Storrs i|riciiltml_CQllep^ : ' voL.'^.sy?.^.^ \ 1 ClassJVo..'r.J7.7 1 Cost \ PRESENTED BY 1? ?n3pD3uuo3 JO AjisjaAiufi SHl •aiBD vpiM 3SB3IJ Digitized by the Internet Archive in 2009 with funding from Boston Library Consortium IVIember Libraries http://www.archive.org/details/dinoceratamonogrOOmars DEPARTMENT OF THE INTERIOR MONOGRAPHS United States Geological Survey YOLUME X WASHINGTON GOVERNMENT FEINTING OFFICE 1886 /v\7 UNITED STATES GEOLOGICAL SUEVEY J. W. POWELL, DIRECTOR DINOCEEATA MONOGRAPH EXTINCT ORDER OF GIGANTIC MAMMALS OTHNIEL CHARLES MARSH WASHINGTON GOVERNMENT PRINTING OFFICE 1886 United States Geological Survey, Division of Paleontology, New Haven, Conn., December 18, 1884. Sir: In compliance with your letter of instructions, dated October 5, 1882, I have the honor to transmit herewith a Monograph of the Dinocerata, an extinct order of Mammals discovered in the Eocene deposits of Wyoming Territory. Very respectfully, Your obedient servant, 0. C. MARSH, Palceontologist-in- Charge. Hon. J. W. Powell, Director of the U. 8. Geological Survey, Washington, D. C. TABLE OF CONTENTS. Title of Volume, .-. iii Letter of Teansmittal, v Table of Contents, vii List of Illustrations, ix Preface, xvii Intiiouuction, 1 Chapter I. The Skull, 11 II. The Lower Jaw, — 35 m. The Teeth, -- 41 IV. The Brain, -.. 53 V. The Cervical Vertebra, ..- 69 VI. The Doeso-Lumbar Vertebra, 19 VIL The Fore Limbs, 87 VIII. The Fore Limbs (continued), 101 IX. The Riiis AND Sternum, 129 X. The Pelvic Arch and Tail, 135 XL The Hind Limbs, 139 XII. The Hind Limbs (continued), . . 145 XIII. Restorations of Dinoceeas and Tinoceeas, 165 XIV. Conclusion, 169 Appendix. — Synopsis, 193 Bibliography, .._ 225 Postscript, 237 ILLUSTRATIONS. LIST OF PLATES. Plate I Skull or Dinoceeas mirabile. " II .. Skttll of Dinocebas mirabile. " III Skull or Dinoceeas mikabile. " IV ... - Skull of Dinoceeas mieabile. " V Skull of Dinocekas mirabile. " VI Bi:ain-cast of Dinoceeas mirabile. <' VII • MoLAES of Dinoceeas mirabile. " VIII.-- --- --- LowEE Jaw and Teeth of Dinoceeas mieabile. " IX -- Teeth of Dinoceeas lucaee. " X Skull of Dinoceeas laticeps. (■ XT .-. - - Skull op Dinoceeas laticeps. « XII LowEu Jaw of Dinoceeas laticeps. " XIII --- LowEE Jaw OF Dinoceeas laticeps. " XIV Skull of Dinoceeas laticeps. " XV Skull of Tinoceeas ingens. " XVI Skull of Tinoceeas ingens. " XVII . - - - - - Skull of Tinoceeas ingens. " XVIII Teeth op Tinoceeas ingens. " XIX LowEE Jaw a-nd Teeth of Tinoceeas pugnax. " XX - -- Atlas of Dinoceras mieabile. (• XXI - Axis of Dinoceeas mii; abile. " XXII --- Ceevical Veetebr2e of Dinoceeas mieabile. " XXIII..- Doesal Veetebe^ of Dinoceeas mirabile. " XXIV Doesal Veetebrje of Dinoceras mieabile. " XXV -- LuMBAE VERTEBEiE OP DiNOCEEAS MIEABILE. " XXVI LuMBAE Vertebeje of Dinoceeas mieabile. " XXVII. Left Scapula of Dinoceeas mieabile. " XXVIII. - - Humerus of Dinoceeas mieabile. " XXIX Radius op Dinoceeas mieabile. " XXX Ulna of Dinoceeas mieabile. X ILLUSTRATIONS. Plate XXXI Scaphoid and Lunar op Dinoceeas mikabile. " XXXII Pteamidai, axd Pisifoem of Dinoceeas mirabile. " XXXni Teapezium and Teapezoid of Dinoceeas mirabile. " XXXIV..- Magnum and Unciform of Dinoceuas mirabile. " XXXV Metacarpals of Dinoceeas ihrabile. " XXXVI --- Metacarpals op Dinoceeas mirabile. " XXXVIT MliTACAEPALS OF DiNOCERAS MIRABILE. " XXXVIII Phalanges of Dinoceras mirabile. " XXXIX Ribs of Dinoceras mikabile. " XL _ Sternum op Diniiceras mirabile. « XLI -- PisLvis OP Dinoceeas mirabile. " XLII Pelvis of Dinoceras mirabile. " XLIII. Caudal Vertebrae op Dinoceeas laticeps. " XLIV Femue op Dinoceeas mirabile. " XLV. Tibia of Dinoceeas mieabilic. " XL VI Fibula and Patella of Dinoceeas mirabile. " XLVII. -- Astragalus op Dinoceras mirabile. " XL VIII Calcaneum op Dinoceeas mirabile. " XLIX Cuboid and Naviculae op Dinoceras mirabile. " L Tarsal bones op Dinoceras mirabile. " LI .. Metatarsals op Dinoceras mirabile. " LII. Metatarsals op Dinoceeas mirabile. " LIII Phalanges op Dinoceeas mieabile. " LIV Feet of Dinoceras mirabile. " XjV --• Restoration of Dinockras mieabilk. " LVI Restoration op Tinoceras in gens. LIST OF WOODCUTS. INTRODUCTION. Page. Figure 1. Map showing region of Z'mocej'fts beds,- . 3 " 2. Section to illustrate vertebrate life in America, 1 CHAPTER I . Figure 3. 'Sa.s^s oi Dinocer'as mirciMle, 13 " 4. 'Na.sdls oi Dinoceras distans,. ... 13 " 5. Nasals of Tinoceras pugnax, 13 " 6. 'Sa.saXs oi Tinoceras aniiectens, ' 13 " 1. Sknll oi Dinoceiris mirabile, with brain-cast in position, 15 " 8. Skull of young specimen of Dinoceras distan.i, . 15 " 9. Skull of Tinoceras zw^e«s, with brain-cast in position, 16 " 10. Skull of Dinoceras distans^ '16 " 11. Skull of Uintatherium latifro)is, J7 " 12. Skull of Tinoceras vagans, .. 17 " 1 3. Posterior surface of skull of Dinoceras mirahile, _. 19 " 14. Posterior surface of skull of Dinoceras laticeps., _- 19 " 1.5. Posterior surface of skull of Z>««oce«ys cr/Zresie, 19 " 16. Posterior surface of skull of Tinoceras affine, .._ 19 " 1 1. Posterior surface of skull of Tinoceras iiigens, 19 " 18. Postei'ior surface of skull of Tinoceras pugnax.^ ^ 19 " 1 9. Side view of skull of Tinoceras pugnax, 21 " 20. Anterior part of skull of Tin oceras grande, 21 " 21. Awtei'iov -pwct of skwW oi Tinoceras aim evtens, 21 " 'i2. Anterior part of palate of Dinoceras laliceps, 25 " 23. Anterior jjart of palate of Tinoceras ingeois, ._. 25 " 24. Anterior part of palate of Tinoceras pugnax, 25 " 25. AntQviov Tj)n.vt of T[>^\Ate ot Hippopiotamus amp)hiMus, 25 " 26. Skull of Dinoceras niirabile; seen from below, 26 " 27. ^\\\\\ oi Dinoceras laticeps; seen from below, 26 " 28. Skull of Tinoceras ingens; seen from below, 27 " 29. Skull of 7'«!0cer«s jOM(///aa7 seen from below, 27 " 30. Horizontal section of skull of Tinoceras crassifrons, 29 " 31. Horizontal section of skull of J? i/iOf'cras (??sto«s, : 29 " 32. Horizontal section of skull of ^Vnocfras /«■«??«, . 30 " 33. Horizontal section of skull of Dinoceras laticeps, 30 " 34. Vertical longitudinal section of skull of 7)Miocer«s «nV«527e, 31 " 35. Vertical transverse section of skull of Dinoceras mirabile, 31 xii DINOCERATA. CHAPTER II. ' Page. Figure 36. Lower jaw of Tinoceras annectens, j 36 " 37. The same jaw; seen from above, 36 " 38. Tuower ]aw oi Tinoceras long icej^s, with n-pper canine in iwsit'ion, SI " 39. Lower jaw of Dinoceras ndrahile, 38 " 40. The same jaw; seen from the front, . 38 " 4] . Lower jaw of Uintatherium. segne, 39 " 42. The sam.e jaw; seen from above, 39 CHAPTER III. FiGUEE 43. Incisor of Dinoceras mii-abile, 42 " 44. IncisoY oi Dinoceras mirahile, 42 " 45. Incisor of Dinoceras mirabile, _ 42 " 46. Upjjer canine of 2)i?ioceras ^wcore, ._ . _.. 43 '• 47. 'U-pY^x canine, of Dinoceras laticeps, . 43 " 48. Upper canine of Tinoceras longiceps, 43 " 49. Upper canine of Tinoceras grande, _- 44 " 50. Upfier canine of Dinoceras laticeps, .- .- 44 '' 51.' Upper canine of Tinoceras ingens, ._ 45 " 52. XSy^gx canine oi Tiyioceras jnignax^ _ 45 " 53. Upi^er molar series of Tinoceras stenojys, .-. 47 '' 54. Lower molar series of same individual, 47 " 55. Upper molar series of 6'o«/p/;of?on Afl«2a?«oce?'as »«V«5«7e/ back view, 77 " 92. The same vertebra; side view, .-.. 77 " 93. Sixth cervical vertebra of Z>moce?-tfs «we2rai/ front view, 77 " 94. The same vertebra; side view, 77 CHAPTER VI. FiGD RE 95. 96. 97. 100. 101. 102. 103. 104. 105. First dorsal vertebra of Dinoceras niirahile; front view, 80 The same vertebra; side view, .-- 80 First dorsal vertebra of Tinoceras anceps; front view, 80 The same vertebra ; side view, . 80 Second dorsal vertebra of Dinoceras mirabile; front view, 82 The same vertebra; side view, 82 Third dorsal vertebra of Uintatheriiim segne; front view, 83 The same vertebra; side view, 83 Posterior dorsal vertebra of Dinoceras lucare; front view, 84 The same vertebra ; side view, .-. . 84 The same vertebra; back view, 84 Xiv DINOCERATA. CHAPTER VII. Page. Figure 106. Section oi huraerns oi Ditiocei'as mirabile, 91 107. Section oi humerus oi Dinocer as mirab He, . . 91 108. Section of radms of Dinoceras mirahile, 94 109. Section of radius of Dinoceras mirdbile, 94 1 1 0. Section of nlna of Dinoceras lucare, 98 111. Section of ulna of Dinoceras mirabile, 98 CHAPTER VIII. Figure 112. Scaphoid of Z>«;ioceras to^ice^js/ side view, 103 113. Scaphoid of Dinoceras mirahile; side view, 103 114. Lunar of Dinoceras mirabile; front view, 105 115. Lunar of Tinoceras ingens; side view, 105 1 16. The same bone; distal end, 105 117. Pyramidal of Tinoceras ingens; distal end, 108 118. Pyramidal of Dinoceras mirabile; distal end, ._ 108 119. Trapezoid of Dinoceras m irabile; side view, 112 1 20. The same bone; distal end, 112 121. Magnum of Dinoceras mirabile; side view, 115 122. '^la.gnuxQ. oi Dinoceras mirabile; side view, .,. ■_ _ 115 123. Unciform of Dinoceras mirabile; side view, - 119 124. Unciform of Tinoceras ingens; side view, 119 CHAPTER IX. FiGUEE 125. Second rih of Uintatherium latiJ''rons; iioatevior Yie-w, 130 126. The same rib; front view, 130 127. The same rib; inner view, 130 1 28. The same rib ; proximal end, 130 1 29. Anterior rib of Dinoceras mirabile; f)osterior view, 131 1 30. The same rib; inner view, 131 131. Tlie same rib; front view, 131 132. The same rib; proximal end, 131 133. Sternum of Dinoceras mirahile ; top view, 134 CHAPTER X. FiGUBE 134. Pelvis of Tinoceras ingens ; seen from below, 136 " 135. Tlie same j)elvis; front view, 136 " 136. Cawiai vertehva oi Di?wceras laticeps, 138 ILLUSTRATIONS. SV CHAPTER XI. Page. Figure 13V. Section oi fexanv oi Dinoceras mirabile, 141 " 138. Section oi iemiir oi J}i>wcet as mii-abile,- 141 CHAPTER XII. Figure 139. " 140. " 141. (( 142. " 143. " 144. " 145. " 146. Astragalus of Dlnoceras laticeps ; top view, 149 The same bone ; bottom view, 149 Astragalus of Tinoceras ingens • top view, 149 The same bone ; bottom view, 149 Calcaneum of Dinoceras mirabile ; top view, 152 Calcaneum of Dinoceras mirabile ; top view, 152 Cuboid of Dinoceras mirabile ; side view, -. 154 The same bone ; proximal end, 154 CHAPTER XIV. Figure 147. Diagram to illustrate the genealogy of Ungulate Mammals, . 173 " 148. Left hind limb of Baptanodon discus, 183 " 149. Right fore foot of water tortoise {Chelydra serpentina), 183 " 150. Left fore foot of Cvryphodon hamatus, 184 " 151. Left hind foot of same, 184 " 152. Left fore foot of -Z>j?ioce?'a!S »ijV«6j7e, 184 " 153. Left hind foot of same, 184 " 154. heit iore foot ot Syrax ca2}ensis, 185 " 155. Left hind foot of same, 185 " 156. Left fore foot of JSlephas Indiciis, 185 " 157. Left hind foot of same, 185 '"■ 158. 'Leit iore ioot oi. Rhinoceros blcornis, 186 " 159. Left hind foot of same, 186 " 160. Right fore foot of Brontotherium ingens, . 186 " 161. Right hind foot of same, - _ 186 " 162. "Leit ioxe toot oi JEporeodoH socialis, 187 " 163. Left hind foot of same, 187 " 164. Left fore foot of Hippopotamus ampjhibius, 187 " 165. Left hind foot of same, — ..... 187 " 166. Left fore foot of horse (.£'(7«M.s ca5aZ^i(«), 188 " 167. Left hind foot of same, 188 '■' 168. Left fore foot of goat ( Capra hircus), 188 " 169. Left hind foot of same, 188 xvi DINOCERATA. "SYlSrOPSIS. Page. FiGUEE 170. 'Nasals oi Dinoceras cnneum, 197 " 171. Skull oi Di7ioceras cuneum / seen from above, 198 " 172. Nasals oi Di?iocer as lucare, .__ 200 " 173. Nasals oi Din oceras lucare,.. 201 " 174. Nasals oi Di?ioceras rejfexuiii, . 201 " 175. Nasals oi Tiiwceras anceps, 202 " 176. Left parietal protuberance of TYjioeeras ance^w y side view, 203 " 177. The same specimen ; front view, 203 " 178. Vertical section through cranium of Tinoceras affitie, 204 " 179. The same specimen ; seen from above, _. . 204 " 180. Skull of Tinoceras cornutum ; side view, 206 " 181. The same skull ; seen from below, 207 " 182. Nasals of Tinoceras crassifrons, — 208 " 183. Nasals oi Tinoceras galeatuni, ... -_ 209 " 184. Posterior surface of same skull, 209 " 185. Nasals oi Tinoceras grande, 210 " 186. Nasals oi Tinoceras Mans, .. 210 " 187. Nasals of l^inoceras jiigum, 212 " 188. Upper molars of 2?Mocer«s ZacMS^re / seen from below, 212 " 189. Nasals oi Tinoceras latum, 213 " 190. Nasals oi Tinoceras latum, 213 " 191. Left maxillary protuberance of Tinoceras longiceps j side view,-- 214 " 192. Left parietal protuberance of same skull ; side view, . . 214 " 193. Skull of Tinoceras Speirianum ; side view, 216 " 194. Skull and lower jaw of Tinoceras stenops ; side view, ._ 217 " 195. Sikvill oi Uintatheriumrobiistum ; hoiX,ov!i.Y\ew, . ... 219 " 196. Lower jaw of TJintatheriiim fissidens ; top view, 220 " 197. The same specimen ; front view, 220 " 198. Skull of Uintatherium Leidianuni ; oblique side view, 221 " 199. Maxillary protuberances of Uintatheriitm segne ; seen from above, 222 " 200. The same specimen ; seen from in fi-ont, 222 All the illustrations in the present volume are original, with the exception of nine woodcuts, for which due credit is given on the pages where they are used. PREFACE. The present Memoir is the second of a series of Monographs designed to make known to science the Extinct Vertebrate Life of North America. In the first volume, on the Odontornithes, or Birds with Teeth, the author gave the result of his investigations of that remarkable group, which he discovered in the Cretaceous deposits on the Eastern slope of the Rocky Mountains. This second Monograph contains the full record of a peculiar order of Mammals, which the author also brought to light in the eai-ly Tertiary strata of the great central plateau of the continent. In preparing the present volume, it has been the aim of the author to do full justice to the ample material at his command, and, where possible, to make the illustrations tell the main story to anatomists. The text of such a Memoir may soon lose its interest, and belong to the past, but good figures are of permanent value in all departments of Natui-al Science. What is now especially needed in Palaeontology is, not long descriptions of fragmentary fossils, but accurate illustrations of characteristic type specimens. In the fifty-six lithographic plates, and nearly two hundred original woodcuts, in the present volume, it is believed that this requirement is fairly met ; since all the more important specimens of the JDinocerata now known are represented, and at least one figm-e is given of every species. xviii DINOCEKATA. The same general plan will be followed in the third Monograph, on the Sauropoda, whicli comes next in the series, and is now approaching completion. Ninety lithographic plates, and a large number of woodcuts, will be used to illustrate it. The fourth volume, on the Stegosauria, which follows, will likewise be very fully illustrated. A great portion of the lithographic plates to accompany it are finished, and part of them are already printed. Other monographs of the series, now in preparation, will appear in due time. To General Sheridan and Greneral Sherman of the United States Army, the author's best thanks are due for important assistance in his Western explorations, during which the discoveries here recorded were made. Other officers of the Army, who commanded his escort, and aided him in many ways, also deserve grateful acknowledgments. For direct aid in collecting the specimens on which the present volume is based, the author is indebted to the members of the Yale College expeditions, which explored so successfully many portions of the AYestern Territories. The thanks of the author are especially due to Mr. Oscar Harger, assistant in the Yale Museum, for valuable aid in the field, and in the preparation of the present memoir Messrs. S. W. Williston, G. Baur, and M. Schlosser, also his assistants, have likewise aided, especially while the volume was passing through the press, Yale College, New Haven, Conn., December 15th, 1884. INTRODUCTIO]^. Among the many extinct animals discovered in the Tertiary deposits of the Rocky Mountain region, none, perliaps, are more remarkable than the huge mammals of the order Dinocerata. Their remains have hitherto been found in a single Eocene lake-basin in Wyoming, and none are known from any other part of this country, or from the Old World. These gigantic beasts, which nearly equalled the elephant in size, roamed in great numbers about the borders of the ancient tropical lake in which many of them were entombed. This lake-basin, now drained by the Green River, the main tributary of the Colorado, slowly filled up with sediment, but remained a lake so long that the deposits formed in it, during Eocene time, reached a vertical thickness of more than a mile. The Wasatch Mountains on the West, and the Uinta chain on the South, were the main sou.rces of this sediment, and still protect it, but the Wind River range to the North, and other mountain elevations, also sent down a vast amount of material into this great fresh-water lake, then more than one hundred miles in extent. At the present time, this ancient lake-basin, now six to eight thousand feet above the sea, shows evidence of a vast erosion, and probably more than one-half of the deposits once left in it have been washed away, mainly through the Colorado River. What remains forms one of the most picturesque regions in the whole West, veritable Mauvaises terres, or bad lands, where slow denudation has carved orxt cliffs, peaks, and columns of the most fantastic shapes, and varied colors. 2 DINOCERATA. This same action has brought to light the remains of many extinct animals, and the bones of the Dinocerata, from their great size, naturally first attract the attention of the explorer. The first remains of the Dinocerata discovered were found by the author, in September, 1870, while investigating this Eocene lake-basin, which had never before been explored. Various remains of this group were also collected by other members of the expedition, and among the specimens thus secured was the type of Tinoceras anceps, described by the author in the following year, and now more fully in the present volume. In the same geological horizon with these remains, a rich and varied vertebrate fauna, hitherto unknown, was found. Among the animals here represented were ancestral forms of the modern horse and tapir, and also of the pig. Many others were found related to the recent Lemurs ; also various Carnivors, Insectivors, Rodents, and small Marsupials ; and of still more importance, remains were hei'e brought to light of another new order of mammals, the Tillodonts, quite unlike any now living. Crocodiles, tortoises, lizards, serpents, and fishes also swarmed in and about the waters of this ancient lake, while around its borders grew palms, and other tropical vegetation. A later Eocene lake-basin, south of the Uinta Mountains, was discovered, in October, 1870, by the same expedition, and named by the author Uinta basin. In the attempt to explore it, our party endured much hardship, and also were exposed to serious danger, since we had only a small escort of United States soldiers, and the region visited was one of the favorite resorts of the Uinta Utes. These Indians were then, many of them, insolent and aggressive, and since have been openly hostile, at one time massacring a large body of government troops sent against them. Two subsequent attempts by the author to explore this basin met with little success. This lower lake was of upper Eocene age, and its extinct fauna appears to correspond more nearly to that of the Paris basin than any other yet discovered in this countrj^.^ ' Some results of this Expedition may be found in an article by the author on the " Geology of the Eastern Uintah Mountains," American Journal of Science and Arts, vol. i, p. 191, March, 1871. INTRODUCTION. 3 The remarkable Eocene basin North of the Uinta Mountains, where alone the Dinocerata had been found, offered so inviting a field for exploration, that in the spring of the following year, 1871, the author began its systematic investigation. An expedition was again organized, with an escort of United States soldiers, and the work continued during the entire season. Among the very large collections thus secured, were numerous specimens of the Dinocerata, Avhich furnished important characters of the group. Map showing region of Dinoceeas beds. In the succeeding spring, 1872, the explorations in this region were continued, and soon resulted in the discovery of the tyjje sjiecimen, including the skull and a large portion of the skeleton, of Dinoceras mirabile, and on this new genus the author based the order Dinocerata 4 DINOCEIIATA. Other important specimens, obtained at tliis time, and described by the author, were the t3qDes of Diiioceras liicare, Tinoceras grande, Tinoceras laciistre, and others of scarcely less interest. In the following season, 1873, the author organized another large expedition, with government escort, and made a very careful examination of the regions in this same basin that remained unexplored. One of the specimens of special importance thus secured was the type of Dinoceras laticeps, with the skull and lower jaw nearly complete. Many other individuals of the Dinocerata were also discovered, and the abundant material then collected was sufficient to clear up most of the doubtful points in this group. The research was continued systematically during the next season, also, 1874, and again in 1875, with good results. Since then, various small parties, at different times, have been equipped and sent out by the author to collect in this basin ; and, finally, during the entire season of 1882, the work was vigorously prosecuted under the direction of the author, and, from July of that year, under the avispices of the United States Geological Survey. The specimens thus brought together by all these various expeditions and parties are now in the museum at Yale College, and represent more than two hundred individuals of the Dinocerata alone. Of these, not less than seventy-five have portions of tlie skull more or less perfectly preserved, and in more than twenty it is in good condition. The present volume is based on this material, amply sufficient, it is believed, to illustrate all the more important parts of the structure of this remarkable group. The remaining material of the Dinocerata, now known, consists of a few specimens collected by Dr. Leidy in 1872, including the type of the genus TJintatlierium ; various remains secured in the same year by Prof. Cope, to which he applied the names Loxolophodon and Eohasileiis, with a later acquisition, called Bathyopsis ; and a number of specimens more INTRODUCTION. 5 recently obtained by parties from Princeton College. Although these remains show few, if any, characters of the JDinocerata not better represented in the larger collection of the Yale Museum, full references to the more important specimens, in most cases with illustrations, are given in the present memoir, especially in the Synopsis at the end of the volume. The Dinocerata have hitherto been found in a well marked geological horizon of the middle Eocene. The relations of this horizon to other deposits of Tertiary age are important, and cannot readily be understood without having in mind the principal changes that took place in the geology of the Rocky Mountain region during this period. These changes and their results may be briefly stated as follows : The Tertiary of Western America comprises the most extensive series of deposits of this age known to geologists, a^nd important breaks in both the rocks and the fossils separate it into three well-marked divisions. These natural divisions are not the exact equivalents of the Eocene, Miocene, and Pliocene of Europe, although usually so considered, and known by the same names ; but, in general, the fauna of each appears to be older than that of its corresponding representative in the other hemisphere ; an important fact, but little recognized. This partial resemblance of our extinct faunas to others in regions widely separated, where the formations ai'e doubtless somewhat different in geological age, is precisely what we might expect, if, as was probable, the main migrations took place from this continent. It is better at once to recognize this general principle, rather than attempt to bring into exact parallelism formations that were not contemporaneous. The fresh-water Eocene deposits of our Western Territories, which are in the same region at least two miles in vertical thickness, may be separated into three distinct subdivisions. The lowest of these, resting unconformably on the Cretaceous, has been termed the Vermilion Creek, or Wasatch, group. It contains a well-marked mammalian fauna, the 6 MNOCERATA. largest and most characteristic genus of which is the ungulate Coryphodon, and hence the author has called these deposits the Coryphodon beds. The middle Eocene strata, which have been termed the Green Eiver and Bridger series, has been designated by the author the Dinoceras beds, as the gigantic animals of this order are only found here. It is, however, better to separate the Green River series, under the term Heliobatis beds, and this is done in the present volume. The name Dinoceras beds will then apply to the Bridger series alone. The uppermost Eocene, or tlie Uinta group, is especially well characterized by large mammals of the genus Diplacodon, and hence termed by the author Diplacodon beds. The fauna of each of these three subdivisions was essentially distinct, and the fossil remains of each were entombed in different and successive ancient lakes. It is important to remember that these Eocene lake-basins all lie between the Hocky Mountains on the east and the Wasatch Range on the west, or along the high central plateau of the continent. As these mountain chains were elevated, the inclosed Cretaceous sea, cut off from the ocean, gradually freshened, and formed these extensive lakes, while the surrounding land was covered with a luxuriant tropical vegetation, and with many strange forms of animal life. As the upward movement of this region continued, these lake-basins, which for ages had been filling up, preserving in their sediments a faithful record of Eocene life-history, were slowly drained by the constant deepening of the outflowing rivers, and they have since remained essentially dry land. The Miocene lake-basins are on the flanks of this region, where only land had been since the close of the Cretaceous. These basins contain three faunas, nearly or quite distinct. The lowest Miocene, which is found east of the Rocky Mou.ntains, alone contains the peculiar mammals known as the Brontotheridce, and these deposits have been called by the author the Brontotherium beds. The strata next above, which represent the middle Miocene, have as their most characteristic fossil the genus Oreodon, and are known as the Oreodon beds. The upper Miocene, which occurs in Oregon, is of great thickness, and from one of its most important fossils, Mioliippus, has been designated as the Miohippus series. The climate here during this period was warm temperate. INTRODUCTION. i&teSS^M Tapir, feccary, uiauu, Llama. Bos, Equus, Megatherium, 3fylodon. Equue, Tapirus Elephas. \ PUoMpp-us, Tapiravus, Mastodon, Protohippus, Procamelus, I Aceratherium, Bos, Morotherium. ^^^ Mioliippus Beds. Oreodon Beds. BronlotheriumBeds Diplacodoii Beds. Diuooeras Beds. Green River, or Heliobatis, Beds, Coryphodon Beds. Laramie Series, or Hadrosaurus Beds. Fo.x Hill group. Colorado Series, or PteranodoD Beds. Dakota Group. Atlantosaurus Beds Baptanodon Beds Otozoiim, or CoDn. River, Beds. MioJdppus, Diceratherium, Thinohyus. Oreodon, Eporeodon, {Moropus). Brontolherium, Menodus, ., Hyracodon. EclentateB Eloiherium. Diplacodon, Epihippus, Amynodnn. miocera^, Tinoceras, Uintatherium, Limnohyxis, PaUso- syops, Orohippus, Helatetes, Hyrachyus, Colonoceras. Heliobatis, Amia, Lepidosteus. Hadrosaurus, Dryptosaurus (Loelapa). Pterodactyls {Pteranodon), Pleslosfturti. Dinosaurs, Atlautosaurus, Brontosaurus, Morosaurus. Diplo docus, Stegosaurus, Catnptonotus, AUosaurus. Turtles Crocodiles. Mauiuials {Dryolestes, Stylaeodon, Tinodon Ctenacodoii) . Bird iZaopteryxi. Baptanodon iSauranodon) First Manimals ( Dromatheriuni) . Dsaur Foot-prints, Amphiaaurus, Crocodiles {Belodon). Nothodon Beds. Reptiles iNothodon, Sphenacodon) . Carboniferous Coal Measures, or Eosaurus Beds. Subcarboniferous. or Sauropus Beds. First Reptiles (?) Eosaurus. First tnown Amphiliians (Labyrinthodonts), Sauropus. Dinichthys Beds. Schoharie Grit. Dinichthys. First known Fishes. Upper Silurian. Lower Silurian. No Vertebrates known. Section to illustrate Vertebrate Life in America. 8 DINOCERATA. Above the Miocene, east of the Rockj^ Mountains, and on the Pacific coast, the Phocene is well developed, and is rich in vertebrate remains. The strata rest unconformably on the Miocene, and there is a well-marked faunal change at this point, modern types now first making their appearance. For these reasons, Ave are justified in separating the Miocene from the Pliocene at this break ; although in Eurojje, where no great break exists, the line seems to have been drawn at a somewhat higher horizon. Our Pliocene forms esseutially a continuous series, although the upper beds may be disting'uished from the lower by the presence of a true Etpms, and some other existing genera. The Pliocene climate was similar to that of the Miocene. The Post-Pliocene beds contain many extinct mammals, and may thus be separated from recent deposits. ^ With this introduction, the table of strata on page 7 will make clear the general position of the g-eological horizon in which the Dinocerata are found, and especially its relation to other deposits of Tertiary age. To make the subject clearer to the general reader, the section is enlarged to include the whole geological series. The names applied to the different horizons, some used here for the first time, are, in general, those of the most important vertebrates found in each, and the section thus becomes a condensed index of vertebrate life in America. The localities in which the Dinocerata have been found are on both sides of the Green River, and mainly south of the Union Pacific Railroad, in Wyoming. Of two hundred individuals in the Yale Museum, about equal numbers were found east and west of this River, the distance between the extreme localities in this direction being more than one hundred miles. The map on page 3 covers this region, and the more important localities referred to in the volume are there indicated. ' For a more complete presentation of this subject, see the author's address on the Introduction and Succession of Vertebrate Life in America, delivered before the American Association for the Advancement of Science, at Nashville, Tenu., Aug., 1877. INTRODUCTION. 9 The remains of the JDinocerata are imbedded usually in indurated clays, gray or green in color, but sometimes they are found in hard sandstone. The series of strata enclosing them are at least five hundred feet in thickness in the same region, and all taken together are probably one thousand feet. Among the fossils found associated with the Binocerata are Limnohyus and PalcBOsyops, two genera of perissodactyl ungulates. They were somewhat larger than a Tapir, and in these strata are next in size to the Binocerata. One or the other of these genera occurs wherever the Binocerata have yet been found, but the remains extend through a greater thickness of strata than those of the former group. Another genus of ungulates in this horizon is OroJiippus, a four-toed ancestor of the horse. Other prominent genera are Cohnoceras, Helaletes, and Hyracliyus, related distantly to the Tapir and Rhinoceros. Two genera, TillotJierium and Stylinodon, also found here, represent a remarkable order, named by the author, Tillodontia. They were nearly as large as a Tapir, and possessed characters resembhng the Ungulates, the Carnivors, and the Rodents. Among the Carnivors, the most formidable was Limnofelis, nearly as large as a lion, Oreocyon, of almost equal size, Bromocyon, somewhat smaller, and Limnocyon, about as large as a fox. Among the Lemuroid forms were Hyopsodus and Lemuravus, forming the family LenmravidcB, and having some affinities with the South American Marmosets. In addition to these, there were Marsupials, Insectivors, Chiroptera, and many Rodents, but apparently no ti-ue Quadrumana, or Edentates. Besides these Mammals, there were numerous Reptiles, especially crocodiles, turtles, Hzards, and serpents, in great numbers. Fishes were also abundant, especially the genera Amia and Lepidosteus. The Binocerata form a well marked order in the great group of Ungulata. In some of their characters, they resemble the Artiodactyls ( Paraxonia); in others, they are like the Perissodactyls (Mesaxonia); and 2 10 - INTRODUCTION. in others still, they agree with the Proboscidians. The points of similarity, however, are in most cases general characters, which point back to an earlier, primitive, ungiilate, rather than indicate a near affinity with existing forms of these groups. This subject will be more fully discussed in the concluding chapters of the present memoir. The Dinocerata, so far as now definitely known, may be placed in three genera, Dinoceras, Marsh, Tinoceras, Marsh, and Uintatherium, Leidy. The type specimen of Uintatherium was discovered near the base of the series of strata containing the remains of the Dinocerata. Dinoceras, so far as known, occurs only at a higher horizon, while Tinoceras has Ijeen found at the highest level of all. The characters of these three genera correspond in general with their geological position. Uintatherium appears to be the most primitive type, and Tinoceras the most specialized, Dinoceras being an intermediate form. The material at hand for determining the characters of the two latter forms is abundant, but in regard to Uintatherium, some important points relating both to the skull and skeleton still remain in doubt. The number of species of the known Dinocerata is a difficult matter to determine, especially as the limitations between species are now generally regarded as uncertain. About thirty forms, more or less distinct, are recognized in the Synopsis at the end of the volume. The number might easily be increased, if fragmentary specimens were used as the basis for specific names. DINOCERATA. CHAPTER I. THE SKULL. (Plates I-XIX, LV, and LVL) The skull of Dinoceras mirabile, the type of the gemis Binoceras, on which the order Binocerata was based, is, fortunately, the most perfect in preservation of any yet discovered in this group. It has in addition the great advantage for study of having belonged to an animal fully adult, but not so old as to have the more important sutures of the skull obliterated. It was, moreover, imbedded in so soft a matrix that the brain-cavity and the foramina leading from it could be worked out without difficulty. In removing the skull from the rock, on the high and almost inaccessible cliff where it was found, two or three important fragments were lost, but the author subsequently made a systematic and laborious search, and recovered them from the bottom of a deep ravine where they had been washed down and covered up. ■ In its present nearly perfect condition, this skull is well adapted to show the typical characters of this part, both in the genus it represents, and in the order Binocerata, and it will be largely used for this purpose in the following pages. The fact that a considerable portion of the skeleton, also, was found with this skull makes the individual especially worthy to be a type. 12 DINOCERATA. The number of this specimen, in the Catalogue of the Yale Museum, is 1036, and in the following pages this number will be used to distinguish this type from other individuals of the same species. Other important specimens will likewise be designated by their catalogue numbers. The skull of Dinoceras mirabile is long and narrow, the facial portion being greatly produced. The basal line, extending from the end of the premaxillaries along tlie palate to the lower margin of the foramen magnum, is nearly straight. The top of the skull supports three, separate, transverse pairs of osseous elevations, or horn-cores, which form its most conspicuous feature, and suggested the name of the genus. The smallest of these protuberances are situated near the extremity of the nasals ; two others, much larger, arise from the maxillaries, in front of the orbits ; while the largest are mainly on the parietals, and are supported by an enormous crest, which extends from near the orbits entirely around the lateral and posterior margins of the true cranium. These general chai-acters are well shown in Plate I, which represents the skull of the type specimen. There are no upper incisors, but the canines in the male are enormously developed, forming sharp, trenchant, decurved tusks, which were each protected by a dependent process an the lower jaws. The premolar and molar teeth are very small. The orbit is large, and confluent with the temporal fossa. The latter is of great extent posteriorly, but the zygomatic arches are only moderately expanded. There is no post-orbital process, but in Dinoceras mirabile, and in some other species, there is a prominence on the frontal bone, directly over the orbit. The Nasal Bones. The nasal bones are greatly elongated, being nearly half the length of the entire skull. They project forward over the anterior nares, and overhang the premaxillaries. Tliey are thick and massive bones, especially in front, and are united together by a nearly straight suture. THE SKULL. 13 In specimens not fully adult, this suture remains an open fissure, and even in some adults it is not closed, especially in the anterior part. The osseous prominences on the extremity of the nasal bones are their most marked feature. These vary much in form and size in the different genera of the group, and appear to be characteristic of the species. PieuKE 3. — "Sasals of Oinoceras mirab If Miisli (N 10 () t^\e <5pecimen. Figure 4. — T\a's:&h- Miocene. THE BRAIN. Fig. 14. 65 Figure 74. — Mastodon Americanus, Cuvier. Pliocene. Fig. 75. Fig. 76. Figure 75. — Elothermm crassum, Marsh. MioceDe. Figure 76. — Platygonus com.prcssus, LeOonte. Plipcene. 9 66 DINOCERATA. Fig. 11. Figure 11. — Elejphas Indicus, Linnteiis. Figure IS. — Tupirvs terrestris, Linn:eiis. Figure l^.—Ii/uuoccros Swnalrensis, CuviBr._ THK BRAIN. 67 Figure 80. — Auchenia vicugna, Molina. PiGOHB 82. — Bippopoiamus amphibius, Linnffiis, FrSUEE 81. — Cervus Virginianus, Boddaut. Figure 83. — Dicotyles iorquatus, Cuvier, CHAPTER y. THE CERVICAL VERTEBRAE. (Plates XX, XXI, XXII, LV, and LVI.) The cervical vertebrse of thd Binocerata, in tlieir main characters, resemble those of tlie Proboscidians. The atlas and axis are somewhat similar to those of the elej^hant. The rest of the cervicals are proportionally longer. The entire neck was abont one-third longer than in the elephant, thus rendering a proboscis unnecessary, as the head could readily reach the ground. All the presacral vertebrae, behind the atlas and axis, have the articular faces of the centra nearly flat, as in the typical Proboscidians. In other respects, they present no strongly marked characters of importance. The Atlas. (Plate XX ; and woodcuts 84, 85, and 86, below.) The atlas in the Binocerata is a massive bone, presenting the ordinary articular faces of this vertebra. The anterior pair of these, for the reception of the occipital condyles, are well separated above and below. The three posterior faces, for articulation with the second vertebra, or axis, are also widely separated from each other. All these three faces are sub-circular in outline, and the lateral ones are somewhat emarginate 70 DINOCEKATA. along the inner side. The median facet, for articulation with the odontoid process, is flattened in front, or slightly convex in antero-posterior direction, and extends longitudinally over the greater part of the inferior arch of the atlas. Its boundaries are well marked on all sides, as are also those of the lateral faces. Hence the articulation between the atlas and axis admitted but little rotary motion to the head. The spine of the atlas is not well marked, although the superior arch is massive, and its anterior surface is rough and tuberculated. This arch is pierced on each side anteriorly by a foramen (figure 84, d), the inner Ojjening of which is just above the inner and upj)er angle of the condylar articular surface. Externally, this foramen is connected bv a more or less evident groove with one piercing the transvei'se ])rocess lengthwise. This groove runs vertically down the side of the atlas, and through a deep notch in the anterior margin of the transverse process. In the tapir, this groove passes through a foramen, instead of a notch in tlie anterior part of the transverse process. A similar arrangement is seen in the horse, ox, sheep, camel, and in various other Ungulates. The transverse processes of the atlas are short, and strong. They are moderately flattened, thicker and stouter behind than before, and placed obliquely, so as to slant strongly downward and backward. Anteriorly, the outer margin runs rapidly down to the lateral arch of the atlas, but is separated from it at the base of the process by the deep notch, mentioned above. Posteriorly, they are thickened and rugose. The base of each lateral process is perforated by a foramen, directed somewhat downward, and forward. The under surface of the atlas (figure 86) is smooth and even, with no rugosity to mark the median line. The atlas of Dinoceras mirahih is shown in Plate XX, and that of Tinoceras grande, in the woodcuts below, figures 84, 85, and 86. The position of the atlas, with reference to the skull, is represented in the restorations in Plates LV and LVI. THE CERVICAL VERTEBRA. 71 Fig. 86. FiGURR 84. — Albs of TmOLCiat, giaiicL, Mu^h (No ]040); front view. Figure 8.5. — The same vei tebia , back view FiGDEK Bfi. — The same vertebra ; bottom view. a. face for axis; 6. fare Air odontoid process of a.xis; c. face for occipital condyle of skull; d. foramen in neural arch for spinal nerve; nc. neural canal. All the fignres are one-fourtli natural size. The following- measfirements give the princijial dimensions of the atlas in one specimen of Dlnoceras : Measurements of Atlas. {Dhiooeras miraUe, No. 12.51.) m. Greatest transverse diameter of atlas, ._ .26.5 Greatest vertical diameter of atlas, . . - . 1 4 _' Transverse diameter of neural canal, , .090 Vertical diameter of neural canal, 080 Antero-posterior diameter of superior arch, - .067 Vertical diameter of superior arcli, .034 Antero-posterior diameter of inferior arch, __ .149 Diameters of faces for occipital condyles, -' .0'72-.05'2 Distance between faces for occipital condyles, above, - .080 Distance between faces for occipital condyles, below, . - . . .058 Diameters of face for odontoid process, — - 04.3-.035 Diameters of lateral faces for axis, 063-.056 Distance between lateral faces for axis, .065 72 DINOCERATA. The Axis. (Plate XXI.) The axis in Binoceras mirahile (number 1036) is robust, and proportionally shorter than the corresponding vert3bra in the tapir. The centrum is moderately flattened below, but not excavated as in the tapir, and presents, medially, a tuberculation at the union of its centrum with that of the first vertebra. The odontoid process is distinctly conical, and not at all excavated above. Its perpendicular diameter, moreover, exceeds its transverse. It is pointed in front, and bears, on its imder surface, a saddle-shaped articular face for union with the atlas. This surface is not confluent with the lateral surfaces, as in the elephant, tapir, and most Ungulates, but is perfectly distinct, as in the kangaroo, and in man. The lateral articular faces are moderately convex in both directions, and have their longest diameter nearly ti-ansverse. The neviral arch is massive, and its lateral walls are not pierced by foramina, agreeing, in that respect, with those of the kangaroo. On the lateral surfaces of the centrum, the vertebrarterial, or lateral, foramen was present, and circumscribed by bone. Its upper wall was much weaker than the lower, instead of subequal, as in the tapir. The neural arch is surmounted by a short and stout neural spine, low in front, and rising behind, though less rapidly than in the tapir, and becoming rather indistinctly bifid at the top. The neural spine is deeply excavated behind. The posterior zygapophyses are robust, slightly convex, and look more downward than outward, and only slightly backward. The posterior face of the centrum is transverse, and broadly oval in outline. The floor of the neural canal is flattened, and presents a number of vascular foramina leading into the centrum. The transverse processes of this specimen are imperfectly preserved, but were evidently pierced, above the middle, by a large lateral foramen. The processes appear to have been directed rather less strongly backward than in the tapir. The principal dimensions of the axis in three specimens of Binoceras are as follows : THE CERVICAL VERTEBRAE. 73 Measurements of Axis. [Dinoceras mirabile, No. 1036.) m. Length of axis, on floor of neural canal (approximate), 150 Length of odontoid process, . .-_ .056 Transverse diameter of odontoid process, .035 Vertical diameter of odontoid process, -_ .052 Transverse diameter of anterior articular face, .068 Vertical diameter of anterior articular face, .065 Transverse diameter of vertebra, across anterior articular faces, .148 Transverse diameter of neural canal, .053 Vertical diameter of neural canal, ._.. .042 Transverse diameter of vertebra, across post-zygapophyses, .122 Transverse diameter of posterior face of centrum, . 093 Vertical diameter of posterior face of centrum, ... .072 Height of axis, to top of neural spine, ._ _. . .175 Transverse diameter of neural spine, . .. .048 Antero-posterior diameter of neural spine, 086 Measuremetits of Axis. [Dinoceras mirabile, No. 1255.) m. Length of axis, on floor of neural canal (approximate), .125 Length of centrum, along under surface, .140 Length of odontoid process, from lateral articular faces, .045 Transverse diameter of odontoid process, . _ . . .037 Vertical diameter of odontoid process, . .038 Transverse diameter of articular face of odontoid process, .035 Antero-posterior diameter of articular face of odontoid process, .042 Transverse diameter of neural canal, . .039 Vertical diameter of lateral foramen, .012 3Ieasurements of A.vis. {Dinoceras litcare. No. 1038.) m. Total length of axis, .170 Length, from end of odontoid process to end of neural canal, . 1 48 IVansverse diameter of odontoid process, .035 Vertical diameter of odontoid process, ■ 046 Greatest diameter of anterior articular face, .070 Transverse diameter, across anterior articular faces, . ; 142 Antero-posterior diameter of face on odontoid process, .044 Transverse diameter of face on odontoid process, _ .033 Distance between antero-lateral articular faces, .050 Transverse diameter of centrum, behind faces, .125 Transverse diameter, across post-zygapophyses, .115 Transverse diameter of posterior face of centrum, _ .093 Vertical diameter of posterior face of centrum, .080 Diameters of lateral foramen, _ ._ _ 01 3-.020 Diameters of neural canal (approximate), .040-050 10 • 74 DINOCERATA. The Third Vertebra. (Plate XXII, figures 1-5.) The third cervical of Dinoceras mirahile (number 1036) is shown in Plate XXII, figures 1-5. This vertebra, in the type specimen, is not in a good state of preservation, but represents fairly the main characters of the third cervical in this genus. The pre-zygapophyses are somewhat concave, to fit the convex post-zygapophyses of the axis. The neural canal is large, and the arch above it is only moderately developed, and without a spine. The lateral, or vertebrarterial, foramen is oval in outline, and is protected by a strong transverse process. The under surface of the centrum is marked by a median longitudinal keel, as shown in figures 3 and 5. The third cervical vertebra of Dinoceras mirahile (number 1255) is short, and the articular faces of the centrum are both somewhat concave. The anterior face is slightly less excavated than the posterior. The length of the centrum is less than its vertical diameter, and the latter is greater than the transverse diameter. The epiphyses are incompletely ossified, and only imperfectly united to the centrum. These general characters apply also to the remaining cervical vertebrae. The principal dimensions of the third A^ertebra in one specimen of Dinoceras are as follows : 3feasurenients of Tliird Cervical J^ertehnt. (Dinoceras mirahile, No. 1255.) m. Length of floor of neural canal (approximate), . ^.- — . .055 Length of centrum, along under surface, — .058 Vertical diameter of posterior epiphysis, ..- .078 Antero-posterior extent of zygapophyses, ._ .092 Diameter of lateral foramen (apj)roximate), . .020 The Fourth Vertebra. (Woodcuts 87 and 88, below.) The fourth cervical vertebra in Dinoceras resembles, in its main characters, the one last described. The pre-zygapophyses are nearly flat. The neural canal is somewhat smaller. The process to protect the lateral foramen is more strongly developed, and the under surface of the centrum is without a distinctly marked keel. THE CEIIVICAL VERTEBRA. 75 The fourth vertebra in Tinoceras grande is similar, in its more important characters, although proportionally shorter, and its principal features are well shown in figures 87 and 88, below. Fif4 "^S Figure 87. — Fourth cervical vertebra of Tinoceras grande, Marsh (Wo. 1040); front view. FiGORE 88. — The same vertebra; side view. /. lateral foramen; nc. neural canal; z. anterior zygapopliysis ; z'. posterior zygapophysis. Both figures are one-fourth natural size. The main dimensions of the fourth vertebra in one species each of Binoceras and Tinoceras are given below. Measurenients of Fourth Cervical J^erteTfra. {Dinoceras mirabile. No. 1255.) m. Length of floor of neural canal, .055 Length of centrum, along under surface, .054 Transver.se diameter of anterior epiphysis, .079 Vertical diameter of anterior epiphysis, . .075 Transverse diameter of posterior epiphysis, .091 Vertical diameter of posterior epiphysis, .075 Autero-posterior extent of zygapophyses, i .089 Diameter of lateral foramen, .024 Transverse diameter of neural canal, .04.3 Measurements of Fourth Cervical Vertebra. {^Tinoceras grande, No. 1040.) m. Length of floor of neural canal, .-^--. .042 Length of centrum, on under surface of vertebra, .045 Transverse diameter of anterior face, .100 Vertical diameter of anterior face, .094 Transverse diameter of neural canal, .055 Vertical diameter of neural canal, .040 Diameters of lateral foramen, .025-015 76 DINOCERATA. The Fifth Vertkhra. (Woodcuts 89 and 90, below.) In the fifth cervical vertebra of Dinoceras mirabile (number 1255), the centrum is nearly round. The articular faces are distinctly concave, especially the posterior one. The neural canal is sub-triang-ular in transverse section. The arch to protect the lateral foramen is more depressed than in the preceding vertebi'a. The more important features of this vertebra are shown in figure 89, below. Figure 89 — Fiflh cervical vertebra ot Iliiwceras mirabile, Marsh (No. 1255); front view. FiauRE 90. — The same vertebra; siJe view. /. lateral foramen; nc. neural caual; z. anterior zygapoplivsis ; z'. posterior lygapophysis. Both figures are one-fourth natural size. The pi'incipal measurements of the fifth vertebra in this specimen of Dinoceras mirabile are the following- : Jtfeasure/nents of Fifth Cervical Vertebra. (Dinoceras ■mirabile^ No. 1255.) m. Length of floor of neural canal, .052 Length of centrum, along under surface, .055 Transverse diameter of neural canal, .046 Vertical diameter of neural canal, _. .035 Transverse diameter of anterior epiphysis,. .079 Vertical diameter of anterior epiphysis, , .074 Transverse diameter of posterior epiphysis, ,._". .089 Vertical diameter of posterior epiphysis, .080 Antero-posterior extent of zygapophyses, _.^ . .083 Transverse diameter, across pre-zygapophyses, _ . .120 Transverse diameter, across post-zygapophyses, .123 Diameter of lateral foramen (approximate), .020 THE CERVICAL VERTEBRA. 77 The Sixth Vertebra. (Woodcuts 91-94, below.) The sixth cervical vertebra of Dinoceras mirabile (number 1255) has the articular faces of the centrum more transverse than in the preceding- vertebra. The neural canal is sub-cordate in outline, and the transverse processes, to protect the lateral foramen, are more strongly developed than in the vertebra last described. Figure 91. — Sixth cervical vertebra oil Dinoceras mirabile, Marsh (No. 1255); bask view. Figure 92. — The same vertebra ; side view. nc. neuraLcanal; z. anterior zygapophvsis ; z'. posterior zygapophysis. Both figures are one-fourth natural size. Fig. 93. Figure 9.3.— Sixth cervical vertebra o!' Dinoceras cuneum, Marsh (No. 1042); front view. Figure 94 — The same vertebra; side view. nc. neural canal; z. anterior zysapopliysis; z'. posterior zygapophysis. Both figures are one-fourth natural size. In the sixth vertebra of Dinoceras cuneum, there is a distinct neural spine, and the centrum is slightly quadrate in outline, as shown in figure 93. The latter is shorter than in the corresponding vertebra of Dinoceras mirabile, as seen by a comparison of figures 92 and 94. Measin-ements of the sixth cervical vertebra in two individuals of Dinoceras are as follows : 78 DINOCERATA. Measurements of Sixth Cervical Vertebra. [Dinoceras niirabile,'So. 1255.) m. Length of floor of neural canal, .049 Length of centrum, along under surface, _ .055 Transverse diameter of neural canal, — .051 Vertical diameter of anterior epiphysis, .076 Transverse diameter of posterior epiphysis, .088 Vertical diameter of posterior epiphysis, .078 Antero-posterior extent of zygapophyses, .087 Ifeasuretnents of Sixth Cervical Vertebra. {Dinoceras cuneutn, No. 1042.) m. Transverse diameter of centrum, .111 Length of centrum, along under surface, -- .053 Transverse diameter of neural canal, .071 Vertical diameter of neural canal (apjjroximate), .044 Transverse diameter of anterior face of centrum, .100 Vertical diameter of anterior face of centrum, , .092 Diameter of vertebra, across pre-zygapophyses (apjDroximate), ._ — .170 Diameters of lateral foi-amen, . .022-034 Antero-posterior diameter of pedicel, .026 The Seventh Vertebra. (Plate XXII, figures 6-10.) The seventli cervical vertebra of Dinoceras mirabile (number 1255) has the anterior face of the centrum nearly circular. The posterior face is expanded transversely, and its lateral margins are cut by the facets for the head of the first rib. The neural canal is distinctly sub-cordate in outline, and there is a rudimentary neural spine. The lateral foramen has disappeared, but the transverse process is notched below for the passage of the vertebral artery. These chai-acters are shown in Plate XXII, figures 8 and 10. Measurements of Seventh Cervical Vertebra. (Dinoceras mirabile, "So. 1255.) m. Length of floor of neural canal, .046 Length of centrum, along under surface, .051 Transverse diameter of neural canal, _ .061 Vertical diameter of neural canal (apjH'oximate), . .046 Transverse diameter of anterior articular face (approximate), .076 Transverse diameter of posterior articular face (approximate), .075 Antero-posterior extent of zygapophyses, ... .084 Diameters of articulation for fii'st rib, .022-. 035 Diameter, across transverse processes (approximate), .185 CHAPTER YI. THE DORSO-LUMBAR VERTEBRA. (Plates XXIII, XXIV, XXV, XXVI, LV and LVI.) The trunk vertebree in the Dinocerata are j^i'oportionally longer than those in the cervical region. The articular faces of the centra are likewise nearly flat, the most of them being distinctly concave. The epiphyses are usually loosely united to the centra, and thin, or imperfectly ossified, near the center. The number of trunk vertebrae in Dinoceras was apparently twenty-three. The First Dorsal Vertebra. (Woodcuts 95-98, below.) The first dorsal vertebra in Dinoceras mirahile (number 1255) has a slender, but elevated, neural spine, as shown in figure 95, below. It is distinguished from the adjoining elements of tlie colunni by the presence of elevated and oblique pre-zygapophyses, for articulation ^vith the last cei'vical. These processes are much farther apart than the post- zygapophyses, and look obliquely upward, inward, and slightly backward, while the latter look almost directly downward. The pedicels of this vertebra stand mostly on the anterior half of the centrum. They are about twice as great in transverse as in antero-posterior diameter, and are directed well outward. The laminae form a much greater proportion of the neural arch than in the tapir, and are depressed at the middle, giving a somewhat triangular outline to the large neural canal. The epiphyses in this specimen are unossified for more than half their diametei-, and imperfectly united to the centnmi. 80 DINOCERATA. The transverse processes are short,, and strongly tnberculated at the end. The articular surfaces for the heads of the first and second ribs are of about equal size, and sub-oval in outline. They are approximate at the sides of the centrum, being separated from each other by less than half their diameter. The face for the tubercular articulation of the first rib is of modei'ate size, oval in outline, concave from before backward, and much less so transversely. These articulations are about on a level with the floor of the neural canal, instead of below it, as in the tapir. PiGUBE 95. — First dorsal vertebra of Dinoceras mirahile, Marsh (No. 1212); front view. Figure 9i;. — The same vertebra; side view. n, neural canal; r. face for head of rib; r'. face for tubercle of rib; s. neural zygapophysis ; z'. posterior zygapophysis. Both figures are one-fourth natural size. spine; z. anterior FtGDRB 91. — First dorsal vertebra of Tinoceras anceps, Marsh (No. 1030); front view. FiCUEE 98 — The same vertebra; side view. nc. neural canal ; z. anterior zygapophysis; z'. posterior zygapophysis ; s. neural spine. Both figures are one-fourth natural size. THE DORSAL VERTEBKiE. 81 The first dorsal in the type specimen of Tinoceras anceps (number 1030) is shown in figures 97 and 98, on page 80. In other specimens of Tinoceras, this vertebra presents the same general characters. The principal dimensions of a first dorsal vertebra of Dinoceras, and of this vertebra in the type specimen of Tinoceras, are given below. MeasuremetiCs of First Dorsal Vertebra. {Dinoceras luirahile, No. 1255.) m. Length of centrum, along floor of neural canal, .048 Length of centrum, along inferior surface, .058 Vertical diameter of anterior face of centrum, . ... ■ .072 Transverse diameter of anterior face of centrum, .075 Vertical diameter of posterior face of centrum, .073 Transverse diameter of posterior face of centrum, .073 Vertical diameter of neural canal, .__ .046 Transverse diameter of neural canal, .005 Greatest diameter, across transverse processes, . .210 Diameter of jwe-zygapophyses, .030 Distance across pre-zygapo[ihyses, -- .140 Diameter of post-zygapophyses, __ . .03 1 Distance across post-zygapophyses, . -. .115 Diameters of anterior face for head of rib, .030-.03S Diameters of posterior face for head of rib, .027-037 Diameters of face for tubercle of rib, .025 -.032 Transverse diameter of pedicel, .- .044 Antero-posterior diameter of jjedicel, . __ _ 022 Distance between faces for head of rib, .015 Measurements of First Dorsal Vertebra. (Tinoceras anceps, 'No. 1030.) m. Length of floor of neural canal, .. .056 Length of centrum, along under surface, : : .056 Transverse diameter of anterior face of centrum, . __. .070 Vertical diameter of anterior face of centrum (approximate), .. .. .063 Transverse diameter of posterior face of centrum, .080 Vertical diameter of posterior face of centrum, .066 Transverse diameter of neural canal, __. .068 Vertical diameter of neural canal (approximate), .037 Diameteis of anterior capitular face, .03 1-035 Diameters of posterior capitular face, .033-040 Antero-posterior diameter of pedicel, .030 Transverse diameter of pedicel, .029 Diameter of vertebra, across transverse jjrocesses, .175 11 82 DINOCERATA. The Second Dorsal Vertebra. (Plate XXIII; and woodcuts 99-100, below.) The second dorsal vertebra in Dinoceras mirahile (number 1255) is especially distinguished from the one last described by the neural spine, which is massive, and more inclined backward. The neural canal is sub-triangular in outline. Tlie pre-zygapophyses are much smaller, less elevated, and look more directly upward. The centrum is somewhat longer than that of the first dorsal, and more expanded transvei'sely. This vertebra is represented in Plate XXIII. The second dorsal vertebra of Dinoceras mirahile (number 1212) has the neural spine still more massive, the neural canal more expanded transversely, and the articular faces of the centrum more nearly circular, as shown in figures 99 and 100, below. In the genus Tinoceras, the second dorsal presents the same general features as in the vertebra above described. Figure 99. — Secimd Uui^al Vfiteljiu uf iJmoceras mirable, Marsh (Xo. 1212): frout view. Figure 100. — The same vertebra ; side view. n. neural canal ; s. neural spine ; z'. posterior zygapophysis. Both tioures are one-fourih natural size. The more important measurements of the second dorsal vertebra of one specimen of Dinoceras are as follows : THE DORSAL VERTEBRA. 83 Measurements of Second Dorsal Vertebra. {Dinoceras mirabile. No. 1255.) Length of centrum, along floor of neural canal, . 048 Length of centrum, along under surface, .060 Transverse diameter of anterior face of centrum, .073 Vertical diameter of anterior face of centrum, .075 Transverse diameter of posterior face of centrum, . .075 Vertical diameter of posterior face of centrum, - -. — .070 Transverse diameter of neural canal, .. . .--- .-- .065 Vertical diameter of neural canal, _ — .057 Diameters of anterior capitular face, _ ,_ — . — .0'29-.033 Diameters of posterior capitular face, -. -- .. .0.!9-.040 Antero-posterior diameter of pedicel, .025 Transverse diameter of pedicel, -040 Diameter of vertebra, across transverse processes, — _ — .200 Diameter of vertebra, across post-zygapophyses, — — .080 Least transverse diameter of neural spine, .035 The Third Dorsal Vertebra. (Woodcuts 101 and 102, below.) The third dorsal vertebra in the genera Dinoceras and Tinoceras differs from the vertebra in front of it, in having the neural spine less robust, and the transverse processes, and the faces for the heads of the ribs on the centrum, more elevated. The centrum itself is less expanded transversely, and its leng'th is greater. Fig. 101. Fig- 1C2. J FiGtJEE 101. — Third dorsal vertebra of Uintatherium segne, Marsh (No. 1194); front view. Figure 102. — The same vertebra ; side view. d. transverse process; nc. neural caual ; r. face for head of rib; r'. face for tubercle of rib; s. neural spine. Both figures are one-fourth natural size. The third dorsal in Uintatherium segne (number 1194) shows essentially the same characteristics, and is represented in figures 101 and 102, above. 84 DINOCERATA. The Median and Posterior Dorsal Vertebra. (Plate XXIV; and woodcuts 103-105, below.) In the dorsal vertebra of Dinoceras, behind the third, the neural spine gradually becomes shorter and weaker, and the neural canal, transversely oval in outline. The transverse processes are more elevated, and sliorter. The centrum becomes more compressed below, so that the articular faces are sub-triangular in outline, as shown in Plate XXIV, figure 2. In the posterior dorsals, the neural spine is quite short, and weak. The anterior zygapophyses have their articular faces recurved, as in the ruminant mammals. The neural canal is a broad oval in transverse outline. The transverse processes are much elevated, and the articular faces for the ribs on these, and on the centrum below, gradually become smaller. The centrum is longer, distinctly keeled below, and its articular faces are triangular in outline, the three sides being nearly equal. These features are shown in figures 103-105. The last dorsal vertebra of Dinoceras mirabile (number 1215) is represented in Plate XXIV, figures 5-9. A posterior dorsal of another species is shown below. Figure 103. — Posterior dorsal vertebra of Dinoceras lucare, Marsh (No. 1038); front view. Figure 104. — The same vertebra; side view. Figure 105. — The same vertebra ; back view. n. neural canal ; r. face for head of rib ; r'. face for tubercle of rib ; «. neural spine ; z. anterior zygapophyses ; z'. posterior zygapophysis. All the figures are one-fourth natural size. THE LUMBAR VERTEBRA. 85 The Lumbar Vertebra. (Plates XXV and XXVI.) The last four lumbar vertebrae of the type specimen of Dinoceras mirabUe (number 1036) are preserved, and are figured in Plates XXV and XXVI. The centra are proportionally much longer than in the mastodon, and the most anterior of the four is excavated at the sides, and keeled below, so as to be nearly triangular in a vertical section near the middle. The excavation becomes less decided in the succeeding vertebra^, which are more nearly circular in section. The keel disappears upon the last lumbar, wdiich has its under surface strongly roughened, especially near the posterior margin. The epiphyses of all these vertebrae are imperfectly united with the centra, and are deficient in ossification near the center, forming only thin, and, in some cases, narrow rings of bone. The deficiency of ossification increases the apparent concavity of the articular faces of the centrum. These faces also become more oval transversely on the posterior vertebrae, and especially upon the last lumbar vertebra. The neural canal in all the lumbar vertebrae is large, but has been considerably reduced, in the vertebras of this specimen, by crushing-. The zygapophyses in the lumbar region are strongl}- articulated together. The pre-zygapophyses present a curved surface, bending around, and firmly grasping, the semi-cylindrical post-zygapophyses, which are inserted into them. This form of articulation is found among living Artiodactyls, and existed also in the Oreodons of the Miocene ; while in the Perissodactyl group, and in Proboscidians, the zygapophyses of this region are loosely applied to each other by nearly flat surfaces. The keel on the under surface of the centrum is stout and short on the second vertebra from the sacrum, where it first appears in this specimen, and is strongest on the anterior part of the centrum. On the next preceding vertebra, it is somewhat thinner, but more elongated, extending along the whole under surface of the centrum. On the fourth vertebra from the sacrum, it becomes thin, and even sharp in front. 86 DINOCERATA. The transverse processes are flattened, especially above, and directed nearly horizontally outward. They are much more elongated than in the mastodon, and appear to have been proportionally much stronger than in the tapir. The principal dimensions of four lumbar vertebrae of the type specimen of Dinoceras mirabile are as follows : Measurements of Fourth Lumhur Vertebra from Sacrum. [Dinoceras mmihile. No. 1036.) m. Length of centrum (anterior epiphysis wanting), .080 Vertical diameter of centrum, .087 Vertical diameter of posterior face of centrum, ._^ .075 Transverse diameter of posterior face of centrum (approximate), .088 Measurements of Third Lumbar Vertebra from, Sacrum. (Dinoceras mirabile, No. 10.36.) m. Length of centrum, -, .08.5 Transverse diameter of anterior epiphysis, .091 Vertical diameter of anterior epiphysis, .080 Transverse diameter of posterior epiphysis, .-. .091 Vertical diameter of posterior epiphysis, ._- .078 Measurements of Second Lumbar Vertebra from Sacrmn. [Dinoceras niirabile,'So. 1036.) m. Length of centrum, .. - .086 Transverse diameter of anterior epiphysis (approximate), .090 Vertical diameter of anterior epiphysis, .- 080 Transverse diameter of posterior epiphysis (approximate), .095 Vertical diameter of posterior epiphysis, .083 Measurements of last Lumbar Vertebra. [Dinoceras mirabile, No. 1036.) m. Length of centrum, _ .-- .083 Transverse diameter of anterior epiphysis (approximate), .095 Vertical diameter of anterior epiphysis, . 080 Transverse diameter of posterior epiphysis (approximate), 105 Vei'tical diameter of posterior epiphysis, 075 CHAPTER YII. THE FORE LIMBS. (Plates XXVII-XXXVIII, LV, and LVI.) The limb bones in the Dinocerata are nearly or quite solid, and this is true of all the skeleton, a portion of the skull alone excepted. The fore limbs in the Dinocerata have a general resemblance to those of Proboscidians. The different segments, however, are more inclined to each other, and the bones that compose them are stouter, and more massive. The Scapula. (Plate XXVII.) The scapula of Dinoceras mirabile, in its general form, is similar to that of the elephant. It is triangular in outline, with the anterior, or coracoid, border slightly longer than either of the other two margins, which are about equal to each other, if the glenoid border be considered as including the glenoid cavity. The coracoid border is excavated by a broad rounded emargination, just above the coracoid process, but beyond this sinus, it runs nearly straight to the apex of the bone, which is more acute than in the mastodon. The supra-scapular border is moderately curved throughout, and the posterior angle appears to be less acute than in the Proboscidians. The glenoid border is nearly in a line with the glenoid cavity, so that the constriction above the cavity is scarcely evident in the posterior margin of the bone. 87 88 DINOCERATA. The external surface of tlie scapula is divided into two unequal fossae. The anterior of these, or pre-scapular fossa, extends the entire length of the bone, but is less than half as wide as the post-scapular fossa, from which it is divided by a thick and stout spine. The latter is less elevated than in the elephant and mastodon, and less expanded, but extends farther downward, nearly to the level of the glenoid cavity. It is destitute of the curved posterior process seen in tlie elepliant and mastodon. The post-scapular fossa is strongly roughened near the posterior angle, which is rounded. The glenoid cavity is onh" moderately concave transversely, and somewhat broader behind than before. The inner surface of the scapula is for the most part smooth, except over a large quadrilateral area in the region of tlie apex. The supra- scapular border is ossified separately from the bodv of the bone. The coracoid is firmly united to the scapula in Dlnoceras mirabile (number 1215), and forms a rounded salient process, projecting freely in front of the glenoid cavity. Seen from the front, it appears to be tri-lobed in outline. The main dimensions of the scapula in one specimen of Dlnoceras mlrahile are as follows : Measurements of Left Scapula. {Dinoceras mirabile, No. 1215.) Aiitero-postei'ior diameter of glenoid cavity, .115 Transverse diameter of glenoid cavity, __- -.-. .090 Greatest vertical diameter of scapula, ' .575 Greatest horizontal diameter, .... ... .480 Lengtli of coracoid border, _ .570 Length of supra-scapular border, . .. .390 Length of glenoid border, .350 Height of- acromion above glenoid cavity, .120 Trreatest diameter of pre-seapuL^T fossa, . . .140 Greatest diameter of post-scapular fossa, .310 THE FORE LIMBS. 89 The Humerus. (Plate XXVIII; and woodcuts 106-107, below.) The liLinierus of D'moceras is a strong bone, presenting- roughened and tuberculated surfaces, evidently for the attachment of powerful muscles. In this respect, it is in strong contrast with the comparatively smootli femur, and a glance at the structure of the skeleton, as shown in the restorations in Plates LV and LVI, will suggest a reason for this difference. The hind leg of Dinoceras, like that of the elephant, could be straightened, so that the weight of the hinder part of the body was supported by a vertical column of bones, rising- from the ankle joint to the pelvis, and comparatively little muscular action was required to keep the bones in the requisite position. The elbow joint, on the contrary, was not capable of sufficient extension to bring' the radiiis and ulna into a line with the humerus, but the Aveight of the fore part of the body was supported, as in ordinary quadrupeds, by a long column with more or less flexure near the middle. Constant muscular action was therefore necessary to sustain the weight of this part of the body. The lieavv and strongly armed bead added still more to the muscular efforts required of the fore limbs, during progression, or even while standing- at rest. The proximal end of the humerus (Plate XXVIII, figure 3,ffl) presents a large rounded articular face, or head, more convex antei'O-posteriorly than from side to side. The axis of the head of the humerus forms an angle of nearly 30° with that of the shaft. This angle, while greater than that seen in the same bone of the elephant, is much less than in most quadrupeds. The great tuberosity of the humerus is prominent, but not elevated, and is separated, by a shallow and narrow bicipital g-roove, from the low lesser tuberosity. The great tuberosity is about as large as in the elephant, but does not extend so high, not rising to tbe head of the humerus. It is stiongly tuberculated and roughened, and is continued down the anterior and outer part of the shaft into a prominent ridge below 12 90 DINOCERATA. the middle of the bone. Here it unites with the oblique, and well developed, deltoid ridge, then descends rapidly, and ends in a roughened surface just above, and. inside of, the coronoid. fossa. The deltoid ridge is strong, oblique, and elongated, as is well shown in the back view of the humerus, Plate XXVIII, figure 3. It does not, however, rise into a hook-like process, as in the rhinoceros. The bicipital groove is single, as in the elephant, and presents no median ridge. The lesser tuberosit}' is small and low, and wholly below the head, which is broad and extensive, covering much the greater part of the superior aspect of the bone, and extending forward to the bottom of the bicipital groove. The shaft of the humerus is most constricted at a point nearly three- fourths of the way toward the distal end, and here is distinctly triangular in section, one of the angles projecting forward, as seen in Plate XXVIII, figure 1. Above and below this point, the shaft expands, and is more flattened, especially distally. Here it is excavated in front, as usual, by a large rounded and deep coronoid fossa, placed well to\yard the outer, or radial, side, as shown in Plate XXVIII, figure 1. The posterior surface is hollowed out, medially, by a comparatively shallow anconeal fossa, as shown in figure 3 of the same Plate. The coronoid fossa in some specimens (number 1224) is even deeper than the anconeal, and is always distinct and rounded. The anconeal fossa is also rounded in general outline, median in position, and is carried but little below the trochlear articular face. The posterior surface of the humerus is bounded, on the inner side, by a ridge running almost the entire length of the shaft. This ridge commences above, near the posterior part of the lesser tuberosity, and the postero-internal angle of the head, and runs nearly straight down the shaft of the humerus, terminating in an expanded and tubercular tract, on the inner condyle. On this ridge, and about the middle of the shaft, nearl}' opposite the strongest part of the deltoid ridge, is another roughened area, often, as in the specimen figured (Plate XXVIII, figures 1, 2 and 3), rising into a distinct trochanter-like eminence, appfi.rently for the insertion of the latissimus dorsi muscle. At the lower end of the humerus, tliis ridge THE FORE LIMBS. 91 ends in a large and prominent inner cond3?le, which does not, hoAvever, extend far back of the trochlear surface, as seen in Plate XXVIII, figure l,a. The outer condyle is nearly on the same level as the inner, and extends to about the same distance laterally, from the axis of the bone, as seen in Plate XXVIII, figures 1 and 3. Above, it descends rapidly to the shaft of the bone, and presents only a short and moderately rugose, or nearly smooth, supinator ridge. The trochlear articulation considerably resembles that of the elephant, but is placed a little more obliquely to the axis of the bone. The radius articulated, during life, with the whole of the anterior part of this surface, and tlie ulna, with the whole of the posterior part, the former bone being, at the proximal end, in front of the latter, and scarcely at all on the outer side. The outer part of the trochlear surface is more rounded in both directions than the inner, the surface of which is only moderately curved in a transverse direction. The shaft of the humerus is more or less cancellated within, as shown in the woodcuts, figures 106 and 107, but is destitute of any medullary cavity. Fig. 106. Fig. 107. ^^S FiGUEE 106. — Section of humerus of Dinoceras mirabile, Marsh (No. 1215) ; near proximal end. Figure 107. — Section of humerus of Dinoceras mirabile (So. 1208); below middle. Botli figures are one-fourtli natural size. Measurements of the humerus in four individuals of Dinoceras are as follows : Measurements of Left Humerus. [Dinoceras mirabile^ No. 1245.) m. Total length of humerus, .... ._. -- — - .655 Antero-posterior diameter of head, . .136 Transverse diameter of head, .120 Greatest diameter of proximal end, -220 Least antero-posterior diameter of shaft, - -070 Least transverse diameter of shaft, ■--- -080 92 DINOCERATA. m. Transverse diameter, through condyles, .200 Transverse diameter of trochlear surface, '_ .127 Antero-posterior diameter of trochlear surface, ulnar side, .109 Antero-posterior diameter of trochlear surface, radial side, .091 Antero-posterior diameter of trochlear surface, least, .078 Thickness of bone between coronoid and aneoneal fossa>, .. .016 Measurements of Left Humerus. [Dinoceras mirabile. No. 1208.) m. Least antero-posterior diameter of shaft, . — . __ .064 Transverse diameter, through condyles, .. . .184 Transverse diameter of trochlear surface, _. .124 Antero-posterior diameter of trochlear surface, ulnar side, . _. .100 Antero-posterior diameter of trochlear surface, radial side, .095 Antero-posterior diameter of trochlear surface, least, __. .080 Thickness of bone between coronoid and aneoneal fossie, .Ola Jfeasureiuents of JRight Iliimenis. [Diiioceras mirabile. No. 1212.) m. Least antero-posterior diameter of shaft, . .058 Transverse diameter through condyles, . .183 Transverse diameter of trochlear surface, - .115 Antero-posterior diameter of trochlear surface, ulnar side, .098 Antero-posterior diameter of trochlear surface, radial side, ... .080 Antero-posterior diameter of trochlear surface, least, .072 Thickness of bone between coronoid and aneoneal fossa^, .014 Measurements of JxigJ:t Uumeiiis. [Dinoceras mirabile, No. 1215.) m. Antero-posterior diameter of head, .. .140 Transverse diameter of head, .138 Greatest diameter of jwoximal end, .220 Antero-posterior diameter of trochlear surface, ulnar side, .116 The Forearm. (Plates LV and LVI.) The two bones of the forearm in tlie B'mocerata are quite distinct throughout in all the specimens observed, and, exclusive of the olecranon process of the idna, differ but little in size. The articular surface for the humerus is formed in about equal parts by each bone, except that it is medially produced back\Yard on the ulna upon the beak of the olecranon. The distal articular face for the carpus was borne more by the radius than the ulna, but the inequality, in size, of the articular faces was comparatively slight. The lunar articulated distinctly with both bones. THE FORE LIMBS. 93 Tlie articular surfaces of the radius and the uhia for each other were nearly parallel with the axes of those bones, and allowed of little else than a slig'ht antero-posterior gliding motion. Tlie roughened and co-adapted surfaces of the bones indicate that, during life, all movements of pronation and supination were prevented by po^verful ligaments. The radius does not appear so distinctly to cross the ulna as in the Proboscidians, being, at the upper end, in front of that bone, and proportionally much larger, then passing down obliquely inward to a position within the distal end of the ulna. The proportion of the two bones to each other is much nearer that seeu'in "the rhinoceros and hippopotamus, than that in the elephant. • The Eadius. (Plate XXIX; and woodcuts 108-109, below.) The radius in Dinoceras is a strong bone, with its shaft about equal in size to that of the ulna. It is considerably larger than that bone at the lower end, and smaller at the upper end. The head, or superior articular face, occupies the entire surface of the proximal end. This surface is elongate oval in outline, the long diameter being placed transversely, and nearly twice as great as the short diameter. The latter is antei'o-posterior in direction, in the ordinary-, nearly vertical position of the bone. It crosses the surface of the bone nearly in the middle, instead of toward the inner side of the middle, as in most Ungulates. Antero-posteriorly, the articular surface is concave throughout, but transversely, it is convex on the inner side, and concave on the outer side of the middle line. The inner half of the articular surface is thus traversed by a low antero-posterior ridge, or elevation, which moves upon tlie groove in the distal articular face of tlie humerus. The proximal surface of tlie radius differs from that of the elephant in being proportionally much larger, and extending quite aci-oss the Immeral articular surface. It differs from that of the tapir, and the liippopotamus, in having only a single antero-posterior ridge, as in the rhinoceros. It still differs from that of the rhinoceros, in the fact, that a transverse section 94 DINOCERATA. is concave in its outer half, and convex in its inner half, while in the rhinoceros, such a section is concave at each end, and convex only near the median portion. On the side of the radius toward the ulna, is a narrow articular surface for that bone, becoming broader toward the outer end. The shaft of the radius is smallest at a point about one-third of the way from the proximal, toward the distal end. Above this point, the bone expands rather rapidly toward the head. It is much roughened, especially on the side toward the ulna, with which, however, it forms no bony union; nor are the bones roughened, or grooved for close adaptation to each- other, as in the tapir and rhinoceros. The bicipital tuberosity is well developed, and placed rather low down on the side of the shaft, instead of on the front part of it. The distal end of the shaft is large, rough, and oblique, and presents no smooth grooves for tendons. The distal articular face is divided by a median ridge into two sub-equal facets, for the scaphoid and lunar bones of the carpus. These facets are confluent along the summit of the median ridge. That for the scaphoid is semi-circular in outline, and concave in both directions, while that for the lunar is four-sided, much broader in front than behind, and concave throughout. Near the back part of the ulnar side of this facet, the articular face is continued into a small tract on the lateral surface of the radius, where it- comes in contact with the ulna. The shaft of the radius has an interior cancellated structure, as shown in the figures below, but no medullary cavity Figure 108. — Section of radius of Diiioceras mirabile, Marsh (No. 1195). Figure 109. — Section ol raiiua oi Dinoceras mirabile, Maish (No. 1234). Both figures are one-fourth natural size. Measurements of the radius in three individuals of Dinoceras are the following : THE FORE LIMBS. 95 Measurements of Left Radius. [Dinoceras mirabile, No. 1208.) m. Total length of radius, .380 Greatest diameter of proximal end, .098 Antero-posterior diameter of proximal end, .061 Least diameters of shaft, 032-.053 Transverse diameter of distal end, _... .102 Antero-posterior diameter of distal end, . 080 Diameters of articulation for humerus, .052-.094 Antero-posterior diameter of face for scajjhoid, .055 Transverse diameter of face for scaphoid, .. .039 Antero-posterior diameter of face for lunar, .056 Transverse diameter of face for lunar, .045 Transverse diameter of distal articular surfaces, .082 3feasHreme?i(s of Left Madius. {Dinocems mirabile, l.^o. 1206.) m. Total length of radius, .254 Greatest diameter of proximal end, ... .116 Antero-posterior diameter of proximal end, .071 Least diameters of shaft, . 062-.041 Transverse diameter, distal end, .011 Antero-posterior diameter, distal end, .097 Diameters of articulation for humerus, 060- 108 Antero-posterior diameter of articulation for scaphoid, .065 Transverse diameter of articulation for scajAoid, .040 Antero-posterior diameter of articulation for lunar, : . .065 Transverse diameter of articulation for lunar, .055 Transverse diameter of distal articular surfaces, .093 Meastirements of Right Radius. {Dinoceras, No. 1548.) m. Length of radius, -_--.. .-_ . .400 Greatest diameter of proximal end, .112 Antero-posterior diameter of proximal end, . .070 Least diameters of shaft, 063-.035 Transverse diameter of distal end, .108 Antero-posterior diameter of distal end, .. . .090 Diameters of articulation for humerus, 060-.104 Transverse diameter of articulation for scaphoid, .047 Antero-posterior diameter of articulation for lunar, .055 Transverse diameter of articulation for lunar, .045 Transverse diameter of distal articular surfaces, . .092 96 DINOCEKATA. The Ulna. (Plate XXX; and woodcuts 110-111, below.) The ulna in the JDinocerata is a solid and heavy bone, longer than the radius, as usual, by the length of the olecranon process. Except near the distal end, it is larger and stouter than that bone, to which it was united in life by ligaments only, but in such a manner as to allow of little motion between them. The shaft of the ulna always made, even at its utmost extension, a distinct angle with that of the humerus. The ulna in Dinoceras is proportionally less robust than in the elephant. Its distal encl is comparatively smaller than in that animal, and, at the proximal end, a much smaller proportion of the articular surface for the humerus is furnished by the ulna. The olecranon process is robust, as in the Proboscidians, but it is carried farther above the articular surface, and less directh" behind it, than in that group. It is much higher within than without, and posteriorly, it is strongly roughened as low down as the middle of the humeral articulation. It is only moderately produced backward, and descends into a broad ridge, insensibly blending below with the shaft of the bone. Below the humeral articular surface, the shaft of the ulna is sub-triangular in section, or, near the distal end, some\^hat quadrilateral. Along the posterior and outer side of the bone, is a rounded ridge, running from the olecranon process above, to the outer angle of the articular face below. The face by which the idna is applied to the radius is broadl}- excavated, and strongly roughened above, '\vhere it is nearly on the front surface of the bone. It is moderately flattened along the shaft of the bone, and is carried around to the inner surface toward the distal end, where it is broad, flat, and distinctly roughened. The anterior face of the bone is also flattened near the distal end, and separated from the outer face by a ridge, which extends upward to ■ near the middle of the shaft. Tlie postero-external face of the bone is flattened, or only moderately rounded, and is somewhat excavated behind the lower part of the humeral articulation. THE FORE LIMBS. 97 This articulation presents a striking difference in direction from that seen in the corresponding face on the nhia of the elephant and mastodon. It is so placed on the shaft of the bone as to look almost directly forward, and only veiy slightly upward, instead of looking nearly upward, as in the mastodon. It forms, comparatively, a much smaller part of the face for the humei'al trochlea. In shape, this articulation is distinctly tri-lobate. One rounded lobe, convex from side to side, runs backward and upward to the summit of the beak of the olecranon. A second, and large lobe, moderately concave in both directions, runs inw^ard, articulating with the ulnar portion of the trochlea of the humerus. An outer, small and flattened, lobe articulates with the posterior part of the radial surface of the trochlea. The front, or lower, outline of the articular face is modei-ately concave, and adapted to the surface of the radius by a narrow face, becoming wider toward each extremity. Tlie distal end of the ulna is terminated by an articular surface, which is somewhat quadrant-shaped. The inner and posterior outlines are nearly straight, and meet at a right angle, while the anterior and outer margins are formed by a curved line. This face is convex in an antero-posterior direction, strongly so behind. In a transverse direction, it is moderately concave, except near the inner edge, where it is broadly beveled off, for union with the lunar bone of the carpus. Much the larger part of the distal articular face of the ulna articulated, during life, with the pyramidal bone, or the cuneiform bone of mauA- anatomists. Posteriorly, a surface was presented for the pisiform, and, on the inner side, a narrow beveled surface united with the lunar bone. Farther within, and on the surface of the shaft of the bone, a small surface was presented to the radius, although the two bones, as ah-eady stated, were strongly fixed, during life, in their relation to each other, 13 98 DINOCERATA. The inner texture of the shaft of the nlna is similar to that of the radius, as indicated in the sections represented below, figures 110 and 111. KiG. nil. Fig. ill. FiG-URB no. — Section of ulna of JDinoceras lucare, Marsh (No. lOSS). Figure 111. — Section of ulna of Binoceras mirabile, Marsh (No. 1548). Eolh figures are one-fourth natural size. The principal dimensions of the ulna in three individuals of JDinoceras are as follows : Measurements of Left Ulna. [Dinoceras mirabile, No. 1206.) m. Total length of ulna, .530 Diameters of proximal end, .095-140 Transverse diameter of shaft, behind humeral articular face, .055 Diameter of shaft, through humeral articular face, 097 Diameters of shaft, near the middle, ,_- .(i57-.081 Antero-posterior diameter of shaft, near distal end, . .085 Transverse diameter of shaft, near distal end, .067 Transverse diameter of humeral articulation, greatest, . 143 Transverse diameter of humeral articulation, least, .060 Antero-posterior diameter of humeral articulation, at the middle, . .085 Antero-posterior diameter of humeral articulation, inner lobe, - . .063 Antero-posterior diameter of humeral articulation, outer lobe, .045 Transverse diameter of distal articular surface, .076 Antero-posterior diameter of distal articular surface, .070 Least and greatest diameters of diital articular surface, _ _. .067-097 Measurements of Right Ulna. {Dinoceras mirabile, ISo. 1232.) m. Total length of ulna, .555 Diameters of jjroximal end, .098-130 Transverse diameter of shaft, behind humeral articulation, .065 Diameter of shaft, through hui-iieral articulation, .103 Diameters of shaft, near the middle, .067-.077 Antero-posterior diameter of shaft, near di.-stal end, .... • .095 Transverse diameter of shaft, near distal end, .084 Least transverse diameter of humeral articulation,. — .058 Antero-posterior diameter of humeral articulation, at the middle, . . . .086 THE FOHE LIMBS. 99 Antero-posterior diameter of humeral articulation, inner lobe,. .066 Transverse diameter of distal articular surface,. - .073 Antei'o-posterior diameter of distal articular surface, .061 Greatest diameter of distal articular surface, .090 Measurements of Right Ulna. [Dinooeras liicare,l^o. 1038.) m. Diameters of proximal end of ulna (approximate), . 070-103 Diameter of shaft, behind humeral articulation, .052 Diameter of shaft, through humeral articulation, . .088 Greatest transverse diameter of humeral articulation, .125 Least transverse diameter of humeral articulation, .052 Antero-posterior diameter of humeral articulation, at the middle, ... .090 Antero-posterior diameter of humeral articulation, inner lobe, . _ .062 Antero-posterior diameter of humeral articulation, outer lobe, . . .038 CHAPTER YIII THE FORE LIMBS. (Continued.) (Plates XXXI-XXXVIII, LIV, LV and LVI). The fore foot in all the Binocerata is larger than the hind foot. The bones composing it are comparatively short and massive. There were five well developed digits, as in Proboscidians, but the carpal bones were interlocked with the metacarpals, as in Perissodactyls. The general appearance of the fore foot in Binoceras mirabile is well shown in Plate LIV, figure 1. The hind foot is represented in figure 2 of the same Plate. The feet were plantigrade, as in the elephant, and in their more important characters were much like those of Coryphodon. The Carpal Bones. (Plates XXXI-XXXIV; and Avoodcuts 112-124, below.) There are eight separate carpal bones in the fore foot of all the Binocerata, and a ninth, the central bone, may be separate in very young animals, and, in adults, either lost or consolidated with the scaphoid, or the trapezoid. 101 102 DINOCEUATA. The Scaphoid. (Plate XXXI, figures 1-6, Plate LIV, figure 1, s; and woodcuts 112-113, below.) The scaphoid in the Dinocerata is a peculiar bone of characteristic shape. It is quite large, its length, along the axis of the limb, being greater than that of any other bone of the carpus. Proximally, it presents a strongly rounded, almost hemispherical surface, for articulation with the radius. This articular face covers the entire proximal end of the bone, and is oblique to its axis, the side toward the lunar being much higher than the opposite side. The ulnar side, in apposition with the lunar, has a proximal articular surface confluent with the radial surface, and extending less than one-fourth the length of the bone. Distally, the scaphoid presents two confluent articular faces, one for the trapezium, and a second smaller one, somewhat in front of the other, for the trapezoid. These two faces are but indistinctly separated from each other, and are, for most of their extent, convex in both directions. The ulnar side of the bone also presents two confluent, but well marked, articular surfaces, making an obtuse angle with each other. Of these, the anterior is nearly flat, and joins the lunar. The jiosterior is more convex, and adapted to the magnum. This face does not reach the anterior angle of the bone, so that the magnum is supported in front by the lunar alone, but articulates behind with the scaphoid also. The projection supporting these two faces may perhaps represent the central bone, coalesced with the scaphoid. The latter shows no face for a separate central bone. The two proximal articular faces are well separated from the four at the distal end of the scaphoid bone by a large area of non-articular surface. This tract becomes elevated, and strongly tuberculated, on the exterior side of the bone, while it is smoother, and somewhat excavated, on the side turned toward the lunar and the magnum. In Plate LIV, figure 1, the scaphoid and lunar bones are slightly out of position, but every anatomist will see their true relations to each other. The scaphoid in Dinoceras laticeps (number 1264), like most others (except number 1208), shows, near the distal i)ortion of the radial side, below the rugose surface, a deep ami somewliat oblique depression. THE FORE FEET. 103 The scaphoid in two specimens of Diuoceras are represented in the figures below. Figure 112. — Left scaphoid of Diuoceras laticeps. Marsh (1261); side view FiGnRE 113. — Right scaphoid of Dinoceras mirabile, Marsli (1200) ; side view r. face for radius; im. tace for trapezium; tr. face for trapr-zoid. Both figures are one-half natural size. The principal dimensions of the scaphoid in three individuals of Dinoceras are as follows : Measurements of Left Scaphoid. [Dinoceras niirabih, No. 1208.) m. Length of longitudinal axis of scaphoid, .077 Length of transverse axes, ■,. . 049-049 Antero-jjostei-ior diameter of radial articular surface, . _ _ _ 051 Transverse diameter of radial articular surface, .045 Antero-posterior diameter of distal articular surface, .070 Transverse diameter of distal articular surface, .044 Measurements of Might Scaphoid. [Diuoceras mirahile, No. 1200.) Length of longitudinal axis of scaphoid, . _ ^ . .(i7l Length of transverse axes, ,_ .073-064 Antero-posterior diameter of radial articular surface, .__._., ... .046 Transverse diameter of radial articular surface, 038 Antero-posterior diameter of distal articular surface, .066 Transverse diameter of distal articular surface, ... . _' .038 Measurements of Left Scaphoid. [Dinoceras laticeps. No. 1264.) Length of longitudinal axis of scaphoid, _ .086 Length of transverse axes, ... 051-.060 Antero-posterior diameter of radial articular surface, ... ... .060 Transverse diameter of radial articular surface, .046 Antero-posterior diameter of distal articular surface, .082 Transverse diameter of distal articular surface, .050 104 DINOCERATA. The Lunae. (Plate XXXI, figures 7-12, Plate LIV, figure 1, I; and woodcuts 114-116, below.) The lunar bone in the Binocerata (Plate XXXI, figures 7-12) bears some resemblance to the corresponding bone in the elephant, but ditfers widely from it in having its 23roximal siu-face, for articulation with the radius and iilna, convex throughout, instead of being for tlie most part concave. The distal surface, also, presents two distinct articular faces, instead of being covered with a single large face, as in the elephant. The exterior surface of the lunar, or the face seen in front when the bone is in its natural position with the other bones of the foot, is represented on Plate XXXI, figure 7. This surface is coarsely roughened, and is widest above. Only a small portion of the edges of any of the articular surfaces can be seen in this view. Tlie inner angle of the distal end of the lunar in Dinoceras (numbers 1215, 1229, and 1230) is truncated by a small face for articulation with the trapezoid bone, as shown in figure 7, and also in woodcut 114, below. On one specimen (number 1575), which may belong to Uintatherium, this face is large and convex. In number 1254, the face is smaller than in the specimens figured. The articulation of the lunar with the trapezoid, or perhaps the trapezo-central bone, occurs also in Coryphodon, Mastodon, and the elephant, especially the African spe'cies. The lateral surface of the bone turned toward the scaphoid, and articulating with it, is shown on Plate XXXI, figure 8. This side has two faces for articulation with the scaphoid. The upper one of these runs along nearly the whole extent of the superior margin of the bone, and is confluent with the surface for articulation with the radius, and hardly to be distinguished from it. A second articular face for union with the scaphoid is broader and more flattened than tlie first, and extends along rather more than half of the distal margin near its front, or anterior, end. Behind this articular surface, the bone is produced into a short, hook-shaped process sustaining the concave portion of the distal articulations. The posterior surface of the lunar is sliown on the same Plate, figure 9, and presents no articular faces. The lateral surface turned toward the THE I'^ORE FEET. 105 pyramidal is shown in fig'ure 10. Two narrow and approximate faces are seen on this surface, becoming somewhat wdder, and approaching each other behind. These faces vary greatly in the degree to which they are developed in different specimens. The upper, or proximal, surface is confluent with the ulnar facet, while the lower, or distal, one is continuous with the face for the imciform, but usually well distinguished from it by a ridge. The proximal surface (figure 11), articulating with the radius, is more or less quadrangular in outline, broader in front, sometimes so much so as to become sub-triangular in outline (number 1218). It is well rounded in both directions throughout, the smooth articular face for radius and ulna being cai-ried over on each side to join both the scaphoid and the pyramidal foces. Fu;. 115. Fig-. 114. FiGUKE 114. — Kight lunar of Dinoceras rairabile, ilarsli (No. 12:;0); front view. FiGDUB 115. — Left lunar of Tiiioceras ingens, Marsh (No. 1504); bottom vieTi'. FiGUEE 116. — Left luuar of Tinoceras ingens (No. 1219) ; front view. m. face for magnum; p. face for pyramidal ; r. face for radius; •?. face for scaphoid; Figure 125. — Second rib of Uintatherium latifrons, Marsh (No. 1231^; posterior view. Figure 126. — The same rib; front view. Figure 127. — The same rib ; inner view. FlGUBE 128. — The same rib ; proximal end. h. head ; t. tubercle. All tlie figures are one-fourth natural size. The second rib is much longer, and less robust, than the first, above described. The head is large, and the two articular faces on it are confluent. The tubercle is well developed, and at nearly the same level as the head. The shaft is only moderately curved, and considerably compressed. The distal end is flattened, and wider than the shaft. THE RIBS AND STERNUM. 131 The ribs behind the second gradually increase in length, and become more cm-ved. The head remains large, and its articular faces are usually separated from each other, as shown in figures 129-132, below. \ \ FlGtTRE 129. — Anterioi' rib of Binoceras mirabile, Marsh (No. 1212); postfirior view. Figure 13U. — Tlie same rib: inner view. Figure 131. — The same rib; front view. Figure 132. — Tlie same rib; proximal end. h. head; t. tubercle. All the figures are one- fourth natural size. 132 DINOCERATA. The main dimensions of the first rib in one individual of Dinoceras mirahile are as follows : Measurements of First Rib. {Dinoceras mirahile, No. 1251.) m. Total length of rib, .320 Greatest diameter of head, .. .038 Transverse diameter of head, •_ .032 Diameters of tubercular articulation, .020-030 Diameters of shaft, near the middle, 021-040 Diameters of shaft, at sternal end, 027-095 The principal measm-ements of the second rib of Uintatheriiim are given below. Measurements of Second Mib. {Uintatherium latifrons. No 1231.) m. Total length of rib, in straight line, _- ... ..... .. .440 Greatest diameter of head, .055 Transverse diameter of head, _. .030 Diameter of tubercular articular face, .. . .024 Diameters of shaft, near the middle, .. .020-.039 Diameters of shaft, at lower end (approximate), _ .025-.060 The dimensions of two dorsal ribs of Dinoceras are as follows : Measurements of Anterior Rih. [Dinoceras mirabile, 'So. 1212.) m. Total length of rib, in straight line, ,500 Greatest diameter of head, : .048 Transverse diameter of head, — .036 Diameter of tubercular articular face (approximate), .. — .. .. — .023 Diameters of shaft, near the middle,..,. _. .022-060 Diameters of shaft, at lower end (approximate), — .025-038 Measurements of Median Rib. [Dinoceras mirahile, No. 1210.) m. Total length of rib, in a straight line, .605 Diameters of head, .047-.ii58-.0U5 Diameters of neck, .034-.039 Diameters of shaft, .017-057 THE RIBS AND STERNUM. 133 The Posterior Ribs. (Plate XXXIX, figures 4-9.) The posterior ribs gradually diminish in length, and become more slender, but the curvature is still strongly marked. In most of them, the head is large, and the two articular faces on it, distinct. The tubercle diminishes in size, and toward the last is a mere sessile articular face. The sternal ribs are not preserved in any of the known specimens of the Dinocerata, and they were probably unossified. Their general form and position are indicated in the restorations, Plates LV and LVI. The more important dimensions of two posterior ribs in the type of Binoceras mirabile are the following : Measurements of Dorsal Rib. (Dinoceras tnirabile. No. 1036.) m. Totnl length of rib, in straight line, .530 Greatest diameter of head, .. _ ._.__ .052 Transverse diameter of head, .037 Least diameter of shaft, near the middle, .015 Diameters of shaft, at broadest point, .. 025-.060 Measurements of Posterior Rib. {^Dinoceras mirabile. No. 1036.) m. Total length of rib, in straight line, ... 520 Greatest diameter of head, .056 Transverse diameter of head, __ .062 Diameters of shaft, at broadest point, .016-051 The Sternum. (Plate XL; and woodcut 133, below.) Sternal bones are preserved in a number of individuals of the Dinocerata in the Yale Museum, but the entire series in any one individual has not been recovered. The general form and character of these bones are shown in the figures, Plate XL. A series in the natural position is represented in the woodcut below. 134 DINOCERATA. The most marked charactev of these bones in the Dlnocerata is that they are flat and horizontal, as in the Artiodactjds, and not vertical, as in the Proboscidians, and the Perissodactyls. The first bone of the series, or the pre-sternum, is compressed, pointed in front, and, at this end, has two distinct facets for the first pair of ribs. This bone is shown in Plate XL, figu]-es 1, 2, and 3. Tlie bones which' follow, and compose the meso-sternum, are broad and flat, somewhat constricted near the middle, with the ends more or less convex. The anterior ends are usually strongly convex, while the posterior exti'emities may be nearly flat. Two examples of these median sternal bones are shown in the same Plate, figures 4-9, as well as in the woodcut below. Figure 133. — Sternum of Dinoceras mirahile, Mnrsb; top view. One-fifth natural size. The last sternal bone of the series, or tlie xiphi-sternum, is also broad and flat, but has tlie posterior extremity pointed. This bone is shown in figures 10-12, of the same Plate. The surface of all the sternal bones is quite i-ugose, and tlie extremities are deeply pitted for union with tlie cartilage that held them in position. No indication of clavicles lias been observed. CHAPTER X. THE PELVIC ARCH AND TAIL. (Plates XLI, XLII, XLIII, LV, and LVI.) The Pelvis. (Plates XLI-XLII ; and woodcuts 134-135, below.) In all the known specimens of the Dinocerata in which the pelvic arcli is preserved, the ilium, ischium, and pubis are firmly coosified with each other, but not with the sacrum. The three pelvic bones on each side unite with each other eai-lier, and much more closely, than they do with the sacrum above, or with the opposite pelvic bones below. The sutures for the latter union remained open until the animal was fully adult, and, even then in some specimens, were readily separated. These features are well shown in Plate XLI. The pelvis of Binoceras may be compared with that of the elephant, to which it bears a considerable resemblance, but from which it differs in many important particulars. The ilia are much expanded, and nearly quadrant-shaped in outline, the supra-iliac border being very regularly curved, and only moderately thickened near its union with the acetabular border, which it joins at about a right angle. The iliac surface is moderately concave in both directions, especially near the surface for union with the sacrum. The gluteal surface is nearly flat where most expanded, but becomes convex in the acetabular region. It rises but little above the sacral articular surface, which is short, somewhat triangular in outline, and 136 DINOCERATA. presents a strong union with the transverse processes of the first two sacral vertebrae. The ilia are more rounded in outline, and tlie puhes are less firmly united at the symphysis, than in the mastodon. The ischia, also, do not unite at all, as in that animal, but are rounded off, and distant from each other. Fig. 134. Figure 134. — Pelvis of Tinoceras ingens, Mavsii (So. 1-197); sceu f'loiu bulow. Figure 135. — The same; front Mew a. aeetabiihiui ; /. thyroid foramen; il ilium; is. ischium; ^>. pubis; s. anterior end of sacrum; 6'. posterior end of sacrum. Both fiKures are one-cii'hlh natural size. THE PELVIC ARCH AND TAIL. 137 The pelvic arch in Tinoceras is similar, in its general featui'es, to that of Dinoceras, but presents various differences which are apparent in comparing the figures 134 and 135, above, with the corresponding views of the type specimen of Dinoceras mirahile represented in Plate XLI. The sacrum in Dinoceras differs from that of Mastodon Americanus in having four sacral vertebrae instead of five, and much larger transverse processes, for articulation with the ilia. The foramina between these processes are also proportionally much larger. Only the first two of the processes unite strongly with the ilium, instead of four, as in the mastodon. Both the sacrum, and the face for attachment to the ilium, are proportionally much shorter than in the mastodon. The more important dimensions of the pelvic arch in the type sj^ecimen of Dinoceras mirahile, and in one individual of Tinoceras ingens, are the following : Measurements of Pelvis. [Dinoceras mirable. No. 1036.) m. Greatest transverse diameter, across ilia, 1.120 Horizontal diameter of pelvic opening (approximate), .350 Vertical diameter of pelvic opening (approximate), .250 Diameter across acetabula, ._ .660 Diameters of acetabulum, ..i .110-. 125 Diameters of thyroid foramen, ..-. . .075-. 150 Length of symphysis pubis, ... ._. .140 Length of four sacral vertebra} (approximate), .245 Extent of transverse processes of first sacral, - - .330 Horizontal diameter of anterior face of first sacral, .110 Vertical diameter of anterior face of first sacral, .075 Length of first sacral centrum, ._ 075 Measurements of Pelvis. [Tinoceras ingens, No. 1497.) m. Greatest transverse diameter, across ilia, 1.180 Horizontal diameter of pelvic opening (approximate), . .400 Vertical diameter of pelvic opening (approximate), .300 Diameter across acetabula, .. .700 Diameters of thyroid foramen, -_ .060— 150 Length of symphysis pubis, •_ .140 Length of four sacral vertebrae, _ _. ._. .295 Extent of transverse processes of first sacral, .355 Horizontal diameter of anterior face of first sacral, ., .117 18 138 DINOCERATA. m. Vertical diameter of anterior face of first sacral, .-. -072 Length of centrum of first sacral, __. .085 Length of centrum of second sacral, .O'ZS Length of centrum of third sacral, . .065 Length of centrum of fourth sacral, . .067 The Caudal Vertebra. (Plate XLIII ; and woodcut 136, below.) The anterior caudal vertebrae of the Dinocerata have the centra short and flat, with long and depressed transverse processes. The neural spine is only moderately developed. The neural arch is low, and situated on the anterior two-thirds of the centra. The zygapophyses are weak, and their articular faces usually curved. In the median caudals, the transverse processes become shorter, and gradually disappear. The distal caudals are cylindrical, and of moderate length. They are without zygapophyses, or neural arches, as seen in figure 136, below. Figure 136. — Caudal vertebra of Dinoceras laticeps, Marsh (No. 1039). a. proximal end; 6. side view; c. distal end. All the figures are one-half natural size. The under surface of the caudal vertebrae is rugose, and there are no chevron bones. CHAPTER XL THE HIND LIMBS. (Plates XLIV, XLV, XLVI, LV, and LVI.) The hind Hmbs of the Dinocerata have a general resemblance to those of Proboscidians, but the bones composing' them are comparatively shorter, and more robust. When the animal was standing at rest, the posterior limb formed a strong and nearly vertical column. The contrast in this respect between the hind and the fore limb has already been stated, in the description of the latter in Chapter VII. The Femur. (Plate XLIV; and woodcuts 137-138, below.) The femur in the Dinocerata is proportionally shorter than in the elephant. It is much smoother throughout than the humerus, and is also somewhat longer than that bone. The head of the femur is hemispherical, and its axis makes an angle of about fifteen degrees with the axis of the shaft of the bone. The diameter of the head is contained about five and one-half times in the length of the femur. There is no indication of any pit for the round 139 140 DIXOCEHATA. ligament, as is seen in Plate XLIV, figure 3 a. The great trochanter scarcely rises above the base of the head. It is flattened, and posteriorly is excavated below. The upper end of the shaft is broad, flattened in a fore and aft direction, and is excavated behind, especially below the great trochanter. It contracts in transverse diameter gradually to a minimum, near the middle of the shaft, and just below the trochanter minor, where it is flattened behind, but strongly rounded in front. Below this point, it becomes flat behind, and, lower still, is excavated, while the anterior surface is rounded throughout. The anterior and posterior surfaces of the bone, along the inner side, pass into each other by gradual curvature, except in the region of the trochanter minor. The latter process is less than one-third of the way down the shaft, and somewhat stronger than in the elephant. There is no third trochanter. The cui-ved front surface of the femur is separated from the flattened posterior face by a rounded ridge, extending along the outer and posterior sides nearly the entire length of the shaft. This ridge sharply separates the two faces, but nowhere rises conspicuously above the general sm-face of the bone, and disappears near the proximal end. Near the distal end, the surface is roughened, but is destitute of the conspicuous fossa above the outer condyle, seen in the horse and the hippopotamus. The condyles resemble those of the elephant, and, as in that animal, are so placed upon the end of the shaft as to permit the knee-joint to be straightened wdien standing at rest, and in walking. The characteristic elephantine gait must, therefore, have been assumed by the Dinocerata. The innei- condyle is a little greater than the outer in transverse diameter, but much less in antero-posterior dimensions. The two are separated from each other by a deej:) narrow sulcus, but both are completely confluent above with the shallow and short groove for the patella. This groove is broadly rounded from side to side, and less distinctly pulley-shaped, than in the elephant. It is near the middle of the anterior surface of the bone, and does not rise above the general sm-face, except to a very small extent along its lateral margins, which are acute, and sub-equal in height THE HIND LIMBS. 141 There is no medullary cavity in the femur, the inner texture of the shaft being merely somewhat cancellated, as shown in the woodcuts below. Figure ]37. — Section of femur oi Dinoceras mirabile, Jlarsli (No. 1206). Figure 138. — Section of same bone (No. ]210). Both figures are one-fourth natural size. The main dimensions of the femur in one specimen of Dinoceras are given below. Measiireinents of Right Femur. (Dinoceras mirabile, No. 1206.) m. Length of femur, . . .. .690 Diameters of head, .12.3-126 Distance from summit of head to tiochanter minor, . .200 Height of trochanter minor, .__ ..._ .015 Transverse diameter through great trochanter, . _ .. . .215 Least diameters of shaft, ... .... .067-.093 Transverse diameter of distal end, _ . _. .170 Greatest antero-posterior diameter of distal end, 160 Least antero-posterior diameter of distal end, . . .100 Transverse diameter of inner condyle, .065 Transverse diameter of outer condyle, ^ .... .. .070 The Tibia. (Plate XLV.) The tibia in the JDinocerata is much shorter than tlie femur, as in the elephant and the mastodon, and considerably resembles the same bone in these animals. It differs noticeably in the greater prominence of the tuberosity for the attachment of the patellar ligament. The proximal articular surfaces for the condyles of the femur are confluent, or very nearly so, being separated by only a low, smooth and rounded ridge, as seen in Plate XLV, figure 3 a. The inner face is larger in antero-posterior diameter than the outer, and is concave 142 DINOCERATA. throughout in both directions, except for a very small area near its posterior margin. The outer face is shoi'ter, but much broader than the inner, and posteriorly is much more convex, and thus adapted, in extreme flexion of the leg, to a concave face on the outer condyle of the femur. These faces may indicate the presence of a flabella. Below the oixter and posterior part of this articular surface, is a small flattened facet, looking nearly downward, and somewhat outward and backward, for articulation with the fibula. The upper end of the shaft presents in front a deep rounded excavation, bounded at the sides and below by a roughened curved ridge for muscular attachment. The shaft is conti-acted in the middle, but expands below, and has its distal end nearly covered by the broad surface for articulation with the astragalus. This articular face is confluent along its outer margin with a small oblique face for the distal end of the fibula. It is concave antero- posteriorly, but, in transverse section across the middle, is at first slightly convex on the internal malleolus, then concave, and again moderately convex to the margin of the fibular articulation. This face is represented in Plate XLV, figure 1 a. The tibia is nearly, or quite, solid, as shown in figure 5 of the same Plate. Measurements of Tibia. {Dinoceras mirabile, No. 1208.) m. Total length of tibia, .-_ .390 Greatest diameter, proximal end, .140 Antero-posterior diameter, below patella, . .096 Antero-posterior diameter of inner proximal articular surface, - .080 Transverse diameter of inner proximal articular surface, . _ . 062 Antero-fiosterior diameter of outer proximal articular surface, — .070 Transverse diameter of outer proximal articular surface, .075 Greatest diaiiieter of fibidar articular surface, . .033 Least diameter of fibular articul.ar surface, .027 Least diameters of shaft, . . — .052-.057 Greatest diameter, distal end, ... ._.... .107 Antero-posterior diametei', distal end, .093 Greatest diameter of astragalar surface (approximate), .095 Antero-posterior diameters of astragalar surface, ...-. .067-080 Antero-posterior diameter of distal fibular surface, _ _ . _ .035 Least diameter of distal fibular surface, - 015 THE HIND LIMBS. 143 The Fibula. (Plate XLVI, figures 1-4.) The fibula is slender, and entire, with articular faces well marked at each extremity. The proximal end is somewhat expanded, and has the articular face for union with the tibia oblique, and sub-oval in outline. The shaft is somewhat twisted, and sub-triangular in transverse section. The distal end of the fibula is larger than that above, and quite rugose. The articulation for union with the astragalus is large, and placed obliquely, as shown in Plate XLVI, figure 4. In some specimens of the Dinocerata, and probably in all, the fibula met the calcaneum, as in Corypliodon, and the Artiodfictyls. Measurements of the fibula in two individuals of JDinoceras are as follows : Measurements of Fibula. [Dinoceras niirabile, No. 1208.) m. Length of fibula (approximate), , .350 Diameters of proximal end, .040-045 Diameters of proximal articular surface, . .028-033 Measurements of Fibula. {Dinoceras mirabile, No. 1210.) m. Diameters of shaft, .028-020 Diameters of distal end, .040-070 Diam.eters of distal articular surface (approximate), .050-045 The Patella. (Plate XLVI, figures 5-8.) The patella in the Dinocerata is a large bone, and resembles, in its general features, that of the elephant, Its external surface is quite rugose. The articular surface for union with the condyles of the femur is sub-oval in outline, concaA^e from above downward, and transversely convex in consequence of the usual median swelling. The general characteristics are well represented in Plate XLVI, and its position in the skeleton is shown in the restorations at the end of the volume, Plates LV and LVI. CHAPTER XII. THE HIND LIMBS. (Continued.) (Plates XLVII-LVI.) The hind feet in the JDinocerata were considerably smaller than those in front. Their component parts are short and robust, forming together a strong support for the massive hind limbs. There were five digits, as in the Proboscidians, and the axis of the foot was through the third, or middle, digit. The general appearance of the hind foot in Dinoceras mirahile is represented in Plate LIV, figure 2. The fore foot, or manus, is seen in figure 1 of the same Plate, and both feet are shown in different positions in the restorations. Plates LV and LVI. The Tarsal Bones. (Plates XLYII-L, Plate LIV, figure 2 ; and woodcuts 139-146, below.) There are seven well developed tarsal bones in the Binocerata, and their relative position in the hind foot is seen in Plate LIV. These bones are described in detail below. An eighth tarsal bone, the tibiale, appears to have been present. 19 145 146 DINOCERATA. The Astragalus. (Plate XLVII, Plate LIV, figure 2, a; and woodcuts 139-142, below.) The astragalus in the Binocerata considerably resembles that of the elephant, the bone being, as in that animal, very short, along- the axis of the leg and foot. The articular faces are, moreovei', but little curved, indicating comparatively slight freedom of motion in the ankle joint. The superior, or proximal, face of the bone, articulating with the tibia, is shown in Plate XLVII, figin-e 1. This surface is sub-quadrate in general outline, with rounded angles, but is jjrolonged posteriorly on the inner, or tibial, side into a large convex lobe. The surface of the tibial articulation is moderately convex from before backward, and, in front, nearly flat from side to side, but, posteriorly, it becomes somewhat excavated, this being the only indication of the conspicuous groove common in Ungulates. The tibial articular surface is confluent, along the posterior part of its outer margin, with a somewhat convex, rounded face for the fibula, as shown in figure 4. The inner surface of the bone (figure 2), or that which is presented upon the tibial side of the foot, is excavated by a large, rounded depression, encroaching above upon the margin of the tibial articular face. Below this depression, the bone is expanded, and presents a rounded and convex articular surface, in close relation with the adjoining, and nearly or quite confluent, face for articulation with the navicular, as shown in figure 140, f below. This convex facet apparently supported a separate bone, as in the existing Hyrax (figure 155, Chapter XIV). This bone, as Baur has suggested, probably represents the tibiale, or inner tarsal of the jjroximal row. The same bone exists also in Hystrix, and many other Rodents, and is regarded by Flower as a sesamoid. Tlie inferior surface of the astragahis (Plate XLVII, figi;re 3) articulated with three bones ; below, with the upper faces of the calcaneum, and, in front, with the navicular and the cuboid. All these articular faces may be confluent, as in the specimen figm-ed on the Plate, and the mode of union with the calcaneum is subject to considerable variation. THE HIND FEET. 147 In the specimen there figured, the face for the calcaneum may be briefly described as in the form of a horse-shoe with the lateral branches so broad as to leave only a narrow interval between them. The lateral portions, or branches, present two oval, concave faces, and they are united behind by a broad band, running' around the posterior end of a deep, narrow groove, dividing the anterior parts of the articulation, and leading backward to a foramen through the bone. In the speciman figured, this foramen is small and oblique, and no opening is seen through the bone. Along the outer, or fibular, margin of the bone, the articular face is confluent for a short distance with that for the fibula on the side of the astragalus. Near the center of the inferior surface, the inner ramus of the calcaneal articular facet is confluent at the end with tlie face for the cuboid. Another, and more common, form of articulation with the calcaneum is shown in figure 140, below, where the lower surface of the astragalus presents two distinct faces for the calcaneum. The outer of these is broad and rounded, nearly flat transversely, concave from before backward, and separated by a deep groove from the inner, more elongated surface. This groove leads backward into a large foramen, passing through the postei'ior part of the bone. The inner portion of the calcaneal face is longer than the outer, and more concave from before backward, From side to side, it is nearly flat, and, in front, it is more or less confluent with the face for the cuboid, and often also with that for the navicular. In a few specimens, the usual foramen near the hinder border of the bone is represented by a notch only, as in figures 141 and 142, below. The anterior part of the under surface of the astragalus presents two flattened, moderately convex, and very unequal, articular faces. The larger one of these is for articulation with the navicular, and the smaller, for the cuboid bone. The presence of a face for the cuboid is in sti'ong contrast with the structure of the foot of the elephant, in which the cuboid is supported by the calcaneum, and the navicular which covers the Avhole anterior face of the astragalus, not allowing the cuboid to come in contact with that bone. In the Dinocerata, this specialization does not occur. 148 DINOCERATA. The face for the navicular is fully twice as large as that for the cuboid. It is somewhat convex from side to side, but is nearly flat from before backward, and is bonnded along its outer, or fibular, and posterior side by a low rounded ridge, indicating the limit of the cuboid face. This facet is more or less triangular in outline, the apex pointing backward and inward. It is only moderately convex. The relation of the navicular face to the articulation for the tibiale bone is well shown in woodcuts 140 and 142, below. The outer, or fibular, side of the astragalus (Plate XL VI I, figure 4) presents a convex articulation for the fibula. This face is confluent above, with the tibial surface, and usually, also, in a much less degree, with the outer face for the calcaneum. In some specimens, however (numbers 1248, 1528, 1531), these faces are quite separated. In an anterior view of the astragalus (figure 5), the exterior, or dermal, surface is seen to be very short, proportionally shorter than in the elephant, but varying within such limits that the longest in the JDinocerata may nearly or quite equal in length the shortest in the elephant. Posteriorly, the astragalus extends backward much farther on the inner, or tibial, side than on the outer side, and is tuberculated. This surface of the bone is, in some specimens, deeply notched near the middle, as in figures 141 and 142, below, but more commonly the notch is converted into a foramen by a bridge of bone, as in Plate XLVII, figure 6, and figures 139 and 140, below. The tibial articular surface is not usually confluent with the calcaneal surface, as is sometimes the case in the elephant. A near approach to confluence is seen in one specimen, number 1209. The astragalus in Gorypliodon is very similar in form to that in the Dinocemta, but is shorter. It has essentially the same articular faces, and the facet for the tibiale is equally well marked. The hind foot of Gorypliodon is shown in figure 151, in Chapter XIV. Its general resemblance to the corresponding foot in Dmoceras is striking, and the structure of the two is essentially the same. The resemblance between the fore foot of Dinoceras and that of Coryphodon is equally marked. THE HIND FEET. 149 The astragalus in one individual of Dinoceras, and in one of Tinoceras, is represented in the woodcuts below. Fig. 139. Fro. UO. FiGUHB 139 — Left astragalus of Dinoceras laticeps, ^larsh {No, IISI); top view ; slmwing foramen. Figure 140. — Tlie same boue; bottom view. h. face for fibula; c. and c'. faces for calcaneum; rM. face for cuboid; n. face for navicular; t. fnce for tibia, i'. face for tibiale. FrenEE 141. — Left astragalus of Tinoceras ingens, Marsh (No. 1209); top view. FiUUKE 142. — Tlie same bone ; bottom view. c. and c'. faces for calcaneum ; ch. face for cuboid ; /. face for fibula ; n. face for navicular, t, face for til:)ia. All the figures are one-half natural size. 150 DINOCERATA. Measurements of the astragalus in four individuals of the Dinocerata are as follows : Measurements of the Left Astragalus. (Dinoceras mirabile, No. 1210.) m. Greatest antero-posterior diameter of astragalus, .112 Greatest transverse diameter, . .121 Greatest vertical diameter, . ^ .070 Greatest diameter of articular face for tibia, .110 Antero posterior diameters of articular face for tibia,. .072-.066-.092 Transverse diameters of articular face for tibia, . .07t3-.071-.085 Antero-posterior diameter of articular face for fibula, .044 Vertical diameter of articular face for fibula, . ._- .._. .036 Antero-posterior diameter of articular face for calcaneum, — .054 Transverse diameter of articular face for calcaneum, _. .080 Transverse diameter of articular face for calcaneum, outer lobe, .033 Transverse diameter of articular face for calcaneum, inner lobe, _ .040 Diameter of band connecting lobes, .- .018 Antero-posterior diameter of united faces for navicular and cuboid, — .056 Transverse diameter of united faces for navicular and cuboid, .107 Diameters of face for navicular, .. .066-.082 Diameters of face for cuboid, .035-062 Minimum length of neck, .014 Measurements of Left Astragalus. {Dinoceras laticeps., No. 1197.) m. Greatest antero-posterior diameter of astragalus, .128 Greatest transverse diameter, ... .128 Greatest vertical diameter, 080 Greatest diameter of articular face for tibia, 127 Antero-posterior diameters of articular face for tibia,.. .(iS9-.080-.105 Transverse diameters of articular face for tibia, .090-.085-.09I Antero-posterior diameter of articular face for fibula, 065 Vertical diameter of articular face for fibula, .. .031 Antero-posterior diameter of outer articular face for calcaneum, .053 Transverse diameter of outer articular face for calcaneum,. _ ... .048 Antero-posterior diameter of inner articular face for calcaneum, . .061 Transverse diameter of inner articular face for calcaneum, .... .035 Distance between inner and outer faces for calcaneum, ..... .009 Antero-posterior diameter of united faces for navicular and cuboid, . .072 Transverse diameter of united faces for navicular and cuboid, 113 Diameters of face for navicular, .064-091 Diameters of face for cuboid, .031-071 Minimum length of neck, ...... 016 THE HIND FEET. 151 Measicrements of Left Astragalus. (T'moceras ingens. No. 1209.) m. Greatest antero-posterior diameter of astragalus, .122 Greatest trausverse diameter, .147 Greatest vertical diameter, ,. .083 Greatest diameter of articular face for tibia, .. _ .125 Antero-posterior diameters of articular face for tibia _ 09 1-.082-. 1 04 Transverse diameters of articular face for tibia, .094-,096-.095 Antero-posterior diameter of articular face for fibula, .000 Vertical diameter of articular f :ice for fibula, .039 Antero-posterior diameter of outer articular face for calcaneum, .050 Transverse diameter of outer articular face for calcaneum, .... . .050 Antero-posterior diameter of inner articular face for calcaneum, .058 Transverse diameters of inner articular face for calcaneum, .033-050 Distance between inner and outer faces for calcaneum, .013 Antero-posterior diameter of united faces for navicular and cuboid, .068 Transverse dinmeter of united faces for navicular and cuboid, .130 Diameters of face for navicular, .068-. 105 Diameters of face for cuboid, 042-.077 Minimum length of neck,, _ .019 Measurements of Right Astragalus. [Dinoceras mirabile, No. 1528.) m. Greatest antero-posterior diameter of astragalus, .100 Greatest transverse diameter, 108 Greatest vertical diameter, 063 Greatest diameter of articular face for tibia, __ .loo Antero-posterior diameters of aiticular face for tibia, .... ,070-.000-.093 Transverse diameters of articular face for tibia, .067-.067-.070 Antero-posterior diameter of articular face for fibula, .040 Vertical diameter of articular face for fibula, . . .030 Antero-posterior diameter of outer articular face for calcaneum, . .035 Transverse diameter of outer articular face for calcaneum, .039 Antero-posterior diameter of inner articular face for calcaneum, .040 Transverse diameter of inner articular face for calcaneum, .040 Antero-posterior diameter of united articular faces for navicular and cuboid, .053 Transverse diameter of united articular faces for navicular and cuboid, .093 Diameters of face for navicular, .076-.053 Diameters of face for cuboid, . .026-055 ' Minimum length of neck, . .015 The Calcaneum. (Plate XLVIII, Plate LIV, figure 2, c; and woodcuts 143-144, below.) The calcaneum in the Dinocerata is short, and comparatively more robust, than in the elephant. As in that animal, it is strongly tuberculated 152 DINOCERATA. below, where, during life, it doubtless supported a thick pad, resting on the ground. The calcaneum articulated mainly with two bones, the astragalus and the cuboid. Some specimens, and j^erliaps all, present a small face where the fibula touched this bone. The articulation with the astragalus is, in most specimens, divided into two distinct facets (figures 144, a and a') by a deep groove. In some cases, however, these facets are coalescent posteriorly, as in Plate XLVIII, figm-es 1 and 5, and in figure 143, corresponding with a similar coalescence of faces on the astragalus. The face for the cuboid is small, and irregularly rounded, or oval, as seen in Plate XLVIII, figure 1, and is usually more or less confluent with the inner face for the astragalus, but is well separated from the outer face for that hone. The great tuberosity for the attachment of the tendo Achillis is very short, proportionally shoi'ter than in the elejjhant. Figure 14'-. — Calcaneum of Dinoceras miriMle, Marsh (^fo. 1210); top view. Figure 144. — GalcaDeum of Dinoceras mirabile, (No. 1208); top view. a. and a', faces for astragalus. Both fisrures arc oue-lialf uatural sizo Two specimens of the calcaneum in different individuals of Dinoceras are represented in tlie woodcuts above. Measurements of three specimens of the calcaneum in the Dinocerata are as follows : THE HIND FEET. 153 Measurements of Left Calcaneum. (Dinoceras mirabile, No. 1210.) m. Length of calcaneum, from great tuberosity to face for cuboid, .096 Transverse diameter, ._- .-. _..-- .090 Vertical diameter, .070 Antero-posterior diameter of inner lobe of articulation for astragalus, . .050 Transverse diameter of inner lobe of articulation for astragalus, .043 Antero-posterior diameter of outer lobe of articulation for astragahis, .043 Transverse diameter of outer lobe of articulation for astragalus (ap]iroximate), .039 Measurements of Right Calcaneum. (Dinoceras mirabile, 'So. 1225.) m. Ijcngth of calcaneum, from great tuberosity to face for cuboid, .107 Transverse diameter (approximate), .... .086 V ertical diameter, .074 Antero-posterior diameter of inner face for astragalus, .053 Transverse diameter of inner face for astragalus, .087 Antero-posterior diameter of outer face for astragalus, .045 Transverse diameter of outer face for astragalus (approximate), .037 Distance between inner and outer faces for astragalus, .010 Measurements of Left Calcaneum. (Dinoceras inirabile,'So. 1208.) m. Length of calcaneum, from great tuberosity to face for cuboid, 093 Transverse diameter, .086 Vertical diameter, . .074 Antero-posterior diameter of inner face for astragalus, , 044 Transverse diameter of inner face for astragalus, ._ .042 Antero-posterior diameter of outer face for astragalus, .. .050 Transverse diameter of outer face for astragalus, . .032 Distance between faces for astragalus, .070 Transverse diameter of face for cuboid, .035 Vertical diameter of face for cuboid, .019 The Cuboid. (Plate XLIX, figures 1-6, Plate LIV, figure 2, cb; and woodcuts 145-146, below.) The cuboid in the Dinocerata corresponds in general with that- of the elephant, and presents similar articular faces, though not to the same bones. It is also more elongated in the line of the axis of the foot, thus appearing less flattened than in the Proboscidea. In general shape, the bone is triangular, the longest side being nearly straight, and lying along the inner, or side for the navicular, while the shortest side is somewhat curved, and is presented to the exterior, or dorsal, surface of the foot. 154 DINOCERATA. This surface (Plate XLIX, figure 1) is moderately roughened, especially at the edges, for attachments of ligaments. The outer, or fibular, side, shown best in figure 4, is short along the line of the foot, being encroached upon by the articular face for the calcaneum on the proximal end, and one for the fifth metatai'sal on the distal end. The plantar aspect of the bone (figure 3) presents a single, or bifid, tubercle, and, on the inuer face (figure 2), is an elongate articular surface for union with the navicular. This surface is confluent with the face for articulation witli the astragalus, and thus serves to distinguish the proximal from the distal end of the bone, which often closely resemble each other. The proximal surface (figure 5) is covered by two articular facets. The inner one, large and sub-triangular, concave in both directions, and nearly perpendicular to the axis of the bone, moved, during life, upon the outer distal face of the astragalus. This face is, in the specimen figured on the Plate, widely confluent with a smaller oval face for the calcaneum. In figure 146, below, the face for the calcaneum (c) is much less widely confluent with that for the astragalus, being nearly separated from it. In both specimens, the calcaneal face is slightly convex transversely, and somewhat inclined to the axis of the bone. PieuRE 145. — Right culioid of Dimceras miraUle, Marsh (No. 1528); siile view Figure 146. — The same bone ; pro.ximal end. a. face for astragalus; c. face for calcaneum ; mt IV. face for fourth metacarpal ; n. face for navicular. Both figures are one-half natural size. The cuboid bone in one individual of Dinoceras is represented in the two cuts above. The distal face (Plate XLIX, figure 6) also presents two articular surfaces, for the, support of tlie fourth and fifth metatarsal bones. The THE HIND FEET. • 155 face for the fourth metatarsal is much the larger. It is narrow, or pointed, below, and moderately concave, or, in the lower part, slightly convex, from above downward, and is at right angles with the axis of the bone. The smaller outer face, supporting the fifth metatarsal, is turned somewhat outward, and is slightly convex in both directions. The principal dimensions of the two cuboid bones above described are as follows : Measurements of Left Cuboid. {Dinoceras mirabile. No. 1208.) m. Length of cuboid, along axis of foot, .035 Transverse diameter, .054 Antero-posterior diameter, _ ._ .060 Antero-posterior diameter of face for astragalus, . . .055 Transverse diameter of face for astragalus, .034 Antero-posterior diameter of face for cuboid, .035 Transverse diameter of face for cuboid, .020 Antero-posterior diameter of face for fourth metatarsal, .049 Transverse diameter of face for fourth metatarsal, . _ .032 Antero-posterior diameter of face for fifth metatarsal, .035 Transverse diameter of face for fifth metatarsal, _. _. .022 3Ieasurements of Right Cuboid. [Dinoceras mirabile, No. 1528.) m. Length of cuboid, along axis of foot, .037 Transverse diameter, . . ...... .066 Antero-posteri6r diameter, _.__ .... . .065 Antero-posterior diameter of face for astragalus, _. _ 058 Transverse diameter of face for astragalus, . .036 Antero-posterior diameter of face for cuboid, .. .032 Transverse diameter of face for cuboid, .026 Antero-posterior diameter of face for fourth metatarsal, .049 Transverse diameter of face for fourth metatarsal, .035 Antero-posterior diameter of face for fifth metatarsal, .039 Transverse diameter of face for fifth metatarsal, .032 The Navicular. (Plate XLIX, figures 7-12, and Plate LIV, figure 2, n.) The navicular is a short bone in the Dinocerata, strongly flattened vertically, much as in the elephant. It is supported b}^ the astragalus, and does not usually, as in that animal, touch the calcaneum. It supports only the three cuneiform bones in front, but presents a narrow, lateral, articular face to the cuboid. 156 DINOCERATA. The surface of the navicular exposed upon the dorsal aspect of the foot (Plate XLIX, figure 7) is short vertically, more or less rounded from side to side, and varies much in the degree of smoothness, or tuberculation, in different specimens. The under, or plantar, surface, shown in figure 9, projects into a large rounded tubercle, and is of considerably greater extent along- the axis of the foot than above. The outer surface (figure 10), presented to the cuboid, is more or less covered by an articular face, extending along the proximal margin of the bone, confluent with the astragalar face, and, in life, moving- upon a corresponding- face upon the inner side of the cuboid. The proximal surface of the bone (figure 11) is mostly occupied by a large articular surface, for union with the astragalus. This surface is somewhat saddle-shaped, being- distinctly concave transversely, but somewhat convex from above downward. Below the articular face, the bone usually extends into a sti-ong- plantar tubercle, which may, however, (number 1218) be much less developed than in the specimen figm-ed. None of the specimens present any indication, on the proximal face, of a surface for articulation with the calcaneum, such as is found on the corresponding bone of the elephant. The distal surface of the navicular (figure 12) presents tliree articular faces, one for each of the cuneiform bones. These faces are confluent with each other, and the inner one, for the entocuneiform, may be small, and indistinct. Usually, it is of considerable size, and elongated fi-om above downward. It is oval in shape, moderately convex in both directions, and oblique to the axis of the bone, looking- somewhat outward. The median of the three faces is sub-quadrate in outline, a little broader above than below, and confluent, on each side, with the adjacent faces. This face is slightly concave from side to side, and from above downward, nearly flat. The face for the ectocuneiform is sub-quadrate, tapering below, concave in both directions, or nearly flat from above downward. THE HIND FEET. 157 These faces may all be considerably shorter and broader than in the specimen figured, and the face for the entocuneiform may be very greatly reduced. The following measurements of three specimens of the navicular in Dinoceras show the more important dimensions of this bone : Measurements of Left Navkidar. [Dinoceras mirabile,'i^o. 1247.) m. Transverse diameter of navicular, ' .085 Antero-posterior diameters (axial), .. .015-.029 Transverse diameter of face for astragalus, .080 Vertical diameter of face for astragalus, .060 Transverse diameter of face for entocuneiform, _. .020 Vertical diameter of face for entocuneiform, .050 Transverse diameter of face for mesocuneif orm, . .025 Vertical diameter of face for mesocuneif orm, ... .045 Transverse diameter of face for ectocuneiform, . .035 Vertical diameter of face for ectocuneiform (approximate), ., .055 Measurements of Left Navicular. {Dinoceras niirabile, No. 1208.) m. Transverse diameter of navicular, .. .. .06 7 Antero-posterior diameters, .015-.025 Vertical diameter, .069 Transverse diameter of face for astragalus, .058 Vertical diameter of face for astragalus, .051 Transverse diameter of face for entocuneiform, 022 Vertical diameter of face for entocuneiform, ..- 033 Transverse diameter of face for mesocuneif orm, .. .02f) Vertical diameter of face for mesocuneif orm, ._ .043 ransverse diameter of face for ectocuneiform, _ __ __ .032 Vertical diameter of face for ectocuneiform, .040 Measurements of Left Navicular. {Dinoceras mirabile, No. 1218.) ra. Transverse diameter of navicular, '. j .082 Antero-posterior diameters, __ .015-022 Vertical diameter, ^ . -065 Transverse diameter of face for astragalus, .065 Vertical diameter of face for astragalus, .' .050 Transverse diameter of face for entocuneiform (approximate), _ .012 Vertical diameter of face for entocuneiform, .028 Transverse diameter of face for mesocuneiform, .029 Vertical diameter of face for mesocuneiform (approximate), 045 Transverse diameter of face for ectocuneiform, _. .037 Vertical diameter of face for ectocuneiform, .052 158 DINOCERATA. The Entocuneiform. (Plate L, figures 1-6, and Plate LIV, figure 2, en.) The entocuneiform in the Dinocerata bears but slight resemblance to the corresponding bone in the elephant. It is much less elongated in the line of the axis of the foot, and even less so than appears in the general view of the hind foot on Plate LIV, since the elongation apparent in that figure is, to a great extent, in front of the articular surfaces. These surfaces are, at their nearest points, scarcely more widely separated in the direction of the axis of the foot, than are those of the other cuneiform bones. The dermal surface of the bone (Plate L, figure 1) is rotigh and tuberculated, often much more so than represented in the figure. It is also usually more elongated in the axial direction, in front of the articular surfaces. The opposite surface of the bone (figure 3) is flattened, and moderately roughened, and presents a small area only for articulation with the mesocuneiform. This articular face is conflxient with the face for the navicular, and lies along the anterior part of its margin. The proximal articular face (figure 5) is of a semi-oval form, and is more or less concave in a direction from the dorsal toward the plantar side of the foot, while transversely it is moderately convex. The distal face (figure 6) is much more distinctly saddle-shaped. In some specimens, it is strongly curved forward in the superior region of the bone, so as to extend through a considerable arch in the direction from the dorsal toward the plantar side of the foot. Transversely, the articulation is moderately convex throughout. The Mesocuneifoem. (Plate L, figures 7-12.) The mesocuneiform is a small, somewhat wedge-shaped bone, tapering toward its plantar extremity, and having its shortest dimension in the line of the axis of the foot. It is much less oblique than the coiresponding bone in the elephant, and also less decidedly wedge-shaped. THE HIND FEET. 159 The dorsal surface of the bone (Plate L, figure 7) is rugose and tuberculated, and tlie jjlantar extremity (figure 9) also presents a rather prominent protuberance. Of the lateral faces, the innor (figure 8), turned toward the entocuneiform, presents, along the proximal part of its margin, a more or less elongated facet, for articulation Avith that bone. The opposite side (figure 10) turned toward the ectocuneiform, is moderately rough, and destitute of any articular face. The proximal articular face (figure 11) is nearly flat, slightly broader above than below, and, along the inner margin, confluent with the lateral face for articulation Avith the entocuneiform. The distal face (figure 12) is also nearly flat, and, in life, supported in part, but not entirely, the second metatarsal bone. The latter presented nearly as large a face to the ectocuneiform, as to the mesocuneiform. The following measurements give the principal dimensions of this bone in two specimens of JDinoceras mirabile : Measurements of Left Mesocuneiform. [Dinoceras mirabile, No. 1210.) m. Greatest diameter of mesocuneiform, 058 Transverse diameter, ..- .0.32 Antero-posterior diameters (axial), .. .014-020 Measurements of Left Mesocuneiform. {Dinoceras mirabile. No. 1208.) m. Greatest diameter of mesocuneiform, .053 Transverse diameter, .026 Antero-posterior diameters (axial), .014-.018 The Ectocuneifoem. (Plate L, figures 13-18.) The ectocuneiform is triangular in outline, tapering distinctly, and in most specimens nearly to a point, toward the palmar surface of the foot. It is much less oblique than the corresponding bone in the elephant, and usually has the two distal faces more distinctly marked. It is also proportionally less elongated from the dorsal toward the plantar side ot the foot. 160 DI^'UCERATA. The dorsal, or dermal, face (Plate L, figure 13) is roughened for ligamentary attachroent, and on the opposite, or plantar, side, the bone is produced into a more or less prominent tubercle (figure 15). In the natural position, during life, this elevation was just back of the proximal end of the third metatarsal. The lateral surfaces of the ectocuneiform (figures 14 and 16) are moderately roughened, and do not present articular surfaces for either the mesocuneiform on the inner side, or for the cuboid on the outer side. The proximal articular face (figure 17) is nearly flat, or slightly convex transversely, while, in a dorso-plantar direction, it may be more or less concave. The distal surface (figure 18) presents two confluent, but usually well marked, articular surfaces. Of these, the inner is narrow and oblique, and supported, in life, the outer part of the second metatarsal. The principal articular face of the distal end is nearly flat, sub-triangular in outline, and narrowed toward the plantar end. In life, it supported the third metatarsal bone. The tubercle upon the plantar side of this bone differs considerably in size and form (numbers 1202 and 1229). The degree of distinction between the two distal faces also varies in different specimens (numbers 1208, 1232, and 1199). The more important measurements of the ectocuneiform in four specimens of Dinoceras are given below. Measurements of Right Ectocuneiform. [Dinoceras mirabile, No. 1199). ID- Greatest diameter of ectocuneiform, .066 Transverse diameter, .045 Antero-posterior diameters, __. .014-026 Diameters of proximal articular face, .030-048 Measurements of Left Ectocuneiform. {Dinoceras laticeps, No. 1202.) m. Greatest diameter of ectocuneiform, .060 Transverse diameter, .040 Antero-posterior diameters, ._ .01 7-.024 Diameters of proximal articular face, -. 033-i050 THE HIND FEET. 161 lleasia-ements of Left Ectocuneiform. {Dinoceras mirabile, No. 1208.) m. Greatest diameter of ectocuneiform, .055 Transverse diameter, 035 Antero-posterior diameters, .016-021 Diameters of proximal articular face, .028-039 Measurements of Left Ectocuneiform. {Dinoceras mirabile, No. 1232.) m. Greatest diameter of ectocuneiform, .064 Transverse diameter, .044 Antero-posterior diameters (axial), . 014-.022 Diameters of proximal articular face, _ 032-046 The Fiest Metatarsal. (Plate LI, figures 1-6, and Plate LIV, fig-ure 2.) Tlie first metatarsal bone of the Dinocerata is the shortest and smallest of the five, but is comparatively much better developed than in the elephant. The first metatarsal in Dinoceras mirabile is short and stout, and strongly roughened on all sides throughout its length, as seen in Plate LI, figures 1-4. As in the other metatarsals jjreserved, there are no distinct indications of epiphysial sutures. This bone does not appear, during life, to have been in very close relation with the adjoining metatarsal, and accordingly presents, on its proximal end (figure 5), only a single articular surface, which is distinctly saddle-shaped, and joined the entocuneiform. The distal end (figure 6) presents a flattened, and somewhat concave, face for the first phalanx, and immediately below this, are grooves for a pair of sesamoid bones. The Second Metatarsal. (Plate LI, figures 7-12, and Plate LIV, figure 2.) The second metatarsal in Dinoceras is the most robust of the series, and is a short, and very stout bone. The surface of the shaft, as seen in Plate LI, figures 7-10, is 162 DINOCERATA. roughened at both the joi'oximal and distal ends, but medially it is smoother and constricted, especially below, where a large, and pi^ominent, tubercle occupies the proximal portion of the under surface of the bone. This tubercle is shown in figure 9, and also, in profile, in figures 8 and 10, where it is seen to project considerably beyond the proximal articular face. The proximal end of the bone (figure 11) is oblique to its axis, and presents two distinct articular faces ; the larger on the inner, or tibial, side of the bone, for the mesocuneiform, and the outer, on the fibular side, for the ecto cuneiform. The latter face is also confluent with a lateral facet, Avliere the bone, during life, touched the third metatarsal. This face is well shown in figure 10. The distal end (figure 12) is large, rounded, and somewhat oblique to the axis of the bone. The articulation for the phalanx is flattened, but may be slightly convex, or, in a transverse direction, more or less concave. Two well developed sesamoids moved in broad shallow grooves below, the faces for these bones, taken together, being about as large as that for the phalanx. The Third Metatarsal. (Plate LI, figures 13-15, Plate LII, figures 1-3, and Plate LIV, figure 2.) The third metatarsal is of about the same length as the second and the fourth, and is a little less robust than the second. It has a distinct shaft, which is smooth and constricted medially, but more or less roughened and tubercular toward the extremities, especially near the distal end. The proximal face of the bone (Plate LII, figure 2) is somewhat oblique to its axis, and presents a sub-triangular articular face for the outer facet of the ectocuneiform. This facet is confluent, along its inner margin, with a small lateral face for union with the second metatarsal, as shown in Plate LI, figure 14. Opposite this, there is also an oval face (Plate LII, figure 1) supported on a flattened tubercle, and meeting, during life, a similar face on the foiu-th metatarsal. THE limn FEET. Igg Tlie distal end (Plate Lll, figure 3) is large and rounded, and, in some specimens, distinctly oblique. It suj^ports the usual face for the first phalanx, and below, two shallow grooves for a pair of sesamoid bones. The phalangeal face is, in all the specimens preserved, distinctly, though slightly, convex in botli directions. The Fourth Metatarsal. (Plate LII, figures 4-9, and T'late LIV, figure 2.) The fourth metatarsal is of about the same size as the third, and considerably resembles it in structure Tliis resemblance is much greater tlian in the elephant, wliere the fourth is decidedly shorter than the third metatarsal. The shaft of the fourth metatarsal is strongly constricted medially, as seen in Plate Lll, figures 5 and 7, and bears on the under side, at the proximal end, a large projecting tubercle. The proximal end (figure 8) bears a nearly flat articular surface, sub-triangular in outline, and nearly perpendicular to the long axis of the bone, and articulating, during life, with the cuboid bone. This surface is confluent on the outer side with a small lateral facet shown in figure 7, which corresponds with a similar face on the fifth metatarsal. On the opposite, or inner side, is an oval facet (figure 5) articulating in life, with a prominent face on the third metatarsal. The distal end of the fourth metatarsal (figure 9) is but little oblique to the axis of the bone, and bears the usual fkces, for articulation with the phalanx, and the sesamoids. The phalangeal articulation may be concave from side to side (number 1199), but is usually slightly convex in both directions. The Fifth Metatarsal. (Plate LII, figures 10-15, and Plate LIV, figure 2.) The fifth metatarsal in Dinoceras is shorter than any of the others except the first, but is robust, and evidently afforded its full share of support to the foot. 164 DINOCERATA. Its surface is strongly tuberculated, especially on the under arid outer sides, as shown in Plate LII, figures 12 and 13. The shaft, being short, does not present a median constriction, as in the three preceding metatarsals. The proximal end (figure 14) bears a comparatively small articular face for support on the cuboid bone. This face is nearly flat, and somewhat quadrangular in outline, and is confluent, on the inner margin, with a small lateral face for the fourth metatarsal, as seen in figure 11. The proximal articular face is nearly at right angles to the axis of the bone. The distal face (figure 15) for the proximal phalanx is turned strongly outward, and is more or less concave. The sesamoid grooves, also, look strongly outward, and the inner is larger than the outer. The Phalanges. (Plates LII-LVI.) The phalanges of the hind foot in the Binocerata are very similar to those of the fore foot, although smaller, and hence need no detailed description. In Plate LIII, these bones are well represented, and with them, some of the sesamoid bones of the same feet. In Plate LIV, figure 2, the phalanges are shown in position, and other view^s of them may be seen in the two restorations on Plates LV and LVI. CHAPTER XTIL RESTORATIONS OF DINOCERAS AND TINOCERAS. (Plates LV and LVI.) The preceding- chapters of this memoir, and the illustrations given in Plates I-LIV, will make known to anatomists nearly all the important cliaracters in the skeleton of the gigantic mammals of the order Dinocerata. In Plate LV, a restoration is given of Dinoceras mirabile, the type of the group, and, in Plate LVI, one also of Tinoceras ingens, a characteristic, and more specialized form of an allied genus. The remains available for these restorations consist of portions of more than two hundred individuals of the Dinocerata. As none of the skeletons of the species here represented were complete when found, it has been necessary to use, in both restorations, the bones of other individuals which could not be distinguished from the type specimens. Some of these bones may, perhaps, belong to allied forms, but it is believed that the restorations, as here given, fairly represent the skeletons of the species named. In the restoration of Dinoceras mirabile on Plate LV, the remains of the type specimen of the species, a fully adult, but not old individual, have been used for the more important parts, and the remaining portions taken from other individuals. This restoration is one-eighth natural size. 165 166 DINOCERATA. The animal is repi-esented as walking, and the position of the head, and the feet, has been cliosen to show, to the best advantage, these portions of the skeleton as they were in life. In this restoration, only those 230rtions are shaded which are represented by actual specimens in the Yale Museum. The parts in outline are either wanting, or so poorly preserved that only their main features can be given with accuracy. In the restoration of Tinoceras ingens, Plate LVI, the animal is represented one-sixth natural size, and standing at rest. The position here chosen shows the massive and majestic form of one of the largest individuals of this remarkable group. Here, likewise, the shaded portions are represented by specimens in the Yale Museum. Some of these bones were used also in the first restoration. In comparing Dinoceras, as here restored, with some of the largest ungulate mammals of the present day, a certain resemblance to the rhinoceros on the one hand, and to the elephant on the other, will naturally suggest itself. In size and proportions, JDinoceras was intermediate between these two existing animals, and in various points of its structiu-e, it resembled the one quite as much as the other. In still other features, JDinoceras resembled the hippopotamus, and its affinities with the groups represented by these three types will be discussed in the succeeding chapter. In its stature and movements, Binoceras probably resembled the elephant as much as any other existing form. Its remarkable skull, longer neck, and more bent fore limbs, gave it, however, a very diiferent appearance from any known Proboscidian. The high protuberances on the head, the long trenchant canine tusks, and the peculiar lower jaw modified for their protection, are features seen together only in this group. The neck was long enough to permit the head to reach the ground, and hence a proboscis was quite unnecessary. The horizontal narial opening, the long overhanging nasal bones, and the well developed turbinal bones, are likewise proof positive against the presence of such an organ. There is some evidence of a thick flexible lip, resembling, perhaps, that of the existing rhinoceros. RESTORATIONS. 167 The remarkably small brain, and tlie heavy massive limbs, indicate a dull, slow-moving- animal, little fitted to withstand sudden changes in its environment, and hence it did not survive the alterations of climate with which the Eocene period closed. That the Dinocerata were very abundant for a long time during the middle Eocene is proved, concliisively, by their numerous remains in dejDosits of this age. That the animals lived in herds is also suggested by the jjosition in which the remains are found. Their favorite resorts would seem to have been around the borders of the g'reat Eocene tropical lake described in the Introduction of the present volume. Here, they found an abundance of food, which was evidently the soft succulent vegetation which flourished, then as now, in such localities. In Tinoceras, represented in Plate LVI, we have the skeleton of a larger, and still more imposing animal, but with essentially the same characteristics. The remains of this genus are found in the same lake-basin as those of Dinoceras, but at a higher level, and the evidence is clear that Tinoceras is a later, and more specialized form. Both the animals chosen for these two restorations were evidently males, as shown by the lofty protuberances, or horn-cores, on the skull, and the powerful canine tusks. In the females, these parts are but feebly developed, as seen in the specimens described in the preceding chapters. The individuals here restored were certainly thrice-armed, and well fitted to protect themselves, and their weaker associates, from any of their Eocene enemies. The exact form and nature of the off"ensive weapons which surmoitnted the head of the Dinocerata cannot, at present, be determined with certainty. That the paired osseous elevations on the skull in all the known species of this group did not support the kind of horns seen in the typical Ruminants is evident from their external surface, which lacks the vascular grooves so distinct on the horn-cores of those animals. 168 DINOCERATA. Possibly the Dinocerata may have been armed with horns similar to those seen in the American antelope (AntUocapra)^ since, in this animal, the horn-cores are even smoother than in the order here described. More probably, however, the bony protuberances on the skull were covered with bosses of thick skin, hard enough to be effective in combat. Evidence of such contests has apparently been recorded in the injuries to the horn-cores of some individuals, received during life. None of the covering of these elevations, or horn-cores, has, of course, been preserved ; yet a fortunate discovery may, perhaps, reveal their nature by the form of a natural cast, as the eye-ball of the Oreodon is sometimes thus clearly indicated in the fine Miocene matrix which envelops these animals. The short robust feet of the Dinocerata were doubtless covered belosv with a thick pad, as in the elephant, since the whole under side of the foot clearly indicates such a protection. No portion of this covering has been preserved in any of the known specimens, and no foot-prints, indicating its form, have been discovered in the Eocene deposits in which the Dinocerata were entombed. The size of Tinoceras ingens, as he stood in the flesh, was about twelve feet (3.65 M.) in length, or sixteen (4.9 M.), measured from the nose to the end of the tail. The height to the top of the back was about six and one-half feet (2 M.), and the width across the hips about five feet (1.5 M.). The weight, judging from that of existing mammals, was at least six thousand pounds (2.75 T.). Dinoceras mirabile was about one-fifth smaller. The neck was longer, but, in other respects,- the proportions were nearly the same. Dinoceras mirabile when standing at rest would have a general resemblance to a very large rhinoceros. When walking, the movement of the hind limbs would at once suggest the elephant, as we know it to-day. The movement of the head in Dinoceras was much freer than that in the elephant, as the neck was longer, and arched upward, and the vertebrse admitted of much more freedom of motion. The eye was small, and deep set, as in the rhinoceros. The head of Dinoceras must have had some resemblance to that of the hippopotamus, but was very different from that of any known animal, living or extinct. CHAPTER XIY. CONCLUSION. (Plates LIV-LVI, and woodcuts 147-169, below.) The more important characters of. the Dinocerata, so far as known, have been given in the preceding chapters, and the anatomist can now form a fair picture of characteristic members of the group. It remains to consider what the relations of this peculiar group are to the nearest allied forms, and, especially, to ascertain, if possible, whether the evidence before us throws any light on the origin of the Dinocerata, and, more remotely, on the genealogy of all Ungulate Mammals. The oldest known mammals are of Triassic age, but the few specimens yet discovered give little information as to the primitive forms of this class. During Jurassic time, mammals were very abundant, and deposits of this age now offer a promising field for exploration. Of Triassic and Jurassic mammals, the author has studied with some care every known specimen in this country, and in Europe, and some of the conclusions here given are based upon this examination. Special attention has been paid to the Jurassic mammals of this country, which the author first discovered in the Rocky Mountain region. Remains of neai-ly four hundred individuals, representing many genera and species, have already been secured, and their investigation promises to clear up many doubtful points in the early history of this class. No Cretaceous mammals are known, and it is this great break in the series of ancient forms that renders any satisfactory classification of the class, living and extinct, at present impossible. 22 169 170 DINOCERATA. At the very base of the Tertiary, we find the class of Mammals well represented by many widely separated groups, which point back to a common ancestry, only in a very remote period. Our present knowledge of the Mammalia, living and extinct, clearly indicates that they must go back at least to the Permian. The generalized mammal of that period, or of still earlier time, was probably quite small, and, in many respects, like an Insectivor. This primitive type would naturally possess all the general characters found in later forms in the various orders of mammals. The characters therefore we should expect to find in this ancestral mammal would be essentially the following : (1.) Brain, small and smooth. (2.) Teeth, more than forty-four. (3.) Vertebrae, biconcave. (4.) Trunk vertebrae, more than thirty. (5.) Sacral vertebrae, separate. (6.) Intercentral bones. (7.) Chevron bones. (8.) Cervical ribs, free. (9.) Clavicles, free. (10.) Coracoids, free. (11.) Sternal bones, flat. (12.) Humerus with supra-condylar foramen. (13.) ■ Feet, plantigrade. (14.) Five digits in manus and in pes. (15.) Carpal and tarsal bones not interlocking. (16.) Separate central bone in carpus. (17.) Pelvic bones, separate. (18.) Epipubic bones. (19.) Acetabular bones. (20.) Femur with third trochanter. (21.) Three bones in first tarsal row. (22.) Astragalus, flat. (23.) Fibula articulating with calcaneum. CONCLUSION. 171 This generalized mammal would belong to the group named Hypotheria by Huxley, who has laid a sure foundation for investigation in this line of research. Genealogy of Ungulates. From this primitive type of mammal, a special line apparently led off through the Triassic and Jurassic to the Cretaceous, where it formed a well marked group, which may be called tlie Protungulata, tlie probable ancestors of all succeeding Ungulate Mammals. The characters of this type would be somewhat as follows : (1.) Brain, small and smooth. (2.) Teeth, forty-four or more. (3.) No frontal appendages. (4.) Odontoid process, conical. (5.) Vertebra;, flat. (6.) Trunk vertebrse, thirty or more. (7.) Chevron bones. (8.) Clavicles present. (9.) Sternal bones, flat. (10.) Humerus with supra-condylar foramen. (11.) Feet, plantigrade. (12.) Five digits in manus and in- pes. (13.), Carpal and tarsal bones not interlocking. (14.) Separate central bone in carpus. (15.) Femur with third trochanter. (16.) Three bones in first tarsal row. (17.) Astragalus, flat. (18.) Fibula articulating with calcaneum. From this generalized ungulate, the skeleton of which we now know almost as well apparently as if we had it before us, a direct line would appear to have continued up to the present day, and be represented by the living Hyrax. Several divergent lines j^assed off probably from the same stem, and three of these have continued to the present time, the survivors beino- the Prohoscidea, the Artiodadyla, and the Perissodactyla. 172 DINOCERATA. The Proboscidian line apparently went off from the main ungulate stem in the Cretaceous. One branch ended in the later Pliocene in Dinotherium ; another, in Mastodon ; while the geniis Elephas alone survives, to represent this old group. Another strong branch, represented by a group which may be called the Holodactyla, probably also led off in the Cretaceous, and its typical members, at least, had the following general characters : (1.) Brain, small and nearly smooth. (2.) Teeth, forty -four. (3.) Post glenoid process. (4.) Odontoid process, conical. (5.) Vertebrae, flat. (6.) Trunk vertebrae, twenty-three or more. (7.) Chevron bones. (8.) Pelvic bones, firmly united. (9.) Femur with third trochanter. (10.) Ulna and fibula, complete. (11.) Fibula articulating with calcaneum. (12.) Five digits in manus and in pes. (13.) Carpal and tarsal bones more or less interlocking. (14.) Astragalus, nearly or quite flat. This line evidently divided near the base of the Eocene into the great groups of Perissodactyls and Artiodactyls, each with many off-shoots, and still existing. The former are now on the decline, and have but three living representatives, the horse, the tapir, and the rhinoceros. One off-set from the Perissodactyl line separated near the top of the Eocene, where it is represented by JDiplacodon, and perhaps ended in the extinct Brontotherium, of the lower Miocene, although this line may have been continued somewhat later in the genus CJialicothcriiim. From the Artiodactyl line, a peculiar group branched off in the early Eocene, and in the Miocene was represented by Oreodon and allied genera, and by later forms in the Pliocene. The Artiodactyls, now the dominant ungulates, have numerous families, and many living genera and species. CONCLUSIOK 173 Another order, also, which may be termed the Amblydactyla, passed off apparently from the main imgulate stem in the Cretaceous, and became extinct in the Eocene. One branch terminated in Corijpliodon, in the lower Eocene, and the other, represented by the Dinocerata, here described, came to an end in the Middle Eocene. In figure 147, below, a diagram is given, which shows graphically these lines of descent, and the most probable genealogy of modern Ungulates. The diagram, being on a plane, can only indicate the general position of these divergent lines. FiGDRE 147. — Diagram to illustrate the genealogy of Ungulate Mammals. A comparison of this diagram with, the section on page 7 of this volume will make clear the special geological horizons of each group here referred to. The Hyracoidea are represented by tlie existing Hyrax, and no fossil remains of the group are known. The principal characters of the o-rder are as follows : 174 DINOCERATA, (1.) Brain, large and convoluted. (2.) Canines, absent. (3.) Incisor tusks. (4.) Maxillo-turbinal bones. (5.) Premolar and molar teeth, similar. (6.) Malar bone articulating with lower jaw, (7.) Alisphenoid canal. (8.) Post-glenoid process. (9.) Odontoid process, conical. (10.) Cervical vertebrae, convexo-concave. (11.) Trunk vertebrae, twenty-nine or more. (12.) Scapula, spatulate. (13.) Iliac bones, parallel. (14.) Femur with third trochanter. (15.) Femur and tibia not in line. (16.) Ulna and fibula, complete. (17.) Feet, plantigrade. (18.) Axis of foot through third digit. (19.) Carpals and tarsals not interlocking. (20.) Central bone in carpus. ^ (21.) Three bones in first tarsal row. (22.) Astragalus, grooved. The Proboscidians, recent and extinct, may all be placed in a single order, with the following distinctive characters : (1.) Brain, large and convoluted. (2.) Canines, absent. (3.) Incisor tusks. (4.) Maxillo-turbinal bones, rudimentary. (5.) Malar bone forming middle of zygomatic arch. (6.) Post-glenoid process, absent. (7.) Alisphenoid canal. (8.) Odontoid process, conical. CONCLUSION. 1T5. (9.) Vertebrse, flat. (10.) Scapula, acuminate. (11.) Sternal bones, flat. (12.) Iliac bones, transverse. (13.) Femur and tibia in line. (14.) Ulna and tiljula, complete. (15.) Femur without third trochanter (16.) Feet, plantigrade. (17.) Axis of foot through third digit. (18.) Five digits in manus and pes. (19.) Two bones in first tarsal row. (20.) Carpals and tarsals, slightly interlocking. (21.) Astragalus, flat. (22.) Fibula articulating with calcaneum. The Holodadijla were the direct ancestors of the great group to which both the Perissodactyls and Artiodactyls, living and extinct, belonged. The two latter form together a well marked order, which may be called the Clinodactyla. Their more important characters are as follows : (1.) Brain, moderate in size, and convoluted. (2.) Lower canines. (3.) Maxillo-turbinal bones. (4.) Malar bone forming front of zygomatic arch. (5.) Post-glenoid process. (6.) Cervical vertebrse, more or less convexo-concave. (7.) Trunk vertebrse, not more than twenty-three. (8.) Scapula, si^atulate. (9.) Iliac bones, parallel. (10.) Femur and tibia not in line. (11.) Feet, digitigrade. (12.) Carpals and tarsals, strongly interlocking. (13.) Central bone, absent. (14.) Scaphoid articulating with magnum. (15.) Astragalus, grooved. 176 DINOCERATA. Returning now to the AmUydactyla, or the group from which the Dinocerata were evidently derived, and to whicli they belong, we may safely assign to them general characters as follows : (1.) Brain, small and smooth. (2.) Teeth, not more than forty-four. (3.) Post-glenoid process. (4.) Odontoid process, conical. (5.) Cervical vertebrfe, flat. (6.) Trunk vertebrae, twenty-three or more. (7.) Scapula, acuminate. ,(8.) Feet, plantigrade. (9.) Five digits in manus and in pes. (10.) Axis of foot through third digit. (11.) Carpal and tarsal bones, somewhat interlocking. (12.) Three bones in first tarsal row. (13.) Astragalus, flat. (14.) Fibula articulating with calcaneum. (15.) Cuboid articulating with astragalus. From this group came off, evidently in the late Cretaceous, first the Coryphodontia, having nearly all the above characters, and becoming extinct in the early Eocene. The Binocerata probably branched off about the same time, and survived to the Middle Eocene, thus becoming much more specialized before their extinction. Classification of Ungulates. Accepting this general view of the origin of the Ungulates, living and extinct, their classification has been outlined in the diagram on page 173, and little more can now be done. The attempts hitherto made to give a detailed classification of all the Mammalia, living and extinct, have signally failed, mainly because only a small part of even the extinct forms now known were included, and almost every new discovery tended to break down the definitions so systematically CONCLUSION. 177 recorded. The time for such an exhaustive classification has not yet arrived, and all that can be safely ventured upon in the present state of knowledge is to indicate the main gi-oups, and their affinities, and await future discoveries. Excluding the aberrant aquatic Sirenians, now regarded as of ungulate ancestry, and leaving out also Toxodon and other little known extinct forms, the Ungulate IMammals may then be arranged in natural groups, as follows : CLASS MAMMALIA. Sub-Class MONODELPHIA. Super-Order Ungulata. (L) Order Hyracoidea. (2.) Order Proboscidea. (3.) Order Amblydactyla \ Di"ocerata. ^ _ •< -I ( Corypliodontia. r A \ r\ -\ r^^^ i j. ^ S Mesaxonia (Perissodactyla). (4.) Order Clmodactyla { ^ . /. • i ^\ ( raraxoma (Artiodactyla). Before proceeding to discuss the relations of the Dinocerata to allied forms, it is important to first consider the relative value of the characters they share with these allies, and with groups still more remote. The characters found in existing mammals, and, to a great extent, in the extinct forms from the Tertiary to the present time, are clearly of two kinds ; general characters, derived from ancestral forms, and special characters, acquired in adaptation to their environment. Some of the latter may be negative characters, acquired by the disuse, or loss, of parts once advantageous. The first series of characters are of most importance, as they indicate a genetic connection, perhaps remote, with the different groups that share them. Special characters, on the other hand, however closely they may correspond in different groups, do not necessarily indicate affinities, but may have been acquired by adaptation to peculiar surroundings, in groups quite distinct from each other. 23 178 DmOCERATA. These facts lie at the foundation of classification, and it is only by keeping the two series of characters separate, that the true relationship between different groups of animals can be made out, and their genealogy indicated with any probability. Bearing this in mind in considering the Dinocerata, we must first seek to ascertain what general characters they have inherited from ancestral forms, and next what special characters they have since acquired. The relation of the group to the orders of existing Ungulates will then be indicated by ascertaining what characters, derived from a common ancestry, they share with each other, and what special characters, due, perhaps, to influences of similar nature, they possess in common. We have seen that the primitive Mammals {Hypotherid) must have possessed a large number of general characters, some of which have already been given in the list on page 170. The primitive Ungulates (Protungitlata), starting off on a particular line from the preceding type, would natui'ally retain nearly all these general characters, as indicated in the list on page 171. Each of the great branches that passed off from this parent stem retained a certain number of these primal characters, and some of them we find in the Ungulates of to-day. The characters jDOssessed by the Holodactyla were most of them still the ancestral features, and the Amblydacti/la, on the line toward the Dinocerata, shared many of the same characters. The Dinocerata, representing a fm-ther stage of progress, had still as their inheritance a number of persistent general characters. Some of these characters are the following : (1.) Brain, small and smooth. (2.) Orbit open behind. (3.) Post-glenoid process. (4.) Alisphenoid canal. (5.) Vertebrse, flat. (6.) Odontoid process, conical. (7.) Sternum, flat. (8.) Feet, plantigrade. CONCLUSION. 179 (9.) Five digits in inanus and in pes. (10.) Three bones in first tarsal row. (11.) Astragalus, flat. The si^ecialized characters of the Bimcerafa, acquired, doubtless, since this line separated from the Protungulata, are as follows : (1.) Pre-nasal bones. (2.) No upper incisors. (3.) Canine tusks. (4.) Skull surmounted with protuberances. (5.) Condyle of lower jaw, posterior. (6.) Pendent processes on lower jaw. (7.) Iliac bones, transverse. (8.) Femur and tibia in line. If we now compare the Binocerata with the Corypliodontia, we find they agree in the following characters : (1.) Brain, small, and nearly smooth. (2.) Greneral form of teeth. (3.) Temporal fossae, widely separated. (4.) Post-glenoid process. (5.) Odontoid process, conical. (6.) Vertebrae, flat. (7.) Scapula, acuminate. (8.) Feet, plantigrade. (9.) Five digits in manus and in pes. (10.) Axis of foot through third digit. (11.) Three bones in first tarsal row. (12.) Astragalus, flat. (13.) Fibula articulating with calcaneum. (14.) Cuboid articulating with astragalus. In compai-ing the Binocerata with living forms, and first with the Proboscidians, we find certain characters common to both, some of which at least, are general features, derived from a remote common ancestry. The more important of tliese characters are as follows : 180 DINOCERATA. (1.) Alisplienoid canal. (2 ) Odontoid process, conical. (3.) Vertebra3, flat. (4.) Scapula, acuminate. (5.) Sternal bones, flat. (6.) Iliac bones, transverse. (7.) Fibula, complete. (8.) Femur and tibia in line. (9.) Femur without third trochanter. (10.) Five digits in manus and pes. (11.) Axis of foot through third digit. (12.) Fibula articulating with calcaneum. (13.) Astragalus, flat. (14.) Digits enclosed in a common integument The characters found in the Dinocerata, and not in the existing Prohoscidea are more important, and more numerous. Among these characters are the following : (1.) Brain, small and smooth. (2.) No upper incisors. (3.) Canine teeth above and below. (4.) Anterior nares in front. (5.) Pre-nasal bones. (6.) Maxillo-turbinal bones, well developed. (7.) Skull surmounted with protuberances.. (8.) Premaxillaries not meeting frontals. (9.) Malar bone forming anterior part of zygomatic arch. (10.) Post-glenoid process. (11.) Condyle of lower jaw, posterior. (12.) Neck of medium length. (13.) Three bones in first tarsal row. (14.) Astragalus articulating with cuboid. CONCLUSION. 181. If now we compare the Dlnocerata with the Perissodactyls, ue find an agreement in the following characters : (1.) Premolar and molar teeth similar in form. (2.) Nasal bones expanding posteriorly. (3.) Malar bone forming front of z3'gomatic arch. (4.) Alisphenoid canal. (5 ) Posterior nares between last molars. (6.) Post-glenoid process. (7.) Carpal and tarsal bones, more or less interlocking. (8.) Axis of foot through third digit. (9.) Astragalus articulating with cuboid. With the typical Artiodactyls, the Dlnocerata have the following' characters in common : (1.) Cranial protuberances in pairs. (2.) No upper incisors. (3.) Premaxillary bones uniting with maxillaries and nasals. (4.) Premaxillaries with palatine plates. (5.) Lower incisors and canine in continuous series. (6.) Sternal bones, flat. (7.) Femur without third trochanter. (8.) Carpal and tarsal bones, more or less interlocking. (9.) Fibula articulating with calcaueum. (10). Astragalus articulating with cuboid. Modification of the Ungulate Foot. The characters of most importance in Ungulate Mammals are found in the teeth, the brain, and the feet. The last are of special interest in tlie present connection, as they mark the stages of development in each group from the primitive Ungulates to the highly modified forms existing to-day. A brief statement of this development will make more clear the relation of the Binocerata to other groups of Ungulates, with which we have already compared them. 182 DINOCERATA. The most generalized limbs in any vertebrates, above the class of fishes, are seen in some of the extinct aquatic reptiles, especially in forms allied to Ichthyosaurus. Here, as the author has shown, i we may find in one group, (1.) Each limb a simple fin, or paddle, (2.) Fore and hind limbs identical in structure, (3.) Axis of limb through intermedial bone and third digit, (4.) Single bone (humerus or femur) in propodial, or first, segment, (5.) Three bones, including intermedial, in epipodial, or second, segment, (6.) Mesopodial bones (carpals or tarsals) circular disks, (7.) Number of digits six or more, (8.) Metapodial bones and phalanges circular disks, (9.) Phalanges, very numerous. This is a primitive aquatic limb, flexible, but without joints, and adapted to swimming only. An example of such a limb is seen in figure 148, below. For progression both in water and on wet ground, an essential modification of such a limb would be required, and a type seen in some of the living reptiles would gradually be developed. This limb woidd be jointed at two points, and have five digits, with the axis through the middle one. The foot in this limb would be very similar to the generalized foot of the primitive Mammal, and may here be taken as its representative. An example of such a foot is shown in figure 149. In the true Ungulate Mammals, the modifications of the feet have undoubtedly taken place very nearly in the following manner : (1.) The primitive Ungidates (Protungulata) must have had plantigrade, pentadactyl, feet, with the carpals and tarsals not interlocking, either with the metapodial bones, or with their own adjoining series. This would give a weak foot, adapted especially to progression in soft ' Limbs of Sauranodon, etc., American Journal of Science, 1880. CONCLUSION. 183 swampy ground. This type of foot Avould be somewliat like that represented in figure 149, below. Fig. 148. OOOOqo 0 0 0^0° OP?o°1 o o FisuEE 148. — Lett hind \imh ot Ba27lanodon discits, Marsh; seen from below ; one-eighth natural size. Figure 140. — Right fore foot of Chelydra serpentina, Linnieus ; front view (after Gegenbaur). F. femur; F'. fibula; «'. intermedium ; c. central bone ;/. fibulare ; to. metatarsals; K. radiiis; r. radiale; T. tibia; t. tibiale; U. ulna; u. ulnare. The Roman numerals denote the ordinal number of each digit present, counting from the inner side of the pentadactyl foot. (2.) For locomotion on dry hard ground, a stronger foot was required, and a modification would soon take place, in the interlocking of the metapodials with the second row of carpals or tarsals that supported them. Examples of nearly this stage are seen in the fore feet of Coryphodon and Dinoceras, as shown in figures 150 and 152, below. The fore foot of the elephant (figure 156) will also serve to illustrate the same stage. (3.) A still stronger foot was produced by the further interlocking of both the first and second row of carpals and tarsals, as well as the latter row with the metapodials below. This general type of foot belongs to the Hohdactyla, and is seen also in some of the early Perissodactyls. 184 DINOCERATA. During these two stages of modification, or at a later period, a reduction in the number of digits in some forms also took place, evidently as a result of the same causes. As progression on dry land ^Yitll the plantigrade five-toed foot began, the first digit, being the shortest of the series, soon left the ground, and was gradually lost. FlOURE 150. Left fore foot of Coryphodon Tiamatus, .Marsh, front view. FiGur.E 1 5 1 —Left liind foot of same. Bolh Iisures are one-third natural size. Flc. 152. 11 III FiGL'EE 152. — Left fore foot of Vinoceras miruhile, Marsh. F'lGUEB 153. — Left hind foot of same. Both figures are one-fifth natural size. The four remaiuhig digits, having to do the work of five, were strengthened by the interlocking already mentioned, and also by coming neai'er together. (4.) In the next change that occurred, two kinds of reduction began. One leading to the existing Perissodactyl foot, and the other, apparently later, resulting in the Artiodactyl type. In the former, the axis of the foot remained in ihe middle of ihe third digit, as in the CONCLUSION. 185 pentadactyl foot. In the latter, it shifted to the outer side of this digit, or between the third and fourth toes. An example of the former is seen in tlie fore foot of JBrontotherium and Rhinoceros, figures 158 and 160, below, while Oreodon and the hippopotamus, figures 162—165, show the latter type. Fig. 155. Figure 154. — Left fore foot of Ilijrax capensis, Scbrebr. FiGUKE ] 55.— Left liind foot of same. c central bone; cT. entocuneifurm ; j). pisiform; t. tibialo. Both figures are natural size. Fig. 156. Figure 156 — Left fore foot o£ E'.ephas Jndicus, Linnseus. FiGURB 157. — Left liiud foot of same. Botll figures are o:ie-ciglith natural size. 24 186 DINOCERATA. The position of tlie axis is the distinctive feature between these two types of feet, and not the number of toes, as the names usually applied to them indicate. In this respect, the terms Artiodactyl and Perissodactyl are misleading, and hence the names Faraxonia and Mesaxonia were proposed by the author, as substitutes, to express the true axial relation. Figure 158. — Left fore foot of Rhinoceros hicornis, Linnteus. Figure 159. — Left hiad foot of same. , Both figures are one-eighth natural size. FiGUEE 160 — Right fore foot of Brontotherium ingens. Marsli. Figure 161.— Right hind fool, of same. Both liijnres are one-si.xtli natural size. CONCLUSION. 187 (5.) In the further reduction of the Perissodactyl foot, the fifth digit, being shorter than the remaining three, next left the ground, and a 17 Figure 1C2. — Left fore foot of Eporeodon socialis, Marsh. Figure ] 63. — Left hind foot of same. Both figures are one-third natural size. M 17 n IV Figure 164. — Left fore foot of: lUppupUamus amphibius, LinujRu.s, Figure 1G5. — Left hind foot of same. Both figures are one-elghlh natural size. gradually disappeared. Of the three remaining toes, the middle, or axial, one was the longest, and retaining its supremacy, as greater strength and speed were required, finally assumed tbe chief support of the foot, while 188 DINOCERATA. the outei' dig-its left the ground, ceased to be of use, and were lost, except as splint bones. The foot of the existing horse (figures 166 and 167) shows the best example of this reduction in the Perissodactyls, as it is the most specialized known in the Ungulates. Fig. 16T. iir M M N m N Figure 1 66. — Left fore foot of horse {Equus caballus, Linnajus). Figure 167. — Left hind foot of same. Both figures are one-eighth natural size. Figure 168. — Left fore foot of goat {Capra Idrcus, Linnaeus). FiGUBE 1 69. — Left hind foot of same. Both figures are one- fifth natural size. (6.) In the Artiodactyl foot, the reduction resulted in the gradual diminution of the two outer of the four i-emaining toes, the tliii'd and fourth doing all the work, and thus increasing in size and power. The fifth digit, for the same i-easons as in the Perissodactyl foot, first left the o-round, and became smaller. Next, the second soon followed, and these two gradually ceased to be functional, or were lost entirely, as in some of the Artiodactyls of to-day. The feet of the goat, figures 168 and 169, above, show this extreme reduction. As the author has shown elsewhere, these reductions of the feet, and of the entire limbs, led to greater strength and speed, as the motion, before irregular, gradually came to act in a single plane. CONCLUSION. 189 The limb of tlie modern race-horse is a nearly perfect piece of machinery, especially adapted to great speed on dry, level, ground. The limb of an antelope, or deer, is likewise well fitted for rapid motion on a plain, but the foot itself is adapted to rough mountain work, as well, and it is to this advantage, in part, that the Artiodactyls owe their present supremacy. The plantigrade, pentadactyl, foot of the primitive Ungulate, and even the Perissodactyl foot that succeeded it, both belong to the past humid period of the world's history. As the surface of the earth slowly dried up, in the gradual desiccation still in progress, new types of feet became a necessity, and the liorse, antelope, and camel, were gradually developed, to meet the altered conditions. The Proboscidians and Perissodactyls now living, except the horse, are doomed to early extinction, but the Artiodactyls, with their greater power of adaptation, will replace them, and perhaps develop new forms. The genealogy of the special Ungulate lines which ended in the hors.e, tapir, and rhinoceros, of the Perissodactyls, and of the pig, camel, and deer, among the Artiodactyls, has already been marked out by the author elsewhere,^ and need not here be repeated, esjjecially as the subject will be fully discussed in a future volume. Extinction of Laege Mammals. During the Mesozoic period, all the mammals appear to have been small, and it is not probable that any of large size existed, as reptilian life then reigned supreme. With the dawn of the Tertiary, a new era began, and mammalian life first found the conditions for its full and rapid development. In the lower Eocene, the largest land mammal was Coryphodon, more than the equal, in size and power, of any of the reptiles of that time. Dinoceras and its allies, in the middle Eocene, were much larger, and were ' Introduction atlcl Succession of Vertebrate Life in America, 1877. See also New Equine Mammals, etc., 1874, and Polydaotyle Horses Recent and Extinct, 1879. 190 DINOCERATA. clearly the monarclis of the region in which they lived. In the upper Eocene, Biplacodon, about the size of the rhinoceros, was the largest mammal, but each of these three died out in the period in which it flourished. At the base of the Miocene, the huge Brontotheridce, nearly as large as the elephant, suddenly appear in great numbers. They remained for a short time the dominant land animals, and then became extinct. The Proboscidians were the giants of the Pliocene, and hold the supremacy in size to-day, but are evidently a declining race, and must soon disappear. The cause of the successive disap23earance of each group of these large Tertiary mammals is not difl&cult to find. The small brain, highly specialized characters, and huge bulk, rendered them incapable of adapting themselves to new conditions, and a change of surroundings brought extinction. Smaller mammals, with larger brains, and more plastic structure, readily adapt themselves to their environment, and survive, or even send off new and vigorous lines. The Dinocerata, with their very diminutive brain, fixed characters, and massive frames, flourished as long as the conditions were especially favorable, but, witli the first geological change, they perished, and left no descendants. Classification of Dinocerata. The relations of the Dinocerata to other orders of mammals have now been fully considered in the preceding pages, and the main conclusions reached are given on pages 173 and 177. The generic sub-divisions of this group do not appear widely separated from each other, although at least three types, from successive geological horizons, can be distinguished. The species are numerous, and well marked, and there is strong evidence that many, if not all of them are from separate horizons. The differences due to age and sex are also manifest, and have been duly considered in estimatino^ distinctive characters. CONCLUSION. 191 The Binocerata now known may be placed in three genera : JDinoceras, Tinoceras, and Uintatherium. These may be separated by characters of the skull, vertebrae, and feet. There are also indications of several intermediate forms, which may, perhaps, be found to represent sub-genera, when additional specimens in good preservation are secured for comparison. Twenty-nine species may be distinguished, mainly by the skull alone, which, at present, offers the best distinctive characters. Sub-order DINOCERATA, Marsh. Family Tinoceratid^, Marsh. Uintatherium, Leidy. Teeth, thirty-six. Lower premolars^ four. Base of canine tusk, nearly vertical. Parietal protuberance above post-glenoid process. Cervical vertebrae of moderate length. Lunar articulating with trapezoid ? Binoceras, Marsh. Teeth, thirty-four. Lower premolars, three. Base of canine tusk, nearly vertical. Parietal protuberance above post-glenoid process. Cervical vertebrae less elongate. Lunar articulating with trapezoid. Tinoceras, Marsh. Teeth, thirty-four. Lower premolars, three. Base of canine tusk, horizontal. Parietal protuberance behind post-glenoid process. Cervical vertebrae short. Lunar not articulating with trapezoid. These three genera clearly represent three stages of development of the Binocerata, and these stages correspond to the successive horizons of the middle Eocene in which the remains of these animals were entombed. Uintatherium, the most generalized type, is found at the lowest level ; Binoceras is from a somewhat higher stratum ; and Tinoceras, the most specialized of all, occurs in the latest deposits. In the S3aiopsis which follows this chapter, a systematic list of all the species of the Binocerata is given in detail. In connection with the preceding pages, and the Plates at the end of the volume, this will place before the reader everything of importance now known in regard to the Binocerata. APPEI^DIX. SYNOPSIS OF DINOCERATA. The present synopsis contains a list of all the known species of the Dinocerata, and at least one characteristic figure of each species not elsewhere illustrated in this volume. Full references, also, are given to all the important literature. The complete titles of the works cited will be found in the Bibliography, which follows this synopsis. A brief history of the discovery of each specimen of importance, with the locality, geological horizon, collector, date, the nature of the remains, and where now preserved, is likewise j)laced on record under each species, as an essential part of a Monograph of the group. The dates of publication of the various papers on the Dinocerata have been carefully reexamined, and those here given are substantiated by conclusive evidence. The names adopted for genera and species are based on priority alone, except in the cases of those already used. For the higher groups, the new names proposed are to replace those previously applied, or to gain appropriate terms for nomenclature. Amblydactyla has thus been substituted for Amhlypoda, and CorypJiodontia, for Pantodonta, the names replaced being both essentially pre-occupied. The last term, moreover', has no significance when applied to the group of which Coryphodon is the original and characteristic type. The names Protungidata, Holodactyla, and Glinodactyla, express, respectively, a jjrominent feature of the groups they represent, and hence have been introduced in the preceding chapter. 25 193 194 DINOCERATA. DINOCERAS; Marsh, 1872. Diiioceras luiraMle, Marsh. (Plates I-VIII, XX-XLII, XLIV-LV.) Woodcuts: 3, p. 13; 7, p. 15; 13, p. 19; 26, p. 26; 34, 35, p. 31; 39, 40, p. 38; 43, 44, 45, p. 42; 63, p. 61; 89, 90, p. 76; 91, 92, p. 77; 95, 96, p. 80; 99, 100, p. 82; 106, 107, p. 91; 108, 109, p. 94; 111, p. 98; 113, p. 103; 114, p. 105; 118, p. 108; 119, 120, p. 112; 121, 122, p. 115; 123, p. 119; 129, 130, 131, 132, p. 131; 133, p. 134; 137, 138, p. 141; 143, 144, p. 152; 145, 146, p. 154; 152, 153, p. 184. Marsh, American Journal of Science and Arts (3), Vol. IV, p. 344, October, 1872; Vol. V, p. 119, Plales I and II, February, 18V3; Vol. XI, p. 164, Plates II-IV, February, 1876; Vol. XXII, pp. 31, 32, Plate II, July, 1881. American Naturalist, Vol. VII, p. 148, Plates I and IT, March, 1873. Proceedings of the American Philosophical Society, Vol. XII, p. 579; 1872; Vol. XIII, p. 256, 1873. Fifth Annual Report of the U. S. Geological Survey, (figures from present volume, viz:) fig. 38, p. 256; 39, p. 257; 40, p. 258; 44, p. 260; 50, p. 263; 61, p. 268; 69, 70, p. 272; 76, 77, p. 275; 80, 81, 82, p. 278; 100, p. 289; 116, 117, p. 295; 120-123, p. 296; 134, 135, p. 301; 136, p. 302, 1884. Garrod, Journal of Anatomy and Physiology, Vol. VII, pp. 267, 268, June, 1873. The same. Complete Writings, i^p. 121, 122, 1881. Nature, Vol. VII (skull figured), p. 366, March 13, 1873. Gaudry, Les Enchainements du Monde Animal, p. 74, fig. 86, 1878. Nicholson, Manual of Palseontology, Vol. II, pp. 870-373, figs. 656, 657, 1879. Dana, Manual of Geology, 3d ed., Plate VII, figs. 1-4 (from pi-esent volume), 1880. LeConte, Elements of Geology, pp. 525, 526, figs. 845, 845rt (from present volume), 1882. Flower, Encyclopedia Britannica, Vol. XV, p. 426, fig. '105, 1883. Cope (Uintatherium mirabile). — Hayden's Report U. S. Geological Survey of the Territories for 1872, pp. 581, 584, 1873. Proceedings of the Philadelphia Academy of Natural Sciences, Vol. XXV, p. 102, 1873. Proceedings of the American Philosophical Society, Vol. XIII, pp. 61, 65, 1873. ' Leidy (Uintatherium mirabile). — Extinct Vertebrate Fauna, pp. 97, 108, 332, 333, 1873. Osborn (Uintatherium mirabile). — Memoir upon Loxolophodon and Uintatherium, pp. 24, 25, 1881. The type specimen (number 1036) of this species was obtained in 1872 and 1873, by Messrs. B. U. Smith, J. W. Chew, and the author, from Big Bone Buttes, about twenty miles east-southeast of Fort Bridger, and twenty-five miles west of Green River, Wyoming-. ' /Isivoi, terrible, and Hspai, a horn. SYNOPSIS. -^. 270, 1884. The nasals in the type of this species (nnmber 1236) bear small, but prominent, tubercles, directed well upward and outward, and placed well back. In front of these elevations, the nasals are produced, and terminated by oblique, but nearly vertical, sutural surfaces for tlie pre-nasals. The maxillary protuberances are high and prominent, and connected by a transverse, elevated, and sharp, ridge. The upper surface of the skull is flattened, and well separated from the lateral surfaces by a ridge, gradually rising into the parietal 2Drotuberances. Tliese protuberances are connected by a distinct transverse ridge, and are elevated, and, in section, somewhat triangular. The olfactory lobes of the brain were short, and the olfactory chambers were not divided by a transverse bony septum. The type specimen (number 1236) of this species was collected by Messrs. L. Lamotte and J. W. Chew, at Cattail Springs, about twenty-five miles southeast from Fort Bridger, and about eighteen miles west of Green River, Wyoming, July, 1874. SYNOPSIS. ■209 The remains of this specimen consist of various portions of a skull. The geological horizon is in the Dinoceras beds of the Middle Eocene. The known remains of this species are in the Museum at Yale College. Tinoceras galeatum, Cope, sp. Woodcuts: 18.3 and 184, below. riCr 184 Ftg. 183. Figure 183. — Xasals of Tinoceras galtatam (iifter Cope); a. side view; b. top view. Figure 184. — Posterior surface of same skull. Both figures are one-eighth natural size. These figures were photogra^ihed on wood from the lithographic plate, cited below. Cope (Eobasileus galeatus). — Hayden's Report U. S. Geological Survey for 1873, pp. 456, 457, Plate I, 1874. Proceedings of the American Philosophical Society, Vol. 5IV, p. 17, 1874. (Loxolophodon galeatus.) — Hayden's Report U. S. Geological Survey for 1873, Plate I, 1874. Osborn, Memoir upon Loxolophodon and Uintatherium, pjj. 21, 22, 1881. The specimen upon which this species was based was obtained by Prof E. D. Cope, in 1873, in the Bad Lands of South Bitter Creek, Wyoming. The remains consist of various portions of the skull. The geological horizon is in the Bridger beds of the Middle Eocene. The known remains are preserved in Prof Cope's collection, 27 210 DINOCERATA. Tinoceras graiule, Marsh. Woodcuts: 20, p. 21; 49, p. 44 ; 84, 85, 86, p. 71; 87, 88, p. 75 ; and 185, below. Fis, ]85. b. \iiiUi4(/ Figure 185. — Nasals of Tinoceras grande, Marsh (No. 1040). a. side view ; b. top view ; c. front view. One-fifth natural size. Marsh, American Journal of Science, Vol. IV, p. 323, October, 1872; Vol. V, pp. 295, 311, April, 1873. American Naturalist, Vol. VII, p. 217, April, 1873. Proceedings of the American Philosophical Society, Vol. XIII, p. 256, 1873. Fifth Anniial Rejjort of the TJ. S. Geological Survey, (figures from the present volume, viz:) fig. 55, p. 264; 86, p. 280 ; 1 13, 114, 115, 1 18, 119, p. 295, 1884. Cope, Proceedings of the American Philosophical Society, Vol. XIII, pp. 54, 61, 1873. (Loxolophodon cornutus). — Hayden's Report U. S. Geological Survey for 1872, p. 575, 1873. The tyj)e specimen (number 1040) of this species was collected at Barrel Springs, about seventy-five miles east of Green River, Wyoming, in 1872, by Messrs. J. W. Chew and B. D. Smith. The remains of this specimen consist of portions of the skull, and cervical vertebri3e. The geological horizon of this sjaecies is in the Middle Eocene, in the Dinoceras beds. The known remains are preserved in Yale College Museum. Tluoceras liians, Marsh. Woodcuts: 32, i>. 30; and 186, below. FiGTJRB 186. — ^Nasals of Tinoceras Mans, Marsh (No. 1499). a. side ■view; 5. top view; c. front view. One-fifth natural size SYNOPSIS. 211 Marsh, Fifth Annual Reijort of the U. S. Geological Survey (figure from the present volume), fig. 67, p. 211, 1884. The snout in tlie type of this species (number 1499) tapers in front, where the nasals are divided by persistent sutures, and bear low rounded tubercles. The maxillary protuberances are connected by a low rounded ridge. The upper surface of the skull behind these protuberances is flattened, and, in the region of the fronto-nasal sutures, elevated. It is separated from the lateral surface by a ridge, rising gradually upon the parietal protuberances, which are connected by a transverse elevation across the sktill, above the brain case. The olfactory chambers were divided transversely by a bony septum as shown in figure 32, page 30. The palato-maxillary foramen extends back nearly to the middle of the second premolar. The premaxillaries are proportionally larger than in Dinoceras laticeps (number 1039), and straighter tlian in Dinoceras mirabile (number 1036). They present pits, as if for rudimentary teeth, as in number 1039. This species is based upon a specimen (number 1499) collected in June, 1874, by Mr. L. Lamotte, at Cattail Springs, Wyoming. The remains of this specimen consist of a skull, vertebrae, etc. The geological horizon is in the Dinoceras beds of the Middle Eocene. The known remains of this species are preserved in the Museum of Yale College. Tinoceras ingeiis, Marsh. (Plates XV-XVIII, LVI.) Woodcuts: 9, p. 16; 17, p. 19; 23, p. 25; 28, p. 27; 51, p. 45; 59, p. 55; 115, 116, p. 105; 117, p. 108; 124, 13. 119; 134, 135, p. 136; 141, 142, p. 149. Marsh, Fifth Annual Report of the U. S. Geological Survey, (figures from the present volume, viz:) figs. 46, j). 261; 52, p. 263 ; 58,"p. 267; 63, p. 269; 88, p. 281; 96, 97, p. 286; 126, 127, p. 297; 137, p. 302, 1884. The type specimen (number 1041) of this species was collected by Mr. S. Smith, near Haystack Mountain, Wyoming, in May, 1875. This specimen consists of a skull, in excellent preservation. The geological horizon of this species is in the Dinoceras beds of the Middle Eocene. The known remains of this species are in Yale College Museum. 212 DINOCERATA. Tinoceras jiigum, Marsh. Woodcut: 187, below. Figure 187. — Nasals of Tinoceras jugum. Marsh (No. 1500). a. side view ; J. top view ; c. front view. One-fifth natural size. In this species, the snout tapers forward, and bears a pair of small flattened tubercles, directed well outward and forward. The nasals are thoroughly coossified, and project in front beyond the tubercles. The maxillary protuberances are high, and strongly divergent. They are connected by a hig'h sharp ridge, which suggested the specific name. The tyjje of this species (number 1500) was found iDy Mr. L. Lamotte, in September, 1874, in Wyoming. The specimen consists of portions of the skull, and fore limbs. The geological horizon is in the Bridger beds of the Middle Eocene. The only remains known are in the Yale Museum. Tinoceras laciistre, Marsh. Woodcut: 188, below. Fig. \i FieuEE 188. — Upper molars of Kjioceras ?oc«sfoe, Marsh (No. 1037); seen from below. m. first true molar,'; pm. first premolar. Three-fourths natural size. Marsh (Dinoeeras lacustris). — American Journal of Science and Arts (3), Vol. IV, p. 344, October, 18'72. Proceedings of the American Philosophical Society, Vol. XIII, p. 266, 1870. Cope (Uintatherium lacustre). — Hayden's Report U. S. Geological Survey for 1872, pp. 581, 584, 1873. Proceedings of the American Philosophical Society, Vol. XIII, pp. 61, 66, 1873. SYNOPSIS. 213 The type specimen (number 1037) of this species was discovered by Messrs. J. W. Chew and B. D. Smith, near Bitter Creek, Wyoming, in 1872. This specimen consists of upper premolars, molars, and a radius. The geological horizon is in the Bridger beds of the Middle Eocene. The known remains of this species are preserved in the Museum of Yale College. Tinoceras latum, Marsh, n. s. Woodcuts: 189 and 190, below. Fi&UEE 189. — Nasals of Tinoceras latum, Marsh (No. li-i'l). a. side view ; b. top view ; c. front view. ODe-fifth natural size. FiGtJPb 190 — Nisilsof y/«f eius latum. Mirsh (No ISSO) a side view , 6 top view , c front view One-fifth natural size. The snout in the type specimen of this species tapers toward the end, but bears a pair of low rounded tubercles, directed nearly forward, and only slightly outward or upward. They are separated in front, along the median line, by an open suture between the nasal bones. These project forward beyond the protuberances, and terminate differently on the two .sides, the left coming nearly to a point, while the right is a little shorter, and ends with an oblique sutural surface. The skull presents a transverse ridge above the brain cavity, uniting the parietal protuberances. 214 DINOC'ERATA. The teeth preserved are but h'ttle worn, indicating a fully adnlt, but not old, animal. Another specimen (nnmber 1533) referred to this species is quite unlike any other in the collection in the form of the nasal bones so far as preserved, but, unfortunately, the specimen is considerably eroded. The snout, instead of tapering, expands forwaixl, and presents on each side a broadly rounded, horizontal protuberance, scarcely rising at all above the general level of the nasal bones. They, also, project forward, far beyond the end of those bones, Avhich were thoroughly consolidated, and directed somewhat downward, underneath the broad shelving- jn'otuberances. The left maxillary protuberance preserved with this specimen is of large size, and flattened on its outer side. This species, with Tiuoceras cornutum, forms a distinct sub-genus of Tinoceras, A^'hich may be called Plafoceras. The type of this species (number 1242) was obtained in September, 1873, by Mr. L. Lamotte and the author, near Spanish John's Meadow, Wyoming. The remains of this specimen consist of portions of the skull, and teeth. A second specimen (number 1533), apparently a very old individual of the same species, was found in Ma}^, 1875, by Messrs. S. Smith and S. Pearson, at Haystack Mountain, Wyoming. This specimen consists of portions of the skull. The extremity of the nasal bones is figured above. The geological horizon of these specimens is in the Bridger beds. The known remains of this species are preserved in Yale College Museum. Tinoceras longiceps, Marsh. Woodcuts: 38, p. 37; 48, p. 43; and 191, 192, below. Fig. 19-'. Figure 191. — Loft maxillary protubei-anco of Tinoceras longiceps, Marsh (No. 1256, female); side view. Figure 192. — Left parietal protuberance of same skull ; side view. The dotted line shows the outline of the caviiies {a and b) at the base of each specimen. Both figures are one-iourth u.atural size. SYNOPSIS. 215 Marsh, Fifth Annual Report of the U. S. Geological Survey, (figures from the present volume, viz:) fig. 75, p. 275; 85, p. 279, 1884. The skull in this species presents some striking peculiarities. The maxillary protuberances are placed well back, and are much above the socket for the weak and slender canine tooth (figure 48, page 43). They are directed upward and outward, and ai-e greatly excavated within, and below, as shown in figure 191. The parietal protuberances are well developed, and are also excavated near the base. The anterior face, as far as preserved, shows no distinct indication of a sharp ridge rising on the frontal bone in front of the protuberance, as in Dinoceras laticeps (number 1202), but the parietal protuberances seem to have risen abruptly, as in Tinoceras ingens. They are flatteiied behind, but are scarcely expanded transversely, as in the males of this type. The zygomatic process of the squamosal is slender, and presents a decided pit for the posterior end of the malar, just in front of the glenoid cavit}^. The lower jaw (figure 38, page 37) is elongated, and presents a small and weak pendent process, for the protection of the small and slender canine tusk (figure 48, page 43). This tusk has a nearly straight root, which suddenly contracts at the apex into a small orifice. The position of its socket is well in front of, and below, the maxillary horn-core, and unlike that of any other specimen in the Museum. This species is based upon a specimen (number 1256, female) obtained b)^ Mr. J. Heisey, at Red Dog Buttes, Wyoming, in June, 1876. The remains of the type of this species consist of portions of the skull, lower jaws, etc. The geological horizon is in the Dinoceras beds of the Middle Eocene. The known remains of this species are in Yale College Museum. Tinoceras pugnax, Marsh. (Plate XIX.) Woodcuts: 5, p. 13; 18, p. 19; 19, p. 21; 24, p. 25; 29, p. 27 ; 52, p. 45; 67, p. 63. Marsh, Fifth Annual Report of the IT. S. Geological Survey, (figures from the present volume, viz:) fig. 42, p. 258; 53, p. 263; 54, p. 264; 59, p. 267; 64, p. 269; 89, p. 282; 104, p. 290, 1884. The type specimen of this species (number 1044) was an individual of moderate size, and a male. The skull is short, and, seen from above strongly wedge-shaped. The nasal protuberances are small, high, and widely separated. The maxillary elevations are somewhat in front of the diastema. They are robust and recurved. The parietal protuberances are of moderate height, and transversely compressed at their summits. The premaxillaries are widely separated in front. The palato-maxillary foramen is opposite the second premolar. The posterior nares open upward through oval apertures, but little behind the bony palate. The 216 DINOCERATA. palate is much expanded between the canine tusks. The lower jaw has the alveoles of the incisors and canines nearly vertical. The flange for protection of the tusk is long-, and rounded in front (Plate XIX, figure 1). This specimen represents a distinct sub-genns of Tinoceras, which may be called Laoceras. The type specimen (number 1044) of this species was found by Mr. S. Smith, May, 1875, at Haystack Mountain, Wyoming. This specimen consists of a sknll in good condition, and various other bones of the same individual. The geological horizon of this specimen is in the Dinoceras beds. The known remains of this species are preserved in the Museum of Yale College. Tinoceras Speiriaiiiim, Osborn, sp. Woodcut: 193, below. -lOmiE 19 — SI nil of Tmoteias Sj t I M u ( I ei O 1 Clb Out eighth mtui il &izp Osborn (Loxolophodon Speirianum). — Memoir upon Loxolophodon and Uintatheriura, pp. 18, 20, 21, 22, 24, 41, 44, Plate I, 18S1. This figure was photographed on wood from the lithographic plate cited above. The restorations of this skidl do not allow some of its important features to be determined, but the generic characters ai-e distinct. In the restoration of this species, as given in the work cited above, the skull belonged to a male, and the lower jaw to a female. The bones of the fore limb, also, are in a position impossible in life. The type specimen of this species was discovered by Mr. Francis Speir, in 1878, in Wyoming. This specimen consists of the skull here figured. The geological horizon is in the Bridger beds of the Middle Eocene. The known remains of this species are in the Princeton Museum. SYNOPSIS. Tlnoceras stenops, Marsh. Woodcuts: 58, 54, p. 4V; and 194, below. Fig. 194. 217 Figure 194. — Skull and lower jaw of Tinoceras stenops, Marsli (No. 156T). e. condyle of lower jaw; d. diastema; m'. maxillary protuberance; n'. nasal protuberance; o. occipital condyle; p'. parietal protuberauce ; pm. premaxillary lione. One-eighth natural size. Marsh, Fifth Annual Report of the U. S. Geological Survey (figures from the present volume, viz:) fig.s. 90, 91, p. 283, 1884. The skull in the type specimen of this species (number 1567) is narrow, and elongated. The nasal protuberances are flat below, and above. They appear to have been divergent, but of moderate size, though situated well forward. The maxillary protuberances were prominent, directed well forward, and connected by a transverse ridge. Behind them, on each side, stands a prominent protuberance over the orbit. Back of this, the superior and lateral surfaces of the skull pass into each other by regular curvature in front of the origin of the latei'al ridges, which rise abruptly upon the parietal protuberances. These elevations are imperfectly preserved, but are flattened in front, and situated behind the post-glenoid processes. 28 218 DINOCERATA. The palate is excavated in tlie region of tlie diastema, and the palato-maxillaiy foramen is just in front of the first premohir, but not so far in front as in Tiiioceras ingens (number 1041). The lower jaw is slender, and expands rapidly in the region of the symphysis for the formation of the flanges pi'otecting the canine tusks. When seen from above, the nngle at . which the rami meet at the symphj^sis is distinctly rounded in front, though somewhat less strongly than in JDinoceras latkeps (Plate Xll, figure 1). The type specimen (nimiber 1567) of this species was collected by Mr. S. Smith, at Haystack Mountain, Wyoming, in May, 1882. The remains of this specimen consist of a skull, with lower jaw, etc. The geological horizon of this species is in the Dinoceras beds of the Middle Eocene. The known remains of this species are in the ^^ale College Museum. Tinoceras vagaiis, Marsh. "Woodeut: 12, p. IT. Marsh, Fifth Animal Report of the U. S. Geological Survey, (figure from the present volume, viz:) fig. 49, p. 26^, 1884. The snout in the type of this species (number 1241) tapers somewhat in front, and the nasal protuberances are flattened and directed forward, outward, and up\^■ard. The nasal bones are united throughout. The maxillary protuberances are slender, but prominent, and united across by a low rounded ridge. The upper surfnce of the skull is separated from the lateral surface, above and fiehind the orbits, by a ridge, which rises upon the parietal protuberances. These are prominent, and are flattened antero-posteriorly. They were connected across the top of the skull by a low transverse elevation. The type specimen (number 1241) of this species was discovered by Mr. S. Pearson, at lied Dog Buttes, AVyomiug, in July, 1875. Tliis specimen consists of portions of the skull, etc. The geological horizon is in the Dinoceras beds of the Middle Eocene. The known remains of this species are preserved in the Yale Museum. SYNOPSIS. 219 UINTATHERIUM,' Leidy, 1872. Uiutjitliei'iiim robiistiim, Leidy. Woodcuts: 61, 62, p. 51; and 195, below. rii 195 muiiiiiiijh FinuRE 195. — Skull of Ulntathermm rohmium, Leidy (type specimen), bottom view of back pan; of skull. /. foramen magnum; /'. oceipilal foramen; g. stylo-mastoid foramen; h foramen lacerum • i. vascular foramen in basisphenoid. One-fourlh naturnl size. Leidy, Proceedings of the Philadelphia Academy of N.T,tiiral Sciences, pp. 169, 241, 1872 American Journal of Science and Arts (;5), Vol. IV, p. 240, September, 1872. Extinct Vertebrate Fauna, pp. 93, 06, 333, 334, Plate XXV, Plate XXVI fio-s 1-8 Plate XXVII, tigs. 3(i-34, 1873. ' ^^ Cope, Proceedings of the Philadelphia Academy of Natural Sciences, p. 102, March 1873- p. 295, for 1882, 1883. ' ' ' Hayden's Report TJ. S. Geological Survey for 1872, pp. 581, 583, 1873. American Naturalist, Vol. VII, p. 159, March, 1873; Vol. XVII, p. 68, January, 1883. Proceedings of the American Philosophical Society, Vol. XIII, pp. 62, 64, 1873. .Alarsh, American Journal of Science and Arts, Vol. V, p. 290, April, 1873. American Naturalist, Vol. VII, p. 147, March, 1873. Proceedings of the American Philosophical Society, Vol. XII, p. 578, 1872. Osborn, Scott and Speir, Palseontological Keport, 1877, pp. 62, 71, 82, 1878. Osborn, Memoir upon Loxolophodon and Uintatheriura, pp. 18, 28, 1881. Leidy (Uintamastix atrox). — Extinct Vertebrate Fauna, pp. 94, 107, 333, 1873. The type specimen of this species was collected iu 1872, by Drs. J. V. A. Carter and J. K. Corson, fifty miles east of Fort Bridg-er, Wyoming. The remains of this specimen consist of the cranial portion of a skull, with fragments of both jaws, and portions of limb bones. The geological horizon of this species is in the Bridger beds of the Middle Eocene. This type specimen is preserved in Prof Leidy's collection. ' Uinta, Indian name, and dijpiov, a wild beast. 220 DINOCERATA, TJintatherium flssidens, Cope, sp. Woodcuts: 196 and 197, below. Fir. 191. FiftURE 193. — Lower jaw of Uintatliernmi flssidens (after Cope); top view. Figure 107. — The same specimen ; front view. Both, figures are two-lbirds natural size. The above fig-ures were made by a direct transfer from the original woodcuts cited below. Cope (Bathyopsis flssidens). — Bulletin of the U. S. Geological Survey of the Territories, Vol. VI, No. 1, pp. 194-196, February, 1881. Proceedings of the American Philosophical Society, Vol. XX, pp. 176, 177, 1882. American "Naturalist, Vol. XV, p. 75, January, 1881; Vol. XVIII, p. 1115, fig. 7, November, 1884. The type specimen of this species was collected by Mr. J. L. Wortman, in 1880, in the Wind River Basin, Wyoming-. This specimen consists of portions of the lower jaws here figured. The geological horizon of this species is not known with certainty, but is apparently in the Bridger beds of the Eocene. The type specimen is preserved in Prof Cope's collection. Uintatlieriiim latifroiis. Marsh. Woodcuts: 11, p. 17; 125, 126, 127, 128, p. 130. Marsh, Fifth Annual Report of the U. S. Geological Survey, (figure from the present volume, viz:) fig. 48, p. 262, 1884. In this species, the snout tapers in front, where the nasals are divided by an open suture. The nasal protuberances are of moderate size, broadly oval at the base, approximate, and moderately divergent. The nasals project well forward beyond them. The maxillary protuberances are large, and I'ounded, and ai-e connected by a very low transverse SYNOPSIS. 221 ridge. Tlie parietal protuberances were robust, and broadly oval in section near the top, and are connected by a low transverse ridge across the top of the skull. All these protuberances in this specimen are smooth, and regularly rounded. The type specimen (number 1231) upon which this species is based was collected by Mr. J. W. Chew, in 1874, two miles from Big Bone Buttes, Wyoming. The remains of this specimen consist of a skull, etc. The geological horizon of this species is in the Dinoceras beds of the Middle Eocene. The known remains of this species are preserved in Yale College Museum. Uiiitatherium Leidianum, Osborn, Scott, and Speir. Woodcut: 198, below. Fig. 198. Figure 198. — Skull of Uintatherium Leidianum (after 0>'bom, Scott, aud Speir) ; oblique side view. About cue-eighth natural size. This figure was photographed on wood from the original heliotype plate, cited below. Osborn, Scott, and Speir, Palseontological Report, pp. 63-80, Plates VI-VIII, 1878. Osborn, Memoir upon Loxolophodon and Uintatherium, pp. 18, 19, 22-24, Plate II, 1881. Cope, American Naturalist, Vol. XVIII, p. 1117, tig. 10, November, 1884. The type specimen of this species was collected in 1877, near Dry Creek, in Wyoming. 222 DINOCERATA. This specimen consists of a sknll, and portions of the skeleton. The geological horizon of this species is in tlie Dinoeeras beds of the Middle Eocene. The ty^je specimen is preserved in the Princeton Museum. Uinta til eiiuiii segue, Marsh. Woodcuts: 41, 42, p. 39; 101, 102, p. S3; and 199, 200, below. T. -,n^ ' Fis- 200. Fig. 199. j! Figure 199. — Maxillary protuberances of Uintatherium segne, Marsh (NTo. 1194); seeu from above. FiGUEE 200. — Tlie same specimen; seen from in front. m'. maxillary protuberance ; n. nasal bone. Both figures are ooe-fouith natural size Marsh, Fifth Arniual Report of the XJ. S. Geological Survey, (figures from the present volume, viz:) figs. 78, 79, p. 276, 1884. The maxillary protuberances of the skull of this specimen ore peculiar for their robust form. They are connected by a well developed transverse ridge. The parietal protuberances are massive, and some\Yhat club-shaped, and present a ridge in front, as in Dinoeeras mirabUe and Tiiioeeras h?ffens, evidently formed by the frontal bone rising nearly to the top of the protuberances. The type specimen (number 1194) of this species was collected by Messrs. S. Smith and J. W. Chew, east of Fort Bridger, AVj'oming, in October, 1873. The remains of this species consist of a lower jaw, and other jjarts of the skeleton. The geological horizon of this species is in the Dinoeeras beds of the Middle Eocene. The known remains of this species are preserved in Yale College Museum. SYNOPSIS. 223 Ambiypoda, see Amblytlactyla. Bathyopsis fissidens, see Uilltatlieriuill flssldeilS. Dinoeerea, see DillOCerJlta. Dinoeeras laeustris, see TinoceraS lacilStre. Eobasileus eornutus, see TillOCeraS COl'llutlllU. Eobasileus fureatus, see TillOCeraS. Eobasileus galeatus, see TillOCeraS galeatUlU. Eobasiliidas, see TillOCeratidse. Lefalophodon bifureatus, see Tinoceras. Lefalophodon exeressieornis, see TillOCd'aS. Lefalophodon diseornutus, see TinoceraS COrilutum. Loxolophodon aneeps, see TillOCeraS aiiceps. Loxolophodon eornutus, see TillOCeraS COrilUtlllU. Loxolophodon fureatus, see TlllOCeraS. Loxolophodon galeatus, see TillOCei'aS galeatUIIl. Loxolophodon grandis, see TillOCeras grailde. Loxolophodon pressieornis, see TillOCGFaS. Loxolophodon Speirianum, see Tinocer.as Speiriamim. Mastodon aneeps, see TillOCeraS aiiceps. Pantodonta, see CorypllOdoiltia. Titanotherium ? aneeps, see TillOCeraS ailCepS. uintamastix atrox, see UiiitatJieriiim robiistum. Uintatherium eornutum, see TlllOCeraS COl'lllltum. Uintatherium laeustre, see TillOCei'aS laCUStre. • Uintatherium latieeps, see DlllOCeraS laticepS. Uintatherium prineeps, see ITintatheriuill. Uintatherium lueare, see DillOCeraS llicare. Uintatherium mirabile, see DillOCeraS lIlil'aMle. Uintatheridee, see TillOCeratidae. BIBLIOGEAPHT. 1871. Marsh, Othniel Charles.— Notice of some New Fossil Mammals from the Tertiary Formation. — American Journal of Science and Arts (3), Vol. II, pj). 35-44. New Haven, July, 1871. First species of Dinocerata described (Titanotheriiim ? a-iceps). TitanoUierium was the tirst generic name applied to any of the Dinocerata. It was then a synonym of Menodus, but having been once used in another grouij, it cannot be retained for any geoiis of tlie Dinocerata. The same well known rule excludes the name Loxolophodon, which was first given to a species of Coryphodon. 1872. M-arshj Othniel Charles. — Preliminary Descrijrtion -of New Tertiary Mammals; Part I. — American Journal of Science and Arts (3), Vol. IV, pjj. 122-128. New Haven, August, 1872. The same, published in advance, July 22, 1872. Abstract of same. — Neues Jahrbuch fur Mineralogie, etc., pp. 990, 991, Stuttgart, 1872. Leidy, Joseph. — On some New Species of Fossil Mammalia from Wyoming. Proceedings of the Academy of Natural Sciences, Vol. XXIV, pp. 167-169. Philadelphia, September, 1872. The same, published in advance, August 1, 1872. The same, American Journal of Science and Arts (3), Vol. IV, pp. 239, 240. New Haven, September, 1872. First description of Uinfatherium robnstum. 29 225 226 DINOCERATA. Marsh, Othiliel Charles. — Preliminary Description of New Tertiary Mammals; Parts I, II, III, and IV (from American Journal of Science and Arts, August and September, 1872), with Postscript and Errata, pp. 1-35; published in advance, August 19, 1872. The genus Tinoceras proposed. Marsh, Othiliel Charles. — Note on Tinoceras anceps. — American Journal of Science and Arts (3), Vol. IV, p. 322. New Haven, October, 1872. The same, jjublished in advance August 24, 1872. Abstract of same.- — Popular Science Review, p. 94, London, January, 1873. Marsh, Othnlel Charles. — Errata. — American Journal of Science and Arts (3), Vol. IV, fourth i^age of cover, September, 1872. The same, p. 604. New Haven, December, 1872. Marsh, Othiliel Charles. — Notice of a new Species of Tinoceras. — American Journal of Science and Arts (3), Vol. IV, p. 323. New Haven, October, 1873. The same, published in advance, September 21, 1872. Description of Tinoceras grande, and family TinoceraiidcR proposed. Marsh, Othniel Charles. — Notice of some Remarkable Fossil Mammals. — American Journal of Science and Arts (3), Vol. IV, pp. 343, 344. New Haven, October, 1872. The same, published in advance, September 27, 1872. Sinoceras mirdbile and S. lacusire first described, and the order Dinooefi-ata proposed. Cope, Edward Brlnker. — Notices of New Vertebrata from the Upper "Waters of Bitter Creek, Wyoming Territory. — Proceedings of the American Philosophical Society, Vol. XII, number 89, for 1872, pp. 483-486. Philadelphia, February, 1873.* The same, published in advance. Philadelphia, 1872. * The authority for the date here assigned to this number of the Proceedings is the written statement of Prof. J. P. Lesley, Secretary of the Society, who then had charge of its publications. Cope, Edward Drinker. — Second Notice of Extinct Vertebrates from Bitter Creek, Wyoming. — Proceedings of the American Philosophical Society, Vol. XII, number 89, for 1872, pp. 487, 488. Philadelphia, February, 1873. The same, published in advance, 1872. Description of specimens named loxolophodon cornutus, L. furcatus, and L. pressicornis. (See note on page 225 of the present volume.) BIBLIOGRAPHY. 227 Cope, Edward Drinker.— Notice of Proboscidians from the Eocene of Southern "Wyoming. — Proceedings of the American Philosophical Society, Vol. XII, number 89, for 18T2, p. 5S0. Philadelphia, February, 1873. The same, with errors. Telegram from Black Buttes, Wyoming, published in advance, 1872. The same, Palasontological Bulletin, No. 5, re-published, Philadelphia, 18'73. Cope, Edward Drinker.— The Proboscidians of the American Eocene.— American Naturalist, Vol. VI, pp. 773, 774. Salem, December, 1872. Leidy, Joseph. — Remarks on Fossil Mammals from Wyoming. — Proceedings of the Academy of Natural Sciences, Vol. XXIV, pp. 240-242. Philadelphia, December, 1872. 1873. Marsh, Othniel Charles. — On some of Professor Cope's Recent Investigations.- American Naturalist, Vol. VII, pp. 51, 52. Salem, January, 1873. Cope, Edward Drinker. — Proboscidians of the American Eocene, Correction. American Naturalist, Vol. VII, p. 49. Salem, January, 1873. Marsh, Othniel Charles. — On the Gigantic Fossil Mammals of the Order Dinocerata. — American Journal of Science and Arts (3), Vol. V, pp. 117-122, Plates I, II. New Haven, February, 1873. The same, published in advance, January 28, 1873. A general description of the Dinocerata, with figures of the skull of Dimceras, and corrections of errors in Prof. Cope's publications on the same subject. Abstract of same. — Zeitschrift filr die Gesammten Naturwissenschaften, vol. vi, pp. 633, 534, Berlin, December, 1872. The same. — Annales des Sciences Naturelles (Zoologie), vol. xvii, 23p. 1-8, Paris 1873. The same. — Journal de Zoologie, vol. ii,pi3. 160-168, Paris, 1873. Abstract of same. — Geological Magazine, vol. x, pp. 115, 116, London, March, 1873. Abstract of same, with figure of skull of Dinoceras mirahilis. — Nature, vol. vii 366 London, March 13, 1873. Abstract of same. — Popular Science Review, p. 213, London, April, 1873. Abstract of same. — Neues Jahrbuch fttr Mineralogie, etc., pp. 334, 335, Stutto-art, 1875. 228 DINOCERATA. Cope, Edward Drinker. — Proceedings of the American Philosophical Society, Vol. XII, number 89, for 1872, p. 515. Philadelphia, February, 1873. Cope, Edward Drinker. — On the Dentition of Metalophodon. — Proceedings of the American Philosophical Society, Vol. XII, number 89, for 1872, pp. 542-545. PhiladeljAia, February, 1873. The name Losolophodon- stated to be a synonym of Bathmodon. Marsh, Othniel Cliarles. — Communication on the Discovery of New Rocky Mountain Fossils. — Proceedings of the American Philosophical Society, Vol. XII, number 89, for 1872, pp. 578, 579. Philadelphia, February, 1873. A general statement of the characters of the Dinocerata. The same. — Annales des Sciences Geologiques, vol. iii, p}). 99, 100, Paris, March, 1873. Cope, Edward Drinker. — On the Short Footed Ungulata of Wyoming. — Proceedings of tlie American Philosophical Society, Vol. XIII, number 90, for 1873, pp. 38-74, Plates I-IV. Philadelphia, 1873. The same, published in advance, March, 1873. Dinocerata considered a suborder of Proboscidea, with a list of species. Cope, Edward Drinker. — Observations on the Structure and Systematic Position of the genus Eobasileus, Coidc. — ^Proceedings of the Academy of Natural Sciences, Vol. XXV, pp. 10-12. Philadelphia, March, 1873. The same, Avith changes, published in advance, 1873. Eobasileuf! and allied genera referred to the Proboscidea. Cope, Edward Drinker. — On the New Perissodactyles from the Bridger Eocene. — Proceedings of the American Philosophical Society, Vol. XIII, number 90, for 1873, pp. 35, 36. Philadelphia, 1873. The same, under the title— On Two New Perissodactyles from the Bridger Eocene. — Palaeontological Bulletin No. 11. Philadelphia, 1873. Marsh, Othniel Charles. — Note on the Dates of some of Professor Cope's recent Papers. — American Journal of Science and Arts (3), Vol. V, jip. 235, 236. New Haven, March, 1873. Errors corrected in the dates of the Philosophical Society's meetings at which Prof. Cope's papers were claimed to have been read. The same, American Naturalist, Vol. VII, p. 173. Salem, March, 1873. BIBLIOGRAPHY. 229 Marsh, Otliniel Charles.— The Fossil Mammals of the order Dinocerata.— American ISTatui-alist, Vol. VII, pp. 146-153 ; Plates I-II. Salem, March, 1873. Characters of the order Dinocerata, with list of errors in Prof. Cope's papers on the same subject, and figures of skull oi Dinoceras inirahile. Cope, Edward Drinker.— The Gigantic Mammals of the Genus Eobasileus.— American Naturalist, Vol. VII, pp. 157-160. Salem, March, 1873. Description of Eobasileus, referring this form and Vintatherium to the Proboscidea. Cope, Edward Drinker.— Table of Genera of Short Footed Ungulates of the American Eocene.^Proceedings of the Academy of Natural Sciences, Vol. XXV, pp. 102, 103. •Philadelphia, March, 1873. Cope, Edward Drinker.— The Eobasileus again.— American Naturalist, Vol. VII, p^ 180. Salem, March, 1873. A denial of errors charged in regard to the Dinocerata. Marsh, Othniel Charles.— Additional Observations on the Dinocerata.- American Journal of Science and Arts, Vol. V, pp. 293-296. New Haven, April, 1873. The same, published in advance, Jlarch 18, 1873. A correction of errors in Prof. Cope's publications, with a list of ihe known species of Dinocerata. Abstract of same. — Nature, vol. vii, p. 491, London, April 24, 1873. Marsh, Othniel Charles. — Supplementary Note on the Dinocerata. — American Journal of Science and Arts (3), Vol. V, pp. 310, 311. New Haven, April, 1873. The same, published in advance, March 22, 1873. Errors in Prof. Cope's statements and plates pointed out, and names Loxolophodon and Eobasileus rejected. Marsh, Othniel Charles. — On the Genus Tinoceras and its Allies.— American Naturalist, Vol. VII, pp. 217, 218. Salem, April, 1873. Enumeration of errors in Prof. Cope's recent papers, and remarks upon photographs of Tinoceras cornutum. Grarrod, Alfred Henry.— On the Affinities of Dinoceras and its Allies —Nature, Vol. VII, p. 481. London, April 24, 1873. Dinocerata regarded as belonging to the Arliodactyla. 230 DINOCERATA. Cope, Edward Drinker. — On some of Professor Marsh's Criticisms. — American Naturalist, Vol. VII, pp. 290-299 ; Plates IV- V. Salem, May, 1873. A denial of errors in description of Eobasileus, and in the dates of publications. The same, with additions, Palseontological Bulletin, No. 13. Philadelphia, 1873. Marsh, Othniel Charles. — On the dates of Professor Cope's Recent Publications.- American Naturalist, Vol. VII, pp. 303-306. Salem, May, 1873. A protest against the authenticity of the dates claimed by Prof. Cope. Marsh, Othniel Charles. — ^Tinoceras and its Allies. — American Naturalist, Vol. VII, pp. 306-308. Salem, May, 1873. Correction of errors contained in Prof. Cope's recent papers. Cope, Edward Drinker. — On the Tusk of Loxolophodon cornutus. — American Naturalist, Vol. VII, p. 315. Salem, May, 1873. Marsh, Othniel Charles. — Notice of New Tertiary Mammals. — American Journal of Science and Arts (3), Vol. V, pp. 407-410. New Haven, May, 1873. Definition of tlie genera Tinoceras and Dinoceras, with first description of D. lucare. Abstract of same. — Najbure, vol. viii, p. 76, London, May 22, 1873. Marsh, Othniel Charles. — Reply to Professor Cope's Explanation. — American Naturalist, Vol. VII, appendix, pp. i-ix. Salem, June, 1873. Statement in detail of the errors and incorrect dates of Prof. Cope's papers on the Dinoceraia. Marsh, Othniel Charles. — New Observations on the Dinocerata. — American Journal of Science and Arts (3), Vol. VI, pp. 300, 301. New Haven, October, 1873. Additional characters of the order, and first description of Dinoceras laticeps. The same, j^ublished in advance, September, 1873, Marsh, Othniel Charles. — On the Gigantic Mammals of the American Eocene. — Proceedings of the American Philosophical Society, VoL XIII, number 90, pp. 255, 256. Philadelphia, 1873. BIBLIOGRAPHY. 2;31 Leidy, Joseph.— Contributions to tlie Extinct Vertebrate Fauna of the Western Territories.— Report of the United States Geological Survey of the Territories, F. V. Hayden, 4to, Vol. I. Washington, ISYS. (Dinocerata, pp. 93-109, 331-334; Plate XXV; Plate XXVI, figs. 1-8; Plate XXVII, figs. 30-34.) A full discussion of the structure, classification, etc., of tlie Dinocerata. On page 95 of this memoir. Dr. Leidy in citing the descriptiou of Dinoceras mirdbile inadvertently oraiuedthcf llowing: "small, compressed, osseous elevations which probably supported a pair of horns. The maxillaries have a pair of." Prof. Cope, referring apparently not to the original paper, hut to this inomplete passage, has since asserted that the author placed the posterior horn-cores of Dinoceras on the frontal bones, a statement without foundation. Cope, Edward Drinkei*.- On the Extinct Vertebrata of the Eocene of Wyoming observed by the Expedition of 1872.— United States Geological Survey of the Territories, Sixth Annual Report, F. V. Hayden, 8vo, pp. 543-649, Plates I-VI. Washington, 1873. Discussion of the Dinocerata, with descriptions of this author's species, and with figures of Tinoceras cornutum. Cope, Edward Drinker.— Palaeontological Bulletins Nos. 1-13, 8vo, Philadelphia, 1873. Contains reproductions, among others, of the following papers, some with additions or corrections, viz: No. 5. — Telegram from Black Buttes, Wyoming. No. 6.— Notices of New Vertebrata from the Upper Waters of Bitter Creek, Wyoming Territory. Reprint. ]Sro. 7.— Second Notice of Extinct Vertebrates from Bitter Creek, Wyoming. Reprint. No. II.— On two New Perissodactyles from the Bridger Eocene. With changes. No. 13. — On some of Professor Marsh's Criticisms. With additions. 1874. Marsh, Othniel Charles.— SmaR Size of the Brain in Tertiary Mammals.— American Journal of Science and Arts (3), Vol. VIII, pp. 66, 67. New Haven, July, 1874. The same, published in advance, 1874. The same.— American Naturalist, vol. viii, pp. 503, 504, Salem, August, 1874. The same.— Annals and Magazine of Natural History (4), vol. xiv, p. 167, London, August, 1874. Abstract of same. — Nature, vol. x, p. 273, London, August 6, 1874. The same.— Journal de Zoologie, vol. ill, pp. 326, 327, Paris, 1874. Abstract of same.— Neues Jahrbuch fur Mineralogie, etc., p. 772, Stuttgart, 1874. 232 DINOCERATA. Cope, Edward Drinker. — Report ou the Vertebrate Palaeontology of Colorado. — Annual Report of the United States Geological and Geographical Survey of the Territories for 1873, F. V. Hayden, pp. 427-533, Plates I— VIII. Washington, 1874. Description of EobasUeus galeatus, wliich, on Plate I, is called Loxolophodon galeatus. Marsk, Othniel Charles. — On the Structure and Affinities of the Brontotheridae. — American Journal of Science and Arts (3), Vol. VII, pp. 81-86, Plates I, II. New Haven, January, 1874. Contains a comparison of the brain in Brontotherium and Dinoceras. Abstract of the same. — Nature, vol. ix, p. 227, London, January 22, 1 The same. — American Naturalist, vol. viii, pp. 79-85, Salem, February, 1874. Abstract of same. — Journal de Zoologie, vol. iii, pp. 61, 62, Paris, 1874. 1875. Marsh, Othniel Charles.— Ancient Lake basins of the Rocky Mountain Region. — American Journal of Science and Arts (3), Vol. IX, pp. 49-52. New Haven, January, 1875. Contains a description of the Eocene Lalje-basin in which the Dinocerata are found. Abstract of same. — American Naturalist, vol. ix, p. 119, Salem, February, 1875. Abstract of same. — Geological Magazine (2), vol. ii, pp. 232, 233, London, May, 1875. Cope, Edward Drinker. — The Feet of Bathmodon.^Proceedings of the Academy of Natural Sciences, Vol. XXVII, p. 73. Philadelphia, May, 1875. The Dinocerata, from the structure of the feet, regarded as a suborder. 1876. Marsh, Othniel Charles. — -Principal Characters of the Dinocerata, Part I. — American Journal of Science and Arts (3), Vol. XI, pp. 163-168, Plates II-VL New Haven, February, 1876. Discussion of the order Dinocerata, with plates of the skull, brain-cast, lower jaw, and feet of Dinoceras. Abstract of same. — Nature, vol. xiii, p. 374", London, March 9, 1876. The same. — Journal de Zoologie, vol. v, pj). 136-145, Paris, 1876. Abstract of same. — Zeitschrift fiir die gesammten Naturwissenschaften, vol. xiv, pp. 31, 32, Berlin, 1876. Abstract of same. — Neues Jahrbuch fiir Mineralogie, etc., pp. 780, 781, Stuttgart, 1876. Abstract of same. — Popular Science Review, pp. 326, 327, London, July, 1876. BIBLIOGRAPHY. 233 Marsh, Othniel Charles. — The Brain of Dinoceras. — American Naturalist, Vol. X, p. 182. Boston, March, 1876. Owen, Richard. — On the existence or not of Horns in the Dinocerata. — American Journal of Science and Arts (3), Vol. XI, pj). 401-403. New Haven, May, ISTG. Doubts expressed as to the presenue of true horns iu the Dinocerata. (See page IST of the present volume). Marsh, Othniel Charles. — On some of the Characters of the genus Coryphodon, Owen. — -American Journal of Science and Arts (3), Vol. XI, pp. 425-428. New Haven, May, 1876. A comparison of the brain-oast in Coryphodon and Dinoceras. Abstract of same. — Popular Science Review, p. 327, London, July, 1876. Abstract of same. — Neues Jahrbuch ftir Mineralogie, etc., p. 781, Stuttgart, 1876. Abstract of same. — Bibliotheque TJniverselle. Archives des Sciences Physiques et NaturelLes, vol. Ivi, pp. 273, 274, Geneva, 1876. Flower, William Henry.— On the Extinct Animals of North America. — Popular Science Review, Vol. XV, pp. 276-298, Plate CXXXVIII. London, July, 1876. Contains a brief dfiscription of the Dinocerata,, with figures of sliuU and hind feet of Dinoceras. Marsh, Othniel Charles. — Recent Discoveries of Extinct Animals. — American Journal of Science and Arts (3), Vol. XII, pp. 59-61. Nov Haven, July, 187G. The same, American Naturalist, Vol. X, pp. 436-439. Boston, July, 1876. Abstract of same. — Neues Jahrbuch fur Mineralogie, etc., p. 782, Stuttgart, 1876. 1877. [Cope, Edward Drinker.] — The Lowest Mammalian Brain. — American Naturalist, Vol. XI, pp. 312 313. Boston, May, 1877. Marsh, Othniel Charles.— Brain of Coryphodon. — American Naturalist, Vol. XI, p. 375. Boston, Jvme, 1877. Abstract of same.— Nature, vol. xvii, p. 340, London, February 28, 1878 Cope, Edward Drinker.— Brain of Coryphodon. — Proceedings of the American Philosophical Society, Vol. XVI, pp. 616-620, Plates I, IL Philadelphia, 1877. Contains a comparison of brain-casts in Coryphodon and Dinoceras. 234 DINOCERATA. Marshy Othniel Charles. — Principal Characters of the Coryphodontidse. — American Journal of Science and Arts (3), Vol. XIV, pp. 81-85, Plate IV. New Haven, July, 1811. A comparison of Coryphodon and Oinoceras, with figures of the feet in both. The same. — Journal de Zoologie, vol. vi, pp. 380-385, Paris, 1877. Abstract of same. — American Naturalist, vol. xi, p. 500, Boston, August, 1877. Abstract of same. — Neues Jahrbuch ftir Mineralogie, etc., p. 767, Stuttgart, 1877. Cope, Edward Drinker. — Report upon the Extinct Vertebrata obtained in New Mexico by Parties of the Expedition of 1874. — United States Geographical Surveys West of the 100th Meridian, Wheeler, Vol. IV, Palaeontology, Part II, pp. 179-186, 273, 282. Washington, 1877. Dinocerata here considered a suborder of the Amblypoda. Marsh., Othniel Charles. — -Introduction and Succession of Vertebrate Life in America. — .A.n Address delivered before the American Association for the Advancement of Science, at Nashville, Tenn., August 30, 1877. Proceedings, Vol. XXVI, I3p. 211-258, Salem, 1878. Contains a reference to the characters and affinities of the Dinocerata. The same published in advance, pp. 1-57. 8vo. New Haven, August, 1877. The same. — Nature, vol. xvi, j^p. 448-450, 470-472, and 489-491, London, September 20, 27, and October 4, 1877. The same. — American Journal of Science (3), vol. xiv, pp. 337, 378, New Haven, November, 1877. The same with jjlate. — Popular Science Monthly, vol. xii, pp. 511-527 and 672-697, New York, March and April, 1878. The same. — Revue Scientifique de la France et de V Etranger (2), vol. vii, pp. 1039- 1046, and 1064-1074, Paris, May 4 and 11, 1878. 1878. Gaudry, Albert. — Les Enchainments du Monde Animal dans les temps Geologiques. Mammif^res Tertiares, 8vo, pp. 1-293, figure 86. Paris, 1878. Marsh, Othniel Charles. — T'inoceras. — Johnson's New Universal Cyclopedia, Vol. IV, pp. 808, 869. New York, 1878. King, Clarence. — United States Geological and Geographical Exploration of the Fortieth Parallel, Vol. I, Systematic Geology, p. 403. 4to. Washington, 1878. A partial list of the species of Dinocerata occurring in the Bridger beds of the Eocene. BIBLIOGRAPHY. 235 Osboru, Henry Fairfield; Scott, William Berryman; Speir, Francis — Palseontological Report of the Princeton Scientific Expedition of 187Y; Contributions from the Museum of Geology and Archaeology of Princeton College, No. 1, 8vo, pp. 146, Plate A, and I-X. New York, ISVS. Contains (pp. 62-82, Plates YI, Til) first descriptions of Uintatherium Leidianum and U. princeps, with figures. Ryder, John A.— On the Mechanical Genesis of Tooth Forms.— Proceedings of the Academy of Natural Sciences for 1878, pp. 45-80. Philadelphia, April, 1878. 1879. Osborn, Henry Fairfield, and Speir, Francis.— The Lower Jaw of Loxolophodon.— American Journal of Science and Arts (3), Vol. XVII, pp. 304-309, Plate I. New Haven, April, 1879. Description of the lower jaw of a female Tinoceras, or allied genus. Nicholson, Alleyne.— Manual of Palaeontology, 8vo, Vol. II, p. 370-373, figs. 656, 657. Edinburgh and London, 1879. Description of the Dirwcerata, with figures of the skull and feet of Binoceras miraUle, from the present volume. 1880. Dana, James Dwight.— Manual of Geology, Third Edition, 8vo, pp. 604, 508, Plate VH, figs. 1-4; Plate XI, fig. 1. New York, 1880. A reference to the Dinoceraia, with figures from the present memoir. 1881. Cope, Edward Drinker.— On the Vertebrata of the Wind River Eocene Beds of Wyoming. — Bulletin of the United States Geological Survey, F. V. Hayden, Vol. VI, pp. 183-202. Washington, February, 1881. Contains (pp. 194-196) first description of Uintatherium Jksidens. Garrod, Alfred Henry. — Dinocerata. — Journal of Anatomy and Physiology, VII, pp. 267-270. London and Cambridge, June, 1873. The same. Complete Writings, edited by W. A. Forbes, 8vo, pj). 121-123. London, 1881. Opinion that the Binocerala belong to a family of the Artiodactyla. Marsh, Othniel Charles. — Restoration of Binoceras mirahile. — American Journal of Science (3), Vol. XXH, pp. 31, 32, Plate II. New Haven, July, 1881. The same, published in advance, June 14, 1881. First restoration of Dinoceras mirahik, new characters in the skull and sternum, and distinction stated between this genus and Uintathmum. Abstract of same. — Archives des Sciences Physiques et Naturelles, vol. vi, pp. 323, 324 Geneva, September, 1881. 236 DINOCERATA. Osborn, Henry Fairfield. — A Memoir upon Loxolophodon and TJintatlierium (Two Genera of the Sub-Order Dinocerata). — Contributions from the E. M. Museum of Geology and Archaeology of the College of New Jersey, Vol. I, No. 1, 4to, pp. 54, Plates I-I Y. Pr inceton , 1 8 8 1 . A general discussion of the Bmocerata, and first description of Tinocera,s Speirianum, witb. a restoration. The statement on page 17 in regard to the discover}' of the Dinocerata is erroneous, as the author was nearly two years earlier in the field than is there implied. See Introduction, page 2, of the present volume. 1882. Cope, Edward Drinker. — Contributions to the History of the Vertebrata of the Lower Eocene of Wyoming and New Mexico, made during 18S]. — Proceedings of the American Philosophical Society, number 111, for 1882, pp. ISO-lD'?. Philadel- phia, 1882. [Cope, Edward Drinker.] — American Naturalist, Vol. XVI, plate XVIT, p. 1029. Philadelphia, December, 1882 ; Vol. XVII, Erratum. A restoration of Tinoceras cornutum, without text. LeConte, Joseph. — Elements of Geology, Second Edition, pp. 525, 526, figs. 845, 845a, 8vo. New York, 1882. A brief description of Dinoceras and Tinoceras, with figures from the present volume. Tomes, Charles Sissmore. — Dental Anatomy, Human and Comparative, Svo, pp. 440. Second Edition, London, 1882. \_Dinocerata, pp. 340-342, figure 146.] 1883. Cope, Edward Drinker. — On Uintatherium and Bathmodon. — American Naturalist, Vol. XVII, p. 68. Philadelphia, January, 1883. Cope, Edward Drinker. — On Uintatherium, Bathmodon and Triisodon. — Proceedings of the Academy of Natural Sciences for 1882, pp. 294-300. Philadelphia, January, 1883. Cope, Edward Drinker. — The Classification of the Ungulate Mammalia. — Proceedings of the American Philosophical Society for 1882. Vol. XX, pp. 438-447. Philadel- phia, 1883. Flower, William Henry. — Mammalia. — Encyclopaedia Britannica, 9th Edition, Vol. XV, p. 426, fig. 105 (from present volume). Edinburgh, 1883. Wortman, Jacob L. — The Carpal bones of the Dinocerata. — Science, Vol. I, p. 151. Cambridge, March 9, 1883. BIBLIOGRAPHY. 237 1884. Marsh, Othniel Charles. — The Gigantic Mammals of the Order Dinocerata. Fifth Annual Report of the United States Geological Survey, 8vo, pp. 245-302, figs. 36-137. Washington, 1884. Ad extended abstract of the present volume, with 102 illustrations. Cope, Edward Drinker.— The Amblypoda. — American Naturalist, Vol. XVIII, pp. 1110-1121, figs. 7, 8, 10. Philadelphia, November, 1884, Contains figures of the lower jaw of Uiniatherium fissidens. POSTSCRIPT. The Plates of the present volume, with their accompanying pages of explanations, were nearly all printed in 1881 and 1882, and the last of the series, in February, 1883. Most of the other illustrations, also, were completed by the latter date. In consequence of an unexpected delay in printing the text, some of the figures prepared for the Monograph first appeared elsewhere. An extended abstract of this volume, with 102 illustrations, was prepared by the author, in July, 1884, for the Fifth Annual Report of the Director of the United States Geological Survey, and references to the pages of this Report will be found in the preceding Synopsis. With the permission of the Director of the United States Geological Survey, an author's edition of 500 copies of this work was printed in Feb- ruary, 1885. INDEX. A. Page. Amblydadty la , characters of the 176 Amia, occurrence of, with Dinocerata remains 9 Anaynodon ads'cnus, xiew of skull of 04 Anterior dorsal ribs, description of the 130-132 Artiodactyla, comparison of, with Diuoceiata 181 ■ development of foot in 188,189 Astragalus, views and description of the (PI. XLVII) 146-151 Atlas, views and description of the (PI. XX) 69-71 Auchenia vicugna, view of skull of 67 Axis, views and description of the (PI. XXI) 72, 73 E. Baptanodon discus, view of left hind limb of 183 Baur, G., acknowledgment of aid of xviii B.bliography of Dinocerata 225-237 Brain, description of the 53-67 Brain-cast, views and description of tbe (PL VI)... 53-55 Brain-growth, description of 57-67 Brain-growth in mammals, laws regulating 58-60 Bridger series 6 Brontotberium beds, situation of the 6 Brontotherium ingens, view of skull of 61 view of right feet of 180 C. Calcaneum, views and description of the (PI. XLViri) 151-153 Canines, di scriplion of the 43-^6 Capra hircus, view t'f left feet of 188 Carpal bones, description of the loi Carter, J. V. A., collection of specimens by 196, 219 Caudal veitebrse, views and description of the (PL XLIII) 138 Cervical vertebrte, views and description of the (PL XXII) 09-78 Cei vua Virginianas, view of skull of 67 Chelydra serpentina, view of right fore footof 183 Cheney, H. G., collection of specimens by 195 Chew, J. W., collection of specimens by 194,195,196, 198. 201, 202, 203, 208, 210, 213, 221, 222 Clinrdactyla, characters of the 175 Colon Ics torquatus, view of skull of 67 Dinoceias, place of, among Dinocerata 10 variation of premaxillaries in 24 dentition of. 41 biain of 56 measurements of first metacarpal of 121 measurements ot fourth metacarpal of 120 characters of the genus 191 list of species of, with account of specimens 194-202 Dinoceras agreste, view of skull of 19 description of ucciput of 20 description of specimens of 197 Dinoceras and Mastodon Americanus, comparison of pelvic arch in 137 Dinoceras and Tinoceras, restorations of 165-168 Dinoceras beds, sit nation of 3, 6 Dinoceras cuneum, views and description of sixth cervical vertebra of 77 measurements of sixth cervical vertebra of 78 description of specimens of 197, 198 Dinoceras diaians, view of nasals of 13 view of skull of 15, 16, 29 description of specimens of 199 Dinoceras laticeps, view of skull of 19, 26, 30, 54 descriptionof occiput of 20 view of palate of 25 views and descriptions of skull of (PI. X, XI, XIV) 26,45 views and descriptions of lower jaw of (PI. XII, Xni) 35,36 measurements of lower jaw of 40 view of upper canine of 43, 44 view and measurements of left scaphoid of 103 views and descriptions of caudal veriebrEe of (PI. XLIH) 138 views of left astragalus of 149 measurements of left astragalus of 150 measurements of left ectocuneiforra of 160 descripl ion of specimens of 200 Dinoceras lucare, maxillary bone in 28 views and descriptions of teeth of (PL IX) 43, 45, 49 239 240 INDEX. Dinoceras lucare — Continued. ■meaauiement nf axis of '3 views of posterior dorsal veretebra of 84 measurements and views of section of ulna of. . . 98, 99 measurements of fourth metacarpal of 126 description of specimens of 200,201 Dinoceras mirabile, views and descriptions of skull of (PI. I-V) 11. 24 view of nasals of 13 view of skull of 15,19,26,31,32.61 tIbws of lower jaw of 38 views of incisors of ^2 views and descriptions of teeth of (PI. "Vn, YjH) 46, 48, 49, 50 views and descriptions of brain-cast of (PI. VI) . . 53-55 views and description of atlas of (PI. XX) 69 measurements of atlas of 71 views and description of axis of (PL XXI) 72 measurements of axis of 73 description and measurements of third cervical vertebra of 74 views and descriptions of cervical vertebrse of (PL XXII) 74.78 measurements of fourth cervical vertebra of 75 views and measurements of fifth cervical verte- bra of 76 views and description, of sixth cervical vertebra of. 77 description and measurements of seventh cervi- cal vertebra of measurements of sixth cervical vertebra of ..-.- description and views of first dorsal vertebra of 79,1 raeasureraentsof first dorsal vertebra of '• description and views of second dorsal vertebra of. views and descriptions of dorsal vertebrse of (PL XXIII, XXIV) 82, 84 measurements of second dorsal vertebra of 83 views and descriptions of lumbar vertebrae of (PL XXV, XXVI) 85 measurements of four lumbar vertebrse of 86 views and descriptions of left scapula of (PL XXVII) 87 measurements of left scapula of 88 views and description of humerus of (PL S XVin) 89 measurements and views of section of humerusof 91, 92 views and descriptions of radius of (PL XXIX) . 93. 94 measurements of section of radius of 95 views and descriptions of ulna of (PL XXX). - . . 96 measurements and views of section of ulna of. . . 98, 99 views and descriptions of feet of (PL LIV) 101, 145 views and descriptions of scaphoid and lunar of (PLXXXI) 102,104 view of right and measurements of right and left scaphoid of 103 view of right lunar of 105 measurements of right lunar of 106 views and descriptions of pyramidal and pisiform of (PL XSXII) v.. 107,109 view and measurements of left pyramidal of 108 measurements of right pisiform of 110 views and descriptions of trapezium and trape- zoid of (PL xxxiH) 110,111 measurements of left trapezium of Ill Page. Dinoceras mirabile — Continued. views and measurements of left trapezoid of 112, 113 views and descriptionp of magnum and unciform of (PL XXXIV) 113,115,116.117.119,120 measurements of first metacai-pal of 121 views and depcriplions of metacarpals of (PL XXXV-XXXVII) 121, 122, 123, 124, 127 views and descriptions of phalanges of (PL XXXVin.LIlI) 121,127,128,164 measurem£nts of second metacarpal of 122 measurements of third metacarpal of 124 measurements cf lourth metacarpal of 125 views and descriptions of ribs of (PL XXXIX) . 129, 133 views of anterior rib of 131 measurements of first anterior and median ribs of 132 measurements of dorsal and x>osterior ribs of . .. 133 views and descriptions of sternum of (PL XL) . . 133, 134 views and desciiptions of pelvis of (PL XLI, XLn) 135,137 measurements of pelvis of 137 views and descriptions of femur of {PL XLIV) . . 139 measurements of right femur and views of sec- tion of femur of I'll views and descriptions of tibia of (PL XLV) .... 141 measurements of tibia of 142 measurements of fibula of 143 views and descriptions of fibula and patella of (PL XLVI) 143 views and descriptions of astragalus of (PL XLVn) 146 measurements of right and left astragalus of 150, 151 views and descriptions of calcaneum of (PL XLVIH) 151, 152 measurements of right and left calcaneum of — 153 views and descriptions of cuboid and navicular of (PL XLIX) 153,155 views of right and measurements of right and leftcuboidof 154,155 measuremeuts of Itft navicular of 157 views and descriptions of tarsal bones of (PL L) . 158, 159 measurementfi of left mesocuneiform of 159 measurements ofright and left ectocuneiform of. 160, 161 views and descriptions of metatarsals of (PL LI, LU) -161,162,163 view and description of restoration of (PL LV).. 165 size and appearance of 165, 166, 168 views of left feet of 184 account of specimens of 194-196 Dinoceras reflexura, description of specimen of 201, 202 Dinocerata, discoveries of remains of 2-4 localities in which remains of, have been found. . 8 fossils fuund associated with 9 place of, among Ungulata 9, 10 genera and species of 10 detailed description of skuU of 11-33 detailed description of lower jaw of 35-40 detailed description of teeth of 41-52 detailed descri ption of brain of 53-67 detailed description of cervical vertebrse of 69-78 description of the dorso-lumbar vertebrae of 79-86 detailed description of fore limbs of 87-128 detailed description of fore feet of 101-128 detail* d description of ribs aud sternum of 129-134 detailed desciiption of pelvic arch and tail of. .. 135-138 INDEX. 241 Page. Dinocerata — Cnntinned, detailed description of bind limhs of 139-1G4 detailed description of hind feet of 145-1 G4 horn-cores of 168 characters of 178-181 contrast of, with living forms 17I)-1?1 classification of 10i>, 101 list of species of, with account of specimens 193-223 bibliography of 225-237 Diplacodon beds, place of 6 Dorsal vertebrae, views of the (PI. XXm, XXIV) . . 82-84 - Dorso lumhai- rei tebraa, description of the 79-86 Di'omocyon. occurrence of, with Dinocerata remains. 9 E. EciocuneiCorm, description of the 159-161 Elcphas Indicus, view of stull of 66 views of left leet of 185 Elutherium crassum. view of skull of 65 .Ebtocuueiform, description of the 158 Eporeodon socialis, view of skull of 64 view of left feet of 187 Equus caballus, view of skull of 61 view of left feet of iS8 F. Femur, views and descriptiona of tlie (PI. XLIV) ... 139 measurements of right and views of section of the 141 Fibula and patella, views and description of the (PI. XLVI) 143 Fifth metacarpal, description of the 127 Fifth metatarsal, description of the 163, 164 Fifth vertebra, description of the 76 First dorsal vertebra, dfscription of the 79-81 First metacarpal, description of the 121 First metatarsal, description of the 161 First rib, descriptions of the 129 Flower, W. H., publications of, respecting Dino- cerata 233, 236 Forearm, description of the 92, 93 Forefeet, views of the (PhLIV) ICl Fore limbs, description of the 87-128 Fourth metacarpal, description of the 124-126 Fourth metatarsal, description of the 163 Fourth vertebra, description of the 74, 75 Frontal bones, description of the 16-18 G. Garrod, A. H., publications of, respecting Dino- cerata 229, 235 Gaudry, Albert, publications of, respecting Dino- cerata 234 Green River, DiDOcerata remains from vicinity of. .. 8 Green River series 6 H. Hargar, Oscar, acknowledgment of aid of xvni collection of specimens by 195 Heisev, J., collection of specimens by 196, 198, 205, 206, 215 Helaletes, occurrence of, with Dinocerata remains . . 9 Helioblitia bcd^ sitnat ion of 6 Hmd feet, views of the (Pl.LIV) 145 Hind limbs, description of the 139-1 G4 Hippopotamus amjjhibius, view of palate of 25 vinwof skull of 67 view of left eit of 187 Holodactyla, characters of 172 Humerus, views of the (PI- XXVUI) 89 description of the 89-92 Hyopsodus, occurrence of, with Dinocerata remains. 9 Hyrachyns, occurrence of, with Dinocerata remains. 9 Hyrachyus Rairdianus, view of skull of 64 Hyijicoidea, characters of 173, 174 Hyiax capensis, views of left feet of 185 I. Incisors, descriptiou of the 41-43 -J. Jurassic and Triassic mammals, studies of the, by 0. C. Marsh 169 King, Clarence, list of Dinocerata published by . Lachrymal bones, description of the 22 Lamotte, L., collection of specimens by . .196, 197, 200, 203, 208, 211,212,214 Lane, E. S., collection of specimens by 195 Le Conte, Joseph, references to Dinocerata in publi- cations of 236 Leidy , Joseph , Dinocerata collections of 4 publications of, respecting Dinocerata 225, 227, 231 Lemuravus, occurrence of, with Dinocerata remains. 9 Lepidnsteus, occurrence of, with Dinocerata re- mains 9 Limnocyon, occurrence of, with Dinocerata remains. 9 Limnofelis, occurrence of. with Dinocerata remains. 9 Limnohyus, occurrence of, with Dinocerata remains. 9 Limnohyus robustus, view of skull of 63 Lower Eocene, mammals of the — 189 Lower .iaw, views of the (PI. YIU, XLt, XIH, XLX) . 35, 49 descrii)tion of the 35-40 Lower molars, description of the 50-52 Lower premolars, description of the 49, 50 Lumbar vertebrae, views of the (PI. XXV, XXVI) . . 85 description of the 85,80 Lunar, description of the 104-100 Lunarandscaphoid, views of the (PI. XXXI) 102-104 II. Magnum, description of the 113-110 Magnum and unciform, views of the (PI. XXXIV) . 113-117 Malar bones, description of the 22 Marsh, O. C, study of Jurassic and Triassic mam- mals by 169 collection of .specimens by 104, 195, 198, 200, 201 , 214 publications of, respecting Dinocerata 225-237 Mastodon Ameiicanus, view of skull of 65 Mastodon Aroericanus and Dinoceras, comparison of pelvic arch in 137 Maxillaries, description of the 23 Median and posterior vertebrce, description of the.. 84 Mesoruneiform, description of the 158, 159 Metacarpal bones, views and description of the (PI. XXXV-XXXVII) 120-127 Metatai-sal bones, views and description of the (PI. I.I, LH) 101-164 Middle Eocene, mammals of the 189,100 Arioccne. mammals of the 190 Miobippus series, situation of the 6 Molars, views of the (Pl.VII.Vm) 46,48,50 242 INDEX. Page. Nasfil bones, tlescription of the 12-14 Naviculai-, viewa and description of the (PL XLIX). 155-157 Nicholson, Alley no, publications of, respecting Dino- cerata 235 O. Oaks, H. A., collection of specimens by 195 Occiput, description of the 19-21 Odontormtht-s, nidnograph on xvii Oieocyon, oocmience of, with Dinocerala remains .. 9 Oreodon bedn, situation of 1 he 6 Oiobippus, occurrence of, with Dinocerata remains . 9 Osborn, H. F., publications of, respecting Dinocer- ata 235,236 Owen, Kichard, publications of. respecting Dinocer- ata 233 P. PalEeosyops, occuixence of, with Dinocerata remains. 9 Palieosyops laticeps. view of skull of 63 Palate, description of the 24-28 Palatine bones, description of the 28 Paleontology, need of illustrations in xvii Parietal bones, desci iption of the 18 Patella and fibula, views and description of the (PL SLVI) 143 Pearson, S., collection of specimens by 195, 214,218 Pelvic arch and tail, description of the 135-138 Pelvis, views and description of the (PL XLI, XLII) . 135-138 Perisf^odactyls, comparison of, with Dinocerata 181 Peiinian age, characters of mammalia in the. 170 Phalanges, views and description of the (PL SXXVIII, Lin) 127,1-28,164 Pisiform, views and description of the (PL XXXH) . 109, 110 Platysonus compressus, view of skull of 65 Posterior ribs, description of the 133 Premaxillarics, description of the... 23,24 Prenasitl bones, description of the 14, 15 Proboscidea and Dinocerata, characters in common of 179,180 Proboscidians, chaiacters of 174,175 Protungulata, characters of 171 Pterygoid bones, description of the 29-31 Pyramidal and pisiform, views and description of the (PL XXXrC) 107-110 K. Radius, views and description of the (PL XXIX) . . . 93-95 Hestorations, views of the (Pl.LV.LVI) 165-168 Ebinoceros bicornis, view of left feet of 186 Rhinoceros Sumatrensis, view of skull of 66 Ribs and sternum, views and description of the (PL XXXIX) 129-134 Ryder, J. A., publications of, respecting Dinocerata. 235 ~ S. Sauranodon, characters of limbs of 182 Saiiropoda, monograph on xviii Scaphoid and lunar, views and description of the (PL XXXI) 102,103 Scapula, views and description of the (PI. XXVH). 87, 88 Schlosser, M., acknowledgment of aid of xviii Scott, "W. B., publications of, respecting Dinocerata. 235 Second dorsal vertebra, description of the £2, 83 Second metacarpal, description of the 122 Second metatarsal, description of the 161, 162 Seventh vertebra, description of the 78 Sheridan, P. H., acknowledgment of assistance by. .. xviii Sherman, W. T.. acknowledgment of assistance by. . xvm Shoshone John, collection of .'specimens by 196 Sixth vertebra, description of the 77, 78 Skull, views and description of the (PI. I-V, X. XI, XIV-XVII) 11-33 Smith. B.D., colUction of specimens by 194, 195, 196,201, 210.213 Smith. S., collection of specinien:s by. . . .195, 196,198,199,202, 208,211,214,216,218,222 Speir, Francis, colli ciion of specimens by 216 publications of, respecting Dinocerata ir35 Squamosal bones, description of the 22 Stegosauria, monograph on xvm Sternum, views and description of the (PL XL) 133, 134 Stylinodon, occurrence of, with Dinocerata remains. 9 Synopsis of Dinocerata 193-2^:3 T, Tapirus terrestris, view of skull of 66 Tarsal bones, views and description of the (PI. L).. 145 Teeth, views and description of the (PI. VII-IX, xvnr, XIX) 41-52 Tertiary, divisions of, in Europe and Western America 5-8 Tertiary age, law of brain-growth in extinct mam- mals of the 58 development of mammalian life in the 189,190 cause of disappearance of mammals of the 190 Third dorsal vertebra, description of the 83 Third metacarpal, description of the 123,124 Third metatarsal, desciiption of the... 162,163 Third vertebra, description of the 74 Tibia, views and description of the (PL XLV) 141,142 Tillodoutia, characters of the 9 Tillotherium, occurrence of, with Dinocerata re- mains - 9 Tinoceras, place of, among Dinocerata 10 variation of premaxillaries in 24 incisors of 43 upper canines of - 46 lower molar teeth of 51 brain of 56 characters of-.. 191 list of species of, with account of specimens 20f-218 Tinoceras alfine, view of skull of 19 description of specimen of 204, 205 Tinoceras anceps, views of first dorsal vertebra of.. 80 measurements of first dorsal veitebra of 81 description of specimens of 202,203 Tinoceras and Dinoceras, comparison of second and third dorsal veitebra in 82,83 comparison of pelvic arch in 137 restorations of (PL LV, LVI) 165-168 Tinoceras annectens, view of nasals of 13 view of skull of 21 views of lowtr jaw of 36 description of specimen of 205, 206 Tinoceras cornutum, description of specimens of... 206-208 Tinoceras crassifrona, view of skull of 29 description ot specimen of 208, 209 Tinoceras galeatum, description of specimen of 209 Tinoceras grande, view of skull of 21 palate of 30 view of upper canines of 44 IJTDEX. 243 Page, rinoceras p-amlc — Coutiuucd. views of atlas of .71 views and measurements of foui tli cervical ver- tebra of 7J description of specimens of 210 Tinoceras bians, view of skull of 30 description of specimen of 210, 211 Tinoceras ingtns, views and descriptions of skull of (PL XV, XVI, X VH) 14, IG, 19, 27 occiput of 20 view of palate of 25,30 nasal bones of 31 measurements of skull of 33 view of upper canine of 45 views and description of teeth of (PI. XVIII) . .45, 46, 49 upper molar series of 49 views of brain cavity of 55 'views of left lunar of 105 measurements ot rigbt and left lunars of lOG view and measurements of left pyramidal of,... 108, 109 measurements of right trapezium of Ill measurements of rij2:bt trapezoid of 113 view of right unciform of 119 measurement s of right unciform of 120 measurements of fourth metacarpal of 126 views of pelvis of 136 measurements of pelvis of 137, 138 view of left astragalus of 149 measurements of left astragalus of 151 view and description of restoration of (PI. LVI) 165 size of .' 166, 168 description of specimen of 211 Tinoceras jiigum, description of specimen of 212 Tinoceras lacustre, description of specimen of 212,213 Tinoceras latum, description of specimens of . - . ... 213, 214 Tinoceras longiceps, view and measurements of lower jaw of 37, 40 ' view of upper canine of 43 description of specimen of 214, 215 Tinoceras pugnas, nasals of 13, 3 1 view of skull of .19,21,27,63 occiput of 20 view of palate of 25 measurements of skull of 33 views and descriptions of lower jaw and teeth of (P1.XIX) 35,41 view of upper canine of 45 description of specimen of 215,216 Tinoceras Speirianum, description of specimen of. .. 21G Tinoceras stenops, view of upper molar series of 47 description of specimen of 217, 218 Tinoceras vagansi, view of skull of 17 description of sptcimen of 218 TinoceratidsB, species of 191 Tomes, C. S., publications of, respectiog Dinocerata. 236 Page. Trapezium and trapezoid, views and description of (PI. XXXIII) 110-111 Tria^sic and Jurassic mammals, studies of, by 0. C. M:.ish 169 U. Uiutatherium. place of, among Dinocerata 10 nasal bones of . 31 dentition of 41 premolars in lower jaw of 49 ■ brain of 56 chaiatters of 191 list of species of, with account of specimens 219-222 Uintatberium fissideus, desciiplion of specimen of.. 220 Uiutatherium lalifrous, view of skull of 17 views and measurements of second rib of 130, 132 description of specimen of 220,221 Uintaiheiium Leidianum, description of specimen of 221, 222 Uiutatherium, robustum, lowerjawof 38 views of brain cavity of . 57 de.scription of specimen of 219 Uiutatherium segue, views and measurements of lower jaw of 39, 40 views of third dorsal vertebra of 83 description of specimen of 222 Uinta Utes, hostility of 2 Ulna, views and description of the (PL XXX) 96-99 Unciform and magnum, views and description of the (PI. XXXIV) 117-120 Ungulates, genealogy i f the .■ 17J-170 classification of Ihe 176-178 modificationof loot in the 181-189 Upper molars, description of the 48, 49 Upper premolars, description of the 46-48 V. Vermilion Creek Group 5,6 Vertebrae, views and description of the (PI. XII-XXVI, XLIII) 69-86 Vomers, description of the 32 W. Wann, \V. N., collection of specimens by 203 Wasatch Group 5, fl Wicks, F. S., collection of specimens by 195 Williston, S. W., acknowledgment of aid of xviii Wortmau, J. L., collection of specimen by 220 publications of, respecting Dinocerata 236 Wyoming, sil nation and dtscripliou of ancient lake basin in, containing Dinocerata remains 1,2 localities in, from which Dinocerata remains have come 8 T. Yale Collie, Dinocerata specimens in museum at.. 4 Yale College expeditions, acknowledgments to mem- bers of XVIII PLATE I. PL^TE 1. DINOCERATA. Skull of DiNOCERAS MIRABILE, Marsh. Two-fifths Natural Size. Skull ; obliaue view, type specimen (No. 1 03G, Yale College Museum,) il This skull, from which the figures on the next six plates are also drawn, belonged to an animal fully adult, as shown by the teeth, but not so old as to have the cranial sutures obliterated. The right canine is restored from the left, which is perfect. PLATE I E Cnfland. lith N»i«r Haven DINOCERAS MIRABILE, Marsh % PLATE II. P^L^TE II. DINOCERATA. Skull of DiNOCERAS MIRABILE, Marsh. One-fourth Natural Size. Pa^e. iSkull ; lateral view, seen from the left, 11 n — Nasal boiie. pm — Premaxillary. c — Canine tooth, m • — Maxillary bone. m' — Maxillary protuberance. I — Lachrymal bone. / —Frontal. ma — Malar. pi — Palatine. pt — Pterygoid. as — Alisphenoid. s — Post-glenoid process of squamosal. hs — Basisphenoid. ho — Basioccipital. o — Occipital condyle. p — ^Posterior crest. p' — Posterior jjrotuberance. PLATE E. U I — I % O Q H > CD I — I PLATE III. p^la^tp:: hi. DINOCERATA. Skull of DiNOCERAS MiRABiLE, Marsh. One-fourth Natural Size, Page. Skull ; front view, ._ -- 11 NOTK. — The surface covered by oblique bars in this and tlio following plates indicates portions concealed by the adhering matrix or otherwise obscured. PLATE III. F Berger, del E.Crisand, lith- New Haven. DINOGERAS MIRABILE, Marsli. ^A. PLATE IV. JPLA.TE lA^. DINOCERATA. Skull of DiNOCiiKAS MiKABiLE, Marsli. One-fourth Natural Size. Pa^o Skull; superior view, 11 PLATE ly b 3 o o m I — I I PLATE V. DINOCERATA. Skull of DiNOCERAS MiRABiLE, Marsh. One-fourth Natural Size. P:i..e Skull; inferior view, .... 24 n ■ — Nasal bone. ■pm — Premaxillary. c — Canine tooth. ni — Maxillary bone. . . >w' — Maxillary protuberance. ma — Malar bone. pi — Palatine. pt — ^Pterygoid. s — ^Post-glenoid process of squamosal. 0 — Occipital condyle. p — Posterior crest. p' — Posterior protuberance, PLATE V u I— I o o > I— I t^ PLATE VI. DINOCERATA. Bram-cast of Dinoceras mikabile, Marsh. Three-fourths Natural Size. Pafe. Fig. 1. — Cast of Brain-cavity ; lateral view, seen from the left, 53 Fig. 2. — The same; superior view, 54 Fig. 3. — The same; inferior view, ■ 55 ol or I- — Olfactory lobes, c — Cerebral hemispheres. s — Sylvian fissure. op or II- — Optic nerves. V — Trigeminal, or fifth, nerve P — Pituitary body. f — Flocculus. f — Sixth nerve. cb — Cerebellum. cf or XII — Condylar foramen for twelfth nerve. m —Medulla. PLATE VI. .-^>s6!w «?■ . '-^ ^s^ f^Sl%i ,_ff^'T^'>^, O/? .Cb XII.. E.Crisand. .del. :,Orisand lith.NevL'Ka-ven DINOCERAS MIRABILE, Marsh.-A PLATE VII DINOCERATA. Molars of Dinocekas mikabile, Marsh. Natural Size, Page. Pig. 1. — Upper molars; exterior view, from left side, -_ 46 Fi^s. 2. — The same ; showing grinding surface, — 48 PLATE VII. ' / J J ^J V/ F Berger,del. E.Crisand, lith. New Haven. DINOCERAS MIRABILE, Marsh. Vi VTE Vir PLATE VIII. DINOCERATA. Lower jaw and teeth of Dixocekas mirabile, Marsh. Fan'-- Fig. 1. — Right lower jaw; lateral view, inner side, one-third natural size, 49 i — First incisor tooth. G — Canine tooth. d — Diastema. s — Section through symphysis. cp — Process for protection of canine tusk. a — Angle of jaw. y — Dental foramen. cd — Condyle. cr ■ — Coronoid process. Fig. 2. — Left lower molars; superior view, natural size,. 50 Fig. 3. — The same; lateral view, natural size, _ . 50 l/»»? — First premolar. Ini — First molar. The first and second premolars in figures 2 and 3 are restored from a second sjjecimen. PLATE vnr. X F.Berger,del. E Gnsand, lith NewHavo DINOCERAS MIRABILE, Marsh. PLATE IX. DINOCERATA. Teeth of Dinoceras lucare, Marsh. Natural Size. Page. Fig. 1. — Upper molars and canine; type specimen, (No. 1038,) lateral view, seen from the left, 45 Fig. 2. — Upper molars ; showing grinding surface, 49 c — Canine tooth. d — Diastema. Ip — First premolar. \m — First molar. f — Posterior palatine foramen. f — Palato-maxillary foramen. PLATE IX E Cnsar.d Uth New Haver. DINOCERAS LUCARE, Marcli H PLATE X. DINOCERATA. Skull of DiNOCERAS LATiCEPS, Marsh One-fourth Natural Size. Pane, Skull; type specimen, (No. 1039,) lateral view, seen from the left, 26 PLATE X. o 5 o Q > > H O PLATE XI. DINOCERATA. Skull of DiNOCERAS LATiCEPS, Marsh. One-fourth Natural Size, Page, Skull; (No. 1039,) superior view, 26 PLATE XI. 2 O Q > U] > l-H o PLATE XII. DmoCERATA. Lo-ro-er jaw of Dinoceras laticeps, Marsh. One-third Natural Size. _ Pace, Fig. 1. — Lower jaw; (Xo. 1039,) superior view, __ _ 35 Fig. 2. — The same; front view, _ g^ PLATE XTl. E.Cnsand, lith. New Haven. DINOCERAS LATIC EPS, Marsh. Vs. PLATE XIII. PL^TE XIII. DINOCERATA. Lower jaw of Dinogeras laticeps, Marsh. One-third Natural Size. Pngi'. Fig. 1. — Lower jaw; (No. 1039,) seen from tlie left, 35 Fig. 2. — Lower jaw; posterior view, 35 c — Socket for canine tooth. m — Mental foramen. p — Process for protection of canine tusk. a — Angle of jaw. cd — Condyle. cr — Coronoid process, d — Dental foramen. S — Symphysis. PLATE xnr. P Berger, del E.Cnsand, lich New- Haven. DINOCERAS LATICEPS, Marsh Vs. xr PLATE XIV. DINOCERATA. Skull of DiNOCERAS LATICEPS, Marsli, (female.) One-fourth Natural Size. P:igi' Fig. 1.— Skull; (No. 1202,) lateral view, seen from the left _ 45 Fig. 2. — The same; superior view, 45 c — Canine tusk. m! — Maxillary protuberance. p' — Posterior protuberance- PLATE XIV: 2 O O > w > O ^ PLATE XV. DINOCERATA. Skull of TiNOGERAS iNGENS, Marsh. One-fourth Natural Size. Page. Skull; type specimen, (No. 1041,) lateral view, seen from the left, 14 PLATE XV: 5 o o M > z o en /■ PLATE XVI DINOCERATA. Skull of TiNOCERAS INGENS, Mai'sh. One-fourth Natural Size. Page, Skull; (Xo. 1041,) front view,- 14 PLATE XVI. E. Grisand, lich. Kew Haven. TINOCERAS INGENS, Marsh. y4_ PLATE XYII DINOCERATA. Skull of TiNOCERAS INGENS, Marsh. One-fourth Natural Size. Pat^e. Skull; (No. 1041,) superior view, ^ 16 PLATE XVH. 5 o n > o GO •CS^'CH _ PLATE XVIII. PL^TE :s:v^iii. DINOCERATA. Teeth of Tinoceras ingens, Marsh. Natural Size. Page, Fig. 1. — Upper molars; (No. 1041,) left side, lateral view, seen from the left, 40 Fig. 2. — The same ; showing grinding surface, 46 PLATE XVIII. a en ^^' T-^^^ PLATE XIX DINOCERATA. Lo-wer jaw and teeth of Tinocekas pugnax, Marsh. i.;,„c. Fig. 1. — Lower jaw; lateral view, seen from the left, oue-third natural size, 35 i — Incisor'tooth. c — Canine tooth. d — Diastema. f — Mental foramen. cp — Process for j)rotectiou of canine tusk. a — Angle of the jaw. cd — Condyle. cr — Coi'onoid process. Fig. 2. — Lower molars; superior view, natui-al size, 41 Fig. 3. — The same ; lateral view, natural size, 41 Ijjni — First premolar lin — First molar. PLATE XIX. cd F Bsrger, del E Criaajid. lich New Haven. TINOCERAS PUGNAX, Marsh. PLATE XX PLATE xx:. DINOCERATA. Atlas of DiNOCEKAS MIR A BILE, Marsh. One-fourth Natural Size. P-pm' Fig. 1. — Atlas; lateral view, seen from the left, __ C9 Fig. 2. — The same; superior view, 09 Fig. 3. — The same; anterior view, 09 Fig. 4. — The same; inferior view, 09 Fig. 5. — The same; posterior view, G9 PLATE XX. ■F Bsrger.del, E.Orisand, lith-Ne-w Haven. DINOCERAS MIRABILE, Maxsh. V^. PLATE XXI. DINOCERATA. Axis of DiNOCERAS MiRABiLE, Marsh. One-fourth Natural Size. Pa^f. Fig. 1. — Axis; lateral view, seen from the left, ._• 72 Fig. 2. — The same ; superior view, _. 72 Fig. 3. — The same; anterior view, ■ 72 Fig. 4. — The same; inferior view, . . _ 72 Fig. 5. — The same; posterior view, _._ 72 PLATE XXT. F Berger, del E.Cnsand, lith. Ne"w Haven. DINOCERAS MIRABILE, Marsh. V4. PLATE XXII. DmOCERATA. Cervical Vertebrae of Dinoceras mirabile, Marsh. One-fourth Natural Size. Page. Fig. 1. — Third cervical vertebra; lateral view, seen from tlie left, 74: Fig. 2. — The same; superior view, . 74 Fig. 3. — The same; anterior view, ■ 74 Fig. 4. — The same; inferior view, 74 Fig. 6. — The same; posterior view, 74 Fig. 6. — Seventh cervical vertebra ; lateral view, seen from the left, 78 Fig. 1. — The same ; superior view, 78 Fig. 8. — The same; anterior view, 78 Fig. 9. — The same; inferior view, - - 78 Fig. 10. — The same; posterior view, 78 PLATE XXTL F Berger.del E.Crisand, lith. New Haven. DINOCERAS MIRABILE, Marsh. V^. PLATE XXIII. DIlSrOCERATA. Dorsal Vertebra of Diin'OCERAS mirabile, Marsh. One-fourth Natural Size. Pace. Fig. 1. — Secoud dorsal vertebra; lateral view, seen fi-om the left, S2 Fig. 2. — The same ; superior view, --. 82 Fig. 3. — The same ; anterior view, — S3 Fig. 4. — ^The same ; inferior view, .. . 82 Fig. 5. — The same; posterior view, 82 PLATE XXIIT. F Berger, del E.Crisand, lith. New Haven. DINOCERAS MIRABILE, Marsli. V^. PLATE XXIY. DINOCERATA. Dorsal Vertebrae of Dinoceras mirabile, Marsh. One-fourth Natural Size. Page. Fig. 1.— Median dorsal vertebra; latei-al view, seen from tlie left, 84 Fig. 2. — The same; anterior view, -- 84 Fig. 3. — The same; inferior view, 84 Fig. 4. — The same ; posterior view, 84 Fig. 5. — Last dorsal vertebra; lateral view, seen from the left, 84 Fig. 6. — The same ; superior view, 84 Fig. 1. — The same ; anterior view, 84 YiG, 8. — The same ; inferior view, 84 Fig. 9. — The same ; posterior view, _ 84 PLATE XXIV F BoTgei, del £ Cnsand, lith New Haven. DINOCERAS MIRABILE, Marsh. V^. PLATE XXY. DINOCERATA. Lumbar Vertebras of Dinoceras mikabile, Marsh. One-fourth Natural Size. Pa"^e. Fig. 1. — Lumbar vertebra, fourth from sacrum ; Literal view, 85 Fui. 2. — The same ; superior view, 85 Fig. 3. — The same; anterior view, 85 Fig. 4. — The same; inferior view, 85 Fig. 5. — The same; posterior view, 85 Fig. 6. — Lumbar vertebra, third from sacrum; Lateral view, 85 Fig. T. — The same; suj^erior view, 85 Fig. 8. — The same ; anterior view, ■ 85 Fig. 9. — The same ; inferior view, - 85 Fig. 10. — The same; posterior view, - 85 PLATE XXV" ■^""^ 3 T\ Crieynri, lith Nnw ffn; DINOCERAS MIRABILE, Marsh. V^. PLATE XXVI. DINOCERATA. Lumbar Vertebrae of Di]s'ocek.\s mikabile, Marsh. One-fourth Natural Size. Page, Fig. 1. — Lvimbar vertebra, second from sacrum; lateral view, seen from the left, 85 Fig. -2. — The same; superior view, , S5 Fig. 3. — The same; anterior view, . S5 Fig. 4. — The same; inferior view, 85 Fig. 5. — The same; jjosterior view, _..__ 85 Fig. 6. — Last lumbar vertebra; lateral view, seen from the left, 85 Fig. 7. — The same; superior view, . 85 Fig. S. — The same ; anterior view, 85 Fig. 9. — The same; inferior view, 85 Fig. 10. — Tlie same; jiosterior view, ._.. 85 P'LATE XXVT. Fi'^orgei.del E-Crisand, ]ich New Haven DINOCERAS MIRABILE, Marsh^ V^. PLATE XXVII. DINOCERATA. Left Scapula of Dinoceras mirabile, Marsh. One-fourth Natural Size. Pai^e. Fig. 1. — Scajjnla ; exterior view, 87 cb — Coracoid border, c — Ooracoid process. .170 — Glenoid cavity. gh — Glenoid border. ss — Suprascapular border. Fig. 2. — ITie same; inner view, 87 Fig. 3. — Tlie same; inferior view, . 87 a — Acromion. s — Spine. P'LATE XX'x'11. E Cnsand, lith Nevr Haven DINOCERAS MTRABILE, Marsh V^ PLATE XXYIII DINOCERATA. Humervis of Dinoceeas mikabile, Marsk One-fourth Natural Size. Page. Fig. 1. — Left Humerus ; anterior view, . .. 89 ] a — Distal end. Fig. 2. — Tiie same; inner view, ..- 89 Fig. 3. — The same; j^osterior view, . 89 3 a — Proximal end. PLATE. XXVIir. i^< l',.fe la E.Crisand, lith.Nev,'- Haven. DINOCERAS MIRABILE, Marsh, y^. PLATE XXIX. DINOCERATA. Radius of Dixoceras mirabile, Marsh. One-fourth Natural Size. Page. Fig. 1. — Left Radius ; anterior view, 93 1 a — Distal end. Fig. 2. — -The same; inner view, 93 Fig. 3. — The same ; posterior view, showing surface apjjlied to ulna, 93 3a — Proximal end. Fig. 4. — The same; exterior view, . __. 93 PLATE XXIX, F Berger, del E Cnsaild, lith Ne-wHavea DINOCERAS MIRABILE, Marsh V^ PLATE XXX. DINOCERATA. Ulna of DiNOCERAS MiiiABiLE, Marsh. One-fourth Natural Size. Page. Fig. 1 . — Left Ulna ; anterior view, showing radial surface, 96 la — Distal end. Fig. 2. — The same ; inner view, ... 96 Fig. 3. — The same; posterior viev/. 96 Fig. 4. — The same; outer view, 96 PLATE XXX. ^1 IX i/ a. ^, \. //,,,/ F Bergei, del E Crisand, Uth New Haver DINOCERAS MIRABILE, Marsh. V4. PLATE XXXI. DINOCERATA. Scaphoid and Lunar of Dinoceras mirabile, Marsh. (Left foot.) One-half Natural Size. Pan-e. Pig. 1. — Scaphoid; outer view, 102 Fig. 2. — The same ; posterior view, 10f> Fig. 3. — The same ; inner view, showing face adjoining hmar, . . 102 Fig. 4. — The same ; anterior view, 102 Fig. 5. — The same ; i^roximal view, showing face for radius, 102 Fig. 6. — The same; distal view, showing faces for trapezium and trapezoid, 102 Fig. v. — Lunar; anterior or outer view, 104 Fig. 8. — The same; lateral view, showing face adjoining scaphoid, 104 Fig. 9.-^The same ; posterior, or palmar, view, 104 Fig. 10. — The same; lateral view, showing face adjoining j^yramidal,. , 104 FiG. 1 1. — The same; proximal view, showing face for radius, 104 Fig. 12. — The same; distal view, showing faces for articulation with magnum and unciform,.. 104 PLATE. "AXXi. E.Crisand, lichNewHa-ven. DINOCERAS MIRABILE, Marsli. Vs. PLATE XXXII PLA.TE XXXII, DINOCERATA. Pyramidal and Pisiform of Dinoceeas mirabile, Marsh. (Left foot.) One-half Natural Size. Page. YiG. 1. — Pyramidal (or Cuneiform) bone; outer view, -. . -. 107 Fig. 2. — The same; anterior view, 107 Fig. 3. — The same; inner view, .showing face adjoining lunar, ... 107 Fig. 4. — The same ; posterior view, 107 Fig. 5 — The same; x^roximal view, showing faces for ulna and pisiform, 107 YiG. 6. — The same ; distal view, showing faces for unciform and for fifth metacarpal, 107 Fig. 7. — Pisiform; anterior view, 109 Fig. 8.— The same; inner view, showing ai'ticulation with pyramidal,- . 109 Fig. 9. — The same; posterior view, 109 Fig. 10. — The same; outer view, 109 Fig. 1 1 . — The same ; proximal view, showing articulation with ulna, 109 Fig. 1 2. — The same ; distal view, 109 PLATE XXXn. 10 11 JL.Orisancl, lich.Ne'wHa: DINOCERAS MIRABILE, Marsh. 1/2. PLATE XXXIII. PJLA.TE x:x:x:iii. DINOCERATA. Trapezium and Trapezoid of Dikoceeas mirabile, Marsh. (Left foot.) One-half Natural Size. Page. Fig. 1. — Trapezium; lateral view, showing outer surface, 110 Fig. 2.— The same; jDosterior view, - 110 Fig. 3. — The same; lateral view, showing inner surface, articulating with trapezoid, 110 Fig. 4. — The same; anterior view, . . - 110 Fig. 5. — The same ; proximal view, showing articulation with scaphoid, 110 Fig. 6. — The same ; distal view, showing metacarpal articulation, 110 Fig. 7. — Trapezoid; front view, showing external surface, 111 Fig. 8. — The same; lateral view, showing face adjoining trajjezium, _. 111 Fig. 9. — The same ; posterior view, — i 111 Fig. 10. — The same; lateral view, showing face adjoining magnum, Ill Fig. 11. — The same ; proximal view, showing articulation with scaphoid, 111 Fig. 12. — The same; distal view, showing metacarpal articulation, HI PLATE. XXXIir. 12 E.Crisand, lith New Haven. DINOCERAS MIRABILE, Marsh. Vs. PLATE XXXIV. Fig. 1.- FlG. 2.- FlG. 3.- FiG. 4.- FlG. 5.- FlG. 6- FlG. 1.- FlG. 8.- FlG. 9.- FiG. 10.- FlG. 11.- FlG. 12.- DINOCERATA. Magnum and Unciform of Dinoceras mieabile, Marsh. (Left foot.) One-half Natural Size. Paee IMagnum ; front view, stowing external surface, 113 The same ; lateral view, showing face adjoining trapezoid, 113 posterior, or palmar, view, 113 lateral view, showing face adjoining unciform, 113 superior, or proximal, view, II3 inferior, or distal, view, showing face for metacarpal articulation, 113 lateral view, showing external surface, __ 117 front view, showing face adjoining magnum, 117 lateral view, showing inner surface, _ 117 posterior view, 117 superior, or proximal, view, showing faces for lunar and pyramidal, 117 inferior, or distal, surface for metacarpal articulations, Hi -The same -The same -The same -The same -Unciform -The same -The same -The same -The same -The same PLATE, ijxxrv: 10 11 12 E.Criaand, lith. TTevr Haver.. DINOCERAS MIRABILE, Marsh. %. PLATE XXXV DINOCERATA. Metacarpals of Dinocekas mirabile, Marsh. (Left foot.) One-half Natural Size. p„„ Fig. 1. — First metacarpal; front view, -jo-i Fig. 2. — The same ; lateral view, showing inner, or tibial, side, 121 Fig. 3. — The same ; posterior, or palmai", view, jo^ Fig. 4. — The same; lateral view, showing outer, or ulnar, side, 12L Fig. 5. — The same; proximal end, j21 Fig. 6. — The same; distal end, . _ jo^ Fig. v. — Second metacarpal ; front view, 122 Fig. 8. — The same ; lateral view, showing inner, or radial, side, 122 Fig. 9. — The same; posterior, or palmar, view, 122 Fig. 1 0. — The same ; lateral view, showing outer, or ulnar, side, 122 Fig. 1 1. — The same ; proximal end, 122 Fig. 1 2. — The same ; distal end, 122 PLATE XXXV: 12 F Berg'ei, del E.Crisand, lith. New Ha-ven. DINOCERAS MIRABILE, Marsh. Va. PLATE XXXYI. Fig. 1 Fig. ■2 Fig. 3 Fig. 4 Fig. 5 Fig. 6. Fig. 7. Fig. 8 Fig. 9 DINOCERATA. Metacarpals of Dinoceras mibabile Marsh. (Left foot.) One-half Natural Size. Page. -Third metacarpal; front view, 123 -The same; lateral view, inner, or radial, side, •_ 123 -The same ; posterior view, 123 -The same; lateral view, outer, or ulnar, side, i . 123 -The same ; proximal end, J23 -The same ; distal end, 123 -Fourth metacarpal ; front view, 124 -The same ; lateral view, inner, or radial, side, 124 -The same; distal end, 124 PLATE XXXVI. •f'> '•''''^■'"' F Berber, del. E-Onsand, lith. New Haven- DINOCERAS MIRABILE, Marslt >2 PLATE XXXYII JPLA.TE XXXA^II. DIlsrOCERATA. Metacarpals of Dinoceras mirabile, Marsh. (Left foot.) One-half Natural Size. Page. Fig. 1. — Fourth metacarpal ; j)osterior, or palmar, view, 124 Fig. 2. — The same; lateral view, showing outer, or ulnar, side, -. 124 Fig. 3. — The same; proximal end, 124 Fig. 4. — Fifth metacarpal; front view, .--- 127 Fig. 5. — The same ; lateral view, showing inner, or radial, side. — 127 Fig. 6. — The same; posterior, or palmar, view, 127 Fig. 7. — The same; lateral view, showing ulnar side, 127 Fig. 8. — The same; proximal end, 127 Fig. 9. — The same; distal end, 127 PLATE XXXVIl v;<4).^ F.Berger, del. E-Crisand, ]uh NewHaveTi DINOGERAS MIRABILE, Marsh Vz. PLATE XXXVIII. DINOCERATA. Phalanges of Dinoceras mirabile, Marsh. Page. One-half Natural Size. Fig. 1. — Proximal phalanx of a median digit; front view, 127 la — Lateral view. lb — Posterior view. Ic — Proximal end. Id — Distal end. Fig. 2. — Proximal ijhalans of a lateral digit; front view, 127 2a — Lateral view. 2b — Posterior view. 2c — Proximal end. 2d — Distal end. Fig. 8. — Median phalanx; front view, 128 Sa — Posterior view. 3b — Proximal end. So — Distal end. Fig. 4. — Median phalanx; front vieWj . 128 4a — Lateral view. 45 — Posterior view. 4c — Proximal end. 4c?— Distal end. Fig. 5- — Ungual phalanx of median digit; front view, 128 5a — Posterior view. 5b — Proximal end. 5c — Distal end. Fig. 6. — Ungual phalanx of lateral digit; front view, 128 6a — Lateral view. 6b — Posterior view. Qc — Proximal end. 6d — Distal end. 'PxG. 7. — Sesamoid bone from metacarj^o-phalangeal articulation; lateral view, 121 7a — Articular surface. PLATE xxxvnr. /a n fc 2h 2d Jh n ^Oi ^rf Ji 6 6d 6a 6c Y Eerg'er, del. E.Cnaand, lith.Ne^Ha.veii. DINOGERAS MIRABILE, Marsh 1/2. PLATE XXXIX li^L^TE XXXIX. DINOCERATA. Ribs of DiNOCERAS MiRABiLE, Marsh. One-fourth Natural Size. Pai't Fig. 1. — First rib ; anterior view, 129 Fig. 2. — The same; inner view, . ._.- 129 Fig. 3. — The same; superior view, showing head and tubercle, ... 129 Fig. 4. — Dorsal rib ; posterior view, 133 Fig. 5. — The same ; inner view, 133 Fig. 6. — The same; superior view, showing head and tubercle, 133 Fig. 7. — Posterior rib ; anterior view, 133 Fig. 8. — The same; outer view, 133 Fig. 9. — The same; superior view, showing head and tubercle, - 133 PLATE 1DCXIX_ E.Orisand, lith New Haven. DINOCERAS MIRABILE, l_aTsh. V^ PLATE XL. DINOCERATA. Sternum of Dinocebas mihabile, Marsh. One-fourth Natural Size. Page. Fig. 1. — First segment; lateral view, seen from, the left, 133 Fig. 2. — The same; superior view, _ _ 133 Fig. 3. — The same ; inferior view, 133 Fig. 4. — Second segment ; lateral view, seen from the left, __ 134 Fig. 5. — The same ; sujjerior view, 134 Fig. 6. — The same; inferior view, 134 Fig. 7. — Third segment ; lateral view, seen from the left, 134 Fig. 8. — The same; sujDerior. view, 134 Fig. 9. — The same; inferior view, 134 Fig. 10. — Last segment; lateral view, seen from the left, 134 Fig. 11. — The same; superior view, . 134 Fig. 12. — The same; inferior view, 134 12 PLATE XL_ 10 E.Crisand, 3ich.New-Ha-ven DINOCERAS MIRABILE, Marsh. V^ PLATE XLI DINOCERATA. Pelvis of DiNOCERAS MIRABILE, Marsh. One-fourth Natural Size. Page. Fig. 1. — Pelvis; anterior view, 135 Fig. 2. — The same; inferior view, 135 ffl — Acetabnlum. f — Obturator foramen. il — Ilium. is — Ischium. p — Pubis. s — Anterior end of sacrura s' — Posterior end of sacrum. E CnsaJid, liih New Haven DINOCERAS MIRABILE, Marsh V4 PLATE XLII. DESrOCERATA. Pelvis of DiifOCERAS mirabile, Marsh One-fourth Natural Size. Pao-e. Fig. 1. — Pelvis; lateral view, seen from the left, I35 Fig. 2. — The same; lateral view, showing inner sufaee, J3o Fig. 3. — ^The same; posterior view, 235 Fig. 4. — Sacrum; inferior view, . I37 a — ^Acetabulum. f — Obturator foramen. i — Sacral face for ilium. il — Ilium. is — Ischium. p —Pubis. s — Anterior end of sacrum. s' — Posterior end of sacrum r:.AT^ XiV.t. E Onaani Uch Newfla-^ DINOCERAS MIRABILE, Marsh Vt PLATE XLIII. DINOCERATA. Caudal Vertebrae of Dinoceras laticeps, Marsh. One-fourth Natural Size. Page. Fig. 1. — First caudal vertebra ; lateral view, seen from the left, 138 la — Superior view. lb — Anterior view. Ic — Inferior view. 1 d — Posterior view. Fig. 2. — Second caudal vertebra; lateral view, seen from the left, ^.. 138 2a — Superior view. 2b — Anterior view. 2c — Inferior view. 2c? — Posterior view. Fig. 8. — Third caudal vertebra ; lateral view, seen from the left, 138 3a — Superior view. 3b — Anterior view. 3c — Inferior view. 3d — Posterior view. Fig. 4. — Fourth caudal vertebra; superior view, 138 4a — Inferior view. PLATE XLIII DINOCERAS LATICEPS, Marsh, 'A. PLATE XLIY. DESrOCERATA. Femur of Dinoceras mieabile, Marsh. One-fourth Natural Size. Page. Fig. 1. — Left Femur; front, or superior, view, .. 139 t — Great trochanter. t' — Lesser trochanter, la — Distal end. Fig. 2. — The same ; inner view, 139 Fig. 3. — The same ; baclv, or inferior, view, 139 3ffl — Proximal end. PLATE XL IV. 3a i^-^" 'V E Oi-isand, lidl Nevf Hitc DINOCERAS MIRABILE, Ma.rsh. 'A, PLATE XLY. PLA.TE S:L^. DINOCERATA. Tibia of DiNOCERAs mikabile, Marsh. One-fourth Natural Size. Page. Fn4. 1. — Left Tibia; anterior view, 141 la — Distal end. Fig. 2. — The same; lateral view, inner side, 141 Fig. 3. — The same ; posterior view, — 141 3a — Proximal end. Fig. 4. — The same; lateral view, outer side, -_. 141 Fig. 5.— Section of shaft of Tibia,.. 141 PLATE, XLV 3a P,Berg-er,del. E.Cnsand, ]ith New Haven DINOCERAS MIRABILE, Marsh. y4. PLATE XLVI DINOCERATA. Fibula and Patella of Dinoceras mieabile, Marsh. One-fourth Natural Siza Page. Fig. 1. — Left Fibula; outer view, 143 la — Distal end. . Fig. 2. — The same; posterior view, - 143 Fig. 3. — The same; inner view, 143 3a — Proximal end. Fig. 4. — The same; anterior view, 143 Fig. 5. — Left Patella; front view, 143 Fig. 6. — The same ; lateral view, showing inner side, ... 143 Fig. 7. — The same ; posterior view, 143 Fig. 8. — The same ; later,al view, showing outer side, 143 PLATE XLVl. 3a- t'X E.Onsand, lith New Haven- DINOGERAS MIRABILE, Marsh. V^. PLATE XLVII. DINOCERATA. Astragalus of Dinoceras mirabile, Marsh. (Left foot.) One-hall Natural Size. Pnge. Fig. 1. — Astragalus ; superior view, showing face for articulation with tiliia, 14G P'lG. 2. — The same; lateral view, tibial side, _ UG Fig. 3. — The same; inferior view, .. 140 Fig. 4. — The same; lateral view, fibular side, 14G Fig. 5. — The same; front view, 14C Fig. C. — The same; posterior view, 140 PLATE XLV[[. ~ti^^ ' Berger, del E.Gnsand, lith New Kaven. DINOGERAS MIRABILE, Marsh Vs. PLATE XLVIII Fig. 1. Fig. 2. Fig. 3. Fig. 4.- Fig. ■5.- Fig. 6.- DINOCERATA. Calcaneum of Dinoceras mirabile, Marsh (Left foot.) One-half Natural Size. Pi"i' -Calcaneum; anterior, or front, view, .. --- 151 -The same ; inner view, tibial side, ._ ... . . . 151 -The same; posterior view, ._.... - 151 -The same; outer view, fibular side, 151 -The same; suj^erior view, showing face for astragalus, 151 -The same ; inferior, or jjlantar, view, ... 151 PLATE XLVIII. P Berger,del. E. Crisand, lith. New Haven- DINOCERAS MIRABILE, Marsh Va. PLATE XLIX DINOCERATA. Cuboid and Navicular of Dinocekas mieabile, Marsh. (Left foot.) One-half Natural Size. p Fig. 1. — Cuboid ; front, or outer, view, jko Fig. 2. — The same ; Literal view, showing face adjoining uavicuhar, . ^53 Fig. 3. — The same; posterior, or plantar, view, jr^ F:g. 4. — The same; lateral view, showing fibular side, j53 Fig. 5. — The same ; proximal surface, jijo Fig. 6. — The same; distal surface, supporting fourth and fifth metatarsals, 153 Fig.' 7. — M avicular (or Scaphoid) ; front view, -. gr Fig. 8. — The same; lateral view, -.-,- Fig. 9. — The same; posterior, or j^lantar, view,. jk- Fig. 10. — The same; lateral view, showing face adjoining cuboid, _. .. ^ ^55 Fig. 11. — The same; proximal end, articulating with astragalus, 255 Fig. 1 2.— The same ; distal end, articulating with cuneif ormes, I55 PLATE XLIX. ^«i3»"?'''"'*=Sf"-"5!«SS^= •'^ E Crisand, lith New Haven. DINOCERAS MIRABILE, Marsh. Vs. PLATE L DINOCERATA. Tarsal bones of Dimogeras mirabile, Marsh. (Left foot.) One-half Natural Size. Page. Fig. 1. — Entocuneiform; outer vie-.v, 158 Fig. 2. — The same; posterior view, 158 Fig. -3. — The same; inner view, showing face adjoining mesocuneiform, 158 Fig. 4. — The same; anterior view, . 158 Fig. 5. — The same ; proximal surface, articulating with navicular, - 158 Fig. 6. — The same; distal surface, supporting first metatarsal, 158 Fig. 7. — Mesocuneiform; outer, or front, view, 158 Fig. 8. — The same; tibial surface, adjoining entocuneiform, ..■ 158 Fig. 9. — The same ; posterior, or plantar, view, -.. 158 Fig. 1 0. — The same; fibular surface, adjoining ectocuneif orm, . 158 Fig. 11. — The same; proximal surf ace, articulating with navicular, - 158 Fig. 12. — The same ; distal end, supporting second metatarsal, 158 Fig. 13. — Ectocuneif orm; outer, or front, view,... .. 159 Fig. 14. — The same; tibial surface, adjoining mesocuneiform, 159 Fig. 1 o. — The same ; posterior, or plantar, view, ..._ 159 Fig. 1 0. — The same; fibular surface, adjoining cuboid, 159 Fig. 1 7. — The same ; proximal end, articulating with navicular, 159 Fig. 1 S. — The same ; distal end, supporting third metatarsal, 159 PLATE L ECrisand. lith Nffw Haven. DINOCERAS MIRABILE, Ma.rsh Vs. PLATE LI P^L^TIll LI. DINOCERATA. Metatarsals of Dinoceras mirabile, Marsh. (Left foot.) One-half Natural Size. Pa"-e. Fig. 1. — First Metatarsal; front view, IGl Fig. 2. — The Sctme; lateral view, showing tibial surface, . .-^ IGl Fig. 3. — The same; posterior, or plantar, view, IGl Fig. 4. — The same; lateral view, showing fibular surface, IGJ Fig. 5. — The same; proximal end, Kil Fig 6. — The same; distal end, — IGl Fig. 7. — Second Metatarsal; front view, .- IGl Fig. 8. — The same; lateral view, showing tibial surface, ...... IGl Fig. 9. — The same ; posterior, or plantar, view, IGl Fig. 10. — The same ; lateral view, showing fibular surface, IGl Fig. 11. — The same; proximal end,- -. _ -_ 161 Fig. 12. — The same; distal end, 161 Fig. 1 3. — Third .Metatars.il ; front view, 102 Fig. 14. — The same; lateral view, showing tibial side, IGU Fig. 1 5. — The same ; posterior, or plantar, view, 102 PLATE LI. F. BbTger, del. E-Cnsand, litli. NewJ DINOCERAS MIRABILE, Marsh. Vs. PLATE LII. PL^TE LIT. DINOCERATA. Metatarsals of Dinoceras mirabile, Marsh. (Lefl foot.) One-half Natural Size. Page. Fig. 1. — Third Metatarsal; lateral view, showing fibular surface, 162 Fig. 2. — The same; proximal end, 162 Fig. 3. — The same; distal end, . 162 Fig. 4. — Fourth Metatarsal; front view, 163 Fig. 5. — The same; lateral view, showing tibial surface, 163 Fig. 6. — The same ; posterior, or plantar, view, 163 Fig. 7. — The same ; lateral view, showing fibular surface, 163 Fig. 8. — The same ; jjroximal end, -- — 163 Fig. 9. — The same; distal end, 163 Fig. 10.— Fifth Metatarsal; front view, 163 Fig. 11. — The same; lateral view, showing tibial surface, 163 Fig. 12. — The same; j)osterior, or plantar, view, -- 163 Fig. 13. — The same; lateral view, showing fibular surface, 163 Fig. 14.— The same; proximal end, 163 Fig. 15. — The same; distal end, ' 163 PLATE Lll. " Eergex, del. E.Criaand, lith. New Haven. DINOCERAS MIRABILE, Marsh y2. PLATE LIII. i>L^TE LIII. DINOCERATA. Phalanges of Dinocekas mirabile, Marsh. One-half Natural Size. Page. Fig. 1. — Proximal phalanx of raediau digit ; front view, lC-4 la — J^ateral view. 15 — Posterior view. Ic — Proximal end. Id — Distal end. Fig. 2. — Proximal phalanx; front view, . 164 2a — Posterior view. 2b — Proximal end. 2c — Distal end. Fig. 3. — Proximal phalanx of lateral digit ; front view, 164 3a — Posterior view. 3b — Proximal end. 3c — Distal end. Fig. 4. — Median phalanx; front view, 164 4a — Posterior view. 4b — Proximal end. 4c — Distal end. Fig. 5. — Median phalanx; front view, 164 5a — Proximal end. 5b — Distal end. Fig. 6. — Ungual phalanx; front view, - 164 6a — Posterior view. 65 — Proximal end. 6c ■ — Distal end. Fig. 7. — Ungual jihalanx; front view, - 164 'Ja —Posterior view. 75 — Proximal end. 7e — Distal end. Fig. 8. — Sesamoid bone from metatarso-phalangeal articulation ; lateral view, 164 8a — Articular surface. Fig. 9. — Sesamoid bone from metatarso-phalangeal articulation ; lateral view, 164 9a — Articular surface. Fig. 10. — Sesamoid bone, probably from hallux; lateral view, 164 10a — -Articular surface. il PLATE Llir 1c Id, i 2b 2c 6b -^b 5h 6a 7b 10 a i9a fO 8a E.Criaand, lith.New Haven DINOCERAS MIRABILE, Maxsh Vz. PLATE LIY. DDTOCERATA. Feet of DiNOCERAS mirabile, Marsh. One-half Natural Size. Page. YiG. 1. — Manus, or fore foot (left), 101 s — Scaphoid. I — Lunar. jtj — Pyramidal. tm — Trapezium. /r — Trapezoid. un — Unciform. I — First digit, or pollex. rr — Second digit. /Ji— Third digit. 7F— Fourth digit. V —Fifth digit. Fig. 2.— Pes, or hind foot (left), -- 145 a — Astragalus. c — Calcaneum. cb — Cuboid. n — Navicular. en — Entocuneiform. I — First digit, or hallux. II — Second digit. Ill— Third digit. JF— Fourth digit. V —Fifth digit. PLATE LTV £ Onsand. lich New Ha:veTi- DINOCERAS MIRABILE, Marsh. Vs. PLATE LY. DINOCERATA. Page. Restoration of Dinoceras mirabile, Mtirsli. 165 One-eighth Natural Size. n,/? £ Cnsand. hth NffwH^tv- DINOCERAS MIRABILE, Marsh Vs_ PLATE LVI. DINOCERATA. Page, Restoration of Tinoceras ingens, Marsh. 165 One-sixth Natural Size.