi a very close ancestor of M. atropos. Acknowledgments I thank Dr. Erie G. Kauffman who accompanied me on the collecting trip to Saudi Arabia and who, with great energy and vigor, found many of the echinoids described herein. Furthermore, I am in- debted to him for cheering me up during those desperate days when no echinoids were found. I thank the Arabian American Oil Company (Aramco), not only for providing all the echinoids collected by their geologists on previous expeditions, but also for arranging and supporting the 1962 collecting trip. Dr. R. W. Powers, Mr. C. D. Redmond, and Mr. H. A. McClure guided us on this trip and collected many specimens. Mr. S. D. Bowers provided much subsequently needed information. Dr. Ralph Imlay provided important data from his study of the am- monites, and Dr. Neil Roth of the Mathematician Information Systems Division of the Smithsonian Institution led me through the labyrinth of pitfalls and terrors of statistics and computers. Mr. Thomas F. Phelan did all the excellent photography, made many of the preparations, assisted in the computer programming, and performed many other tasks. The art work was done by Mr. Lawrence B. Isham, scien- tific illustrator of the Department of Paleobiology. The following curators most kindly lent me speci- mens: Miss Ailsa M. Clark and Dr. R. P. S. Jefferies of the British Museum (Natural History) ; Dr. R. B. Rickards and Dr. Colin Forbes of the Sedgwick Museum, Cambridge, England; Dr. Ian Rolfe of the Hunterian Museum University, Glasgow, Scotland; Dr. Jean Roman of the Museum National d'Histoire Naturelle, Paris; Dr. J. Manivit of the University D'Orsay, Centre d'Etudes et de Recherches de Paleon- tologie Biostratigraphique, France; Dr. K. N. Prasad of the Geological Survey of India, who very kindly obtained for me casts of some of Clegg's type speci- mens; Dr. Leo G. Hertlein of the California Academy of Sciences. Also, I thank Dr. Richard E. Grant of the United States Geological Survey, Professor J. Wyatt Durham of the University of California, Berkeley, Dr. Erie G. Kauffman of the Smithsonian Institution, and Mr. H. A. McClure, staff paleontologist of Aramco, who critically read the manuscript and made many useful suggestions. Mr. McClure, in particular, pre- pared the locality section besides making valuable suggestions throughout the manuscript. Dr. Richard H. Chesher of Westinghouse Research advised me on the living habits of some spatangoid echinoids. Stratigraphy and Echinoid Faunas Mesozoic and Tertiary strata crop out in a great curved belt in central Arabia. The stratigraphy of these formations has been described in detail in Powers, Ramirez, Redmond, and Elberg (1966), and a chart of the formations from that work is repeated herein as Figure 2 with ages, generalized lithologies, and thicknesses. Echinoids have been found only in the Lower Jurassic Marrat Formation, Middle and Upper Jurassic Dhruma Formation, Upper Jurassic Tuwaiq Mountain Limestone, Lower Cretaceous (Valanginian) Yamama Formation, Upper Creta- ceous Aruma Formation, unnamed Eocene-Oligocene beds, and the Miocene Dam Formation (Table 1). The Jurassic collections made in the 1962 Smith- sonian-Aramco expedition were made from measured sections selected by R. W. Powers. These Jurassic sections occur in a small area southeast of the city of Riyadh (Figure 1). The position within the section was located for each fossil collection within one-half meter. Each horizon was measured vertically (strati - graphically) from a well-known marker bed such as the Dhibi limestone of the lower Dhruma Formation. Many of the collections made earlier or later by the Aramco geologists also came from measured sections. The Lower Cretaceous echinoids came from the vicinity just south of the town of Al Yamamah; Upper Cretaceous echinoids came from various localities scattered along the approximate northern extent of the Aruma plateau. Miocene collections came mostly from the northeast near-littoral area, excepting sev- eral localities from the extreme northwest corner of Saudi Arabia. Lower Jurassic—Marrat Formation The Marrat Formation was designated and published by Steineke and Bramkamp (1952). Particulars of NUMBER 10 900 KILOMETERS 0 I 500 MILES FIGURE 1.—Map of Saudi Arabia showing location of the Jurassic measured sections collected from by the Smithsonian-Aramco expedition of 1962. The location of the area of the upper geological map is indicated on die lower map by a small black rectangle southwest of Riyadh. After Imlay 1970 (emended). SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY Age Formation Generalized lithologic description Thickness (Type or reference section) Major stratigraphic divisions QUATERNARY AND TERTIARY o a> *> r: Thanetjan_ Montian(?) Surficial deposits Gravel, sand, and silt Kharj Limestone, lacustrine limestone, gypsum, and gravel Hofuf Sandy marl and sandy limestone; subordinate cal careous sandstone. Local gravel beds in lower part * Dam Marl and shale; subordinate sandstone, chalky lime stone, and coquina Hadrukh Dammam Calcareous, silty sandstone, sandy limestone; local Lutetian^ Ypresian chert Limestone, dolomite, marl, and shale Rus Marl, chalky limestone, and gypsum; common chert and geodal quartz in lower part. Dominantly an- hydrite in subsurface Maestrichtian Campanian Turonian(7) Umm er Radhuma Limestone, dolomitic limestone, and dolomite Possible disconformity - Aruma •* Limestone; subordinate dolomite and shale. Lower part grades to sandstone in northwestern and southern areas of outcrop Wasia (Sakaka Sandstone of northwest Arabia) Biyadh Cenomanian Aptian Sandstone; subordinate shale, rare dolomite lenses Barrejnia_n_ Hauterman Valanginian Berriasian Sandstone; subordinate shale Buwaib Biogenic calcarenite and calcarenitic limestone in- terbedded with fine sandstone in upper part Yamama •*• Biogenic pellet calcarenite; subordinate aphanitic limestone and biogenic calcarenitic limestone Sulaiy Chalky aphanitic limestone; rare biogenic calcarenite and calcarenite limestone 28 m 95 m 91m 84m 33 m 56m 243 m 142 m 42 m 425 m 18 m 46 m 170 m Miocene and Pliocene Clastic Rocks Upper Cretaceous to Eocene Carbonate Rocks Middle Cretaceous Clastic Rocks Late Lower Cretaceous Clastic Rocks Mith Anhydrite 90 m Tithonian Kimmeridgian Arab Jubaila Calcarenite, calcarenitic and aphanitic limestone, dolomite and some anhydrite. Solution-collapse carbonate breccia on outcrop due to loss of inter- bedded anhydrite Aphanitic limestone and dolomite; subordinate cal- carenite and calcarenitic limestone. Lower part sandstone between 20° N. and 22° N. 124 m :118 m Upper Jurassic and early Lower Cretaceous Carbonate Rocks Hanifa Aphanitic limestone, calcarenitic limestone, and cal- carenite 113 m Tuwaiq Mountain*** Dhruma •*• Jilh Sudair Khuff Oxfordian Callovian Callovian(?]_ Bathonian Upper Middle Lower Aphanitic limestone; subordinate calcarenitic lime- stone and calcarenite. Abundant corals and stroma- toporoids in upper part Aphanitic limestone and shale; subordinate calcar- enite. Dominantly sandstone south of 22° N. and north of 26° N. Sandstone, aphanitic limestone, and shale; subordi- nate gypsum Red and green shale Limestone and shale; dominantly sandstone south of 21°N. Umm Sahm Ram Quweira Siq Precambrian basement complex 203 m 375 m :326 m 116 m Lower and Middle Jurassic Clastic and Carbonate Rocks Permian and Triassic Clastic Rocks NUMBER 10 the type section were published by Steineke, Bram- kamp, and Sander (1958), and an additional refer- ence section was designated and described by Powers, Ramirez, Redmond, and Elberg (1966). The forma- tion consists of aphanitic and calcarenitic limestone, dolomites, siltstones and sandstones, but the echinoids were mainly collected from fine-grained limestones. The formation has been dated by ammonites as Toar- cian (Arkell 1952). It is locally very fossiliferous containing also numerous brachiopods and mollusks. Although a large number of echinoids were collected, only two species are recognized: Echinotiara arabica Melville, and Acrosalenia marratensis Kier, new species. These species are confined to Saudi Arabia and therefore provide no further information as to the age of the Marrat. Middle, Upper Jurassic—Dhruma Formation Beds of the Dhruma Formation, with its apex near Riyadh, form an arc that extends a distance of more than 900 kilometers. The formation was formally named and type section designated in publication by Steineke, Bramkamp, and Sander (1958). A more detailed reference section was published by Powers, Ramirez, Redmond, and Elberg (1966). The outcrop belt is at its maximum 25 kilometers wide and the formation reaches a maximum thickness of 375 meters at the reference section. The echinoids collected in 1962 by the Smithsonian-Aramco party came from three measured sections (KK7, KK8, KK9) south- west of Riyadh (Figure 1) where the Dhruma is exposed in a steplike series of high limestone-capped scarps and broad dip slopes. The three sections were stratigraphically measured from the Dhibi limestone member which separates the lower and middle Dhruma, and therefore collections made from these sections can be related to each other stratigraphically. No echinoids were collected from the lower Dhruma but many were found in the middle and upper Dhruma. Because the fauna from the middle Dhruma is entirely different from that of the upper they are treated here separately. FIGURE 2.—Saudi Arabian outcrop sequence. Copied directly from Powers, Ramirez, Redmond, and Elberg (1966, table 1, opposite page D6). Asterisks have been added to this section to show where the echinoids were collected. Three species were found in Eocene-Oligocene ? beds which are not in- dicated on this section. MIDDLE DHRUMA FORMATION Most of the echinoids came from calcarenitic and aphanitic limestones. Most specimens were weathered out on the surface, although some were collected from limestone still in place. Generally, the echinoids appeared to have weathered out very nearly in place, and only a few specimens were found which had obviously moved any great distance down slope. Eleven new species are described from the middle Dhruma. At least four more species are present, but not enough is known of these species to permit de- scription because only fragments of them were found. Acrosalenia arabica Kier, new species Acrosalenia dhrumaensis Kier, new species Heterosalenia dhrumaensis Kier, new species Pseudocidaris depressa Kier, new species Polycyphus arabica Kier, new species Pseudosalenia magniprocta Kier, new species Farquharsonia crenulata Kier, new species Leioechinus namus Kier, new species Plesiechinus altus Kier, new species Bothryopneustes arabica Kier, new species Bothryopneustes dhrumaensis Kier, new species According to Imlay (1970:5) the lower few meters of the middle Dhruma are definitely of late Bajocian age because they contain the ammonite Spiroceras bifurcatum (Quenstedt). Imlay considers the rest of the middle Dhruma to be Bathonian also on the evidence of the ammonites. The echinoids are of little help in determining the age of the beds because all the species are new. The fauna, however, has its closest affinities with Bathonian and Callovian species. Polycyphus arabicus is very similar to P. textilis L. Agassiz from the late Bathonian and Cal- lovian of France and Callovian of Madagascar, and P. drayi Fourtau from the Callovian of Egypt. Hetero- salenia dhrumaensis resembles H. alloiteaui Zoeke from the Middle Jurassic of Lebanon, and Acrosalenia arabica Kier resembles A. humei Fourtau from the Bathonian of Egypt. Many of the species have a fairly wide stratigraphic range within the middle Dhruma (Figure 3) but only one species extends more than 112.5 meters above the Dhibi limestone member. Bothryopneustes dhrumaensis has the widest range of any of the species, extending from 32.5 to 161.5 meters above the Dhibi limestone. SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY TABLE 1.—The stratigraphic distribution of the echinoids of Saudi Arabia. JURASSIC CRETACEOUS CENOZOIC BAJO- CIAN- TOAR- BATHO- CIAN NIAN CALLOVIAN CAMPA- NIAN- MAE- NEOCO- STRICH- MIAN TIAN EOCENE- OLIGO- CENE? MIOCENE Species Tuwaiq Middle Upper Moun- Marrat Dhruma Dhruma tain Forma- Forma- Forma- Lime- tion tion tion stone Yamana Aruma Dam Forma- Forma- Forma- tion tion tion Acrosalenia arabica Kier, new species A. bowersi Kier, new species A. dhrumaensis Kier, new species A. marratensis Kier, new species Actinophyma cf. A. spectabile Cotteau & Gauthier Agassizia (Agassizia) power si Kier, new species . Agassizia (Anisaster) arabica Kier, new species . Bothryopneustes arabica Kier, new species B. dhrumaensis Kier, new species B. inflata Kier, new species B. kauffmani Kier, new species B. orientalis Fourtau Brissus latidunensis Clegg Coptodiscus nomiae Cotteau & Gauthier Echinodiscus desori Duncan and Sladen E. ginauensis Clegg Echinotiara arabica Melville Eupatagus sp Farquharsonia crenulata Kier, new species F. somaliensis Currie Fibularia damensis Kier, new species Globator mortenseni Checchia-Rispoli Goniopygus superbus Cotteau and Gauthier Heterosalenia brocki Kier, new species H. dhrumaensis Kier, new species H. ornata Kier, new species Holectypus phelani Kier, new species Hypodiadema nanituberculata Kier, new species Iraniaster affinidouvillei Kier, new species /. affinimorgani Kier, new species /. bowersi Kier, new species Laganum tumidum Duncan and Sladen Leioechinus amplus Kier, new species L. namus Kier, new species Lovenia cf. Lovenia elongata (Gray) Moira adamthi Clegg Opechinus costatus (D'Archiac and Haime) Plesiechinus altus Kier, new species X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X NUMBER 10 TABLE 1.—The stratigraphic distribution of the echinoids of Saudi Arabia—Continued. JURASSIC CRETACEOUS CENOZOIC BAJO- CIAN- TOAR- BATHO- CIAN NIAN CALLOVIAN CAMPA- NIAN- MAE- NEOCO- STRICH- MIAN TIAN EOCENE- OLIGO- CENE? MIOCENE Species Tuwaiq Middle Upper Moun- Marrat Dhruma Dhruma tain Forma- Forma- Forma- Lime- tion tion tion stone Yamana Aruma Dam Forma- Forma- Forma tion tion tion Polycyphus arabicus Kier, new species P. parvituberculatus Kier, new species Pr or aster granti Kier, new species Pseudocidaris depressa Kier, new species P. raratuberculata Kier, new species P. romani Kier, new species Pseudosalenia magniprocta Kier, new species Pygurostoma cf. P. morgani Cotteau and Gauthier Pygurus (Pygurus) arabicus Kier, new species P. (P.) yamamaensis Kier, new species Rhynchopygus arumaensis Kier, new species .. Schizechinus pentagonus Kier, new species .... Zuffardia cf. Z. cerullii Checchia-Rispoli X X X X X X X X X SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY UPPER DHRUMA CO rr UJ I- LLI MIDDLE DHRUMA ■-6 •-7 -1 -3 > 160- 150- 140- 130- 120- 110- 100- 90- 80- 70- 60- 50- 40- 30- 20- 10- Dhibi Member LOWER DHRUMA FIGURE 3.—Range of the middle Dhruma echinoids: 1. Poly- cyphus arabicus Kier, new species; 2. Pseudosalenia magni- procta Kier, new species; 3. Leioechinus namus Kier, new species; 4. Acrosalenia dhrumaensis Kier, new species; 5. Acrosalenia arabica Kier, new species; 6. Pseudocidaris depressa Kier, new species; 7. Heterosalenia dhrumaensis Kier, new species; 8. Farquharsonia crenulata Kier, new species; 9. Plesiechinus altus Kier, new species (this species is known from the "middle" but has not been collected at a measured section) ; 10. Bothryopneustes dhrumaensis Kier, new species; 11. Bothryopneustes arabica Kier, new species. meters of calcareous shale. All the echinoids came from the lower section. In fact, twelve of the thirteen species from the upper Dhruma were collected at one horizon 11 meters above the base of the upper Dhruma at measured section KK9 (Figure 1). Only Pygurus (Pygurus) arabicus Kier, new species, was not found here. The upper Dhruma is richly fossiliferous with many species of corals, sponges, mollusks, Foraminif- era, ostracods, and brachiopods. Imlay (1970) reports sixteen species of ammonites from the upper Dhruma. Powers, Ramirez, Redmond, and Elberg (1966:D47) give a comprehensive list of the species of Foraminif- era, ostracods, mollusks, and corals from the Dhruma Formation. The following species of echinoids were found in the upper Dhruma Formation: Acrosalenia bowersi Kier, new species Pseudocidaris romani Kier, new species Pseudocidaris raratuberculata Kier, new species Hypodiadema nanituberculata Kier, new species Heterosalenia brocki Kier, new species Heterosalenia ornata Kier, new species Farquharsonia somaliensis Currie Leioechinus amplus Kier, new species Polycyphus parvituberculatus Kier, new species Holectypus phelani Kier, new species Pygurus (Pygurus) arabicus Kier, new species Bothryopneustes kauffmani Kier, new species Bothryopneustes inflata Kier, new species Imlay (1970:7) assigned a middle Callovian age to the upper Dhruma Formation on the basis of the ammonites. The echinoids confirm this age assign- ment. Farquharsonia somaliensis, the only Arabian species occurring outside of Arabia, has been reported from the Callovian of British Somaliland. Pygurus (Pygurus) arabicus is very similar to P. (Pygurus) smelliei Currie also from the Callovian of British Somaliland. Pseudocidaris romani and P. raratubercu- lata are very similar, and one of the species may be conspecific with P. migliorinii Maccagno from the Callovian-Oxfordian of Italian Somaliland. UPPER DHRUMA FORMATION The upper Dhruma Formation is composed of a lower Atash Member of calcarenitic and aphanitic limestone approximately 25 meters thick at the refer- ence section where we made our collections, and an upper section, the Hisyan Member, composed of 64 RELATIONSHIP BETWEEN MIDDLE AND UPPER DHRUMA ECHINOID FAUNAS It is significant that the middle and upper Dhruma echinoid faunas do not contain any of the same echinoid species. None of the thirteen upper Dhruma species occurs among the eleven lower Dhruma species. NUMBER 10 Furthermore, the upper Dhruma species are quite distinct from the lower Dhruma species of the same genus. This great difference suggests either a major environmental change and a major time interval, or both, between the time of deposition of the beds containing the two faunas. The echinoid faunal break coincides with one found by Imlay (1970:D7 and oral communication, 1971) in the ranges of the ammonites. He reports no ammonites ranging from the middle Dhruma to the upper Dhruma, and sug- gests that the lower Callovian may be represented by a disconformity between the middle and upper Dhruma, or the lower 11 meters of the upper Dhruma. Although a few echinoid specimens have been col- lected in float from the lower 11 meters, I suspect that they came from the main echinoid-bearing bed 12 meters above the base, and that the upper Dhruma echinoid species do not extend into these lower beds. This disconformity, if it encompassed all the early Callovian, could not represent a time hiatus of more than 2—3 million years. The fact that the lower Miocene echinoids of Arabia are strikingly similar to Recent species, having lasted 15 million years with little change, suggests that the echinoids evolved at a faster rate during this Jurassic time in Arabia than since the lower Miocene. There is no evidence of a major change in the environment that could explain this dichotomy in the faunas, for all but two of the genera present in the middle Dhruma are also present in the upper, including Acrosalenia, Heterosalenia, Pseudocidaris, Polycyphus, Farquharsonia, Leioechi- nus, and Bothryopneustes. The two faunas generally are morphologically similar and probably lived in similar environments. Upper Jurassic—Tuwaiq Mountain Limestone The Tuwaiq Mountain Limestone was defined by Steineke, Bramkamp, and Sander (1958); more de- tails and particulars are given in Powers, Ramirez, Redmond, and Elberg (1966). The base of this for- mation forms a prominent cuesta extending a distance of more than 1,200 kilometers, with a maximum outcrop of 20 kilometers, and a maximum thickness of 215 meters. The western boundary is marked by a west-facing vertical limestone cliff. In the region where the echinoids were collected it is a massively bedded aphanitic limestone except in its lower part where it is a well-bedded, very fossiliferous, soft, chalky limestone with some soft calcarenitic limestone, calcarenite, and shale. Although only one echinoid species, Bothryopneustes orientalis Fourtau, has been found in the Tuwaiq Mountain Limestone, it occurs in great numbers in the lower part. The echinoid was collected at six localities but in only one of them is its exact stratigraphic position known and at this place it was found 14 meters above the base of the formation. B. orientalis is known elsewhere from the Callovian of Egypt and the Callovian-Oxfordian of Italian Somaliland. Arkell (1952) considered the lower beds of the Tuwaiq Mountain Limestone to be middle Callovian, as did Imlay (1970:7), both on the basis of the ammonites. Lower Cretaceous—Yamama Formation This formation was defined in a publication by Stei- neke, Bramkamp, and Sander (1958:1308) and fur- ther redefined by Powers, Ramirez, Redmond, and Elberg (1966:D70). The formation crops out in a thin, curved band extending nearly 300 kilometers, with a maximum width of 9 kilometers and a maxi- mum thickness of 45 meters. It is largely a carbonate unit of calcarenite, calcarenitic limestone, and aphan- itic limestone. Although Redmond (1964) has described several Foraminifera from this formation, his species are re- stricted to Saudi Arabia and are of no assistance in determining the age of the formation. Many mollusks occur in the formation but they have not yet been described. The only evidence for age comes from the echinoids. The species Pygurus (Pygurus) yamama- ensis occurs in great numbers in the lower part of this formation. This species is most similar to the Neocomian species Pygurus montmolini Agassiz from western Europe. Furthermore, its phyllodes are typical of those found in other Neocomian species as de- scribed in an evolutionary trend delineated by Kier (1962, chart 3, opposite p. 6). Jean Roger (in Steineke, Bramkamp, and Sander (1958:1308) iden- tified a species of Trematopygus similar to T. grasi d'Orbigny known from die Valanginian of France, but no specimens were well enough preserved in the collection I studied to permit a more exact identifi- cation. In summary the echinoids indicate that the Yamama Formation is Neocomian. 10 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY Upper Cretaceous—Aruma Formation The Aruma Formation was defined by Steineke, Bram- kamp, and Sander (1958:1310). It crops out over a distance of about 1,600 kilometers with a width rang- ing from 20 kilometers in the south to 200 kilometers in the north where it passes into Iraq. Its thickness is 140 meters at the type locality. More details are given in Powers, Ramirez, Redmond, and Elberg (1966: D79—D83). The echinoids all came from the lower part of the Aruma where it is a cream, fine-grained nodular bedded calcarenitic limestone. Eleven echi- noid species are present: Coptodiscus nomiae Cotteau and Gauthier Globator mortenseni Checchia-Rispoli Rhynchopygus arumaensis Kier, new species Pr or aster granti Kier, new species Goniopygus superbus Cotteau and Gauthier Actinophyma cf. A. spectabile Cotteau and Gauthier Iraniaster affinimorgani Kier, new species Iraniaster affinidouvillei Kier, new species Iraniaster bowersi Kier, new species Zuffardia cf. Z. cerullii Checchia-Rispoli Pygurostoma cf. P. morgani Cotteau and Gauthier One of the more interesting aspects of this fauna is the presence of the pair of species of Iraniaster— I. affinimorgani and I. affinidouvillei. These species occur together at the same localities and same strati- graphic level and are another example of sympatric pairing in spatangoids. Chesher (1968) discusses in great detail the occurrence of sympatric pairs in both the Recent and fossil record. He notes that there is consistently a high and low form. This is also true with these Arabian species. This discovery is even more interesting in light of the fact that another sympatric pair of species of this same genus is present from the Senonian of Iran—Iraniaster morgani Cot- teau and Gauthier and I. douvillei Cotteau and Gauthier. These species likewise consist of a low and high form. Unfortunately, the age relative to each of these Arabian and Iranian species is not known, but morphologically the Arabian species ap- pear to be more advanced. The plastron of the Arabian I. affinimorgani is much more advanced than I. morgani. Its plastron is composed partially of a second plate (2a) ; whereas in I. morgani the plastron is more primitive, with only one plate. Furthermore the more deeply depressed petals of the Arabian species indicate that they are more specialized for burrowing than the Iranian. I. affinimorgani appears to be descended from I. morgani; whereas I. affinidouvillei is descended from I. douvillei. I. affinidouvillei is more similar to the Iranian I. dou- villei than to its sympatric partner I. affinimorgani. This fauna has close affinities with a fauna described by Cotteau and Gauthier (1895) from the Senonian of Iran. Both Coptodiscus nomiae and Goniopygus superbus occur in Iran (C. nomiae is also present in the Campanian of Oman), and there are some Arabian specimens very similar to the Senonian Iranian species Pygurostoma morgani and Actino- phyma spectabile. Proraster granti is very similar to P. morgani (Cotteau and Gauthier), Iraniaster affini- morgani is similar to I. morgani Cotteau and Gauthier, and I. affinidouvillei is similar to Iraniaster douvillei Cotteau and Gauthier, all three from the Senonian of Iran. The fauna also has affinities with some northeastern African echinoids. Globator mortenseni was first de- scribed from the Maestrichtian of Tripolitania (Libya). One Aruma specimen is very similar and probably belongs to Zuffardia cerullii Checchia- Rispoli, also from the Maestrichtian of Tripolitania. Finally, Rhynchopygus arumaensis is quite similar to R. hori (Fourtau) from the Aptian of Egypt. The fauna is distinct from faunas of similar age in Europe, India, and Pakistan and is apparently confined to the central Tethys. On the basis of the echinoids, it is certainly Senonian and probably Campanian or early Maestrichtian. Powers, Ramirez, Redmond, and Elberg (1963:83) considered the lower part of the Aruma to be Campanian on the basis of the Foraminifera and mollusks. Tertiary EOCENE—OLIGOCENE? Three species of echinoids occur at two localities (S—761, S—1603) at the northwestern tip of Saudi Arabia in the Wadi Sirhan area. These species were collected from a sandy marl that has been dated tentatively as Eocene according to the geological map of Saudi Arabia (1963). Detailed stratigraphic rela- tionships and formal nomenclature for the units in the area were never established. According to Dr. O. W. Nine (1970, personal correspondence), "S—761 was collected by Schultz and Wells from the Lower (sandy) Marl Member of the Sirhan Formation in NUMBER 10 11 1939. (These are informal rock names and were never adopted.) The late Dr. R. A. Bramkamp dated the contained fauna as Miocene in 1940. He held the opinion the beds were near equivalent of the Syrian Burdigalian because they contained a probable Schi- zaster parkinsoni DeFrance." However, no specimens of a Schizaster are present among the specimens I have studied from this locality or from S-1603. The three species that occur are Echinodiscus ginauensis Clegg, Agassizia arabica Kier, new species, and Eupa- tagus species. Echinodiscus ginauensis is known from Iran where Clegg (1933:4) reported it from strata below a bed with nummulties, and reported diat Pilgrim mentioned having found a limestone in the same region crowded with Echinodiscus, Ortho- phragmina, and Assilina spira. On the basis of these latter two Eocene Foraminifera, Clegg considered E. ginauensis to be of Khirthar (middle Eocene) age. Although the Foraminifera cannot be younger than Eocene, I am suspicious of the Eocene age for the echinoid. No Echinodiscus is known elsewhere from below the Miocene and no Amphiope (a very closely allied genus) is known from before the Oligocene. Furthermore, E. ginauensis has lunules, and I know of no sand dollar with lunules before the Oligocene. Agassizia arabica resembles most A. power si from the Burdigalian Dam Formation of eastern Saudi Arabia but appears to be ancestral. Eupatagus species is quite distinct from all other species of this genus and provides no information relative to its age. Therefore, no definite age determination can be made of these echinoids, but they are probably late Eocene or Oligocene. Some echinoids have been collected from East- ern Aden (Beydoun 1966:H37) from the middle Eocene Habshiya Formation. Five of the species also occur in the Karkar Series of British Somaliland and it is apparent that these two regions once belonged to the same faunal province. No echinoids of the same age have been found in Saudi Arabia and therefore it is not possible to know whether this echinoid prov- ince extended northward into Saudi Arabia. MIOCENE—DAM FORMATION The Dam Formation was first published by Thralls and Hasson (1956) with type-section details given by Steineke, Bramkamp, and Sander (1958:1313) and Powers, Ramirez, Redmond, and Elberg (1966: D95). The formation crops out near the coast of the Persian Gulf in northeastern Saudi Arabia where it is from 30 to 100 meters thick. Further inland, it passes into continental facies indistinguishable from nonmarine beds above and below. It thus represents a transgressive wedge of the Miocene sea. In its marine facies, it is a marl with minor interbeds of sandstone, chalky limestone, and coquina. Fossils are abundant locally throughout the formation, but the most prominent marker bed is the "Button bed" which is composed of large numbers of Fibularia damensis Kier, new species (called Echinocyamus species in all previous works). Nine species of echinoids occur in the Dam For- mation : Schizechinus pentagonus Kier, new species Fibularia damensis Kier, new species Laganum tumidum Duncan and Sladen Echinodiscus desori Duncan and Sladen Brissus latidunensis Clegg Lovenia cf. Lovenia elongata (Gray) Moira adamthi Clegg Agassizia powersi Kier, new species Opechinus costatus (d'Archiac and Haime) This formation is middle Miocene according to Steineke, Bramkamp, and Sander (1958), and Powers, Ramirez, Redmond, and Elberg (1966:D97). They state that it approximately correlates with the Lower Fars Formation of Iraq, as indicated by the "presence of Ostrea latimarginata Vredenburg Echinocyamus sp., and "Archaias" sp. —." Their "Echinocyamus" sp. is Fibularia damensis, but no Echinocyamus or Fibularia have been reported from the Lower Fars. Powers, Ramirez, Redmond, and Elberg, however, list from the Dam many other echinoids that also have been reported from the Lower Fars, including Agassizia cf. A. scrobiculata Valenciennes var. persica Clegg (herein referred to Agassizia powersi Kier, new species), Brissus latidunensis Clegg, Lovenia elongata Gray, Moira adamthi Clegg, and Temnopleurus persica Clegg. I have found all these except Temno- pleurus persica and agree with these authors that the Dam correlates with the Lower Fars. Furthermore, Laganum tumidum, which occurs in the Dam, is also known from the Fars. Although Powers et al. considered on this evidence that the Dam was middle Miocene, the Lower Fars is now considered to be Burdigalian by most recent authors, or upper lower Miocene. Of the four species that also occur in the Fars Formation, only one 12 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY (Brissus latidunensis) has been reported definitely as occurring in the Lower Fars. The others are reported from the Fars without any indication as to whether they are from the Lower, Middle, or Upper Fars. Three of these species, Lovenia elongata, Moira adamthi, and Brissus latidunensis, however, occur together in the Dam at the same locality and strati- graphic position, so it is a fair assumption that they also occur together in the Lower Fars. Clegg (1933:5) reported that Brissus latidunensis came from the Lower Fars in beds that he considered to be Bur- digalian or Helvetian. Eames, Banner, Blow, and Clarke (1962:12, 15) put the lower part of the Lower Fars in the Bur- digalian and correlated it with the Gaj Series of Paki- stan and India. Two of the Dam echinoids, Opechinus costatus and Echinodiscus desori, are known from the Gaj. Furthermore, Ostrea latimarginata Vreden- burg, which is present in the Dam Formation, is considered an "index fossil" of the Lower Fars (van FIGURE 4.—Distribution of the Arabian Miocene echinoids within and outside of Arabia. The species are represented by the following symbols: 0= Opechinus costatus (D'Archiac and Haime); I \ —Moira adamthi Clegg; /\ = Laganum tumidum Duncan and Sladen; %= Agas- sizia powersi Kier, new species; U = Brissus latidunensis Clegg;^^= Lovenia elongata. NUMBER 1 0 13 Bellen 1959:166) and also is known from the Gaj (Eames, Banner, Blow, and Clarke 1962:15). It is evident that the Dam and Lower Fars also correlate with the Gaj. Contemporary workers consider the Gaj to be Burdigalian on the basis of the Foraminif- era and mollusca (Mohan and Chatterji 1956; and Eames, Banner, Blow, and Clarke 1962:15). There- fore, these Dam echinoids are probably Burdigalian. PALEOGEOGRAPHY.—Geographically, the echinoids of the Dam Formation are part of an echinoid faunal province extending from the west side of the Persian Gulf in Arabia, through southern Iran, southern Pakistan, and northwestern India (Figure 4). None of die species has been reported from anywhere else. There is no evidence that all the species reported from the Dam Formation lived together at the same time. Five of the species are found at the same local- ity: Echinodiscus desori, Lovenia cf. L. elongata, Moira adamthi, Brissus latidunensis, and Schizaster pentagonus. It is not known for certain, however, that they all came from the same stratigraphic level. Fibularia damensis occurs with Opechinus costatus at one and possibly two localities, and with Agassizia powersi at one locality. The exact stratigraphic posi- tion within the Dam Formation is known for only one species, Fibularia damensis, which is reported in Powers, Ramirez, Redmond, and Elberg (1966.D146) as occurring 11.8 meters above the base of the Dam at its type section. COMPARISON WITH LrviNG SPECKS.—I am surprised by the great similarity between many of the species of echinoids in the Dam Formation and species now living. The Burdigalian is considered by the most recent estimates (Berggren 1969:1073) to be at least 14 million years old, but some of the Dam species have undergone little or no change during this long period of time. Brissus latidunensis Clegg is indistin- guishable from the living B. agassizii Doderlein, and only the lack of sufficient specimens prevents decision as to whether it is really conspecific. The specimens from the Dam referred tentatively to Lovenia elongata are indistinguishable from this living species. Agas- sizia powersi is very similar to the living A. scrobicu- lata Valenciennes, and Moira adamthi Clegg strongly resembles M. stygia Liitken. Laganum tumidum Dun- can and Sladen is so similar to the living L. depressum L. Agassiz that most authors have considered them to be synonymous. Furthermore, all these above echi- noids are very advanced, highly specialized spatangoids or clypeasteroids far removed from the old conserva- tive stocks, such as the cidarids. PALEOECOLOGY.—The echinoids from the Dam Formation occur in a quartz grain, marly sandstone containing numerous shell fragments. Three of the species are conspecific or strikingly similar to species now living in the littoral zone. Lovenia elongata (Gray) today lives on a sandy bottom from the ebbzone down to 94 meters. Clark (1938:440) observed that at low tide "it made every effort to pace with the rapidly receding tide. The long spines of the oral surface raised the entire animal very considerably from the sand as it walked upon and by means of them, while the still longer spines of the dorsal surface stood out even more strikingly as if in defense from any attack." Moira adamthi Clegg is quite similar to M. stygia Ltitken, now living in the Gulf of Suez. According to Mortensen (1951:337) this species is "an emi- nently littoral species living buried deep in the ground." Brissus latidunensis Clegg may be con- specific with Brissus agassizii Doderlein, now living off Japan buried in shallow water down to 10 meters. Laganum tumidum is very like L. depressum, a shallow-water species commonly found just below low tide on a sandy bottom. The living habits of the echinoids would probably be as follows: Schizechinus pentagonus morphologi- cally resembles the modern Lytechinus variegatus (Lamarck) and probably lived as it does (Kier and Grant 1965:21), in shallow water on die sandy bottom in grass with its test covered with shells and bits of grass. Fibularia damensis Kier occurred in great numbers in the interstices of the sand and shell fragments in the bottom sediment. Both Laganum tumidum and Echinodiscus desori would be in the littoral zone, no doubt in great numbers, with their tests covered by sand but not truly buried. Brissus latidunensis Clegg, Lovenia elongata Gray, and Moira adamthi Clegg would be deeply buried in the sub- strate. Opechinus costatus is structurally very similar to Mespilia globulus (Linne), which I have seen living off Eniwetok Atoll, Marshall Islands, in water 10-feet deep on a sandy bottom under small loose rocks holding detritus over their tests. Presumably O. costatus lived similarly. 14 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY Comparison of the Echinoid Faunas of Saudi Arabia with those of North Africa, Iran, and India The Jurassic echinoid fauna is largely endemic to Saudi Arabia with only two out of twenty-seven species occurring elsewhere (in Egypt and Somali- land) . Large echinoid faunas of the same age are known from Egypt and Somaliland, and the fact that only two species are shared with the Arabian fauna indicates a high degree of endemism. The Late Cre- taceous fauna has a broader distribution, extending into Iran and with close affinities with a few North African species but none to the east in India. The Miocene fauna differs in sharing no species with North Africa but in being part of a fauna occurring along the present borders of the Persian Gulf and the Arabian Sea of Saudi Arabia, Iran, West Paki- stan, and northwestern India. The Miocene distri- bution reflects the present distribution of the land masses, whereas the Mesozoic distribution indicates faunal provinces in the Jurassic largely confined to Saudi Arabia, and in the Cretaceous confined to Iran and Saudi Arabia with some connections to North Africa but not to India. The dissimilarity between the Mesozoic echinoids of India and Saudi Arabia and similarity in the Tertiary may support the view of some of the advo- cates of continental drift that the subcontinent of India was not in its present position in pre-Tertiary time. Considerable more evidence relative to this question will be available when the extensive Arabian Mesozoic collections of corals, brachiopods, mollusks, sponges, and Foraminifera have been described. A detailed description is given below of the affini- ties of the Arabian echinoids. JURASSIC—Most of the Jurassic Arabian echinoids are distinct from those known from elsewhere, and have their strongest affinities with Egyptian and Somaliland species. Only two of the twenty-seven species reported herein are known outside of Saudi Arabia: Farquharsonia somaliensis Currie from So- maliland and Bothryopneustes orientalis Fourtau from Egypt and Somaliland. Polycyphus arabicus Kier, new species, is very similar to P. drayi Fourtau from Egypt (and P. textilis L. Agassiz from Madagascar and France), and likewise Acrosalenia arabica Kier, new species, resembles the Egyptian -species A. humei Fourtau. Acrosalenia dhrumaensis Kier, new species, is very similar to the Somaliland A. somaliensis Cur- rie. Pseudocidaris romani Kier, new species, may be conspecific with the Somaliland P. migliorinii. P. raratuberculata Kier, new species, is also similar to this Somaliland species. Heterosalenia dhrumaensis Kier, new species, and H. brocki Kier, new species resemble H. alloiteaui Zoeke from Lebanon, and Pseudocidaris depressa Kier, new species, is quite similar to P alhadasensis de Loriol from Portugal. Finally Bothryopneustes arabica Kier, new species, strongly resembles B. galhauseni Lambert from Mo- rocco. The presence of five species of Bothryopneustes in Saudi Arabia is of particular paleogeographic sig- nificance. This genus is common in Somaliland and Egypt and has been reported in Madagascar and Morocco but never outside of this African-Arabian region. None of the Arabian species resembles Indian species. The five species from Cutch specifically iden- tified by Gregory (1893) resemble none of the Arabian species, and it may be significant that no specimens of Bothryopneustes have been found in India. However, the paucity of Jurassic Indian echi- noids makes it impossible to determine the significance of this lack of affinity between Indian and Arabian echinoid faunas. CRETACEOUS.—The Late Cretaceous (Campanian or early Maestrichtian) echinoid fauna of Saudi Arabia is, like the Jurassic, distinct from faunas of similar age in Europe, India, and Pakistan. It is, however, very similar to that of Iran, and several species are very like North African species. Two species, Goniopygus superbus Cotteau and Gauthier and Coptodiscus nomiae Cotteau and Gauthier, occur in both Saudi Arabia and Iran. Specimens occurring in Saudi Arabia are very similar to the Iranian Ac- tinophyma spectabile Cotteau and Gauthier and Pygurostoma morgani Cotteau and Gauthier. Pro- raster granti Kier, new species, is very similar and may be conspecific with P. morgani Cotteau and Gauthier from Iran. The Arabian species of Irani- aster, I. affinimorgani are quite similar to the Iranian /. douvillei Cotteau and Gauthier and /. morgani Cotteau and Gauthier, respectively. Globator morten- seni (Checchia-Rispoli) occurs in Saudi Arabia and Tripoli (Libya) and is similar to G. orientalis Cot- teau and Gauthier from Iran. Likewise an Arabian specimen is very similar and probably conspecific with Zuffardia cerullii Checchia-Rispoli from Tripoli. Finally, Rhynchopygus arumaensis Kier, new species, NUMBER 10 15 is very similar and may be conspecific with R. hori (Fourtau) from Egypt. The Late Cretaceous Arabian echinoids have no known affinities with the Indian-Pakistan Late Cre- taceous echinoids. Three Late Cretaceous echinoid faunas are known from India-Pakistan: the Ceno- manian (?Turonian) echinoids from the Bagh Beds described by Chiplonker (1937), Fourtau (1918), and Duncan (1887); the Danian echinoids from Baluchistan described by Noetling (1894, 1897); and the Maestrichtian-Danian echinoids described by Stoliczka (1873) from the Ariyalur Group of southern India. The echinoids considered by Duncan and Sladen (1882) to be Late Cretaceous are now attributed to the Paleocene. The Arabian echinoids bear no resemblance to the fourteen species known from the Bagh Beds. However, these Bagh echinoids are older (Ceno- manian, PTuronian) and this lack of resemblance may only reflect their age difference and may not be of paleogeographical significance. The fifteen species from the Danian of Baluchistan are also dis- tinct from the Arabian species and from the fifty- five species described by Cotteau and Gauthier (1895), and Gauthier (1902) from the Senonian of Iran. Finally, none of the thirty-eight species from the Ariyalur Group of southern India resembles any of the Arabian-Iranian species. Hence the Arabian- Iranian fauna appears to belong to an entirely dif- ferent faunal province than the Indian. Its affinity is with North Africa and not the east. Cotteau and Gauthier (1895:107) likewise noted that the Iranian echinoids resembled the North African but little re- sembled the echinoids of southern India. Noetling (1897:7) considered that the similarity between the echinoids of Baluchistan with those of the Pyrenees indicated that a great faunistic province extended from southwestern Europe toward Central Asia, but that this province was separated from southern India by a land barrier. MIOCENE.—Although the Arabian Mesozoic echi- noids are distinct from the Indian, the Miocene echi- noids belong to a faunal province that includes south- ern Iran, soudiern Pakistan, and northwestern India (Figure 4). Two of the species that occur in Arabia are found in the Gaj Series of Pakistan and north- western India: Opechinus costatus (d'Archiac and Haime) and Echinodiscus desori Duncan and Sladen. Fossil Echinoid Localities in Saudi Arabia (Prepared by H. A. McClure) Echinoid localities in Saudi Arabia studied in this paper are, with exception of several from the north- west portion in the Wadi As Sirhan area, distributed in the outcrop belt of Mesozoic and Tertiary rocks in the approximate central eastern portion. Those that also contain ammonites are listed in Steineke and Bramkamp (1952:252-256, and fig. 3) and Im- lay (1970, table 3). Other Jurassic echinoid localities are in the same general area. Cretaceous echinoid localities are mostly from the central area of the Al Aruma plateau on outcrops of the Aruma Formation, and from the vicinity of Al Yamama near the capital city of Riyadh. Most of the Tertiary sites are near the Persian Gulf littoral and further inland, where rocks of this age crop out. The Aramco S series is from collections made by Aramco geologists between the approximate years of 1933—1953 in routine geo- logical mapping. The Aramco L series was collected in 1961. In the KK series, the first Arabic number is the sample section designation; in the case of actual samples, the Arabic number after the hyphen indi- cates meters above base of the section. In the ma- jority of cases, geographic coordinates are given, so that precise location can be determined by re- course to proper maps of the Miscellaneous Investi- gations series of the area compiled by the United States Geological Survey and Aramco. In several cases, where precise coordinates are not available, other data serve to place the locality approximately. All the individual localities studied in this paper, with as much pertinent information as available, are listed below. Collector's Stratigraphic assignment, description field number of locality, and collector LOWER JURASSIC—MARRAT FORMATION KK6:1 Base of section 21.5 meters above base of formation. Lat 24°14'N, long 46°06'E. Northern Tuwayq quadrangle. Aramco S-989: 14 to 16 meters above base of for- mation. Lithology compact, fine-grained limestone, 1 All KK locality collections were made by P. M. Kier, E. G. Kauffman, R. W. Powers, H. A. McClure, and C. D. Redmond in 1962. 16 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY in part marly and detrital, with abundant small oys- ters. In measured section 3.4 km. S 67° W of Al Bakhra. Lat 24°09'18"N, long 46°09'24"E. North- ern Tuwayq quadrangle. Collectors: F. R. Wal- dron, R. A. Bramkamp, 1944. Aramco S—1034: About 6 to 10 meters above base of formation. Lithology tan and golden, fine-grained limestone with limonite nodules. At base of isolated jebel, 24.8 km. S 1° W of Al Bakhra. Lat 23°56' 36"N, long 46°11'00"E. Southern Tuwayq quad- rangle. Collectors: E. L. Berg, R. L. Myers, W. T. Short, R. A. Bramkamp, 1945. MIDDLE-UPPER JURASSIC—DHRUMA FORMATION Aramco S—1045: 14.5 to 16.5 meters above Dhibi limestone. Golden brown, soft, oolitic limestone and fine grained, hard, marly limestone. 8.4 km. N 73.5° E of Al Bakhra. Lat 24°11.4'N, long 46°16.'E. Northern Tuwayq quadrafigle. Collec- tors: E. L. Berg, R. L. Myers, W. T. Short, R. A. Bramkamp, 1945. Aramco S—1046: 24.8 meters above Dhibi limestone. Golden-tan oolite with thin beds of tan, soft, fine- grained limestone and tan shale. Location: same as S-1045. Collectors: E. L. Berg, R. L. Myers, W. T. Short, R. A. Bramkamp, 1945. Aramco S—1956: Dhibi limestone, at top of escarp- ment. 4.5 km. N 28° E of Al Bakhra astro station. Northern Tuwayq quadrangle. Collectors: C. W. Brown, M. Steineke, E. L. Berg, R. L. Myers, W. T. Short, 1945. Aramco S—1064: 31.6 to 34.4 meters above Dhibi limestone. Golden-tan oolite. On south side of re- entrant in scarp, 38.8 km. N 40° W of Ayn al Bakhra. Lat 23°31'00"N, long 46°16'24" E. South- ern Tuwayq quadrangle. Collectors: E. L. Berg, R. L. Myers, W. T. Short, R. A. Bramkamp, 1945. Aramco S—1148: 126 to 148 meters below top of formation. .75 km. S 70°W of Khashm al Haysi- yah. Lat 24°50'27"N, long 46°01'46"E. Northern Tuwayq quadrangle. Collectors: D. A. Holm and M. P. Yackel, 1947. Aramco S—1154: Middle Dhruma. 0 to 35 meters below "B" bench. In measured section 13.5 km. N45°W of town of Dhruma. Lat 24°42'14"N, long 46°03'00" E. Northern Tuwayq quadrangle. Col- lectors: D. A. Holm and M. P. Yackel, 1947. Aramco S—1157: Middle Dhruma. 24.8 to 34.9 meters below "B" bench. Same locality as S—1154. Col- lectors: D. A. Holm and M. P. Yackel, 1947. Aramco S—1160: Middle Dhruma, lower part, about 50 to 60 meters above Dhibi limestone. 3.5 km. N36°W of town of Dhruma. Lat 46°38'12"N, long 46°07'30"E. Northern Tuwayq quadrangle. Collectors: D. A. Holm and M. P. Yackel, 1947. Aramco S—1164: 13 to 32 meters below top of Dhibi limestone. 10.5 km. N53°W of N corner of town of Dhruma. Lat 24°40'06"N, long 46°03'00"E. Northern Tuwayq quadrangle. Collectors: D. A. Holm and M. P. Yackel, 1947. Aramco S-1167: 13 to 33 meters below top of Dhibi limestone. 9 km. N58^4°W of N corner of town of Dhruma. Lat 24°39'18"N, long 46°03'18"E. Northern Tuwayq quadrangle. Collectors: D. A. Holm and M. P. Yackel, 1947. Aramco S—1176: Upper Dhruma, probably Atash Member. Measured section .75 km. S70°W of Khashm al Hasiyah. Lat 24°50'27"N, long 46°01' 46"E. Northern Tuwayq quadrangle. Collectors: D. A. Holm and M. P. Yackel, 1947. Aramco S-1503: Middle Dhruma. 39.4 to 40.4 me- ters below Micromphalites clay. Golden-tan oolite and shale. 3.8 km. N89°W of town of Juraifa. Lat 25°31'48"N, long 45°13'18"E. Northern Tuwayq quadrangle. Collectors: N. J. Sander, D. B. Eicher, W. M. Furnish, O. B. Fenner, R. A. Bramkamp, 1950. Aramco L—921 :z Middle Dhruma. 2.2 meters below top of chalky limestone bench. Dhrumaities or Micromphalites zone. Lat 24°52'5"N, long 45°54' 4.5"E. Northern Tuwayq quadrangle. Aramco L—922: Middle Dhruma. 11.7 meters higher than L—921, and at same location. Aramco L—926: Atash Member of upper Dhruma. Equivalent to level of KK9-112. Lat 24°54'N, long 45°58'34"E. Northern Tuwayq quadrangle. KK7: Lower Dhruma. Top of section, 8.5 meters above Dhibi limestone, at Khashm Dhibi. Lat 24°12'N, long 46°11'E. Northern Tuwayq quad- rangle. KK8: Approximately lower 61 meters of middle Dhruma. Base of section 2.5 meters above Dhibi limestone, at Khashm Dhibi. Lat 24°H'N, long 46°17'E. Northern Tuwayq quadrangle. KK9: Upper 101 meters of middle Dhruma, and all of upper Dhruma. Top of section 30 meters above 2 All Aramco L locality collections were made by N. M. Layne, Jr., and H. A. McClure in 1961. NUMBER 10 17 Dhruma in Tuwaiq Mountain Limestone. Lat 24°11'N, long 46°19'E. Northern Tuwayq quad- rangle. UPPER JURASSIC—TUWAIQ MOUNTAIN LIMESTONE Aramco L-916A: Lowermost Tuwaiq Mountain Limestone. 14 meters above base of cliff. Approxi- mately 15 km. N slightly E of town of Az Zilfi. Lat 26°21'32"N, long 44°47'59.5"E. Wadi Ar Rimah quadrangle. Aramco L-918: Blocky, calcareous bed at base of 40 meter section near town of Az Zilfi. Lat 25°41' 14.5"N, long 45°11'59"E. Northern Tuwayq quad- rangle. Aramco S—293: From Tuwayq scarp near town of Az Zilfi. S35°W of Camp Rumaythan. Approxi- mate location: Lat 26°18'N, long 44°48'; Wadi Ar Rimah quadrangle. Collectors: M Steineke and J. W. Hoover, 1936. Aramco S—1800: From Tuwayq scarp near town of Az Zilfi. Finely oolitic, argillaceous, detrital lime- stone. Lat 26°02'33"N, long 44°57'11"E. Wadi Ar Rimah quadrangle. Collectors: S. J. Roach and W. M. Furnish, 1952. Aramco S-1804: 24.4 to 34 meters above base of measured section. Chalky, granular and oolitic limestone. Approximately 5 km. NW of town of Az Zilfi. Lat 26°21'06"N, long 44°47'13"E. Wadi Ar Rimah quadrangle. Collectors: S. J. Roach and W. M. Furnish, 1952. Aramco S-1805: 34 to 39 meters above base of measured section. Oolitic and detrital limestone. Location same as S-1804. Collectors: S. J. Roach and W. M. Furnish, 1952. LOWER CRETACEOUS—YAM AM A FORMATION KK1—41: 24.5 meters above base of formation. About 17 km. south of town of As Sulaymaniyah. Lat 24°00'37"N, long 47° 15'40"E. Northern Tuwayq quadrangle. Aramco L—901: 9.18 meters down from top of Buwaib Formation. (Questionably assigned to Bu- waib Formation, but is more likely Yamama—H. A. McClure 1971.) Vicinity of Khashm ath Tha- mamah. Lat 25°18'18.75"N, long 46°37'05"E. Northern Tuwayq quadrangle. Aramco L-902: At same stratigraphic level as L-901. (Questionably assigned to Buwaib Formation, but is more likely Yamama—H. A. McClure 1971.) Yellow (limonitic) calcareous sandstone. West side of Irq Banban. Lat 25°04'16.75"N, long 46°3V 12.75"E. Northern Tuwayq quadrangle. Aramco L—905: Whitish marl, and brown, sandy limestone. About 5.75 km. S of town of As Sulay- maniyah. Lat 24°05'48.5"N, long 47°18'36"E. Northern Tuwayq quadrangle. Aramco L—908: Lowermost part of formation. On immediate back slope of Sulaiy scarp. 8 km. SE of Al Dilam. Yellow marl. Lat 23°58,N, long 47°13'E. Southern Tuwayq quadrangle. Aramco L-910: On level of air-drilled hole T-32. Approximate top of formation, associated with oyster bed. Approximate location: Lat 23°55'N, long 47°20'E. Northern Tuwayq quadrangle. Aramco S-1262: 50 to 54 meters above base of for- mation. Molluscan and finely detrital limestone, and cream, compact, fine-grained limestone. Lat 24°9'N, long 47°19.4'E. Northern Tuwayq quad- rangle. Collectors: S. B. Henry and R. A. Bram- kamp, 1949. UPPER CRETACEOUS—ARUMA FORMATION Aramco S—71: From 3 meter member, base of which is 96.2 meters above base of measured section. Just to W of Wadi al Atj, at Khashm al Hiqaqah. Lat 25°45'N, long 46°15'E. Northern Tuwayq quadrangle. Collectors: T. W. Koch and C. W. Brown, 1934. Aramco S-285: About 34 meters above base of for- mation. White marly member in hard, slabby limestone. 11.5 km. N14°E of Aqibba. Approxi- mate location: Lat 27°30'N, long 44°20'E. Wadi Ar Rimah quadrangle. Collectors: M. Steineke and J. W. Hoover, 1936. Aramco S-286: Probably lower Aruma. Just above sandstone of Wasia. 10.5 km. N48°W of Aqibba. Approximate location: Lat 27°28'N, long 44°12/E. Wadi Ar Rimah quadrangle. Collectors: M. Stei- neke and J. W. Hoover, 1936. Aramco S-289: Lower part of formation. Tan, chalky weathering, fine-grained limestone. Approximate location: Lat 26°16,N, long 45°17.5'E. Northern Tuwayq quadrangle. Collectors: M. Steineke and J. W. Hoover, 1936. Aramco S-290: Near base of formation. White, chalky limestone. Approximate location: Lat 26° 16.3'N, long 45°18.7'E. Northern Tuwayq quad- 18 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY rangle. Collectors: M. Steineke and J. W. Hoover, 1936. Aramco S-748: Lower part of formation. About 8 km. ENE of Khashm at Tawqi, on Darb at Tawqi. Approximate location: Lat 25°28'N, long 46°33'E. Northern Tuwayq quadrangle. Collectors: T. C. Barger, J. W. Thomas and U. S. Armstrong, 1939. Aramco S—1234: 10 to 72 meters above base of for- mation. Lat 25°36'40"N, long 45°52'35"E. North- ern Tuwayq quadrangle. Collectors: A. F. Pocock and R. P. Kopp, 1948. Aramco S—1419: Wadi Atj area. Northern Tuwayq quadrangle. Collectors: S. B. Henry, N. J. Sander, R. A. Bramkamp, 1949. KK11: Lowermost Aruma. Cream, nodular bedded limestone. Between 79 and 85 kilometer markers in cut on Khurais-Riyadh road. Approximate location: Lat 25°00'N, long 47°17'E. Northern Tuwayq quadrangle. KK12: Lower Aruma in vicinity of Khashum Buway- biyat. Approximate location: Lat 46°49.2'N, long 25°17.4'E. Northern Tuwayq quadrangle. TERTIARY LOCALITIES Eocene—Oligocene Aramco S-761: White, finely sandy marl and marly sandstone. Bottom of Wadi As Sirhan, near west side, NW of Qurayyat al Milh. Very approximate location: Lat 31°22'N, long 37°18'E. Wadi As Sirhan quadrangle. Collectors: J. R. Schultz and J. C. Wells, 1940. Aramco S—1603: "Rashrashiyah" chalk. South side of Faida Rashrashiyah. 14.5 km. N85°W of the town of Kaf. Lat 31°25'N, long 37°20,E. Wadi As Sirhan quadrangle. Collectors: D. A. Holm and A. E. Clements, 1950. Miocene—Dam Formation Aramco S—126: 6 to 10 meters below red sandstone. Marl and green clay. On Jibal al Uqayr scarp, 21 km. S9°W of town of Al Uqayr. Lat 25°29'N, long 50°08'E. Western Persian Gulf quadrangle. Collectors: T. W. Kock and M. Steineke, 1935. Aramco S—137: White marls of "button" (Fibularia) beds. S64°W, 23.7 km. from Jabal Qurayn. Lat 26°30'N, long 49°27'E. Western Persian Gulf quadrangle. Collectors: T. W. Koch and M. Stei- neke, 1935. Aramco S-178: Weathered coquina capping hill. "Button" (Fibularia) beds with molluscs, crab claws, and orbitoid Foraminifera. About 1 km. E of Jabal Insib. Lat 26°13'50"N, long 49°31'40"E. Western Persian Gulf quadrangle. Collectors: M. Steineke, T. F. Harriss, F. A. Davies, J. W. Hoover, 1935. Aramco S—357: 16 meters above Placenta horizon. Cream, sandy marl. Qariya al Ilya area. Probable approximate location: Lat 27°00'N, long 48°30'E. Western Persian Gulf quadrangle. Collectors: T. F. Harriss and W. H. Hoag, Jr., 1937. Aramco S-360: Marl. Near As Sarar. Lat 26°57'N, long 48°19'E. Western Persian Gulf quadrangle. Collectors: T. F. Harriss and W. H. Hoag, Jr., 1937. Aramco S—361: 4 meter high, conspicuous white hill in center of basin. Marl. Lat 27°22'N, long 48° 25'E. Western Persian Gulf quadrangle. Collectors: T. F. Harriss and W. H. Hoag, Jr., 1937. Aramco S—532: South side of sabkha. Al Uqayr area. Approximate location: Lat 25°30'N, long 50°12'E. Western Persian Gulf quadrangle. Collectors: M. Steineke and R. A. Bramkamp, 1936. Aramco S—553: Upper half of "button" (Fibularia) bed. 1.5 to 3 meters above base of upper part of formation. Selwa area. Probable approximate loca- tion: Lat 24°45'N, long 50°42'E. Western Persian Gulf quadrangle. Collectors: T. F. Harriss and W. H. Hoag, Jr., 1937. Aramco S—568: About 25 meters above base of upper dam. Buff and pinkish marl. Selwa area. 1.7 km. S28°W of Khashm an Nukhsh. Approximate loca- tion: Lat 24°52,N, long 50°52'E. Western Persian Gulf quadrangle. Collectors: T. F. Harriss and W. H. Hoag, Jr., 1937. Aramco S—1392: Marl, and saccharoidal limestone. Near Al Mashakhil, NE end of jabal. Approximate location: Lat 24°31'N, long 50°53'E. Western Persian Gulf quadrangle. Collector: R. D. Gierhart (?), 1937. Aramco S—1914: Upper part of formation. Cream, finely sandy limestone. Near Jawan quarry just off Ras Tanura road. Lat 26°42'02"N, long 49° 58' 04"E. Western Persian Gulf quadrangle. Collectors: H. A. McClure and R. W. Morris, 1965. NUMBER 10 19 SYSTEMATICS Detailed locality data by H. A. McClure is avail- able in the preceding section. The following abbreviations are used: L (length), D (diameter) S.D. (standard deviation), CV. (co- efficient of variability—the S.D. as percentage of the mean), N (number of specimens measured). All the measurements, their means, variances, standard deviations, standard errors, variability co- efficients, and counts are available by application to the curator of fossil echinoderms, National Museum of Natural History, Washington, D.C. 20560. The formula for the student t-test is available in most statistic textbooks, but in particular in Simpson, Roe, and Lewontin (1960:176). JURASSIC SPECIES Superorder DIADEM AT ACE A Duncan Order DIADEMATOIDA Duncan sum of its morphological characters suggests, however, that it belongs in the Diadematacea. Farquharsonia belongs to the order Diadematoida rather than the Pedinoida, as indicated by its conspicuous gill slits and generally insert ocular plates V and I. In the Pedinoida the gill slits are shallow, and the apical system dicylic. Although the tubercles are noncrenu- late in Pedinoida, the fact that some tubercles are crenulate and some noncrenulate in F. somaliensis suggests that this feature may not be as important as formerly thought. Farquharsonia is quite distinct from the other diadematoid genera, resembling most Eodiadema in having greatly reduced tuberculation adapically, and generally having ocular plates V and I insert. Farqu- harsonia differs in having its ambulacra consisting of pairs of plates with a tubercle covering each pair separated by a single plate with a smaller tubercle, whereas Eodiadema has simple plates throughout most of its ambulacra except near the peristome. Family DIADEMATIDAE Gray Genus Farquharsonia Currie The affinities and even necessity for the erection of this genus have been argued. Currie had only two poorly preserved specimens at the time she described the genus and did not know the character of the ambulacral plates except adapically. She was con- vinced that her species had to be placed in a new genus but realized that she could not know its affini- ties until more was known about the arrangement of the ambital and adoral ambulacral plates. Mortensen (1940:333-334) questioned the need for this genus. He wrongly assumed that Currie was incorrect in her belief that the primary interambulacral tubercles were crenulate in some places on the test and noncrenulate in others. Mortensen places the genus incertae sedis in the suborder Diademina. Fell (1966:365) in the "Treatise" puts the genus in the order Pedinoida but excludes it from the family Pedinidae because "it now seems probable that the tubercles are crenulate." Unfortunately, no part of the lantern in the type species or in Farquharsonia crenulata has been seen, and it is therefore not certain that the genus belongs in the superorder Diadematacea or Echinacea. The Farquharsonia somaliensis Currie FIGURES 5, 6; PLATE 2: FIGURES 3-6; PLATES 3, 4; PLATE 5: FIGURE 1 Farquharsonia somaliensis Currie, 1927:416—420, fig. 3; Mortensen 1940:333-334, fig. 167; Currie 1935:45 This species, the type species, has never been ade- quately described or illustrated. Currie had only two specimens available to her when she erected the genus and species from material from the Callovian of British Somaliland. These specimens were partially covered with matrix. I have borrowed these specimens from the British Museum (Natural History) and three specimens from the Sedgwick Museum which Currie identified in 1935. Two of these specimens are illustrated herein (Plate 4: figures 1—3, 6, 7; Plate 5: figure 1). The description below is based entirely on the Arabian material. MATERIAL.—Seventeen specimens. SHAPE.—Average horizontal diameter 18.9 (S.D. 5.2, CV. 27.4, N-12), smallest specimen 11.8 mm, largest 27.7 mm; marginal outline circular; adapical surface inflated with gently sloping sides; adoral sur- face not depressed around peristome; height of test 59.2 percent of diameter (S.D. 3.8, CV. 6.4, N-12) (Figure 5A) ; plates of test diin. 20 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY 20r 18 16 14 12 o> a> X 8 6 4 o o o o o o O o D Somaliland specimens G Arabian specimens D o ■ i i i i i i i i i—i—i—i 10 12 14 16 18 20 22 24 26 28 30 32 34 Diameter of test I4r 12- lio o- 8 £ 6 o E o Q4 2h 1 1 1 1 1 1 O o a - o G G © O G 1 1 1 o G G : B D Somaliland specimens o Arabian specimens i i i i i i i 1 1 1 1 1 i i i i i i i i i i i i i i i i • ' 4 6 8 10 12 14 16 18 20 22 24 26 28 30 Diameter of test FIGURE 5.—Farquharsonia somaliensis Currie: scattergrams of the height relative to die diameter (A), diameter of peristome relative to the diameter of the test (B), number of plates in an interambulacrum (c), and number of porepairs in a half-ambulacrum (D) in specimens from Arabia and British Somaliland. NUMBER 10 21 60 55 w50 o o 3 45 -Q §40 k. a> c 35 c — 30 ^25 a. £ 15 E = 10 -0- Somaliland D Arabian 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 Diameter of test 70 65 - 60 D O 55 a E = 50 o i« J? E40 o 1 - o 0 o GO O o"35 o C30 - w ~25 o. ■ £20 15 □ Somaliland 10 D « Arabian 5 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 Diameter of test 22 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY APICAL SYSTEM.—Small, width 25 percent of diam- eter of test of specimen 13.7 mm in diameter, 23 per- cent of specimen 18.7 mm in diameter, 19 percent of largest specimen 27.2 mm in diameter; periproct large, elongated in axis passing through genital 2 and ocular V (Plate 2: figure 3); genital plates pointed into interambulacra; genitals 2,3 larger than others; plate arrangement visible in seven specimens, ocular plates V and I insert in five specimens, V, II, and I insert in one (Figure 6A). AMBULACRA.—Straight, wide, at ambitus 17.8 per- cent as wide as D (S.D. 0.9, CV. 4.9, N-ll), great- B FIGURE 6.—Farquharsonia somaliensis Currie: A, apical sys- tem of hypotype USNM 170371 from the upper Dhruma Formation at locality KK9-108, X7; B, ambulacrum at midzone showing plate arrangement consisting of pairs of primary plates with tubercle covering each pair separated by single primary plate in hypotype USNM 170374 from the upper Dhruma Formation at locality KK9-112, X8. est width above ambitus; interporiferous zones wide, 70-77 percent as wide as ambulacra; ambulacra from near apical system to near peristome consisting of pairs of primary plates with tubercle covering each pair, separated by single primary plate with smaller tubercle (Figure 6B) ; 38 porepairs in single poriferous zone in smallest specimen 11.8 mm in diameter, 48 in specimen 18.7 mm, and 57 in specimen 27.1 mm (Figure 5D) ; shape of pores visible on Plate 2: fig- ure 6. INTERAMBULACRA.—Each interambulacrum com- posed of 22 plates in specimen 11.8 mm in diameter, 28 in specimen 18.7 mm, 32 in largest 27.2 mm (Figure 5c). PERISTOME.—Diameter averaging 35.9 percent of diameter of test (S.D. 4.0, C.P. 11.2, N-10) in small- est specimen 39 percent, in largest 30 percent (Figure 5B) ; gill slits deep, each bilobed (see Plate 3: figure 7) with elevated flange facing interambulacra. TUBERCULATION.—Interambulacral plates bear one primary tubercle; adapically tubercles small on first six to eight plates in each half-interambulacrum (Plate 2: figure 3), scrobicule rings of these tubercles slightly developed, not confluent, scrobicules flush to slightly depressed below general level of test; tubercles slightly above ambitus to below ambitus much larger (Plate 3: figure 1), with well-developed confluent scrobicular rings, slightly depressed scrobicules, dis- tinct basal terraces; all primary tubercles perforate, but crenulation variable, present on most primary tubercles above and below ambitus but absent on larger tubercles at ambitus on most specimens except on one of smaller specimens (13.7 mm in diameter) in which all interambulacral primary tubercles crenu- late (Plate 4: figure 5); secondary tubercles slightly developed particularly adapically (Plate 2: figure 3) where only miliaries present; slightly above ambitus, miliaries abruptly increase in size and secondary tu- bercles first appear extending in an irregular line with one series between primary tubercle and ambulacra and other between primary tubercle and medial su- ture in interambulacrum. In ambulacra, single small, perforate, crenulate tubercle on pair of plates separated by single plate with smaller secondary tubercle (Plate 3: figure 6); as in interambulacra, miliary spines very small above ambitus. ARABIAN LOCALITIES.—Late Jurassic, Callovian, upper Dhruma Formation, most of the specimens (12) NUMBER 10 23 come from KK9-112 (11 meters above the base of the upper Dhruma; two specimens from KK9-112- 114 (11-13 meters above the base, one specimen from KK9-111 (14 meters above the base), one specimen at KK9—108 (7 meters above the base), and two specimens at KK9-95-96 which is in the middle Dhruma (Bathonian) one to two meters below the upper Dhruma. I suspect that these two specimens, which were float, rolled down from the higher intervals. REMARKS.—Using an airbrasive machine, I have been able to expose many features on Currie's holo- type and paratype and three other specimens she (1935:45) referred later to this species. The Somali- land specimens are indistinguishable from the Arabian. As can be seen on the scattergrams on Figure 5 the Somaliland specimens have similar diameter to height ratios, similar sized peristomes, and similar number of interambulacral and ambulacral plates in each col- umn. The Somaliland specimens also have noncrenu- late interambulacral tubercles at the ambitus but crenulate ones below, and crenulate ambulacral tu- bercles. Although the Somaliland specimens are larger than the Arabian, this difference is probably of no significance, and the Arabian specimens can be re- ferred with little doubt to F. somaliensis. Because no photographs have ever been published of the Somali- land specimens, several are included here (Plate 4: figures 1—3; Plate 5: figure 1). Farquharsonia crenulata Kier, new species FIGURE 7; PLATE 1: FIGURES 1-6; PLATE 2: FIGURES 1, 2 DIAGNOSIS.—Species characterized by all its pri- mary interambulacral tubercles being crenulate, and large peristome. MATERIAL.—One extremely well-preserved speci- men. SHAPE.—Test large, 27.2 mm in horizontal diam- eter, moderately high, 15.0 mm high or height 55 percent of diameter, widi gently curving sides, margi- nal outline circular, adorally slightly depressed B FIGURE 7.—Farquharsonia crenulata Kier, new species: A, apical system of holotype USNM 170370, from the middle Dhruma Formation, X 10. A photograph of this area is on Plate 1: figure 6; B, ambulacrum III of holotype, X 10. A photograph of tfiis ambulacrum is on Plate 1: figure 5; c, half-ambulacrum III at ambitus of holotype showing pair plate arrangement con- sisting of pairs of primary plates with tubercle covering each pair separated by single primary plate, X 10. A photograph of this area is on Plate 1: figure 4. 24 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY around peristome. Test very thin as indicated by buckling of some plates (Plate 1: figure 1). APICAL SYSTEM.—Small, 5.7 mm wide or 29 percent of diameter of test; periproct large (Plate 1: figure 6), elongated through anteroposterior axis; genital plates pointed into interambulacra; genital 2 larger than others; ocular plates V and I insert, others exert (Figure 7A). AMBULACRA.—Straight, wide, at ambitus 4.6 mm wide or 40 percent as wide as interambulacra, great- est width above ambitus; interporiferous zones wide, 67 percent as wide as ambulacra; ambulacra from apical system to peristome consisting of pairs of primary plates with tubercle covering each pair, separated by single primary plate (Figure 7B, c) with much smaller secondary tubercle (Plate 1: figures 4, 5) (miliary adapically). Fifty-eight porepairs in sin- gle poriferous zone; outer pore of pair more elongate transversely and more adapical than inner (Plate 1: figure 4). INTERAMBULACRA.—Each interambulacrum com- posed of 32 plates; at ambitus approximately 5 am- bulacral plates beside each interambulacral. PERISTOME.—Small, diameter 9.5 mm or 35 per- cent diameter of test; gill slits deep (Plate 2: figure 1) with elevated flange facing interambulacra, slightly bilobed. TUBERCULATION.—Interambulacral plates each bear one primary, perforate, crenulate tubercle; adapically tubercles small on first seven or eight plates in each half-interambulacrum (Plate 1: figures 1, 5) ; scrobi- cules of these tubercles slightly developed, flush with test; tubercles slightly above ambitus to below ambitus much larger (Plate 2: figure 2), with well-developed confluent scrobicular rings, slightly depressed scrobi- cules, distinct basal terraces, 10 to 12 crenulations on each tubercle; extrascrobicular areas covered with irregularly arranged miliaries greatly reduced in size adapically. In ambulacra, single small, perforate, crenulate tubercle on pair of plates (Plate 1: figure 4) separated by single plate with smaller secondary tubercle; as in interambulacra, miliary spines very small above ambitus. REMARKS.—This species is congeneric with the type species and only other species of Farquharsonia, F. somaliensis. Both species share the following fea- tures: small apical system with large periproct, and commonly ocular plates V and I insert; straight, wide ambulacra composed of pair of primary plates covered by a single tubercle separated by single plate bearing a smaller tubercle; small peristome with deep gill slits; reduced tuberculation adapically, single, perforate primary tubercle on each interambulacral plate, generally crenulate, with confluent scrobicules; and a test composed of thin plates. F. somaliensis is known from the Callovian of British Somaliland and is herein reported from the Callovian (upper Dhruma Formation) of Arabia. It occurs at the same locality as F. crenulata but higher in the section. The speci- men of F. crenulata came from 69 meters lower in the middle Dhruma Formation (Bathonian). F. crenu- lata differs from F. somaliensis in having all its pri- mary interambulacral tubercles crenulate, in having a larger peristome, and in having its gill slits less bilobed (compare Plate 2: figure 1 with Plate 3: figure 7). However, the species are enough alike that it must be assumed that they are closely related. The fact that many of the primary tubercles in the later species, F. somaliensis, are not crenulate indicates that the species might have been evolving toward noncrenulate tubercles. This is significant in the light that most echinoid workers have attached consider- able importance to the presence or absence of crenu- lations and that this feature is considered to be of ordinal importance in some groups. TYPE SPECIMEN.—Holotype, USNM 170370. STRATIGRAPHIC OCCURRENCE AND LOCALITY.—Mid- dle Jurassic, Bathonian, middle Dhruma Formation, 106.5 meters above Dhibi Limestone Member. Local- ity KK9-43. Order PYGASTEROIDA Durham and Melville Family PYGASTERIDAE Lambert Genus Plesiechinus Pomel Plesiechinus altus Kier, new species FIGURE 8; PLATE 32: FIGURES 1-4 DIAGNOSIS.—This species is characterized by its high test with smoothly rounded adapical surface, and steep sides. MATERIAL.—One specimen. NUMBER 10 25 SHAPE.—Test wider than long, width 32.3 mm, length 31.7, marginal outline pentagonal with apices at ambulacra; test 17.7 mm high, height 54 percent of width; adapical surface smoothly rounded, sides steep, test deeply depressed around peristome. APICAL SYSTEM.—Central, wider than high, 5.5 mm wide, 3.1 mm high; all four genital plates in contact with periproct (Plate 32: figure 1); genital 2 largest, genital 1 smallest; no sign of genital 5. AMBULACRA.—Narrow, greatest width 4.2 mm, 120 porepairs in single poriferous zone of half-ambula- crum; pores slightly larger adapically; plates simple primaries except near peristome (Figure 8) where several plates enlarged; petals II, III, IV straight, petals V and I curving posteriorly from apical system. INTERAMBULACRA.—Twenty-four plates in each half-interambulacrum. PERIPROCT.—Supramarginal, in contact with genital plates, nearly flush with test, 12.1 mm long, 6.4 mm wide, widening adorally. PERISTOME.—Central, circular, 6.8 mm in diameter, gill notches well developed. TUBERCULATION.—Tubercles eroded from test. COMPARISON WITH OTHER SPECIES.—I hesitate to erect a new species on just one specimen, but this genus has never been reported from the Middle East, and its occurrence here is of significance. This species FIGURE 8.—Plesiechinus altus Kier: adoral ambulacral area of die holotype USNM 170419 from die middle Dhruma Formarion at locality L-921, X 12. is easily distinguished from all the other species of this genus by its inflated test with steep sides. TYPE.—Holotype, USNM 170419. STRATIGRAPHIC OCCURRENCE AND LOCALITY.—Mid- dle Jurassic, Bathonian, middle Dhruma Formation, locality L-921 which according to Imlay (1970:8) is in the Micromphalites, Dhrumaites zone. Superorder ECHINACEA Claus Order SALENIOIDA Delage and Herouard Family ACROSALENIIDAE Gregory Genus Acrosalenia L. Agassiz Four species of Acrosalenia, all new, occur in the Jurassic of Arabia. The oldest is the Toarcian A. marratensis from the Marrat Formation, followed by A. arabica from the Bathonian middle Dhruma, and A. dhrumaensis which overlaps with it and extends slightly above it. The youngest species is A. bowersi from the Callovian upper Dhruma Formation. These species are distinct from each other, and there is no evidence that they are members of the same stock. No obvious evolutionary trends are discernible between them. The youngest species is the largest, but this may or may not be significant, because too few speci- mens are present in two of the species to be able to predict the size of these species. No trend is present in the height of the test, which is 50 percent of the diameter of the test in the oldest species A. marratensis, 60 percent in A. arabica, 47 percent in A. dhrumaensis, and 52 percent in the youngest A. bowersi. Although the apical system is largest in the oldest species A. marratensis, with a length 45 percent of the diameter of the test, it is smallest in the next oldest A. arabica (30 percent), slightly larger in the next species A. dhrumaensis (35 per- cent), and larger again in the youngest A. bowersi (35—42 percent). Likewise there is no trend in the number of suranal plates. Their number is not known in A. marratensis, but 2—4 are present in A. arabica, 1—2 in A. dhrumaensis and 2—4 in A. bowersi. The number of ambulacral plates are similar in all four species, but it may be significant that the oldest species has the smallest number of interambulacral plates. As a result its plates are higher relative to their width than in the other species. Likewise it may 26 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY be significant that the differentiation of the primary tubercles is less developed in the two older species. The primary tubercles in A. marratensis do not in- crease abruptly at the ambitus, whereas there is some increase in A. arabica and considerable increase in A. dhrumaensis. Furthermore, the scrobicules are not depressed in A. marratensis and are circular, whereas in A. arabica they are slightly depressed and slightly subcircular, and in A. dhrumaensis they have very deep scrobicules which are much lower than wide. These trends do not continue to the youngest species, A. bowersi, which is rather intermediate in these characters between A. dhrumaensis and A. arabica. Finally, it also may be significant that although the older species have bigeminate ambulacral plates alter- nating with single primary plates, the youngest species, A. bowersi, has trigeminate plates. In summary, the older species have less differentiated interambulacral primary tubercles with less depressed and rnore circu- lar scrobicules, higher interambulacral plates, and bigeminate ambulacral plates. Acrosalenia marratensis Kier, new species PLATE 27: FIGURES 3-7; PLATE 28: FIGURE 1 DIAGNOSIS.—Species characterized by large apical system, 45 percent as long as test, and nonconfluent tubercles which do not increase in size abruptly at the ambitus. MATERIAL.—This description is based on one well- preserved specimen showing clearly the surface orna- mentation and plate arrangement from locality S— 1054. Two other specimens are present from locality KK6-14. SHAPE.—Test small, subcircular, 19.1 mm wide, 18.1 mm long (as measured through axis passing through ambulacrum III, interambulacrum 5), 9.2 mm high; adapical surface moderately inflated, adoral flat, not depressed around peristome. APICAL SYSTEM.—Genital and ocular plates not preserved but margin of system indicating large apical system, 8.3 mm long, 6.1 mm wide, extending deeply posteriorly into interambulacrum 5; other genitals indented slightly into interambulacra. AMBULACRA.—Greatest width at ambitus, or slightly below, where 3.15 mm wide, 42 percent as wide as interambulacra; poriferous zone straight from apical system to ambitus where becoming slightly arcuate in threes (Plate 27: figure 7) from there to peri- stome ; at ambitus pore zone approximately 40 percent as wide as half -ambulacrum; inner pore of pair slightly adoral to outer; 44 porepairs in half-ambulac- rum; 4-5 ambulacral plates for each interambulacral plate at ambitus; ambulacra at ambitus composed of pairs of plates with large primary tubercle on each pair, separated by single primary plate with smaller tubercle; this pattern extending to near peristome, and approximately midway from ambitus to apical system; first 10-15 plates in each half-ambulacrum simple primaries with single small tubercle on each plate (Plate 27: figure 6). INTERAMBULACRA. — Each half-interambulacrum composed of 10 plates. PERISTOME.—Diameter 40 percent of diameter of test; gill slits not sharply indented, shallow, 0.38 mm deep; notches with elevated flanges facing inter- ambulacra (Plate 27: figure 4). TUBERCULATION. — Primary tubercles perforate, crenulate; interambulacral tubercles gradually increas- ing in size from apical system to ambitus, decreasing in size from ambitus to peristome; tubercles shifting in position from near ambulacra on adapical plates (Plate 27: figure 6) to nearer middle of plate at ambitus (Plate 28: figure 1), and nearer medial suture near peristome; dimensions of ambital inter- ambulacral tubercle: width of plate, 3.8 mm; width of scrobicule, 2.56; width of basal terrace, 1.52; width of boss at platform, 0.85; height from top of mamelon to base of basal terrace, 0.99; 10—11 crenu- lations on each boss; sides of boss straight; scrobicules not depressed below level of extrascrobicular surface; scrobicules not confluent; secondary tubercles cover- ing area outside of scrobicules, no medial naked zone; one larger secondary tubercle present on most of ambital interambulacral plates near ambulacral in adapical region of each plate (Plate 28: figure 1). Ambulacral tubercles much smaller than interambu- lacral ; reaching dieir largest size at ambitus or slightly below (Plate 27: figure 7). COMPARISON WITH OTHER SPECIES. — Although clearly an Acrosalenia, this species is easily distin- guished from the other Arabian species of this genus by its far larger apical system, with a length 45 per- cent of the diameter of the test as opposed to 30-35 percent in A. arabica and A. dhrumaensis. The am- bital tubercles in A. marratensis are not confluent nor do they increase abruptly in size near the ambitus as in the other Arabian species. NUMBER 10 27 TYPE SPECIMEN.—Holotype, USNM 170411. STRATIGRAPHIC OCCURRENCE AND LOCALITY.—Lower Jurassic, Toarcian, Marrat Formation, 10.2-35.5 me- ters above base. Localities S-1034, KK6-14. Acrosalenia arabica Kier, new species FIGURES 9, 10; PLATE 28: FIGURES 2-5; PLATE 29; PLATE 30: FIGURES 1-4 DIAGNOSIS. — Species characterized by high test (height 60 percent of diameter), gently sloping sides, genital plates 1, 2, 3, and 4 large, two to four suranal plates, large peristome (40 percent of diameter of test), and slightly depressed scrobicules. MATERIAL.—219 specimens can be referred to this species, most of which were collected from sections KK8 and KK9 from a vertical interval 92.5 meters thick. The specimens were collected as float on these two measured sections, and therefore it is not possible to describe a population. A detailed comparison was made between specimens from two widely separate intervals: KK9 from 30 to 40 meters and KK8 from 30 to 40 meters. No significant differences were found between these two groups of specimens, described below in greater detail. The following species descrip- tion, however, is based only on the 155 specimens found in section KK8 from 30 to 40 meters. SHAPE. — Test small, average specimen approxi- mately 15 mm in diameter, smallest 7.5, largest 21.5; marginal outline varying from circular to slightly pentagonal, ambulacra forming apices; many tests slightly wider than long, with width 0 to 5 percent greater than length; height in larger specimens aver- aging 60 percent of diameter, 55 percent in smaller; adoral surface flattened, not depressed around peri- stome; adapically interambulacra slightly depressed medially in each area in some specimens. APICAL SYSTEM.—Genital and ocular plates pre- served on most specimens, suranal on only three; apical system large, length approximately 30 percent of diameter of test in adult; prolonged into posterior interambulacrum, width of system approximately 85 percent of length; genital plates pointed into inter- ambulacra, genital 2 (Figures 9A,B) largest, genital 5 much smaller than others, forming together with posterior oculars a ring around periproct; oculars II, III, and IV exert, but V and I insert; three suranal plates present in two specimens (Figure 9A; Plate 28: figure 5) ; four in third (Figure 9B; Plate 30: figure 1); number of facets for suranal plates in rest of specimens suggests that there were always more than one but not more than four; periproct longer than wide, length approximately 15 percent of diameter of test. AMBULACRA.—Narrow, at ambitus 45 percent as wide as interambulacra; poriferous zone straight, approximately 40 percent as wide as half-ambulac- rum; inner pore of pair highly adoral to outer; inner pore entering test vertically, outer obliquely tilted toward perradial suture (radial water vessel) ; 26 porepairs in half-ambulacrum of smallest specimen 7.5 mm in diameter, 46 in specimen 16.3 mm in di- ameter, 56 in specimen 21.5 mm in diameter; rate of introduction of new plates slightly decreasing in larger specimens (Figure 10c); 4.5 ambulacral plates for each interambulacral plate at ambitus in adult specimens; ambulacra (Figures 9C,D,E; Plate 29; Plate 30: figure 4) composed of pairs of plates (largest adoral) with a large primary tubercle on each pair, separated by a single primary plate with a smaller tubercle; this pattern extending from apical system to peristome; pores more crowded at peristome (Fig- ure 9D; Plate 29: figure 2). TUBERCULATION. — Primary tubercles perforate, crenulate; interambulacral tubercles abruptly (ap- proximately doubling) increasing in size (Plate 30: figure 3) at ambitus or one plate above ambitus; two to three large tubercles in each row; tubercles decreasing in size from first tubercle below ambitus to peristome; tubercles shifting in position from very near ambulacra on adapical plates to nearer medial interambulacral suture adorally; dimensions of ambital interambulacral tubercle in specimen 16.5 mm in diameter width of plate, 4.23 mm; width of scrobicule, 1.85 mm; width of basal terrace, 1.35; width of boss at platform, 0.90; width of mamelon, 0.35 mm; height from top of mamelon to base of basal terrace, 0.52 mm; 12—15 crenulations on each boss; sides of boss slightly concave; basal terrace present on most ambital tubercles, absent on some; scrobicule slightly below level of extrascrobicular surface in some ambital tubercles, same level in others; scrobicules confluent in tubercle immediately above ambitus or at ambitus and in all tubercles adoral to ambitus, separate above; secondary tubercles covering area outside of scrobi- cules; ambulacral tubercles much smaller than inter- ambulacral; boss of tubercle covering two ambulacral plates with single plate without primary tubercle sep- 28 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY D FIGURE 9.—Acrosalenia arabica Kier, new species: A, Apical system of figured paratype USNM 170413 from the middle Dhruma Formation at locality KK8-34, X 13. A photograph of diis area is on Plate 28: figure 5; B, apical system of figured paratype USNM 170416 from die middle Dhruma Formation at locality KK8-35-38, X 13. A photograph of this area is on Plate 30: figure 1; c, adapical portion of ambulacrum III of figured paratype USNM 170415 from the middle Dhruma Formation at KK8-35-38, X 13. A photograph of this region is on Plate 29: figure 3; D, ambulacrum I at peristome of figured paratype USNM 170414 from the middle Dhruma Formation at locality KK8-30-35, X 13. A photograph of this area is on Plate 29: figure 2; E, ambulacrum at ambitus of figured paratype USNM 170415 from the middle Dhruma Formation at locality KK8-35-38, X 13. A photograph of this area is on NUMBER 10 29 arating each primary tubercle; dimensions of ambital ambulacral tubercle in specimen 16.5 mm in diameter (Plate 30: figure 4) : width of plate, 1.42 mm; width of scrobicule, 0.71 mm; width of boss, 0.45; approxi- mately 12 crenulations on each boss. EVOLUTION.—Because the specimens occur through- out a 92.5 meter vertical section, some evolution might be expected. A detailed comparison was made between 32 specimens from section KK8 (30-40 meters) and ten specimens from KK9 (30-40 meters). These two levels are separated by 51 meters of ver- tical section. The following characters were recorded for each specimen and plotted on scattergrams (Fig- ure 10) : horizontal diameter, height, diameter of peristome, number of ambulacral plates in each half- area; number of suranal plates, and number of large tubercles from the ambitus to the peristome. No sep- aration of points occurred in any of the plots, and the two collections cannot be separated by visual examination. No evolution is evident and it must be assumed that either the rate of deposition of the sedi- ments was rapid or the rate of evolution of the echinoid was slow. COMPARISON WITH OTHER SPECIES.—This species resembles most Acrosalenia humei Fourtau (1924:12) from the Bathonian of Egypt but differs in having a higher test, as is evident on a scattergram in which the points for the Egyptian species generally fall below those of A. arabica. The sides of the test in A. arabica are more gently sloping, and genital plates 2 and 3 are smaller. A. arabica differs from A. somaliensis from the Callovian of British Somaliland in having a higher test, with its height in larger specimens averaging 60 percent of the diameter as opposed to 53 percent in A. somaliensis. The peristome is larger in the Arabian species, averaging a diameter that is 40 percent of that of the test as opposed to 33 percent in A. somaliensis. Finally, the scrobicules in the interambu- lacral plates are much less deep in A. arabica (Plate 29: figure 4) than in A. somaliensis (Plate 26: figure 4), and in the Arabian species more than one suranal plate is present, whereas in A. somaliensis eight of the ten specimens showing the suranal plates had only one. A. arabica occurs in the higher part of the section with A. dhrumaensis, from which it is easily distin- guished by its smaller ambital tubercles, with rounder scrobicules which are flush rather than depressed, and by its higher test, more numerous suranal plates, and wider ambulacra. TYPE SPECIMENS.—Holotype, USNM 170412; fig- ured paratypes, USNM 170413-170417. STRATIGRAPHIC OCCURRENCE. — Middle Jurassic, Bathonian, middle Dhruma Formation, most of the specimens were collected between 20 and 112.5 meters above the top of the Dhibi limestone. Two specimens came from the Dhibi limestone, but because only two were found and none between the Dhibi limestone and twenty meters farther up the section, these two may be float. LOCALITIES.—S-1046, S-1056, S-1157, S-1160, S- 1503, KK8-23, 30-35, 33-35, 34, 35-38, 37, 38.5, 40.5, 44, KK9-30-40. Acrosalenia dhrumaensis Kier, new species FIGURES 11, 12; PLATE 31: FIGURES 1-8 DIAGNOSIS.—Species characterized by low test, height 47 percent of horizontal diameter, one or two suranal plates, narrow ambulacra, large ambital tubercles which are wider than high, and depressed scrobicules. MATERIAL.—Eight specimens. SHAPE.—Test small, average specimen 12 mm in diameter, smallest 9.8, largest 16.1; marginal outline circular; test low, height 47 percent of horizontal diameter (Figure 12A) ; adoral surface depressed around peristome; adapically interambulacra slightly depressed medially. APICAL SYSTEM.—Genital and ocular plates pre- served in three specimens, suranal on two; apical system large, length approximately 35 percent of diameter of test; prolonged into posterior interam- bulacrum, width approximately 85 percent of length of system; genital plates pointed into interambulacra (Figure 11A; Plate 31: figure 8), genitals 1, 2, 3, 4 of approximately same size, genital 5 smaller, to- gether with posterior oculars forming ring around posterior edge of periproct; oculars II, III, and IV exert, but V and I insert; one suranal plate present in one specimen, two in other, number of facets for suranal plate in third specimen indicates only one suranal plate was present; periproct longer than wide, length approximately 17 percent diameter of test. AMBULACRA.—Narrow, at ambitus 30-35 percent (Figure 12B) as wide as interambulacra; poriferous 30 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY - 10 - • 8 E x KK9-30-40 o °°o% 0 '56 o KK8-30-40 X ° oo x 0 X o Ox 0°0 Q. «^ O k. I4 9 E o i i i o oo o o_x o ° o ° O Ox x x O Q 2 - A - Acrosalenia arabica 1 1 1 1 1 1 1 1 1 1 1 _l— 1 1 1 1 20 22 18 14 16 10 12 Diameter E o (0 l_ 20 a> a. o 18 c F lb o E 14 F e 12 «•- (0 a> 10 o 8 £ 6- o 4 w O e 2 _ x KK9-30-40 o KK8-30-40 1 1 1 1 1 1 1 1 03 x o o o x O QO X XOOO xoo xx oox 0 o o*o o - Acrosalenia arabica " 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 14 16 18 20 22 10 12 Diameter FIGURE 10.—Acrosalenia arabica Kier, new species: scattergrams showing the relation of the diameter of the test to the diameter of the peristome (A), to the number of tubercles from die margin to the peristome (B), to the number of plates in a half-ambulacrum (c), and a half- interambulacrum (D). Specimens from two widely separated stratigraphic levels are included and no separation of their plots occurs, indicating no evolution of these characters. NUMBER 10 31 18 E 3 l_ O f70r -O E 60 o | 50 !s40 j? 30 .o £20 o x KK9-30-40 o KK8-30-40 Acrosalenia arabica -i 1 1 1 i i__ X°0 °xo o x o o 10 12 14 Diameter o x o o Oo X 16 oo . 0*o 20 22 §^u k. 8 18 3 1 « o o « 14 0 o ox o *I oo o o o o o o o ^ x KK9-30-40 «L 12 - o* X ° XOO o o 0 o - o KK8-30-40 x oxo o o X * 10 - o o c " xo 2 8 - o o Q. 6 ~ D _ 4 - ® - 1 2 Acrosalenia arabica 3 Z 1 1 1 1 1 1 1 1 I 1 14 18 20 22 10 12 Diameter FIGURE 10—Continued zone straight, approximately 40 percent as wide as half-ambulacrum; inner pore of pair slightly adoral to outer (Plate 31: figure 4) inner pore entering test vertically, outer obliquely tilted toward perradial suture (radial water vessel); 35 porepairs in half- ambulacrum of smallest specimen, 9.8 mm in diam- eter; 44 in holotype, 16.1 mm in diameter; 5 am- bulacral plates for each interambulacral plate at ambitus in holotype; ambulacra (Figure 11B) com- posed of pairs of plates (largest adoral) with a large primary tubercle on each pair (Plate 31: figure 4), separated by single primary plates with smaller tu- 32 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY FIGURE 11.-—Acrosalenia dhrumaensis Kier, new species: A, apical system of holotype USNM 170418 from the middle Dhruma Formation at locality KK9-51.5, X 15. A photograph of this area is on Plate 31: figure 8; B, ambulacrum I at ambitus in die same specimen, X 15. bercles; this pattern extending from apical system to peristome; pores more crowded at peristome. INTERAMBULACRA. — Each half-interambulacrum composed of 10 plates in the smallest specimen, 9.8 mm in diameter, 12 plates in the largest, 16.1 mm in diameter; height of plate at ambitus between 50 and 55 percent of its width; new plates still being introduced in largest specimen. PERISTOME.—Diameter averaging 38 percent of diameter of test; relatively larger in smaller specimen (40 percent in specimen 10 mm in diameter) ; gill slits moderately deep, 0.35—0.45 mm deep in speci- men 16.1 mm in diameter; notches with elevated flanges facing interambulacra (Plate 31: figure 2). TUBERCULATION. — Primary tubercles perforate, crenulate; interambulacral tubercles abruptly increas- ing (approximately 60 percent) in size (Plate 31: figure 5) at ambitus or one plate above ambitus; two to three large tubercles in each row; tubercles de- creasing in size from first tubercle below ambitus to peristome; tubercles shifting in position from very near ambulacra in adapical plates to nearer medial interambulacral suture adorally; dimensions of am- bital interambulacral tubercle in specimen 16.1 mm in diameter: width of plate, 3.80 mm; width of scrobicule, 2.52 mm; width of basal terrace, 2.04 mm; width of boss at platform, 0.99 mm; width of mamelon, 0.52 mm; height from top of mamelon to base of basal terrace, 0.95; 10-12 crenulations on each boss; sides of boss slightly concave, more con- cave on adapical side of boss; scrobicule recessed below level of extrascrobicular surface; scrobicules confluent in tubercle immediately above ambitus and in all tubercles adoral to ambitus, separate above; secondary tubercles covering area outside of scrobi- cules; ambulacral tubercles much smaller than inter- NUMBER 10 33 I4r 13 12 II 10 9 8 JC ?7 a> X 6 5 4 3 2 I °D o A. dhrumaensis o A. somaliensis 2 3 4 5 6 7 8 9 10 II 12 13 14 15 Diameter of test 16 17 18 19 20 (A 3 *- 5 4 . E o .4— a £, DD 3 3 k- □ o _o D 3 n O Si a D © e E2 - a o ° «*- a o idth a A. somaliensis $ B ■ . i i i o A. dhrumaensis i i , i i i , i , i i i . i 20 8 10 (2 Diameter of test FIGURE 12.—Scattergrams showing the diameter of the test relative to die height of the test (A) and relative to the width of die ambulacrum (B) at die ambitus in Acrosalenia somaliensis and A. dhrumaensis Kier, new species. 34 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY ambulacral; boss of tubercle covering two ambulacral plates with single plate with smaller tubercle separat- ing each primary tubercle (Plate 31: figure 4). COMPARISON WITH OTHER SPECIES.—A. dhruma- ensis is very similar to A. somaliensis Currie from the Callovian of British Somaliland. It differs in having a slightly lower test (see scattergram on Figure 12A) ; slightly smaller peristome; and smaller primary am- bital tubercles which are wider relative to their height. These tubercles in A. dhrumaensis are approxi- mately 67 percent as wide as the interambulacral plate upon which they occur, whereas in A. somali- ensis the tubercles are only 58 percent as wide. Finally, the ambulacra are narrower in A. dhruma- ensis, only 30 percent as wide as the interambulacra as opposed to 40—45 percent in A. somaliensis. A. dhrumaensis is easily distinguished from A. arabica, with which it occurs, by its far larger am- bital tubercles which are wider than high as opposed to the circular tubercles of A. arabica. Furthermore, its scrobicules are deeply depressed, whereas they are more flush with the extrascrobicular surface in A. arabica. The test is much lower in A. dhrumaensis, there are fewer suranal plates, and the ambulacral are narrower, only 30—35 percent as wide as the interambulacra instead of 45 percent as in A. arabica. TYPE SPECIMENS.—Holotype, USNM 170418. STRATIGRAPHIC OCCURRENCE AND LOCALITY.—Mid- dle Jurassic, Bathonian, middle Dhruma Formation, two specimens from KK9—21—22.5 and six from KK9-51.5 (82-112.5 meters above Dhibi limestone). Acrosalenia bowersi Kier, new species FIGURE 13; PLATE 25; PLATE 26: FIGURES 1, 2 DIAGNOSIS.—Species characterized by large, low test, trigeminate ambulacral plates, and interambu- lacral tubercles which do not decrease in size abruptly adapically. MATERIAL.—Four specimens, three well preserved. SHAPE.—Test large, three specimens 21 mm in horizontal diameter, one 17 mm; marginal outline circular to subpentagonal; length (as measured through axis passing through ambulacrum III, inter- ambulacrum 5) approximately equal to width; height 48—58 percent of length; adapical surface moderately flattened, adoral surface depressed around peristome in one specimen, not depressed in others. APICAL SYSTEM.—Preserved on three specimens; large, length from 35-42 percent of diameter of test; prolonged into posterior interambulacrum, width be- tween 80-90 percent of length of system; genital plates pointed into interambulacra, genitals 2, 3 larg- est, genitals 3, 4 slightly smaller, genital 5, together with posterior oculars, forming ring around posterior edge of periproct; oculars II, III, IV exert on two specimens but ocular II insert on one; oculars V and I insert on all specimens; four suranal plates present in one specimen, two in second, and four or more on third (number not clear because of silicification; peri- proct longer than wide, length in holotype 14 percent diameter of test. AMBULACRA.—Wide, at ambitus 45 percent as wide as interambulacra; poriferous zone straight, approxi- mately 32 percent as wide as half-ambulacrum; in holotype, 21.4 mm in diameter, poriferous zone 0.57 mm wide; inner pore of pair slightly adoral to outer, slightly less elongated transversely; 48 porepairs in half-ambulacrum in three specimens between 21.0 and 21.4 mm in diameter; 4J/2 to 5 ambulacral plates for each interambulacral plate at ambitus in larger specimens; ambulacra (Figure 13) composed of trigeminate plates extending from apical system to near peristome, with primary tubercle covering three plates; pores more crowded at peristome. INTERAMBULACRA. — Each half-interambulacrum composed of 12—13 plates in larger specimens (21- 21.4 mm in diameter); height of plate at ambitus between 50 and 55 percent of its width. PERISTOME.—Diameter between 35 and 40 percent of diameter of test; gill slits deep, 0.66 mm deep in specimen 21.4 mm in diameter; notches with elevated flanges facing interambulacra (Plate 25: figure 3). TUBERCULATION. — Primary tubercles perforate, crenulate; interambulacral tubercles gradually not abruptly increasing in size toward ambitus; tubercles shifting in position from very near ambulacra adapi- cally to nearer medial interambulacral suture ador- ally; dimensions of ambital interambulacral tubercle in specimen 21.4 mm in diameter: width of plate, 4.3 mm; width of scrobicule, 2.4 mm; height of scrobicule, 1.6 mm; height from top of mamelon to scrobicule, 1.07 mm; 10—12 crenulations on each boss; sides of boss straight to slightly concave; scrobi- cule (Plate 26: figure 1) recessed below level of extrascrobicular surface; scrobicules confluent in first or second tubercle above ambitus and in all tubercles NUMBER 10 35 FIGURE 13.—Acrosalenia bowersi Kier, new species: ambu- lacrum II of figured paratype USNM 170410 from the upper Dhruma Formation at locality S—1148, X 15. adoral to ambitus, separate above; secondary tubercles covering area outside of scrobicules; no adapical naked medial zone; ambulacral tubercles at ambitus much smaller (40 percent less in width) than interambu- lacral; difference in size less marked adapically (Plate 26: figure 2); boss of tubercle covering three ambulacral plates. COMPARISON WITH OTHER SPECIES.—A. bowersi differs from the other species of Acrosalenia from Arabia in having trigeminate ambulacral plates in which the primary tubercle covers three plates throughout the length of the ambulacra. In the other Arabian species the ambulacra are composed of pairs of plates covered by a primary tubercle separated by a single primary plate with a smaller tubercle. A. bowersi is further distinguished from A. arabica by its larger, lower test, and interambulacral tubercles which are largely adapically and do not increase as abruptly in size at the ambitus. It differs from A. dhrumaensis in its larger adapical tubercles, smaller ambital tubercles with less depressed scrobicules, more numerous suranal plates, and wider ambulacra. Fi- nally, it further differs from A. marratensis in having lower interambulacral plates, depressed scrobicules, and more sharply indented gill slits. TYPE SPECIMENS.—Holotype, USNM 170409; fig- ured paratype, 170410. STRATIGRAPHIC OCCURRENCE AND LOCALITY.—Upper Jurassic, Callovian, upper Dhruma Formation, local- ity S-1148. Genus Heterosalenia Cotteau Heterosalenia dhrumaensis Kier, new species PLATE 9: FIGURES 2-4 DIAGNOSIS.—Species characterized by three primary tubercles in each interambulacra, lack of knobs on plates of apical system, lack of depressions in trans- verse sutures of interambulacral plates, and low test. MATERIAL.—One well-preserved specimen. SHAPE.—Horizontal diameter 15.1 mm, height 8.6 mm; marginal outline circular. APICAL SYSTEM.—Width 43 percent of diameter of test; plates thickened, covered with granules (Plate 9: figure 2); ocular plates exert except for insert ocular I; genital plates 1, 2, 3, 4 of approximately same size, genital 5 smaller because of intrusion of periproct; single suranal plate as large as larger geni- tal plates; periproct oblong, wider than high, situated to right of center of system, adjacent to ocular plate I. AMBULACRA.—Sinuous, broad, at ambitus 42 per- cent as wide as interambulacra, greatest width below ambitus, narrowing just at peristome; interporiferous zones wide, 65—70 percent as wide as ambulacra; simple primary plates from apical system to near peristome where compounded bigeminately to poly- porously trigeminately; 33 porepairs in single porifer- ous zone; inner pore slightly adoral to outer. INTERAMBULACRA.—Approximately eight plates in each interambulacrum; plates not depressed at sutures. PERISTOME.—Not preserved. TUBERCULATION.—Three large primary tubercles in each area, a smaller fourth tubercle partially devel- oped in some areas; primary tubercles crenulate, perforate, with well-developed ring of 13—14 scrobi- 36 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY cular tubercles, not confluent with adjacent ring; scrobicules narrow, depressed below general level of test, basal terrace absent; boss with straight or slightly concave sides; mamelon undercut, circular in outline; granules cover rest of interambulacra except near peristome where occur large secondary tubercles, diree or four of larger of these perforate, crenulate, ambu- lacra from apical system to near peristome covered with secondary tubercles in irregular arrangement except for single row of larger secondary tubercles running along margin of interporiferous zone beside inner pore of pair; near peristome, tubercles much larger, similar in size and arrangement to those in interambulacra near peristome; perforated, crenula- tion not certain. COMPARISON WITH OTHER SPECIES.—This species is distinguished from both H. ornata and H. brocki in lacking the large knobs on the plates of the apical system, in not having its transverse interambulacral plate sutures depressed, and in having a lower test. It further differs from H. ornata in having smaller primary tubercules and in having three instead of two in each interambulacrum. Of the non-Arabian species, H. dhrumaensis re- sembles most H. alloiteaui Zoeke from the Middle Jurassic of Lebanon. Both species have a small num- ber of interambulacral primary tubercles and lack depressions in the transverse sutures of the inter- ambulacral plates. However, the test is lower in H. dhrumaensis. Unfortunately, H. alloiteaui is based on three poorly preserved specimens and many of its specific characters are not clear in Zoeke's (1952) figures. TYPE SPECIMEN.—Holotype, USNM 170380. STRATIGRAPHIC OCCURRENCE AND LOCALITY.—Mid- dle Jurassic, Bathonian, middle Dhruma Formation, 78.5 meters above the top of the Dhibi limestone, locality KK9-15. Heterosalenia brocki Kier, new species FIGURE 14; PLATES 7, 8; PLATE 9: FIGURE 1 DIAGNOSIS. — Species characterized by high test (height 64—68) percent of diameter, slight knobs on plates of apical system, and small number (4) of interambulacral primary tubercles. MATERIAL.—Two specimens. SHAPE.—Specimens 15.1 and 17.1 mm in diameter, 10.3 and 11.0 mm high; marginal outline pentagonal with apices in interambulacra, sides high, steep, test high, height 64-68 percent of diameter; adapical surface flattened except for slightly inflated apical system; adoral surface flat. APICAL SYSTEM. — Preserved on both specimens, width 40-43 percent of diameter of test, pentagonal with apices formed by ocular plates (Plate 7: figure 5; Plate 9: figure 1) ; single protuberance or knob on each ocular, genital, and single suranal plate, upper surface of knob flattened, granular or warty; sutures depressed between plates with deeper pits at junction of sutures (Plate 7: figure 5); ocular plates exert (Figure 14) except for insert ocular I; periproct oblong, wider than high, situated to right of center of system, adjacent to ocular I, strongly elevated rim around periproct. AMBULACRA.—Slightly sinuous, narrow, at ambitus 30 percent as wide as interambulacra, widening below ambitus and then slightly narrowing at peristome; interporiferous zones wide, 55-60 percent as wide as ambulacra; simple primary plates from apical system (Plate 8: figure 2) to near peristome where com- pounded bigeminately or trigeminately; 40—43 pore- pairs in single poriferous zone; inner pore slightly adoral to outer. INTERAMBULACRA.—Eight or nine plates in each area; depressed in transverse sutures (Plate 8: fig- ure 1). PERISTOME.—Diameter 41 percent of diameter of test in one specimen, 44 percent in other; circular to FIGURE 14.—Heterosalenia brocki Kier, new species: apical system of figured paratype USNM 170379 from the upper Dhruma Formation at locality KK9-111, X 8. For a photo- graph of this area see Plate 9: figure 1. NUMBER 10 37 subpentagonal in outline with moderately indented gill slits (Plate 8: figure 3). TUBERCULATION. — Four primary, crenulate, per- forate tubercles in each interambulacrum (Plate 7: figure 4), well-developed ring of scrobicular tubercles, 12-14 in each ring, not confluent; scrobicule narrow, depressed below general level of test, basal terrace slight; boss with straight or slightly concave sides; mamelon undercut, circular in outline; small granules cover rest of interambulacra except near peristome where occur large imperforate, secondary tubercles (Plate 7: figure 6; Plate 3: figure 3), presence of crenulation not clear; ambulacra from apical system to near peristome covered with small secondary tuber- cles in irregular arrangement except for single row of larger secondary tubercles running along margin of interporiferous zone beside inner pore of pair; near peristome, tubercles much larger, similar in size and arrangement to those in interambulacra near peristome; perforation visible only on best preserved, crenulation not certain. COMPARISON WITH OTHER SPECIES.—This species resembles in many of its features H. ornata Kier, new species, from the same locality but a meter higher in the section. Both species have few interambulacral primary tubercles, nodes developed on the apical plates, similar ambulacral plate arrangement and tubercula- tion, and depressed transverse interambulacral sutures. Probably the species are closely related. They differ in that H. brocki has much less prominent knobs on its apical system, higher sides to its test, and four interambulacral primary tubercles (instead of two in H. ornata). It differs from H. dhrumaensis from lower in the Dhruma Formation by its large knobs in the apical system, higher test, four instead of three pri- mary tubercles in each interambulacrum, and de- pressed transverse interambulacral sutures. Of the non-Arabian species, H. brocki most resembles H. alloiteaui Zoeke from the Middle Jurassic of Lebanon. Both species have the same number of interambulacral plates and perhaps the same number of large primary interambulacral tubercles. Unfortunately, H. alloiteaui is based on three poorly preserved specimens, and many of its specific characters, particularly its tuber- culation, are not clear in Zoeke's (1952) figures or description. Apparently, H. alloiteaui lacks nodes on its apical system, and its transverse interambulacral sutures are not depressed. TYPE SPECIMENS.—Holotype, USNM 170378; fig- ured paratype, USNM 170379. STRATIGRAPHIC OCCURRENCE AND LOCALITY.—Upper Jurassic, Callovian, upper Dhruma Formation (10 meters above contact between middle and upper Dhruma), locality KK9-111. One specimen was col- lected at locality S—1167 which is considered to be stratigraphically 13—33 meters below the top of the Dhibi limestone in the lower Dhruma (Middle Ba- jocian). This specimen is similar in every way includ- ing its matrix to the figured paratype which occurs far higher in the section. Furthermore, one specimen of H. ornata occurs in this lower horizon with this specimen. This species likewise occurs far higher at KK9-112. I suspect that this specimen was either mislabeled as to its locality, or S—1167 is not as stratigraphically low in the Dhruma as it has been considered to be. Heterosalenia ornata Kier, new species FIGURE 15; PLATE 5: FIGURES 2-6; PLATE 6 DIAGNOSIS.—Species characterized by highly in- flated apical system with a large protuberance or knob on each ocular, genital, and single suranal plate; two large primary tubercles (one in small specimens) in each interambulacrum. MATERIAL.—Twelve well-preserved specimens, and one fragment. SHAPE.—Average horizontal diameter 15.3 mm, smallest 13.3 mm, largest 19.7; marginal outline pen- tagonal with apices at interambulacra; sides almost vertical, adapical surface flat except for highly in- flated apical system; adoral surface flat; height of test varying from 63 to 70 percent of diameter (Figure 15A). APICAL SYSTEM.—Preserved on all but two speci- mens, large, width 55 percent of diameter of test, pentagonal with apices formed by ocular plates (Plate 5: figure 4; Plate 6: figures 1, 4) ; ocular, genital, and single suranal plate greatly thickened with large knob rising high above general surface of apical system; upper surface of each knob flattened, over- hanging lower part of knob, granular or warty; deep pits in corners of plates; in some specimens (Plate 6: figure 1) ridges join knobs of adjacent plates; ocular plates exert except for insert