eens serene Sone wegen nme Senet i net “AB AYP vie my sii ¥ the OD bl i i neha ‘ ihe Wy Gases DEPARTMENT OF THE INTERIOR MONOGRAPHS: or THE UNITED STATES GEOLOGICAL SURVEY Cf VOLUME X WASHINGTON GOVERNMENT PRINTING OFFICE 1886 ts s vex fi aoe cana ose . UNITED STATES GEOLOGICAL SURVEY J. W. POWELL, DIRECTOR PeENOO nn AT A. A a Zeek i £7, %s MONOGRAPH = (27 Me, io s OF AN Nau Se” WASHINGTON GOVERNMENT PRINTING OFFICE 1886 a 'f p27) At 3 , aan: © - 7 =f ‘a iscu t 2 ba,’ a | oy, hs ent Lie ve ai i ie | ie P - . i 4 : i ‘ ” * { } 7 < 7) i ‘ y Le Li ' f a z « = ie ~ = Pm Unirep Srates GroLocicaL Survey, Division oF PALMONTOLOGY, 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 DrnoceratTa, an extinct order of Mammals discovered in the Eocene deposits of Wyoming Territory. Very respectfully, Your obedient servant, O. C. MARSH, Paleontologist-in- Charge. Hon. J. W. Powett, Director of the U.S. Geological Survey, Washington, D. C. i} yy t = heen Hts “aes ; ‘ore y i 7. ad 1! i ' baal ’ ‘ t i j a h Aa vin sR eg Thea fa : e's bi - y me ° hs Niet pert ea ae Tn et ks - ’ [ 1% a : Vy ia 1 . * y ' * te * hy heh be th ALAS ‘he onan reed Uv ea: a j ‘ ‘ , ier ra : J - 1 1 a ig & } i = Ly a ‘ | ‘ AS bn (Ol = CONLRENTS. TirLE oF VoLuME, Lerrer oF TRANSMITTAL, AE TO KieO ONIDEND SSS ame Mas oe enna ise sata kee Ass aS SnSe oye jae leslie TS TRO RUE UG ERAT ONS sae Mee gee eons = oe ewe Hes. ane Seo eine ae cia eS EARISICA Geren ae eee ate Se ee A be eee le cals che coke Pek S Peek NSO. OCR Nee ee ee ee etn bees Sey ee See rice oe wae Sea Cuarter I. SDS ASME SS OS tage oe ly eer ee a sc Il. AUST IDOE, SWANS See eee ee Se oo ane ee ee a ts Til. Sen eee ee aes eto er eM Le Se webs ON ay eee & IV. ST ea gE RAS NARS pene aap ee eee era tea eee eS ee te g ING Rn CM RVAC ATV (ER ERE Ras ieee eet en om oat Nene ee Ae eee Se es VI. Tae ORsO-lUMBAR) VERREBR AI) <=. 52 252526525. 525 022525 u: Vill ED A OR mIGUMBSe Pe os lee ne Nl ete ke & WA ere Monn elamiBs a (CONTENTED) y seer sees ss S22 see ease == Ke IX. AERIS CAND SLERNIUMS =) snp es Ses oe Saye eC ees a aati cs X. Pee mnVviC wAROH AND AWAIT 225 foc Je ee ate Gs XI. BREE EEN D PIEEMIBE SE eee aos eae te RL se GN ey Eire e EEN De sINtBS ia CONTINUED). eee e eee eae = aes nee eee we XIII. Restorations or DirnocerAs AND TINOCERAS, -_------------ gs NST ees © ONCLUSIONS Se Soe eae ee ete at 2 oho eee ae Se eh FARPEND [cS VNOPSI Sse eee ee Se ee eee a eer e = eo He ke Seis cma ee sees IBIBETOGH APH ee te ie ean yer sett Se Se ees SL a Md el IROSTSCRIPD aati a ee Soo eweaioeine Seseanod ckecs ee ceet ease vil 35 53 69 79 87 101 129 135 139 145 165 169 193 225 237 Pa ea ei? . . Hn iS A PIONS. EIST Ok PEATHS: Jeti lis 2 SES ao SE on ee ree ea eee eee SKULL OF DINOCERAS MIRABILE. SOT PA] ee a a Be Ree Ova _..-------SKULL OF DINOCERAS *MIRABILE. CB oT TAS of NES ue OM Sas og ne ag ee SKULL OF DINOCERAS MIRABILE. OF) MW ere eg ee ee ee ee eee So See ak ee SKULL OF DINOCERAS MIRABILE. eA Sy Sheree: eo te eh _.---..------_SKULL OF DINOCERAS MIRABILE. CREED Vt [nets eee 9 wh dn ee Soe. Ne Birarn—casr oF DINOCERAS MIRABILE. BG We ee eee Oe = Morars' of DINOCcERAS' MIRABILE: “Wil 2-22 222-88 _. _--- Lownr JAw ann Trrete or DINOCERAS MIRABILE. ONG RRM he Sy pres ea pe 3 A Trerro or DInocERAS LUCARRE. GS! NG oe BES eee Soe Se ee eee eee aes SKULL OF DINOCERAS LATICEPS. c Da) ink See eer ee ht Se Se Se SkuLt oF DINOCERAS LATICEPS. a XO) [ape ef ier ee es we PP On le Lower Jaw or Dinoceras LaTICEPs. CNG) See ee howe UAW OF DINOCHRAS MATICERS: 85 RETINY Ge eS ee ee ee es a a ee SKULL OF DINOCERAS LATICEPS. GaN) PSD CV SS ye ee, ae pe ee ee SKuLL oF TINOCERAS INGENS. Cine “FON GSS 5 Se ae _... SKULL OF TINOCERAS INGENS. CORO Lin eee. pe) Sear ae eat ke Se __....--SKULL OF TINOCERAS INGENS. O31) OMNI DE at ke eee se meet nee TrerruH or TINOCERAS INGENS. Go" DC) Dy 0 2 an eee a Lower Jaw anv TretH or TINocERAS PUGNAX. COXON Cesena pe ee Se AE on Oe Da cee S Svcre = ATLAS OF DINOCERAS MIRABILE. (3: DON es St oe RE Se eet ee ee eee ae Axis OF DINOCERAS MIRABILE. CRE NON Sn ee ee. ee _..CrryicaL VERTEBR& OF DINOCERAS MIRABILE. Econ NON ree safe Saw fen et Fo ne DorsaL VERTEBRA OF DINOCERAS MIRABILE. CO ONG LON Geter aay hee ed Soe ON | DorsaL VERTEBRA OF DINOCERAS MIRABILE. Gat NOU Sed EL eS eS Lumpar VERTEBR2Z OF DINOCERAS MIRABILE. Ge a NOQVI GS 28 So ee a), Saree ene Lumpar VERTEBRA OF DINOCERAS MIRABILE. OOD U1 ce cee a na ere Lerr ScaruLa OF DINOCERAS MIRABILE. LS BOO IES aa es ee Re Megs eee RS ese Humerus or DryocrRASs MIRABILE. GG. OCC Suen eee ee ee eee eee es Rapius or DrNoceraAs MIRABILE. G2” « BOLO NAR ae e Ne oe ee Shee ee ee __.. Una oF DINOcERAS MIRABILE, B ; ix Ne ILLUSTRATIONS. (Pak. SXOXOR DS << See eh eee ScapHorp AND LUNAR Cry “AXE NONI Sapte oe = ener __. PyRAmIpAL AND PistrorM (Cos AXGREXGE ee yee apres TRAPEZIUM AND TRAPEZOID Coy SXEREXUTIV Ao oe cers rere Maenum ano UNcirorm ae). ree ek pe tos, de ee Meracarpats et INEROXN SVS ey es eee ee eee eae _... METACARPALS 0 XOXEXOWI Ree See oe ee ees MrTACARPALS 6 OXCXGRS VAR ee es ee PHALANGES GE KEK RID 65 Mie Be ek So oe ea eee Riss Cor GIXGE Ma Pouch GI: Set pee She cto ee Oe ee STERNUM 66 ROR TIES AiO AIR Se ae een eee Petvis Co NOT. hen ee ee ee eee eee PeELvis CO XG EA eat Bees Se re are olor CaupaL VERTEBR.® Coe XC Re eee nh re Ye NE BES pepe etree eae Ae ate Femur S6, WOXSILWic 2e SE S aS ee erie ee oe TrBra SCS XSI Wile eee a SS ee ae ae Fisunta AND PATELLA cca POX Vile aa ETP Re nee SE ASTRAGALUS Tee SUNY 0) eet Sere eee ee eee a CAM MONST URN COP PECK ee tae oo. eee eee Cusoip AnD NAvIcuLaR C6 Me dG: 8 BSS 1h ols Oe ee ee TARSAL BONES C6: STD, od ue ny eS ee ee Oe ee MeraTARSALS Fs $3 FI eae eee We acy eiies paren a ote tan igre a Pee MrrararsaLs CCR TI TT Leet Se ey a a pe aro pe ce ee me greta PHALANGES COMES Si! hic ee apt RM ee. ys 5 eres EPO ee Freer CTS hl [FY degtS Pee ech ct Sect Sets ee en, ed te _.. RESTORATION “cc OF OF DInocERAS Drnoceras Dinoceras DinxocEras DINOCERAS DiInocERas DinocEeras Drtnoceras DINocERAS DInocEeRrAs Drnocreras DINnocERAS Dixocreras Dinocreras Dinoceras DINocERAS DinocEras DINOcERAS DINOCcERAS D1nocERAs Dinoceras DtnocEerRas Drnoceras Dinoceras DINocERAS MIRABILE. MIRABILE. MIRABILE, MIRABILE. MIRABILE. MIRABILE. MIRABILE, MIRABILE. MIRABILE. MIRABILE. MIRABILE. MIRABILE, LATICEPS. MIRABILE. MIRABILE. MIRABILE. MIRABILE. MIRABILE. MIRABILE. MIRABILE. MIRABILE, MIRABILE, MIRABILE. MIRABILE. MIRABILE, FIGURE “ Ficurr ce “ it3 “ “c cc “ee “c “ec c “cc “ “ “c “c “cc “ “cc c “ —_ 21. 22, 23. 24. 25. 26. ile 28. 29. 30. 31. 32, 33. 34. 35. EIST OF WOODCUTS. TNR OID UE CuE ON Map showing region of Dinoceras beds,-..._.-..-.---------.------ Section to illustrate vertebrate life in America, _._-______________- CHAPALE DR, 1: INR HS C8 LOOCTRAS TTL, ALES BR Oe Sa eee See gee eee INSP OE IOC OGHIS CATIOTIS See 2S Se ee oa INasals of Wuroceras pugnan).- <2 <= 220028. <2 sake eek wee INSANE SnO Lae ONTO CENOS IT ECCLES eames ee te ee, eye ee De Skull of Dinoceras mirabile, with brain-cast in position,---.—.—___- Skull of young specimen of Dinoceras distuns, ---------_-. -.----. Skull of Tinoceras ingens, with brain-cast in position,---...--. —.—- fSikavlll, GE LDOMOGARIS CURMAMISS 3 oss alte aon does se aeoneee. ceseeese Seo fe Ciera eneniI ne LLL ONG = eee we ee SicnlllRotaelyzeocenas suc (is apenas tee ee ne es ee Posterior surface of skull of Dinoceras mirabile, ......---------.-- Posterior surface of skull of Dinoceras laticeps, ...--.------------- Posterior surface of skull of Dinoceras agreste,.....---.----------- Posterior surface of skull of Zinuceris affine, ---- - Soh pe te Se One Posterior surface of skull of 7inoceras ingens, -.....-..------- ---- Posterior surface of skull of 7inoceras pugnax, ------------------- Side view of skulll of Zimoceras pugnaz,.......- .---.------------- Anterior part of skull of Zinoceras grande, ..--------------------- Anterior part of skull of Tinoceras annectens,......--------------- Anterior part of palate of Dinoceras laticeps, .--. .-.-------------- Anterior part of palate of Tinoceras ingens, _...-.-- .---.------=-- Anterior part of palate of Tinoceras pugnax,.......-.------------ Anterior part of palate of Hippopotamus amphibius, -...--------- Skull of Dinoceras mirabile; seen from below, .-------.--- ---- ---- Skull of Dinoceras laticeps; seen from below, --- ------- pee ieee Skull of Tinoceras ingens; seen from below, -------------------- -- Skull of Zinoceras pugnax; seen from below, ---. ----------------- Horizontal section of skull of Zinoceras crassifrons, ---------.-- --- Horizontal section of skull of Dinoceras distans, _--.-------------- Horizontal section of skull of Zinoccras hians, -..----..--. ------ Horizontal section of skull of Dinoceras laticeps, Vertical longitudinal section of skull of Dinoceras mirubile,..-. ---- Vertical transverse section of skull of Dinoceras mirabile,...-.---_- Page. ail Figure 36. “ce “ce “ FIGURE “cc “ “ce ee FieurE oc ae “ 3 “ “ Ts “ ee “cc 3 b ie 38. 3 4 4 49 43. 4 9: 0. 1. 4, 45. 46. 47. 48. 49. 50. 51. 52. 53. 5 5 5 4, 5. 6. DINOCERATA. CHART Hin al: Towers awaot MerOcenas amrecien Sa eats seen ithe jsame Haw. seen tromvabo ver |) = eee ae ee Lower jaw of Tinoceras longiceps, with upper canine in position, - - -- Mowernjawot Lin oce as art.cDile eae ee Dhelsamenawssseenstromythe tro niae ss | ee ee WO WieTa | awn OL etal ented SCG 11 = ae ae eee re ae Mheysame’ jaw: Seen trom abo wens eee a ee eee CHAP DR, Wi. Imcisorot Dio Cena sist Ute a eee eee Imeisoncot LDinioce asin a0. ese ae ee eee ee Incisor of Dinoceras mvirabile,._...--------- eS 2 eee er eres Upper canine of Dinoceras lucare,---_---------- Ch ee A Wippernicaninero e710 Cenas 1000eGe))s === ee Uippercanme\loke/7oceras lo gncepss ee ne (Uippericanineton 2iocends:giai1d esse eee Upper canine of Dinoceras laticeps, ---- - Bee Ae Ree tee ty eee tel Wipperkcammevon i7CCer.as) iG Cr simmer ee : Upper canine of Tinoceras pugnax Uppermolar series of Zinoceus stenops, 225..25 2222 = 22 Lower molar seriesiof samelmdividtalses =e eee Upper molar series of Coryphodon hamatus, ..--.----------------- Lower molar series of same individual, == 222-225 9-225 -a ee eee GEATE EE Re Vie Skulliof Dinoceraslaticens,.male. =e. 2 eee =e ee SKU O REIT OCE AS NUCLCC I) SCT | Cte mt eae ae Cast of braim-cavity of 7inoceras ingens,._-22---------==----- --=- Mal iceante erin. SUSIE WON Wenn s sede ene ecosamets ces Saosedenue Cast of brain-cavity of Uintatherium robustum, | -.--------------- The same cast ; superior view, ---- --- = Outline of skull of Dinoceras mirabile, with brain-cast in position, -- Outline of skull of Brontotheriinm ingens, with brain-cast im position, Outline of skull of horse (Aguas caballus), with brain-cast in position, Skull of Coryphodon hamatus, with brain-cast in position, - ---. -~--- Skull of Zinoceras pugnax, with brain-cast in position, -...---- ---- Skull of Pulwosyops laticeps, with brain-cast in position, ----------- Skull of Limnohyus robustus, with brain-cast in position,--—- ---- ---- Skull of Colonoceras agrestis, with brain-cast in position, .-~-_------ 54 54 55 55 57 57 61 61 61 63 63 63 68 64 ILLUSTRATIONS. Sabin Page Fieure 71. Skull of Hyrachyus Bairdianus, with brain-cast in position, ———- --—- " 64 “72. Skull of Amynodon advenus, with brain-cast in position, _-___-- -_-. 64 «73. Skull of Zporeodon socialis, with brain-cast in position, __--—--- --_- 64 “74. Skull of Mastodon Americanus, with brain-cast in position,--——. -__- 65 “75. Skull of Alotherium crussum, with brain-cast in position, —-----_—__- 65 “76. Skull of Platygonus compressus, with brain-cast in position, ..—. __—- 65 “77. Skull of Llephas Indicus, with brain-cast in position, --—--- -——- ee 66 “78. Skull of Zapiraus terrestris, with brain-cast in position, —-~— ~~. - Roe 66 «79. Skull of 7thinoceros Sumatrensis, with brain-cast im position, —_—— ._- 66 «80. Skull of Auchenia vicugna, with brain-cast in position, ---..-._ ___- 67 “81. Skull of Cervus Virginianus, with brain-cast in position, 67 « 82. Skull of Zippopotamus anphibius, with brain-cast in position, —— .--- 67 “ 83. Skull of Dicotyles torquatus, with brain-cast in position, . -___--__-- 67 CHAPTER V. MiGHRE S4e se stlasion Uiocerasmande trout Views 9--2.-5--2-- 022-222 452--- = ail Loo ane asamenvenicola sla CkavilGWas ae fae Soe eee A eee ee eee 71 ECO Uhesame: vertebra: bothomuviGw. 2-24 222... -95552- 2425-42222 - 71 “87. Fourth cervical vertebra of Zinoceras grande; front view, -----___- 75 ero Otmmnl Cr sdmenvericbrassldouwlews ates ) distances Cleese es ee Pyramidal of Tinoceras ingens; distalsendsa== === Pyramidal of Dinoceras mirabile; distal end, .-_- ~-- Trapezoid of Dinoceras mirabile; side view, ---- ---- Ute same) One| asta) emda meer sear Magnum of Dinoceras mirabile,; side aval GI Wise eect > oe Magnum of Dinoceras mirabile; side view, -------- Unciform of Dinoceras mirabile; side view, ---- ---- Unciform of Tinoceras ingens; side view, --.- ---- -- CHHVACR AT aE exer Second rib of Uintatherium latifrons; posterior view, The same rib; front view, -=--=------- ees eee UMS GHyeAe) une Ta WN = 22 2 See aes ae ee Mhe|same ribs) proximall/end) = 222 2— eee Anterior rib of Dinoceras mirabile; posterior view, - - Wives tanatey alloyS aM WAN, Soe See ee ees ee Sas MDS EMAVs) THOS ROM NAO, o-oo 22 == 2-25 222 S28 ac MTheysame ribs proximal end; ==—=2=====-=)-=-=—= == Sternum of Dinoceras mirabile ; top view, ---- ----- CEVA His xe Pelvis of Tinoceras ingens ; seen from below, ---- -- The same pelvis; front view, ----------------- -=-- Caudal vertebra of Dinoceras laticeps, -------- ----- 108 103 105 105 105 108 108 Nae 112 115 115 ILS) 119 130 130 130 130 131 131 131 131 134 136 136 138 ILLUSTRATIONS. XV CHARA ER) XT: Page Figure 137. Section of femur of Dinoceras mirabile,...........2.--------_-- M1 < 138. Section of femur of Dinoceras mirabile,.........---.--.-------- 141 ; CRECASEALBY Rie Noel FicurE 139. Astragalus of Dinoceras laticeps ; top view, -------------------- 149 cc 140%) Whe sameybone:s bottom views = - S622 5-5 one 5552-522 ee 8k 149 ss 141. Astragalus of Tinoceras ingens ; top view, .-----.---.---.------ 149 as 1A Zee bheysame boner botbOmaview.. 6 eee ee 149 ue 143. Calcaneum of Dinoceras mirabile ; top view,---- --. ------ Pope 152 SS 144, Calecaneum of Dinoceras mirabile ; top view, __----------------- 152 by 145. Cuboid of Dinoceras mirabile , side view,.---. ..-----.-------- 154 Gs iGo Ubessamerponey a proximallendsee ee eens eee eee ees 6 1d (COAG ESI eG Vis Figure 147. Diagram to illustrate the genealogy of Ungulate Mammals,_-__ ___- 173 cs 148. Left hind limb of Baptanodon discus,......=.___.._.-_..--.._-- 183 cs 149. Right fore foot of water tortoise (Chelydra serpentina), -.-._---- 183 ae 150!) Weft tore foot of Coryphodon hamatus, -_.2._...-.-.-..2-._--___ 184 0 iS peeelcettphindeto Otol samers <2 2yS2 252A ose feet 184 & 152. Left fore foot of Dinoceras mirabile, _... .......-..-----__--_- 184 3 (ioe lettin mindstoo ino hisametes eye ae ee Sey) ke ke 184 os 4A eich erOLetOOl Oley Om (CO PCISTS. nso a eae ee 2 ee eee 185 se US cuelehtenn det oottotesames: ssh eevee a etek ee ee ek ge we 15 Game Went tOLes LOO Ole LCpLaSLiRL Cus ee ee ne sys ee ee ee 185 ec Demme hiahindshOOunOiBAMne aa 1 oahu see ee 8 Ls ele 185 cs 158. Left fore foot of Rhinoceros bicornis,.___-__- Doo PE ee 186 ce is OMe etpshindyt otro fsa csp sak eee ete ne tn ke ee 186 « 160. Right fore foot of Brontotherium ingens, .....--_.__. ---. ..---- 186 ve Gl mlulcnt china OO tonsa ews esa er eee Se tee PT 186 x 1625 lett torestiootiot Mporcodon sociaus.. 2-24). 25 Lies see 187 ee iG Seem lbekt rnin dekootrotesamenens =e ayer ee SNe ke A ok 187 = 164. Left fore foot of Hippopotamus anphibius, -.-.---.--_______-- 187 s NG OMe hoon yhoo tOtaSAMete woe New Ie wee oy Soe sk BY 166. Left fore foot of horse (gus caballus),......-.------.-------- 188 ae 167. Left hind foot of same, ---- - ean eee oe Sere cease sass Sonne 188 << UG Ctee beth foretoonotmoroatn (Gapna eres) spe. so aoe ea 188 ot NIGEL ALR nln ote ool Or GAN eS ese see a Seeeo ee see ene =o eene See aes 188 XV1 DINOCERATA. SYNOPSIS. Page WTGuE TON wNasals ton D7OcenQshclaeUn ie ae eae ee eee 197 ES 171. Skull of Dinoceras cuneum ; seen from above, --_---------- eine a e198 ce V5 WiERRIRGONE JO OUIRIENMIOHR a= on SS ces escactceeccacsse ees ee. | || AOD ve U7iB5= pNiasal s Ot 2227 OCENCS aL COG: man ee ee ee 201 U3 174. Nasals of Dinoceras reflewwin, .--- ---- Ate ee 201 “ Wij INEGI OLE TM ROCERD CCT Da 4.5 Je Ble cas teecs ees eoas chasse 202 ue 176. Left parietal protuberance of Tinoceras anceps; side view,.-..... 203 oe i? ‘Lhe same specimen: front) views <2) >= eee eee eee 203 % 178. Vertical section through cranium of Tinoceras affine, ---.---- ---- 204 es 179. The same specimen ; seen from/above,_22--=- = =222252-------222- 204 es 180. Skull of Tinoceras cornutum ; side view, ---------=-----------+-- 206 se (Silke ithersamers kul aise emmhnoms bel Oya yee sere ee eee 207 US 1825 Nasalsiot 7i0cerasenassnjmOns: a= ee ee ee a ae 208 of 18326 a Niasalstob ezvocen sig Mecca, aye tee ee ee eee eer 0.0) cs S45 Posterior suntace cosas ai Cys rll meee ene pee ne ae gene a ene 209 s USS 3 eeNasal Si Olle7cO CCR CS) OT OUe (1 6 ee ae re nee ee 210 ¢ SCH Nasal siote7mocendsii71G71Gy ase aes ae a en ea ee 210 ss USia Niasalslot Li OGenashy con Uits a eee ee eee re 219 188. Upper molars of Zinoceras lacustre ; seen from below, ---- ----- -- 212 oe 189s UNasal sot we OCernGS Lali sense ee ere aye ta eee eee 213 ce 1902, ONasalstoie/irocerasilatinse= = serene eee ee eee 213 ce 191. Left maxillary protuberance of Zinoceras longiceps ; side view,-- 214 es 192. Left parietal protuberance of same skull ; side view, ---- - aeeet y Bele ue 193. Skull of Tinoceras Speirianum ; side view,-~-------------------- 216 ue 194. Skull and lower jaw of Tinoceras stenops ; side view,------------ 217 ce 195. Skull of Uintatherium robustum ; bottom view, -..-. ------------ 219 196. Lower jaw of Uiniatherium fissidens ; top view, .--------------- 220 cs 1975 Ahelsame specimens; Shronty vile wales saan ee ee 220 us 198. Skull of Gintathertum Leidianum ; oblique side view, ---------- 221 ee 199. Maxillary protuberances of Uintatherium segne ; seen from above, 222 ue 200) Nhe same specimen: sseen fromm front yee ee ee 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. JE Jers ave ct 2 ON Dye Tue 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 early 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 Natural Science. What is now especially needed in Paleontology 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 Dinocerata now known are represented, and at‘least one figure is given of every species. xvii XVvill DINOCERATA. The same general plan will be followed in the third Monograph, on the Sauropoda, which 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 Stegosawria, 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 General 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 Western 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. 8. W. Williston, G. Baur, and M. Schlosser, also his assistants, have likewise aided, especially while the volume was passing through the press. Yate Cortecr, New Haven, Conn., December 15th, 1884. DN OD auee sl ON: Amone the many extinct animals discovered in the Tertiary deposits of the Rocky Mountain region, none, perhaps, 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 sources 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 out cliffs, peaks, and columns of the most fantastic shapes, and varied colors. 1 1 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 here 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 country.? *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, which furnished important characters of the group. Fie. 1. . v A KE uy Dia Ey ty a Bini St “Gweet Water JS i "Riss. MAP SHOWING REGION OF DINOCERAS BEDS. In the succeeding spring, 1872, the explorations in this region were continued, and soon resulted in the discovery of the type specimen, 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 DINOCERATA. Other important specimens, obtained at this time, and described by the author, were the types of Dinoceras lucare, Tinoceras grande, Tinoceras lacustre, 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, fimally, 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 auspices 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 the 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 = ro up . 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 Uintatherium ; various remains secured in the same year by Prof. Cope, to which he applied the names Loxolophodon and Hobasileus, 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 Dinocerata 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, and 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 Kurope, 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 are 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 DINOCERATA, 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 River 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 the 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 Rocky 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 Mountains, alone contains the peculiar mammals known as the Brontotheride, 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, Miohippus, has been designated as the Miohippus series. The climate here during this period was warm temperate. INTRODUCTION, Fig. 9 Recent. Yapir, Peceary, Bisun, Liuma. Quaternary. Bos, Equus, Megatherium, Mylodon. ; Equus Beds. Equus, Tapirus Elephas. i Pliocene. r \ Pliohippus, Tapiravus, Mastodon, Protohippus, Procamelus, Phohippus Beds. i Aceratherium, Bos, Morotherium. * ae = S Miohippus Beds. Miohippus, Diceratherium, Thinohyus. 3 : . § Oreodon, Eporeodon, Hyawnodon, Hyracodon, Edentates S | Miocene. |Oreodon Beds. i (Moropua). Z =) Brontotherium Beds] Brontotheriwm, Menodus, Mesohippus, Elotherium. ue i ® —___|— —— == i 2 ei Diplacodon Beds. Diplacodon, Epihippus, Amynodon. Dinoceras Beds. \ Dinoceras, Tinoceras, Uintatherium, Limnohyus, Paleo- moce: o 2 syops, Orohippus, Helaletes, Hyrachyus, Colonoceras. Eocene. Green River, or Heliobatis, Amia, Lepidosteus. me Heliobatis, Beds. 5 CCRC. Eohippus. Lemurs, Carniyores, Ungulates, Coryphodon Beds. |? Tillodonts, Rodents, Serpents. ee cee =. Hadrosaurus, Dryptosaurus (Lelaps). adrosaurus Beas. Fox Hill group. | Cretaceous. |AQ- oa Goce op [Birds with Leeth ( vuvntorniunes rorni i o “< ), Hesperornis, Ichthyornis. s Colorado Series. or Mosasaurs, Edestosaurus, Lestosaurus, Tylosaurus. | 3 Pteranodon Beds. Pterodactyls (Pteranodon). Plesiosaurs. 3 SS = | N Dakota Group. na = = = rs] Dinosaurs, Atlantosaurus, Brontosaurus, Morosaurus, Diplo- Ss a Atlantosaurus Beds} docus, Stegosaurus, Camptonotus, Allosaurus. Turtles. Jurassic. Bapte don Beds. Crocodiles. Mammals (Dryolestes, Stylacodon, Tinodon, aptanodon Be ; Ctenacodon). Bird (Laopteryx). Baptanodon (Sauranodon). f ‘ Otozoum, or First Mammuls (Dromatherium). Triassic. Conn. River, Beds.|Dinosaur Foot-prints, Amphisaurus, Crocodiles (Belodon), Permiav. Nothodon Beds. Reptiles (Nothodon, Sphenacodon). Coal Measures, or : Bosaurus Beds First Reptiles (?) Hosaurus. Carboniferous ; Subearboniferous, or Sauropus Beds. irst known Amphibians (Labyrinthodonts), Sauropus. Dinichthys Beds. | Dinichthys. Devonian. x Schoharie Grit. First known Fishes. = _eiss SS S .- . 3 Upper Silurian. 3 Silurian. Lower Silurian. Cambrian, — | Primofdial. No Vertebrates known, Huronian. Archean. — |Taurentian. L SECTION TO ILLUSTRATE VERTEBRATE LIFE IN AMERICA. 8 DINOCERATA. Above the Miocene, east of the Rocky Mountains, and on the Pacific coast, the Pliocene 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, we are justified in separating the Miocene from the Pliocene at this break; although in Europe, where no great break exists, the line seems to have been drawn at a somewhat higher horizon. Our Pliocene forms essentially a contimuous series, although the upper beds may be distinguished from the lower by the presence of a true Hquus, 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. 1 With this introduction, the table of strata on page 7 will make clear the general position of the geological 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, Tenn., Aug., 1877. INTRODUCTION. 9 The remains of the Dimocerata 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 Dinocerata are Limnohyus and Paleosyops, two genera of perissodactyl ungulates. They were somewhat larger than a Tapir, and in these strata are next in size to the Dinocerata. One or the other of these genera occurs wherever the Dinocerata 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 Orohippus, a four-toed ancestor of the horse. Other prominent genera are Colonoceras, Helaletes, and Hyrachyus, related distantly to the Tapir and Rhinoceros. Two genera, Tillotherium 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 resembling 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, Dromocyon, somewhat smaller, and Limnocyon, about as large as a fox. Among the Lemuroid forms were Hyopsodus and Lemuravus, forming the family Lemuravide, and having some affinities with the South American Marmosets. In addition to these, there were Marsupials, Insectivors, Chiroptera, and many Rodents, but apparently no true Quadrumana, or Kdentates. Besides these Mammals, there were numerous Reptiles, especially crocodiles, turtles, lizards, and serpents, in great numbers. Fishes were also abundant, especially the genera Amia and Lepidosteus. The Dinocerata form a well marked order in the great group of Ungulata. In some of their characters, they resemble the Artiodactyls ( Paraxonia); 1 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, ungulate, 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 Uintatheriwm, Leidy. The type specimen of Uintatheriwm 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 been 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. ENO i ACT AY: CHeAse ii. 1. THE SKULL. (Plates I-XIX, LV, and LVI.) The skull of Dinoceras mirabile, the type of the genus Dinoceras, on which the order Dinocerata 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 Dinocerata, 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. = 11 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 the 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 characters 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 on 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 Déinoceras mirabile, and in some other species, there is a prominence on the frontal bone, directly over the orbit. THe Nasat 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. They 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. Figure 3.—Nasals of Dinoceras mirabile, Marsh (No, 1036); type specimen. Figure 4,—Nasals of Dinoceras distans, Marsh (No. 1601); young male. Figure 5.—Nasals of Tinoceras pugnay, Marsh (No. 1044). FIGURE 6.—Nasals of Tinoceras annectens, Marsh (No. 1043). a. side view; b. top view; c. frent view. All the figures are one-fifth natural size. 14 DINOCERATA. In Dinoceras, they are small and sessile, and are directed upward, and somewhat outward; in Zinoceras they are larger, in most specimens, and project more horizontally, usually not beyond the apex of the nasals. Some of the characteristic forms of these nasals are given above, figures 3-6, page 13, and others will be found under the different species in the Synopsis at the end of the volume. On their lateral margins, the nasal bones unite by suture with the superior branch of the premaxillary, and, behind this, with the maxillaries up to the point where they joi the frontals. These lateral sutures disappear in old animals, but are shown in the skull of Dinoceras mirabile, figured in Plate IV. Between the osseous protuberances, or horn- cores, of the maxillaries, the nasals thicken into a transverse ridge, which greatly strengthens the skull in this region. The development of this ridge varies in different species. The suture between the nasals and maxillaries thus appears to rise on the inner face of each maxillary prominence, but the nasals do not form any essential part of these elevations. From this transverse ridge, the nasals expand posteriorly, and meet the frontals by oblique sutures, converging behind to the median line. At the union with the frontals, the nasal bones are comparatively thin. On their under surface, the nasal bones are each excavated by a broad deep groove, which is separated from its fellow by a sharp median ridge. These grooves extend from the anterior nasal opening back to the frontal bones, and then expand into large cavities immediately in front of the olfactory lobes of the brain. These olfactory chambers differ in form and size in different species. This part of the skull is shown in the sections represented in figures 30-33, pages 29 and 30. Pre-Nasaut Bones. The anterior extremity of the nasal bones, in both Dinoceras and Tinoceras, is formed of an osseous projection, pointing forward and downward, and situated in front of and below the nasal protuberances. Several specimens in the Yale Museum show that this projection is formed THE SKULL. 1 oO of two separate ossifications, each in front of its respective nasal bone. In figure 5, page 13, they are shown in position, with the sutures uniting 8 » pag ’ ’ 8 them to the nasals, and to each other. These bones are a_ peculiar feature in the skull of Dinocerata, and may be called the pre-nasal bones. ’ Me In very young animals, they are unossified; in adult animals, they are distinct, as in the specimen figured; but in very old animals they become co-ossified with the nasals, and with each other. Fig. 7. Figure 7.—Skull of Dinoceras mirabile, Marsh (No. 1036); with brain-cast in natural position; seen from above. Figure 8.—The same view of a young specimen of Dinoceras distans, Marsh (No. 1601). 7. frontal bone; m. maxillary bone; m’. maxillary protuberance ; n. nasal bone; n’. nasal protuberance ; p- parietal bone; p’. parietal protuberance; pm. premaxillary bone; s. supra-occipital crest. Both figures are one-eighth natural size. When separate, they are subquadrate in form, flattened on the median line where they meet each other; and rugose posteriorly, for sutural union with the nasals. These pre-nasal bones appear to be homologous with the ossicle sometimes found at the extremity of the snout in suillines, especially in the genus Sus. ~ 16 DINOCERATA. Frontat Bones. The frontal bones in Dinoceras mirabile ave shorter than the nasals. In all of the known skulls of the Dinocerata, the median suture uniting the two frontals is entirely obliterated. The sutures joining them with the nasals in front, and with the maxillaries on the side, is distinct in the type Fic. 9. Fie. 10. FiguRE 9.—Skull of Tinoceras ingens, Marsh (No. 1041); with brain-cast in position; seen from above. Figure 10.—Same view of skull of Dinoceras distans, Marsh (No. 1235). J. frontal bone; m. maxillary bone; m’. maxillary protuberance; 7. nasal bone; »’. nasal protuberance ; p. parietal bone; p’. parietal protuberance; pm. premaxillary bone; s. supraoccipital crest. Both figures are one-eighth natural size. of Dinoceras mirabile, as shown in Plates IL and IV. In this specimen, there appeared to be indications of a suture uniting the frontals with the parietals, which indicated that the former bones were very short, and the latter very long. The fortunate discovery, however, of a very young individual of this genus has cleared up this point beyond doubt. THE SKULL. 17 In this young specimen, the fronto-parietal suture is still open, and passes in a nearly straight line across the top of the cranium just in front of the summit of the cerebral hemispheres. It also divides the posterior elevations, or horn-cores, so as to leave the anterior part of them on the frontals, and the posterior and highest portion on the parietals. In all the other known specimens, this suture is nearly or quite obliterated, but distinct traces of it are seen in several crania in the Yale Museum. Fic. 11 Iie. 12. Figure 11.—Skull of Utituicwerium latifrons, Marsh (No. 1231); seen from above. FIGURE 12.—Same view of skull of Zineceras vagans, Marsh (No. 1241). 7. frontal bone; m. maxillary bone; m’. maxillary protuberance; m. nas 1 bene; 2’. nasal protuberance p. parietal bone; p’. parietal protuberance ; pm. premaxillary bone; s. supraoccipital crest. Both figures are one-eighth natural size. The position of this suture, and also that uniting the frontals with the nasals, and the latter with their adjoining bones, is well shown in figure 8, page 15, which represents the young specimen (number 1601) above referred. to. In Dinoceras mirabile (number 1086), the frontals are comparatively thin in front where they join the nasals. Over the orbits, they become 3 18 DINOCERATA. thicker, and swell into a distinct prominence, which afforded protection to the eye below. From this point back to the posterior protuberances, or horn-cores, the lateral margin of the frontal is thickened into a strong crest, which rises nearly to the summit of the elevations, leaving a distinct notch where they terminate. This depression marks the position of the fronto-parietal suture, here entirely obliterated. On the side of the cranium, the frontal bones are bounded anteriorly by the maxillary above, and, lower down, by the lachrymal, as shown in Plate I]. Further back on the top of the skull, the frontals are depressed, forming a deep concavity, the lowest portion of which is usually in front of the brain-case. In the posterior portion of the frontals, there are numerous air cells, which materially lighten these bones in this part of the cranium. Toe ParietTaL Bones. In all of the crania of the Dinocerata examined, the parietal bones are firmly united to each other on the medial line, and with the supra-occipital behind. In the single young specimen already mentioned (number 1601), the anterior border of these bones is distinctly marked by sutures, as shown in figure 8, page 15. The large posterior protuberances, or horn-cores, are thus mainly on the parietal bones, and the lateral crest, behind these elevations, appears to be also composed of the parietals. These bones are thick and massive, especially over the brain-case, but like the frontals are lightened somewhat by air cavities, as shown in figure 35, page 31. Between the osseous elevations, or horn-cores, on the parietals, there is a distinct transverse ridge, which strengthens this part of the cranium, and partially divides into two portions the deep concavity enclosed by the lateral and posterior crests. On the sides of the cranium, the parietals form the upper portion of the large temporal fosse. The suture between the parietal and squamosal below may often be distinctly made out, as shown in Plate II. The share of the parietals in the lofty occipital crest, cannot, at present, be determined with certainty, as here, even in the youngest specimens known, the sutures are obliterated. THE SKULL. als) THe Occrput. The occipital region in all the known Dinocerata is large, elevated, and subquadrate in outline. It varies much in shape and size in the - different genera and species, and several of the principal forms are represented below in figures 15-18. Fic. 13, Fie. 14. Fie. 16, Figure 13.—Posterior surface of skull of Dinoceras mirahile, Marsh (No, 1036). Figure 14.—Posterior surface of skull of Dinoceras laticeps, Marsh (No. 1039), male. Figure 15.—Posterior surface of skill of Dinoceras agreste, Marsh (No. 1221). Figure 16.—Posterior surface of skull of Tinoceras affine, Marsh (No. 1574) Figure 17.—Posterior surface of skull of Ti:oceras ingens, Marsh (No. 1041). Figure 18.—Posterior surface of skull of Tinocerus pugnaz, Marsh (No. 1044). c. occipital condyle; f. foramen magnum; J. lateral crest; 0. occipital crest; p. post-tympanic process ; t. crest behind temporal fossa. All the figures are one-eighth natural size. In Dinoceras mirabile (number 1036), the occiput is remarkably rectangular in“ outline, as shown above in figure 13. Its general surface is coneave, for the attachment of the powerful muscles and 20 DINOCERATA. ligaments which supported the head. The lofty occipital crest extends upward and backward, overhanging the occipital condyles, when the skull is in a horizontal position. The posterior margin of the large temporal fossa also extends well backward, forming the side of the occipital concavity, which is partially divided into two equal portions by a median vertical ridge. In some species, this ridge is very distinct, but, in others, it is almost entirely wanting. The occipital condyles are large, and bounded externally in front and below by a deep groove. They project downward and backward, showing that the head was declined when in its natural position. In Dinoceras laticeps (number 1039), the occiput is less elevated, and more expanded transversely, figure 14, page 19. Its concavity is divided into two portions by a distinct median vertical ridge. The foramen magnum, also, is expanded transversely, and is of moderate size. The occipital condyles are more elevated than in Dinoceras mirabile, a line joining their upper margins passing entirely above the foramen magnum. In Dinoceras agreste (number 1221), a third type of occiput is seen, much more expanded above, as shown in figure 15, page 19. The foramen magnum is here subtriangular in outline, and the occipital condyles are placed similarly to those of Dinoceras mirabile. In the genus Tinoceras, two distinct types of occiput are represented in the Yale Museum. In Tinoceras ingens (number 1041), the occiput is greatly elevated, somewhat concave above, and expanded at the sides. There is no median crest. The foramen magnum is triangular in outline, and comparatively small, with its upper border lower than the superior margins of the occipital condyles, as seen in figure 17, page 19. In Tinoceras pugnax (number 1044), the occiput is less elevated, and more nearly quadrate in outline. The foramen magnum is large, and transversely expanded. The occipital condyles extend above its upper margin, as shown in figure 18, page 19. In other species of the Dinocerata, the occiput shows an equal variety of forms. In Dinoceras mirabile (number 1036), there is a small, but distinct, par-occipital process of the ex-occipital, directed downward and eutward., THE SKULL. 21 In the type of Uintatherium, this process appears to be nearly obsolete. In front-of this process is the suture uniting the ex-oecipital directly with the squamosal, thus excluding the mastoid from the external surface of the skull, as in Rhinoceros. The tympanic portion of the periotic, also, does not reach the external surface. Figure 19.—Side view of skull of Tinoceras pugnax, Marsh (No. 1044). Figure 20.—Anterior part of skull of Tinoceras grande, Marsh (No. 1040). Fietre 21.—Anterior part of skull of Tinocerus annectens, Marsh (No, 1043). m’, maxillary protuberauce; me, external auditory meatus; n’. nasal protuberance; 0. occipital condyle; p’. parietal protuberance; pm. premaxillary bone; pn. prenasal ossicle. All the figures are one-eighth natural size. 22 DINOCERATA. Tur SquamMosat Bones. The squamosal forms the lower portion of the temporal fossa, and sends down a massive post-glenoid process (Plate II, s), which bounds in front the external auditory meatus. The latter has for its posterior - border the post-tympanic process of the squamosal, which unites directly with the par-occipital process by close suture. The periotic and tympanic bones are co-ossified, but not with the squamosal. The periotic has a distinct floccular fossa on its inner side. The tympanic is small, and is not expanded into a distinct bulla. The squamosal sends forward a strong zygomatic process, which resembles that in Tapirus. This process overlaps the malar, uniting to it by a straight, horizontal, suture, which, in very old animals, may nearly or quite disappear. Tar Matar Bones. The malar bone completes the anterior portion of the zygomatic arch, extending to the front of the orbit, as shown in Plate II, ma. he suture uniting the malar with the maxillary remains distinct till adult life, and may usually be traced, even in old animals. This forward extension of the malar bone is a general ungulate character, and quite different from what is seen in the Proboscidians, where the malar forms the middle portion only of the zygomatic arch. Union of malar with zygomatic process. Tur LAcCHRYMAL BONES. The lachrymal is large, and forms the anterior border of the orbit, as shown in Plate II, l. It is perforated by a large foramen. In Dinoceras, this opening is well within the orbit. In some species of Tinoceras, it is outside the orbit. The base of the lachrymal is excavated for the posterior opening of the large antorbital foramen. . THE SKULL. 23 THe MAxtILuARIgEs. In all the Dinocerata, the maxillary bones form a large portion of the lateral surface of the skull. They contain all the teeth, except those of the lower jaw, and also expand into the large median pair of osseous elevations, or horn-cores. On the external lateral surface, the maxillaries unite above with the frontals by suture; below this, with the lachrymals, and further down with the malar. This is well shown in the figure of Dinoceras mirabile, Plate II, m. In front, the maxillaries unite with the pre- maxillaries by a nearly straight, and nearly vertical, suture. Above, they join the nasals, as already described. The large canine tusk is entirely enclosed in the maxillary, and in the genus Dinoceras its root extends upward into the base of the maxillary horn-core. In all known Dinocerata, there is a diastema between the upper canine and the pre-molars. he latter are small, and form with the molars a continuous series. On their inner surface, the maxillaries send in strong palatine plates, which meet on the median line. The maxillary is perforated. by a large antorbital foramen, the outlet of which is concealed, in the side view of the skull, by a ridge extending upward in front of the orbit. Its position is shown in figures 22-24, c, page 25. THE PREMAXILLARIES. The premaxillary bones are edentulous, and, even in young specimens, contain no teeth. These bones have three distinct branches, the largest of which extends well forward below the anterior nasal opening. The second branch also extends forward above this opening, forming with the nasal its superior border, as shown in the type of Dinoceras mirabile, Plate II, pm. he third branch is a horizontal plate extending inward to the median line, where it joins its fellow, and thus completes the anterior portion of the palate. The anterior free portions of the premaxillaries are well separated on their palatal surface, but these bones meet somewhat in front of the anterior 24 DINOCERATA. palatal foramina. Near this point, the palatine plates are united by suture on the median line, and this suture is continued backward along the palate until it meets with the median suture between the maxillaries. The anterior palatine foramina are narrow fissures, rounded in front, and separating the lateral portions of the premaxillaries from the palatine plates, as in Equus. The latter plates unite posteriorly by suture with the adjoining maxillaries, as shown in Plate V, pm. The premaxillaries vary much in form in the different genera and species of Dinocerata. Two of the principal forms in the genus Dinoceras are shown in figures 26 and 27, page 26, and two of the genus Tinoceras, in figures 28 and 29, on page 27. THe PALATE. In all the Dinocerata, the palate is very narrow, and much excavated, especially in front. The bony palate extends back as far as the last upper molar, and in some specimens beyond it. Each maxillary articulates with the corresponding premaxillary by a suture commencing on the palatal surface, in front of the large canine alveolus, and running just within the border of the alveolus to near the middle of its inner margin. At this point, the suture turns inward, across the end of the main branch of the premaxillary, and then obliquely backward, along the posterior end of its palatine plate. ‘The median suture is continued backward, separating the maxillaries, to a point nearly opposite the middle of the penultimate molar, where the maxillaries join the palatines. The maxillo-palatine suture is at first transverse, extending across the palate nearly to the alveolar border of the maxillary, and is then continued backward near this border, and around behind the last molar, whence it turns outward, and ascends the side of the skull in the orbital region. The palatal surface of each maxillary is deeply excavated in front between the canines, along the diastema, and as far back as the second or third premolar; but on the median line these hones meet in a sharp ridge, nearly on a level with the outer opposite border of the maxillaries. THE SKULL. bo OL Fie. 22. Fig. 25. Ficure 22.—Anterior part of palate of Dinoceras laticeps, Marsh (No. 1039). Tigure 23.— Anterior part of palate of Tinoceras ingens, Marsh (No. 1041). Figure 24.—Anterior part of palate of Tinoceras pugnax, Marsh (No. 1044). Figure 25.—Anterior part of palate of Hippopotamus amphibius, Linnzeus. a, anterior palatine foramen; 0. jalato-maxillary foramen; c. antorbital foramen; d. alveole of canine ; m. maxillary bones; m. nasal bones; pm. premaxillary bones; pn. prenasal ossicles. All the-figures are one-fifth natural size. 26 DINOCERATA. The bony palate is thus deeply excavated on each side in the region of the diastema, and near the posterior part of each excavation on either side is situated a large foramen, which may be called the palato- maxillary foramen. This foramen is shown in Plate V, and also in figures 22-24, b, page 25. The same foramen is. seen, also, in the hippopotamus. Fig. 27. Fig. 26. Figure 26.—Skull of Dinoceras mirabile, Marsh (No. 1036); seen from below. FIGURE 27.—Skull of Dinoceras laticeps, Marsh (No. 1039); same view. a. anterior palatine foramen; 0. palato-maxillary foramen; c. antorbital foramen; d. posterior palatine foramen; e. posterior nares; f. foramen magnum; /”. occipital foramen; g. stylomastoid foramen; h. foramen lacerum posterins; ¢. vascular foramen in basisphenoid; 7. posterior opening of alisphenoid canal; /, anterior opening of alisphenoid canal; /. optic foramen. Both figures are one-eighth natural size. The palatine surface of the maxillary bone is perforated with small foramina, along the line of the enclosed canal, as in the hippopotamus, evidently for the transmission of blood-vessels and nerves to the gums and surface of the palate. THE SKULL. 27 a The maxillary bones contain the sockets of all the upper teeth. The socket for the canine is a large and deep cavity, elongate-oval in section, and extending upward and backward to the posterior part of the base of the large maxillary protuberance. The outer surface of the maxillary Figure 28.—Skull of Tinoceras ingens, Marsh ; seen from below. FIGURE 29.—Skull of Tinoceras pugnax, Marsh; same view. a. anterior palatine foramen; b. palato-maxillary foramen; c. antorbital foramen; d. posterior palatine foramen; e¢. posterior nares; f. foramen magnum; /”. occipital foramen; g. stylo-mastoid foramen; h. foramen lacerum; 7. vascular foramen in basisphenoid: j posterior opening of alisphenoid canal; k, anterior opening of alisyhenoid canal; /. optic foramen. va Toth figures are one-cighth nattiral size. = 28 DINOCERATA. bone is swollen by this socket, so as to present, in the males at least, a prominent rounded ridge on the side of the face. The alveoli for the pre- inolar and molar series of teeth are similar to each other, each presenting three pits for the reception of roots, viz: an inner large pit, and two outer small ones. Over these, the bone is thin, as is usual on the buccal surface of the maxillary. Behind and above the posterior molar teeth, in the orbital region of the skull, the maxillary bone presents several fissures, or foramina, close to, or in, the suture with the palatine. 'The first of these may be indistinct, or of different shape on the opposite sides, and is just back of the last molar, as shown in the skull of Dinoceras lucaye, on Plate IX, figure 2. In Dinoceras mirabile (number 1036), three such fissures are situated on the right side of the skull, in or near the maxillo-palatine suture, back of the orbit. One or more of these apertures appear to be the posterior openings of the posterior palatine foramina, an arrangement similar to that seen in the hippopotamus. Troe Pauattne Bones. The palatine bones form only a small part of the bony palate in Dinoceras. The ‘palato-maxillary suture in Dinoceras mirabile (number 1036) is nearly opposite the middle of the second molar, and about 20™™ in front of the posterior border of the bony palate, (Plate V). It is at first nearly transverse to the palate, then runs backward around the last molar, and turns upward into the orbital region, where it cannot be followed with certainty. Posteriorly, the palatine is in contact with the pterygoid, and the pterygoid plate of the alisphenoid. On the median line of the palate, the suture between the opposite palatines is obliterated. The palatines continue the lateral walls of the posterior nasal cavities considerably behind the last molar, and these walls are still further extended by the pterygoid bones. THE SKULL. 29 THe Prerycorp Bones. The pterygoid bones in Dinoceras mirabile (aumber 1036), are applied to the inner surface of the palatines, and to the pterygoid plates of the alisphenoid (Plate V, pt). They appear to unite on the median line in the roof of the posterior nares, but the suture is not distinct. The suture with the palatine is oblique, and that with the alisphenoid can be traced upward beneath the zygomatic arch. The lower margin of the pterygoid is thickened, and nearly straight. The posterior margin is thinner, and moderately curved. FiGuRE 30.—Horizontal section of skull of Tinoceras crassifrons, Marsh (No. 1236). Figure 3!.—ITorizontal section of skull of Dinoceras distans, Marsh (No. 1601). a@ cavity behind base of canine tooth; 6. brain-cavity; c. alve le of canine tooth; 7 anterior olfactory chamber; /’. posterior olfactory chamber; m’. maxillary protuberance; . nasal bones; 7’. uasal protuberance ; p’. parietal protuberances. Both figures are one-eighth natural size. 30 DINOCERATA. In the skull of Tinoceras ingens (number 1041), the palate is only slightly excavated in its anterior part, and the palato-maxillary foramina are brought forward in front of the entire series of molar teeth, instead of being situated nearly opposite the second premolar. The palate between the whole series of molar teeth is nearly flat. ‘The foramen in the maxillo- palatine suture behind the last molar is largé and conspicuous, especially on the left side. These foramina are shown in figure 28, page 27. Fie. 32, Fig. 33. Figure 32.—Horizontal section of skull of Tinoceras hians, Marsh (No. 1499). Figure 33.—Horizontal section cf skull of Dinoceras laticeps, Marsh (No, 1202), female. «. cavity behind base of canine tooth; b. brain-cavity; ¢. alveole of canine tooth; # anterior olfactory chamber; /”. posterior olfactory chamber; m’. maxillary protuberance; m. nasal bones; 7’. nasal protuberances ; p’. parietal protuberances. Both figures are one-eighth natural size. In the type of Tinoceras grande (number 1040), the maxillo-palatine foramen is behind the beginning of the molar series, and the excavation of the palatal region also extends behind the first premolars. THE SKULL. ol In the type of Dinoceras, the palatine fossa of the posterior nares is roofed over, so that the passage from the palate into the large nasal cavities above leads forward and upward, as shown indistinctly in figure 26, e, page 26. In Tinoceras ingens and Tinoceras pugnax, the roof of this fossa is excavated in front by a pair of oval apertures, and through these the posterior nares open directly upward, as represented in figures 28 and 29, e, on page 27. The existing perissodactyls, the horse, the tapir, and rhinoceros, have the same type of palate. In Uintatherium, the structure of this portion of the skull has not yet been determined with certainty. FigurE 34.—Vertical median longitudinal section of skull of Dinoceras mirabile. Marsh. FIGURE 35.— Vertical transverse section of skull of Dinoceras mirabile. b. brain-cavity ; c. cavities in cranial walls; / frontal bone; m. maxillary bone; mm’. maxillary protuber- ance; . nasal bone; x’. nasal protuberance ; 9. occipital condyle; o/. olfactory lobes of broin; op. optic foramen; p. parictal bone; p’. parietal protuberance; pg. post-glenoid process; pl. palatine bone; pm. premax Mary bone; pt. pterygoid hone; s. supra-occipital crest; z. zygomatic process of squamosal. Both figures are one-eighth natural size. These palatine characters of the Dinocerata are important, but unfortunately they can be made out only in skulls unusually well preserved. The value of these characters in classification will. be discussed in a subsequent chapter 32 DINOCERATA. Tot VoMERS. The vomers in the Dinocerata do not appear upon the surface of the palate. They are narrow bones, closely united, and deeply concave upon their upper surface. They are wedged in between the palatine plates of the maxillaries, and in old animals are closely united with them. The groove formed by the upper concave surfaces of the vomers is filled by the turbinal bones, which are well developed. The following are the principal dimensions of three of the skulls described in the present chapter. Measurements of others will be found in the Synopsis at the end of the volume: Measurements of Skull. (Dinoceras mirabile, No. 1036.) m. Total length of skull from nasals to occipital crest,_--- .--.-. -.------- oe 0.76 Total length, from premaxillaries to occipital condyles, ------------- -------- 0.66 Greatest transverse diameter, through parietal protuberances, _.. _. - E 0.385 Greatest transverse diameter, through occipital crest,..-.-.----..----------- 0.26 Greatest transverse diameter, through maxillary protuberances, ------_. —----- 0.205 Least transverse diameter, behind maxillary protuberances, ---- -------- ------ 0.155 Greatest transverse diameter, through zygomatic arches, --_--_-------------- 0.285 Greatest transverse diameter, through post-glenoid processes, ---- ------------ 0.25 Length of palate, from end of premaxillaries to posterior nares, - --- --- aoe 0.35 Length of palatine bone, on median line, _--.--.=--..--------==- ee eee 0.030 Length of maxillary bone, on median: linG: <>< ..2. Sees See 0.185 Wadthvotepalate; bet weens) ast m0) ars) ste. = ee eee eee 0.050 Width of palate, between first molars, ______-_--- --=-=-==2-=-==-=--=-----= 0.065 Width of palate, between first premolars, -...--_.--_-------=====-==--= =_-- 0.050 Wadthcot palates across dias terials === === ete ee 0.07 Wadth’ of; palate, between Ganines; === =e ee 0,105 Antero-posterior diameter of zygomatic fossa, —- -- - a ee 0.165 Mrans verse (dra mMe ber On «ZAyse ONN AUT C iOS Sees eee 0.08 Distance from top of parietal protuberance to end of post-glenoid process, - - - 0.37 Distance from top of maxillary protuberance to end of canine, --------------- 0.415 WVerticall diameter ofworamien) sive.o mis ese a ee ee 0.051 Transverse diameter of foramen magnum, -----.-------.------------- -~---- 0.055 THE SKULL. Measurements of Skull. Total length of skull from nasals to occipital crest, . ~~~ _- ‘Total length, from premaxillaries to occipital condyles, ( Tinoceras ingens, No. 1041.) Greatest transverse diameter, through parietai protuberances,___._-----_-_-- Greatest transverse diameter, through parietal angles of crest, Greatest transverse diameter, through maxillary protuberances, Least transverse diameter, behind maxillary protuberances, - --- Greatest transverse diameter, through zygomatic arches, Greatest transverse diameter, through post-glenoid processes, --.-.--. ~~~ ---- Length of palate, from end of premaxillaries to posterior nares, Width of palate, between last molars, -_--__. Width of palate, between first molars,_..._..__-_-.------.- Width of palate, between first premolars, Width of palate, across diastema,.------- -_- Width of palate, between canines, --...-.. - Antero-posterior diameter of zygomatic fossa,_______- Transverse diameter of zygomatic fossa, - - - - Distance from top of parietal protuberance to end of post-glenoid process Vertical diameter of foramen magnum, Transverse diameter of foramen magnum Measurements of Skull. Total length of skull from nasals to occipital crest, ‘Total length, from premaxillaries to occipital condyles Greatest transverse diameter, through parietal protuberances, Greatest transverse diameter, through parietal angles of crest, Greatest transverse diameter, through maxillary protuberances, - Least transverse diameter, behind maxillary protuberances Greatest transverse diameter, through zygomatic arches, Greatest transverse diameter, through post-glenoid processes Length of palate, from end of premaxillaries to posterior nares, Width of palate, between last molars, Width of palate, between first molars, Width of palate, between first premolars, Width of palate, across diastema, Width of palate, between canines, Antero-posterior diameter of zygomatic fossa, Transverse diameter of zygomatic fossa, y--- (Tinoceras pugnax, No. 1044.) ga oo = Hae = == = - (Sees Sas Se se i Distance from top of parietal protuberance to end of post-glenoid process, -- - Distance from top of maxillary protuberance to end of canine, about _- Vertical diameter of foramen magnum, ‘Transverse diameter of foramen magnum 5 >--- m. 0.87 0.815 0.47 0.33 0.35 0.21 0.37 0.30 0.40 0.064 0.065 0.056 0.09 0.10 0.19 0.08 0.52 0.075 0.045 0.305 0.255 0.19 0.34 0.28 0.55 0.084 O.O84 0.056 0.096 0.132 0.12 0.096 0.48 0.050 0.075 pal Lie an cS | eae 2 Cobelli, lel: THE LOWER JAW. (Plates) Villy Ox XT, XX IV, cand? VI.) The lower jaw in Dinoceras is as remarkable as the skull. Its most peculiar feature in the male is a massive decurved process on each ramus, extending downward and outward. These long pendent processes were apparently to protect the upper canine tusks, which would otherwise be very liable to be broken (Plate XIII, figures 1 and 2, p). Indications of similar processes are seen in Similodon, and in some other extinct carnivors with long canines. In Dinoceras mirabile (number 1212), the process is concave from above downward on its external surface, and its lower extremity is somewhat thin, and narrowed longitudinally. In Dinoceras laticeps (Plate XIII, figures 1 and 2, p), this process is more massive, and more rounded below. 3 In the female, this process is much reduced in size, but is quite sufficient to protect the diminutive tusk, which overlaps it. With the exception of these processes, the lower jaw is comparatively small and slender. The symphysis is completely ossified, and deeply excavated above. Another remarkable feature in the lower jaw of the Dinocerata is the posterior direction of the condyles, hitherto unknown in Ungulates (Plate 5 35 36 DINOCERATA. VIL, figure 1, cd). The position of the condyles was evidently necessitated by the long upper tusks, since with the ordinary ungulate articulation the mouth could not have been fully opened. The low position of the condyle, but little above the line of the teeth, is also a noteworthy character. In some Marsupials and Insectivors, the condyle has the same position as in the Dinocerata, but in no other Ungulates, living or extinct, has this position been observed. Figure 36.—Lower jaw of Tinoceras annectens, Marsh (No. 1043); seen from the left. Figure 37.—The same jaw, seen from above. c. alveole of lower canine; d. diastema; 7. alveole of incisor; m. mental foramen; p. process for protection of canine tusk ; s. symphysis. Both figures are one-fourth natural size. In Dinoceras laticeps (Plates XII and XIIT), the entire lower jaw is more massive than in Dinoceras mirabile. The angle of the jaw is stouter, and distinctly inflected (Plate XIII, figure 2, a.) THE LOWER JAW. =. BT The coronoid process of the lower jaw in Dinoceras is large and elevated, somewhat curved backward, and pointed above (Plate VIII, figure 1, cr). The angle of the jaw is rounded in outline, and projects downward somewhat below the main portion of the ramus. The dental foramen is large, and bounded above by a ridge, which extends upward and backward to the condyle. The mental foramen is of moderate size, and situated near the base of the anterior pendent process. Fig. 38. FiguRE 38.—Lower jaw with upper canine in position of Tinoceras longiceps, Marsh (No. 1256), female; seen from the left. a. angle of jaw; c, upper canine tooth in its natural position; c’. lower canine tooth; cd. condyle ; cr. coronoid process; d. diastema; p. process for protection of canine tusk. One-fourth natural size. In the genus Tinoceras, the same general characters of the lower jaws are seen. In the male, the pendent process is large and elongate, but less massive than in the genus Dinoceras, and its lower outline less regularly rounded (Plate XIX, figure 1, cp). This corresponds with the position of the large upper canine tusk, which it protects. In the female of Tinoceras, the pendent process is much reduced, its size in all cases corresponding to the size of the canine tusk above. In the female of Tinoceras longiceps (figure 38, above), the lower jaw is remarkably long and slender, and the pendent process nearly obsolete. 38 DINOCERATA. That the same relation in size between the tusk and process below it holds equally in both the genera Dinoceras and Tinoceras, is conclusively shown by various specimens in the Yale Museum. Fic. 39. Fia. 40. FiaurE 39.—Lower jaw of Dinoceras mirabile, Marsh (No. 1251); seen from the left. Figure 40.—The same jaw; seen from the front. c. alveole of canine; f. anterior foramen; di. deciduous incisor; 7. alveole of incisor; m. mental foramen; -p. process for protection of tusk. Both figures are one-fourth natural size. In the genus Dinoceras, there are three incisor teeth, and a small incisiform canine on each side forming a continuous series at the front extremity of the lower jaw. ‘These are all of moderate size, and inclined well forward, as in the ruminant mammals. Behind this series, and immediately over the dependent process, is a long diastema (Plate VIII, figure 1, d). Further back, there are three premolars, and three molars, forming together a close series. This is the dentition, essentially, in the lower jaw of both Dinoceras and Tinoceras, and will be described more fully in the following chapter. In a lower jaw found near the locality of the type of Uintatherium robustum, and here referred to that genus, there are four premolars instead of three. The first premolar, wanting in Dinoceras and Tinoceras, is of small size, and is placed just behind the lower canine. It is separated from the second premolar by a diastema, as shown in figures 41 and 42, page 39. THE LOWER JAW. 39 Od In the present state of knowledge of the Dinocerata, this first lower premolar may be regarded as a distinctive feature of the genus Uintatherium, the type specimen of which, unfortunately, is too fragmentary for a complete identification of its principal characters. Fig. 41. Wipe’ M Fie. 42. Figure 41.—Lower jaw of Uintatherium segne, Marsh (No. 1194); seen from the left. FIGURE 42.—The same jaw; seen from above. a, angle; c. alveole of canine; cr. coronoid process; ed. condyle; d. diastema; p. process for protection of tusk; pm. alveole of premolar ra Both figures are one-fourth natural size. 40 DINOCERATA. The principal dimensions of three of the lower jaws described in this chapter are as follows: Measurements of Lower Jaw. (Dinoceras laticeps, No. 1039.) m, Greatest length of ramus, 2-4) --.Re=") Slee eae ee eee ee eee ee eee 0.54 Extent (of ‘symphysisye2- s332,22e6 esac sess ae ace ee Bee MR ge ee 0.18 Height of coronoid process from bottom of ramus,.--.¢-.. =-------.--- --.-- 0.235 Depthioframus at last molar 2222522252 == Bees Weave) oe SM 0.09 Depthtor mammstat tusk processes ops s se a et en 0.185 Extent rolwdiastiem a se ere ee eee ies ane oe 0.10 Extent of molatiserles) 4.522.622 st ot oe eee =e eee = 0.18 areatest width across condyles, ..-..-....---. ----- Ee i a te 0.295 Mransyerse diame tersoticon diy leer = are a 0.087 WVerticaliciametenon condyle) ee ssr= sms ee 0.048 Measurements of Lower Jaw. (Uintatherium segne, Marsh, No. 1194.) ™m. Createstll enethvoteramis eee es ee ee Pe NR ee, ee 0.49 Extent yor isymmphiysisies 8. 8. 2s St ae ee ee ee eee eee ee 0.165 Height of coronoid process from bottom of ramus (approximate), .--._--- ~~ -- 0.19 Depth oh ramusvatwlastumolane ss 952 eee Sees Jo eS eet arrears 0.075 Depth of ramusiat) cusks processs=== = ss sss] se = se see= OD op s2, Dee lae ere ee 0.17 Hxtentiofanolariseries) (functional) == 2s sss e= eee eg eee E 0.145 Transverse diameter of condyle, -- ~~ -.- er rR a at it ee oe Sc tS 0.076 Wenticalidiamevenotconty le sesame ee Pre ee Met nee Be Ay 0.040 Measurements of Lower Jaw. (Tinoceras longiceps, Marsh, No. 1256, female.) 5 m™m. Greatest length of ramus (approximate), —-________ SRR Ft pee 0.57 Extent: ofa symp Ny S1S. sete te pee ee Be Ae ee ee 0.185 Height of coronoid process from bottom of ramus, .---.-.------------------ 0.26 Depth of manaus atillast mmol erga es es ee ea oe le Oe eae 0.084 Depthiofiramusiatitusk: rocessitr. == messetse cers eee ee ree en 0.10 Extentiotdiastemas. 2... cS be Se accion nae nee Se es eee ee 0.145 Dam Ole NOM ONCE = -—— os soon nee eas eee = 5 eee wes ee = eee 0,175 Transverse diameter of condyle nat i oe a epee IPL oe eee een 0.070 Viertical:diameter of condyle; S252 22s. eae See e ree See eee 0,045 Cee thik TEE RAR: THEE: (Plates I-V, VII-X, XIJ-XIX, LV and LVI.) The teeth of the Dinocerata constitute one of their most interesting teatures, differmge widely in form and dentition from most of the other Ungulata. In the genus Dinoceras the dentition is represented by the following formula: 2 9) ° U . 1 oO vo Incisors —, canines —, premolars —, molars — — 3 9? 1 ? 9 5 Ot, pvp vo o So far as now known, the same formula applies equally well to the genus Tinoceras. In Uintatheriwn, the dentition is apparently as follows : 0 il 3 3 Incisors =, canines 1 premolars me molars a= 36. Oo THE INCISORS. In none of the Dinocerata have any upper incisors been found, even in the youngest specimens. The premaxillary bones appear to be entirely edentulous, although in some specimens, especially in Dinoceras laticeps (number 1039), there are shallow depressions at irregular intervals that strongly suggest the probability of embryonic teeth in very young, or foetal individuals.A fortunate discovery in the future may, perhaps, settle this point. 6 41 42 DINOCERATA. In the lower jaws of all the known Dinocerata, there are three well- developed incisors on each side. They are inserted, each by a single root, and are procumbent, all directed well forward. Their inner surfaces a. Fie. 43. C. a. Fie. 44, Q Fie. 45. Figure 43.—Incisor of Dinoceras mirabile, Marsh (No. 1491). Figure 44 —Incisor of Dinoceras mirabile (No. 1492). Figure 45.—Incisor of Dinoceras mirabile (No. 1490) a, side view; b. top view; c. antero-posterior view. All the figures are of natural size. THE TEETH. 43 continue the deep groove on the upper part of the lower jaw, above the symphysis. ‘The position of the sockets for these teeth in Dinoceras is shown in Plates XII and XIII, and the form of the teeth, in Plate VIII, figure 1. The crowns of these incisors are covered with enamel, and the special features of both crown and root are shown in figures 43-45, page 42. In the genus Tinoceras, the incisors are similar in form, but have a less inclined position, as indicated in Plate XIX, figure 1. Fig. 47. Figure 46.—Upper canine of Dinoceras lucare, Marsh (No. 1038); male, 0. lateral view, inner surface; ” b’. outline of section of tooth; 6”. section of tooth showing pulp eavity; ¢. front view of tooth. Fraure 47.—Upper canine of Dinoceras laticeps, Marsh (No. 1202); female. a. outer surface; 6. inner surface; b’. outline of sec ion; ¢. front view. Figure 48.—Upper canine of Tinoceras longiceps, Marsh (No. 1256); female. a. outer surface; b. inner surface; c. front view of tooth. The dotted line on the teeth marks the position of the alveolar border, below which the tusk was exposed. All the figures are one-fourth natural size. THe CANINES. The superior canines of Dinoceras are long, recurved, trenchant tusks. The crown is covered with enamel, and the root extends upward into the base of the maxillary protuberance, or horn-core. When the animal is 44 DINOCERATA. young, these tusks grow from a persistent pulp, but im old age the cavity becomes nearly closed. In the male, these tusks are large and powerful, and extend downward nearly or quite to the extremity of the pendent process of the lower jaw. Fie. 49. Fie. 50. Figure 49.—Upper canine of Tinoceras grande, Marsh (No, 1040); male. Figure 50.—Upper canine of Dinoceras laticeps, Marsh (No. 1222); male. a. lateral view showing outer surface; b, inner surface; b’. b’’. sections; ec. front view. The dotted line on the teeth marks the position of the alveolar border, below which the tusk was exposed, All the figures are one-fourth natural size. In Dinoceras mirabile (number 1036), the canine tusks are oval in section, where they emerge from the jaw, then become somewhat constricted, before expanding into a wide, thin, lanceolate extremity, as shown in Plate I. On the outer surface of these tusks, there is a distinet ridge in the lower half exposed, giving there a subtriangular, or bayonet- like form. THE TEETH. 45 In Dinoceras lucare, the wpper canines are not constricted, but taper to the lower end, which has, also, a bayonet form (Plate IX, figure 1, c). > ie>| 28 a a eS Ee) a i oan ip GSE = ell a og 4.533 2 ® 2 qa 5 : nae CS! IG) or 228 a Og 8B q4oo sh B28, a oS oe = is es 8 Bee aus —- Dee 8 Sy as a USS > 8Sse OL cemees gs =| ag AE ISESe., a ie FERS dah Se nm E22 a i) See ee Sa PS Sh fist eo hens fae Sh Bg 2 22 a =) See's i} i Res Ss > i=} zoe ©. es) Se jek Soe N nm 2 © Q st S = nm ° Fh ie>t a = S 3 S : oO: 1 SH “es i 2 Ee S = a i In the female of Dineceras, the upper canines are small and slender, and protrude but little below the jaw (Plate XIV, figure 1, ¢). 46 DINOCERATA. In Tinoceras, the upper canines are much more curved than in: Dinoceras, and the end of the root, instead of being inserted in the base of the maxillary horn-core, starts well back of it, so that the general direction of this elevation is nearly at right angles to the tusk. The general form of the upper canine tusks in the Dinocerata is shown in figures 49-52, on pages 44 and 45. In the lower jaw of Dinoceras, the canine is very small, and very similar in form to the ineisors, which it adjoins (Plate VIII, figure 1, ¢). b] a} , Do ’ The same is true in the genus Tinoceras, where the lower canine, as well as the incisors, has a more erect position than in Dinoceras. Tur Upper PREMOLARS. The crowns of the premolar and molar teeth in Dinoceras, and, in fact, in all of the known Dinocerata, are remarkably short, with the roots well developed, forming a true brachyodont dentition, as in all early Tertiary ungulates. ‘These teeth are all inserted by three roots, two small ones on the outer side, and a larger one on the inner side. In the type of Dinoceras mirabile (number 1036), the upper molar series is remarkably well preserved. The entire set of premolars and molars is in position, indicating that the animal was fully adult, and yet the amount of wear shown by these teeth is so slight as not to obscure in the least their essential characters. The form and relative position of the series on the two sides is well shown in Plate VII, figure 2. There are three premolars, and three true molars on each side, forming together a close series. There is, in this skull, no trace of what may be regarded as the first premolar. If present during the immature condition of the animal, it has entirely disappeared. In one specimen of this genus (number 1039), the alveole of this first upper premolar remains, but no other trace of the tooth has been seen. The first premolar of Dinoceras mirabile in place, which would correspond to the second in the complete ungulate dentition, is the THE TEETH. 47 smailest of the present series. Its crown is subtriangular in outline, with the apex in front. The antero-external face is cordate in outline, somewhat concave, with the point below. On the inner side, there is an elevated lobe, somewhat inside of, and separated from, the apex of the external face. On the inner and posterior faces of this premolar, there is a strong basal ridge, which is nearly or quite obsolete on the anterior face. Figure 53.—Upper molar series of Tinoceras stenops, Marsh (No. 1567); seen from below. Figure 54,—Lower molar series of same specimen; seen from above. m. molar; pm. premolar. The figures are three-fourths natural size. The second upper premolar in this series is much larger than the one last described. ‘The crown is sub-cordate in outline, the apex pointing inward, and somewhat backward. ‘The essential features of the crown consist of two transverse ridges, which meet internally, forming a V-shaped figure. This is the characteristic type of the upper molar series in the Dinocerata. The anterior transverse ridge of this tooth has its external extremity somewhat curved backward. This premolar has a well marked basal ridge, entirely surrounding it, although somewhat thin near the middle of the anterior border. 48 DINOCERATA. The last upper premolar is very similar to the one just described. Its crown is somewhat more triangular in outline, and the crests of the transverse ridges are straighter. ‘The basal ridge is continued and well developed. THe Uprer Mo.ars. The first true molar is much like the last premolar in general form. It shows by its greater wear that it made its appearance betore the last premolar, and in this way its true position in the series is indicated. The anterior transverse crest in this tooth is considerably larger than the posterior crest, and the valley between them is much wider than in the premolars. Behind the posterior crest, moreover, there is, on the inner posterior angle of the crown, a distinet tubercle. This is seen in all of the true molars in Dinoceras, and will distinguish them, at ence, from pre- molars of similar general form. The basal ridge of this first molar is well developed, except on the outer side, opposite the outlet of the transverse valley. The second, or penultimate, upper molar is much larger than the first, but similar in general form. The transverse and antero-posterior diameters of the crown are nearly equal, the former being somewhat greater. The basal ridge is well developed on the posterior side of the crown, and distinct on the internal and anterior faces, but is obsolete on the external face, near the middle. The last upper molar is much the largest of the series, and the transverse diameter of the crown is considerably greater than the antero-posterior diameter. The anterior crest is larger than the posterior, and considerably curved, with the convexity in front. The posterior crest is nearly straight, but does not join the anterior crest closely at its imner extremity, the two forming a U-shaped figure. Back of the crest, on the posterior, internal border, there are two distinct tubercles in this specimen, as shown in Plate VII, figure 2. The basal ridge is continuous, except between the outer margin of the lateral crests, where it is lost in the depression on this part of the crown. THE TEETH. 49 In Dinoceras lucare (number 1038), the upper molar teeth agree with those already described, in their main characters, but as this individual was considerably older than the type of Dinoceras mirabile, the teeth show a greater degree of wear, as represented in Plate LX, figure 2. In the genus Tinoceras, the upper molar series is essentially the same in position and structure as in Dinoceras. In Tinoceras ingens (number 1041, Plate XVIII, figure 2), the upper series of molar teeth is shown, with a still greater degree of wear than in those above described. In figure 53, page 47, the upper molar series of Tinoceras stenops is represented, THe Lowrr PREMOLARS. In each ramus of the lower jaw of Dinoceras, there is a close series of six teeth, three of which are premolars, and three true molars. These are all inserted each by two roots. This is also true of the genus Tinoceras. In these two genera, so far as known, there is no indication of any premolar in front of this series. The first premolar of the typical ungulate dentition has not been detected in any specimen, young or old, of these genera. In the lower jaw of Utntatherium, as this genus is here defined, there were four premolars. The first lower premolar is here present, situated somewhat in front of the others, and but little separated from the lower canine. — It was a small tooth, inserted by two roots, and in all probability had no predecessor. The position of this tooth is shown in figures 41 and 42 on page 39. The second lower premolar, the first of the series in Dinoceras, was inserted by two roots. Its crown consists of a large anterior lobe, and a small posterior one. There is a distinct basal ridge on the external surface, which curves around upon the anterior and posterior faces, but is wanting on thé inner surface. F — ( 50 DINOCERATA. The second premolar of this series, representing the third premolar, is considerably larger than the one in front of it, and its crown is less compressed transversely. The anterior and posterior lobes of the crown, especially the former, are here elongated in the transverse ridges, approximating to the V-shaped figure in the corresponding upper premolars. The basal ridge is here on the external face, and curves around behind, so as to enclose the posterior tubercle. The last lower premolar is very similar in form and size to the one before it, but is somewhat larger. The basal ridge has a similar position. THe Lower Monars. The first true lower molar is smaller than the last premolar, but is similar in the general form and composition of its crown. It shows a greater degree of wear than the tooth in front of it, thus indicating that it appeared earlier, and is the first of the true molar series. The inner end of the anterior lobe, or crest, has its summit divided by a distinet notch, a trace of which was seen in the corresponding part of the last lower premolar. The basal ridge is distinct on the outer face, and likewise curves around behind the posterior lobe. The second, or penultimate, lower molar is much larger than the first, and has the transverse ridges much more strongly developed. The anterior one is considerably elevated, and the two do not meet closely on the inner side. The basal ridge is here distinet on the outer surface, and swells in front into a distinet ridge, and behind into a broader crest, or heel. : The last lower molar in Dinoceras is much the largest of the series. The anterior crest is nearly straight transversely. The posterior crest is inclined inward and forward, the two meeting on the inner face, forming a distinct V-shaped pattern. The posterior lobe, or heel, is here largely developed, and more distinctly separated by a deep valley, from the two crests just described. The position and general form of the lower molar teeth in Dinoceras laticeps is shown in Plates XII and XIII. THE TEETH. 51 The corresponding teeth in the genus Tinoceras are well shown in Plate XIX. The posterior transverse crest of the penultimate and last lower molar have here a distinct tubercle at their inner extremity, at the apex of the typical V-shaped pattern. This is shown especially in figure 2 of Plate XIX. In figure 54, on page 47, the lower molar series of Tinoceras stenops is represented. All of the incisors, canines, and premolars in Dinoceras and Tinoceras appear to have been preceded by a series of temporary teeth. The incisors, and lower canines sometimes made their appearance before their small predecessors had disappeared. In one specimen, represented in figures 39 and 40, page 38, these immature teeth are seen in place in small cavities in the sides of the alveoles of the permanent dentition. The lower incisors and their accompanying canines are usually more or less worn. This is due mainly to the food consumed, and in part to the attrition of the upper canines, and, perhaps, also to a heavy, coarse, upper lip. The premaxillaries, being edentulous, probably supported a pad, as in ruminants. The upper canines show distinct traces of wear on their inner surface near the base, and, also below, near the apex of the crown. This wear is probably due to the action of the agencies just described. A more difficult problem is presented by the worn surface sometimes seen on the outer face of these tusks, somewhat below the insertion in the jaw, as shown in figure 51, page 45. This is probably due to the wearing action of a heavy upper lip. The molar teeth in Dinocerata appear to resemble more closely the corresponding teeth in the genus Coryphodon than those of any other animal. The general dentition, however, is quite distinct. Coryphodon has well developed upper incisors, and a medium-sized upper canine, thus differing widely in these features from the Dinocerata. The position and size of these teeth in Coryphodon are shown in figure 66, page 63. The upper and lower molar series are shown in figures 55 and 56, page 52. 52 DINOCERATA. Figure 55.—Upper molar series of Coryphodon hamatus, Marsh (No. 1334); seen from below. Figure 56.—Lower molar series of same specimen; seen from above, Both figures are one-half natural size. OERANP THR IV, THE BRAIN. (Plate VI.) The brain of the Dinocerata is one of the most peculiar features of the group. It is especially remarkable for its diminutive size. It was proportionally smaller than in any other known mammal, recent or fossil, and even less than in some reptiles. It was, indeed, the most reptilian brain in any known mammal. In Dinoceras mirabile (aumber 1036), the entire brain was actually so diminutive that it could apparently have been drawn through the neural canal of all the presacral vertebrie, certainly through the cervicals and the lumbars. The size of the entire brain in Dinoceras, as compared with that of the cranium, is shown in the accompanying cuts, figures 7 and 8, page 15, and figures 57 and 58, page 54. ‘The size of the brain-cavity, and its position in the skull in Tinoceras, also, is represented in figure 9, page 16, and figure 67, page 63. The most striking feature in the brain-cavity itself, is the relatively small size of the cerebral fossa, this being but little larger than the cerebellar portion. This is well shown in Plate VI, the figures of which are drawn from the cast of the brain-cavity of Dinoceras mirabile, the type of the genus. o oo 54 DINOCERATA. The cerebral hemispheres did not extend at all over the cerebellum or the olfactory lobes. ‘The latter were large, and continued well forward. The hemispheres were probably conyoluted, and the sylvian fissure appears to be distinctly marked. Fig. 57. Fria. 58. FIGURE 57.—Skull of Dinoceras laticeps, Marsh (No. 1039); male; with brain-cast in position. FigurRE 58 —Skull of Dinoceras laticeps (No. 1202); female; with brain-cast in position. f. frontal bone ; m. maxillary bone; m’. maxillary protuberance ; 7. nasal bone; 7’. nasal protuberance ; p. parietal bone; p’. parietal protuberance ; s. supraoccipital crest. Both figures are one-eighth natural size. The cerebellar fossa is but little larger, transversely, than the medullar canal, and has lateral cavities, which were probably occupied by floceuli. There was a rudimentary tentorial ridge. The pituitary fossa is nearly round, and of moderate depth. There are no clinoid processes. THE BRAIN. out with reasonable certainty. Plate VI, figure 2 Tur CRANIAL NERVES. Fic. 59 The nerves passing off from the brain were large, and can be made The olfactory lobes were separated in - front by an osseous septum, the position of which is shown distinetly in Fig. 60. ft. Figure 60.—The same; superior view. V. fifth nerve; XII. twelfth nerve. Figure 59.—Cast of brain-cavity of Tinoceras ingens, Marsh (No. 1041); side view. c. cerebral hefnispheres; cb. cerebellum; /. floceulus; m. medulla ; ol. olfactory lobes; op. optic nerves ; Both figures are three-fourths natural size. 56 DINOCERATA. The cribriform plate, bounding these lobes in front, is thin and easily _displaced, but its position in the specimen is shown approximately by the extremity of the olfactory lobes represented in Plate VI. In front of this plate the olfactory nerves were spread out ina large cavity, which is represented in figures 30 and 31, page 29. The nasal canals extend forward from this cavity to the external nares, as indicated in the same figures. In these canals there were thin, well developed, ethmo-turbinal bones, which were easily displaced, and broken up. The presence of these bones is strong evidence that there was no proboscis. The optic nerves, or second pair, were well developed. Their position, size, and place of exit, are shown in Plate VI, figure 3, op. The fifth pair of nerves, or tri-geminals, were very large, and were given off on either side, behind the optics, and opposite the depression for the pituitary body, as shown in Plate VI, figure 3, ». The sixth pair of nerves passed off immediately behind and below the last pair. Their position and relative size are shown in Plate VI, figure 3, f The twelfth pair, or hypoglossal nerves, passing off through the condylar foramina, were large, and their position is given in Plate VI, figure 3, xu, and cf The position and exit of the other nerves sent off from the brain cannot be determined with certainty. In the genus Tinoceras, the brain was similar in its general characters to that of Dinoceras, but appears to have been somewhat more highly developed, as shown in figures 59 and 60, page 55. The hemispheres were more elongate, and the olfactory lobes relatively smaller. The cavities for the flocculi were quite large, and directed well forward. The twelfth pair of nerves were largely developed. In Uintatherium, the brain of the type specimen was nearly, or quite, as small as in Dinoceras. The hemispheres were short, and moderately expanded transversely. The olfactory lobes were separated by a wide septum, and were much more divergent than in Dinoceras or Tinoceras. These characters are shown in figures 61 and 62, page 57, which are of the same relative size as the figures in Plate VI. THE BRAIN. 5 -~I Fig. 61. Figure 61.—Cast of brain-cayity of Uintatherium robustum, Leidy; type specimen, lateral view. Figure 62.—The same; superior view. c. cerebral hemispheres; cb. cerebellum; f. flocculus; m. medulla; ol. olfactory lobes; op. optic nerves; V. tifth nerve; XII. twelfth nerve. Both figures are three-fourths natural size. Brain GrowrTu. The Dinocerata are, by far, the largest of all known Eocene land animals, and that they have, also, a very diminutive brain is a noteworthy fact, which attracted the author’s attention soon after their discovery. 8 58 DINOCERATA. The comparison of the brain in this group with that of other mammals from the same formation soon showed that the Dinocerata, although most remarkable in this respect, were not alone in diminutive capacity of brain power. A more extended comparison led to the fact that all of the early Tertiary mammals had very small brains, and in many of them the brain was of a low, almost reptilian, type. As the comparison was extended to include the mammals from the higher divisions of the Kocene, and from the Miocene, the same fact became more apparent, but a gradual increase in size and quality of the brain soon became evident in extending the investigation to the animals of more recent geological age. In bringing into the investigation the mammals from the Pliocene and Quaternary, the improvement in brain power became still more apparent, and the outline of a general law of brain growth was soon determined. In tracing thus the different groups of mammals, each from the early Tertiary to the present time, it was found that in every series where the material was sufficient to make a fair comparison, the brain-growth had been constant, and followed the same law. The results of this investigation were embodied by the author in a general law of brain-growth in the extinct mammals throughout Tertiary time. ‘This law, briefly stated, was as follows: 1. All Tertiary mammals had small brains. 2. There was a gradual inerease in the size of the brain during this period. 3. This increase was confined mainly to the cerebral hemispheres, or higher portion of the brain. 4. In some groups, the convolutions of the brain have gradually become more complex. 5. In some, the cerebellum and the olfactory lobes have even diminished in size. 6. There is some evidence that the same general law of brain growth holds good for Birds and Reptiles from the Cretaceous to the present time.! 1 American Journal of Science and Arts, Vol. VIII, p. 66, July, 1874; and Vol. XII, p- 61, July, 1876; see also the author’s Monograph on the Ononrornirurs, p. 10, 4to, Washington, 1880, THE BRAIN. 59 The author has since continued this line of investigation, and has ascertained that the same general law of brain growth is true for Birds and Reptiles from the Jurassic to the present time. To this general law of brain growth two additions may now be made, which briefly stated are as follows: (1.) The brain of a mammal belonging to a vigorous race, fitted for a long survival, is larger than the average brain, of that period, in the same group. (2.) The brain of a mammal of a declining race is smaller than the average of its cotemporaries of the same group. An example of the first of these statements is seen in figure 70, page 64, representing the genus Colonoceras, one of the Eocene ancestors of the Rhinoceros. The second case is illustrated by figure 82, page 67, of the Hippopotamus, evidently one of the last members of a long line. A study of a larger number of extinct and recent specimens will make these conclusions more apparent. The results of this study of the whole subject of brain growth, the author intends to bring together in a separate memoir. Some of the principal facts, however, may be appropriately presented in the present volume in connection with the brain characters of the Dinocerata, which naturally form the beginning of one series in the investigation. In any comparison of the size of the brain in different animals, whether in the same group or in others widely different, it is important to bear in mind that : 1. The brain of small animals is proportionally larger in bulk than that of large animals. 2. The brain of young animals is proportionally larger than in those fully adult. In a general comparison of brain growth of mammals, the first of these facts can have only a limited effect, which would not change, essentially, the general results. The effects of the second fact may be readily eliminated by confining the comparison to adult animals. 60 DINOCERATA. In this comparison, moreover, of the extinct forms with those of more modern time, including recent mammals, it may be taken for granted that the brain-cavity of the extinct forms, as well as of those now living, was entirely filled by the brain; since, with a possible single exception, no mammal is known in which this is not the case. In comparing the size of the brain in mammals with that of reptiles and fishes, an important point to be borne in mind would be the fact, that in the two latter classes the brain-cavity is not always entirely filled by the brain. The present comparison deals with mammals alone, and this restriction is here of no importance. The fact that among existing mammals there are some anomalous features in the size of the brain in allied groups has not been forgotten, but such instances, even if they occurred among extinct mammals, would ~ not materially affect the general comparison here proposed. In the following pages a series of figures is given, showing the comparative size of the brain, and its position in the skull in a number of the larger ungulate mammals, recent and extinct. To make the comparison a fair one, the skulls are all drawn of the same absolute size, thus showing, at once, the relative proportion of the brain in each. The skulls are placed horizontally, the plane of the molar teeth being as a rule taken as a base. In the case of the four artiodactyls, figures 80 to 83, page 67, this position has been somewhat changed, as, in this group of ungulates, the brain is more or less inclined backward in the skull. In these cases, the skull is represented as somewhat inclined forward, thus raising the posterior part of the brain. The angle of inclination of the face and of the brain, is made equal, thus giving to both the best position for comparison, and not materially affecting it for the present purpose. A striking illustration of the development of the brain from the early Tertiary to the present time may be seen in figures 63-65, page 61, where is shown, first, the skull of Dinoceras, the largest land mammal of the Eocene, with the brain in position; second, the skull of the gigantic Miocene Brontotherium, with the brain also in position; and third, the skull of the recent horse. Other comparisons, equally striking, can readily be made. THE BRAIN. 61 lie. 63. Fic. 65. Figtre 63.—Outline of skull of Dinoceras mirabile, Marsh; with cast of brain-cavity in position: about one- eighth natural size. Hocene. Figtre 6! —Outline of skull of Brontotheriwm ingens, Marsh; with cast of brain-cavity in position; one-tenth natural size. Miocene. Tigure 65,—Outline of skull of horse, Equus caballus, Linu.eeus; with cast of brain-cavity in position; abont one-sixth natural size. Recent. 62 DINOCERATA. The small size of the brain in early Tertiary mammals will be indicated by an examination of the Dinocerata skulls, with the brain in position, shown in figures 57 and 58, page 54. This is further shown by figure 66, page 63, which represents the skull and brain of Coryphodon, the largest mammal in the lower Kocene, from beds of earlier age than those containing the Dinocerata, as shown in the section, figure 2, page 7. The size of the brain in the middle Eocene genera Palcosyops, Lymnohyus, Colonoceras, and Hyrachyus are shown in figures 68 to 71, pages 63 and 64. Amynodon from the upper Eocene is represented in figure 72, page 64. The larger brain of the Miocene mammals is indicated by the figure 64, page 61, representing the skull of Brontotheriwm, which is found at the © base of the Miocene, as shown in figure 2, page 7. Llotheriwm from the same horizon is represented in figure 75. The skull of Eporeodon, with its brain in position, figure 73, page 64, also affords a good illustration of a mammal from this formation. ‘This genus is found in the middle Miocene, as shown in the section, page 7. The still more developed brain of the Pliocene mammals is seen in figure 74, page 65, which gives a view of the skull of the Mastodon, with the brain in position. In figure 76, page 65, the skull and brain of an extinct Pliocene peccary further illustrates the same law of brain-growth. On comparing these various figures with those representing the brains and skulls of the existing Ungulates, as shown by the succession in figures 77-83, on pages 66-67, the reader will have before him a series of facts which illustrate the laws of brain-growth given on page 58. The comparison, here confined to the representative ungulate mammals, might easily be extended much farther, but would not come within the scope of the present volume. The author has made similar comparisons in other groups of mammals, including those that can be followed from the early Tertiary to the present time, and the results are uniformly the same. These results the author hopes to present fully elsewhere at no distant day. THE BRAIN. FiGuRE 66.—Coryphodon hamatus, Marsh. Eocene. Figure 67.—Tinoceras pugnax, Marsh. Figure 68.—Palwosyops laticeps, Marsh. Wocene. Figure 69,—Limnohyus robustus, Marsh. Focene. er) Eocene. jo) 64 DINOCERATA. Fig. 70. Fig. 72. FIGURE 70,—Colonoceras agrestis, Marsh. Focene. FIGURE 72.—Amynodon advenus, Marsh. TFocene, Figure 71.—Hyrachyus Bairdianus, Marsh. Kocene. Figure 13.—Zporeodon socialis, Marsh. Miocene. THE BRAIN. Fig. 74, Fig. 75. Fig. 76. Figure (5.—Elotherium crassum, Marsh, Miocene, 9 FIGURE 76.—Platygonus compressus, LeConte. Pliocene a fon) DINOCERATA. Fig. 77. Figure 7§.—Zapirus terrestris, Linnieus. Figure 79.—Rhinoceros Sumatrensis, Cuvier. Figure 80.—Auchenia vicugna, Molina. Figure 82.—Hippopotamus amphibius, Liunzeus, THii BRAIN, Fig. 81. Figure 81.—Cervus Virginianus, Boddaut. FiGuRE 83.—Dicotyles torquatus, Cuvier, (Wels aed Feld a THE CERVICAL VERTEBR. (Plates XX, XXI, XXII, LV, and LVI.) THE cervical vertebre of the Dinocerata, in their main characters, resemble those of the Proboseidians. The atlas and axis are somewhat similar to those of the elephant. The rest of the cervicals are proportionally longer. The entire neck was about 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 Dinocerata 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 69 70 DINOCERATA. 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 opening of which is just above the inner and upper angle of the condylar articular surface. Externally, this foramen is connected by a more or less evident groove with one piercing the transverse process 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 the 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 mirabile 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 VERTEBRZ:, Teal Figure 84.—Atlas of Tinoceras grande, Marsh (No. 1040); front view. Figure 85.—The same vertebra; back view. Figure 86.—The same vertebra; bottom view. a. face for axis; b. face for odontoid process of axis; c. face for occipital condyle of skull; d. foramen in neural arch for spinal nerve; ne. neural canal. All the figures are one-fourth natural size. The following measurements give the principal dimensions of the atlas In one specimen of Dinoceras : Measurements of Atlas. (Dinoceras mirable, No. 1251.) m. (CrealextauLans versed tam eclemOneatlas saree ===)" oe SRL Sy ot ee 265 (Greavestuventi caligiameten or alas =e eae meee! OE Es eS es 142 WNranswersevdiameter-otmeunrdiacanales ste een See Je lee! ue lt .090 Vertical diameter of neural canal, _---._-.-------- | once he a SRE eee 080 AMLGRO-pDOStewor diametelor supenioGaLChy= 29. =5 2625 8 28-ase- sea een se. «067 Merticalmdiameter of eipenion aLchyes= es) aes eee ne ee Se ee .034 AANILeLO-pPOsterion diameter, otemfertor arch, §2.2--- 252. 222. (222 js. 522s s-25- = 252 .149 Diametersion faces'for occipital condyles, —2=2-2--222-2..25 2). =) =e ~--- .072-.052 Distance between faces for occipital condyles, above, -------------- .----------- .080 Distance between faces for occipital condyles, below, ----------.-.-------.----- .058 Diameters of facestor!od ontoidlprocess, = === 2-22 2-9-5 = ss gee 043-035 Diamierers;Ollateralt acesmon axisq ee eee esa os ee ee ee ee. -063-.056 Wistancesbet ween lateral. facesstoramisymes: —- soe: yaaa ee oe ae ee 065 72 DINOCERATA. Tue Axis. (Plate XXI1.) The axis in Dinoceras mirabile (number 1036) is robust, and proportionally shorter than the corresponding vert2bra 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 under 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 transverse. The neural 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 vertebrarteriai, 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 Dinoceras are as follows: THE CERVICAL VERTEBRA, 73 Measurements of Axis. (Dinoceras mirabile, No. 1036.) m. Length of axis, on floor of neural canal (approximate), _..-....-.--.----.------ 150 Hen sthjotmodontol dyprOcess,ses ta ene arene ne - BOS, Sate nae Shee aes Soa 056 iransverseydiameteron odontoid processy==-- 202-262 o=> 522 jaan a--2-2-5-2--- 035 Wentical/diameter tof odontoid' process, s2---.-2--=---2-=-------- See see ee SOD iiraneverse diamerenomantenonaniewlamtace, 2952-255 22-2 96 2-2- 622221 ante .068 Werticalkdiamectemotemtenorarweulanmace, 22. se. 522 0406 22 soe ee .065 Transverse diameter of vertebra, across anterior articular faces,_________._ __- Pe 148 rans verscsdiameterrOlmmn Guralucanaless 922 955 s25 0. oo oss gece nee ee eee ene e ee .053 Werticaleaiametenotimncuralycanalwesas.-2-2-— = 2-2 Pe 2 soe oe .042 Transverse diameter of vertebra, across post-zygapophyses, - ---- - - Been ees Set es a1) iiransverserdiamerenor postenmottaceer centrum, --- .2-22----5-5-2-42=.----.-- .098 Vertical diameter of posterior face of centrum,..-.---.------------ Deas Seu ea MANO Heichitolta ies tomonso tmeunalespine: ss seseces- 22s = on- ote oee sae ees | LTD pina verserdicineten Om MeuUnalgs pines sone: 2) wey ss = SES ee eee ee tesa 5 1048 Antero-posterior diameter of neural spine, --+--...--..-------.-- ches songs ee .085 Measurements of Axis. (Dinoceras mirabile, No. 1255.) Tm. Length of axis, on floor of neural canal (approximate), -...---. --.-.---------- 125 enothvot centrum along undersurface, -22 22-2 2225 224-2222. £2. 22e oc ot .140 Length of odontoid process, from lateral articular faces, _....-. .--------------- .045 ransverseidiameter of odontoid process;------...-----_-------2--_-- ee eee OST Wenticaladiamerer.ot od ontoldeprocessyese= 98+ 9-8-2 oe se eee ee ee ek .038 Transverse diameter of articular face of odontoid process,__-------------------- 6035 Antero-posterior diameter of articular face of odontoid process, -_- nS ae dD iMransversediameteron neuralucumals sso. 2252-2 ska 2 ee sues, ORY) Vertical diameter of lateral foramen,--_---__------ SES me A atoeee ae 2 ee te ees .012 Measurements of Axis. (Dinoceras lucure, No. 1038.) m. ‘IMawell Verayecilay UE R ASS 2 = ene Tee le gee Ney ae A ee eee 170 Length, from end of odentoid process to end of neural canal,_-... --.--- ---. -_-- .148 Aransverse diameter of odontoid process, -----.----’.------------------= pees 035 Wenticaludiametenor od ontoldsprocessas 455 2 4.7 22h ee ee oe ee ee ee 046 CGrestest diameter Of antenon aniicilan tices. so 56]. 52652502 5= 25 oe = ee .070 Mransverse diameter, acrossianterior articular faces, _ 2. /.2-.-----2--+:-----.--=- 142 Antero-posterior diameter of face on odontoid process, ----.--------------------- 044 ‘transverse diameter of face on odontoid process,-_---.--...3.--=----+=------=-- .033 Distance between antero-lateral articular faces,. ....---.-2-,:---.--.----------- .050 Transverse diameter of centrum, behind faces, —-----.--_- See es Ae ek ae 125 ‘Transverse diameter, across post-zygapophyses, -.-.-----...-=-----------:- aes Silo Transverse diameter of posterior face of centrum, .--..------------------------ .093 Vertical diameter of posterior face of centrum, ---- -- Se eee ene eae ee Se” 080 Diameters of lateral foramen, -__--_---__-_---- ea ee ene ee OS — 020) Diameters of neural canal (approximate), Ra pe he Pee A eee pt ud .040-,050 10 74 DINOCERATA. THe Turrp Vertepra. (Plate XXII, figures 1-5.) The third cervical of Dinoceras mirabile (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 mirabile (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 vertebrix. The principal dimensions of the third vertebra in one specimen of Dinoceras are as follows : Measurements of Third Cervical Vertebra. (Dinoceras mirabile, No. 1255.) m. Length of floor of neural canal (approximate), -----.-----.------- ------------ .055 Length of centrum, along under surface, - --------.--------------- 2 Sate er a eee ODS Vierticall diameter of posterior epiphysis, 22-2 .078 Antero-posterior extent of zygapophyses, -- .-------------. ------------------- -092 Diameter of lateral foramen (approximate), -=--_--_ ___--_=- ---- -==2=2=25--—— .020 Tur Fourrn Vertesra. (Woodeuts 87 and 88, below.) The fourth cervieal. 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 CERVICAL 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. Figure 87.—Fourth cervical vertebra of Tinoceras grande, Marsh (No, 1040); front view. FiaurRE 88.—The same vertebra; side view. J. lateral foramen; ne. neural canal; 2. anterior zygapophysis; 2’. posterior zygapophysis. Both figures are one-fourth natural size, The main dimensions of the fourth vertebra in one species each of Dinoceras and Tinoceras are given below. Measurements of Fourth Cervical Vertebra. (Dinoceras mirabile, No, 1255.) Weng throtetloomomucuralicanalven 2st te Se ss es oe se 055 Length of centrum, along under surface, - ot, eo iy ape eles Oh Re eS .054 sRranAVerse: dlaneter ommeanterOnMenip iy Sissy eee 2 oeu a= oom. Naess ee eee O78 Weriicaladiameterouantenonepiphysisy as 462 a8 =e eee el ee 07 jinansverse diameter ots posueniomepiphysisy 22225252 222 — 8 222 8 a .091 Werticaludiam eterno posteriomepiphiysis, ae sas ses 228 lees eee 075 Antero-posterior extent of zyeapophyses,.-—- 2-22-2222 --. -- =. 5222 58--- se .089 Drameterorslateralekoram ene em see sos de SS Se ey 024 iiransvyersewirameterormmeuralecanalyes 52.555 582) ee a ees ee eee O45 Measurements of Fourth Cervical Vertebra. (Tinoceras grande, No. 1040.) m. ene throtioorormennralicantal mae meee nee Sess os st be ee oe 042 Length of centrum, on under surface of vertebra, .__..__.. __..-_--_---.-..--- 045 Mransverscrdlameter OlaltenlOmiaceseee ssn. os. ee ese) eee ees ee .100 Wert calsdiameteroijanteriontaceses soo e oor ee ee 094 iliransverse.diametenonneuralicanaly == 22222 hss sees Le ee a Pee eee ee .055 Werticalkdiameteroimeuralicanal es pee eee one ere ewes hee Se oyeree ye 2s hee o .040 MDiametersvotelateral foramen see eae go Skee Se ee ee eG 025—.015 ae a (on) DINOCERATA. Tap Frern Verresra. (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-triangular in transverse section. The arch to protect the lateral foramen is more depressed than in the preceding vertebra. The more important features of this vertebra are shown in figure 89, below. Figure 89 —Fifth cervical tertebra of Dinuceras mirabile, Marsh (No. 1255); front view. Figure 90.—The same vertebra; side view. f. lateral foramen; nc. neural canal; z. anterior zygapophysis; 2’. posterior zygapophysis. Both figures are one-fourth natural size. The principal measurements of the fifth vertebra in this specimen of Dinoceras mirabile are the following : Measurements of Fifth Cervical Vertebra. (Dinoceras mirabile, No. 1255.) m. Length of floor of neural canal, ----------------- ee oe ee 052 Length of centrum, along under surface, __-. -___- ie feo eee ee 058 Transverse diameter Otme mal Canal pre syeee = are = eee ne ee ee ee terete 046 Merticalidiame tern tame tiralli cert 2) mes ene ae eee p pape e a 035 Transverse diameter of anterior epiphysis, - a FA ee eee 079 Werticaldiameter of anterior e pip liyisissy sprees eee ee O74 Transverse diameter of posterior epiphysis, -__- .--- A oe eee et 089 Wierticalidiameter of posterion epiphysis, == see ee O80 Antero-posterior extent of zygapophyses,_.--.__---.--.---- --- ; _ .083 Transverse diameter, across pre-zygapophyses,..-._.... -- --- eR Ieee 120 Transverse diameter, across post-zygapophyses, _---_-.>------_--_-= ------= EOE) Diameter of lateral foramen (approximate), ....-...-....-----.----- eee eee 20 THE CERVICAL VERTEBRA, “I “1 Tue Srxta Verresra. (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 of Dinoceras mirabile, Marsh (No. 1255); back view. Figure 92.—The same vertebra; side view. nc, neural. canal; z. anterior zygapophvsis; 2’. posterior zygapophysis. Both figures are one-fourth natural size. Fig. 93. Figure 93.—Sixth cervical vertebra of Linoceras cunewm, Marsh (No. 1042}; front view. Figure 94 —The same vertebra; side view. nc. neural canal; 2. anterior zygapophysis; 2’. 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. Measurements of the sixth cervical vertebra in two individuals of Dinoceras are as follows: 78 DINOCERATA. Measurements of Sixth Cervical Vertebra. (Dinoceras mirabile, No. 1255.) m. Length of toorof meunalicania lee see ees a aan eee eee .049 hens throticentrum alone aun d eras uta ce. eee eee ee .055 ‘ransverse diameterso te meur alls cata see a eee ee age ee .051 Vertical diameter of anterior epiphysis, —- -_- SE IES ces Se ath al 076 Transverse diameter on posterior epiphysis. == = =e == eee ae .088 Vierticallidiameterotpostentore pip tiysisy mse ses eee eee .078 Antero-portenorsextent ofezyeapophySess =e a= ee meen ee eee ea -087 Measurements of Sixth Cervical Vertebra. (Dinoceras cuneum, No. 1042.) m. Transverse diameteniot cenit unsere oe eee eee era ee 111 Ihengthvot centromiyalonc umd erisurta ces ess as ae ee w= -0b3 transverse) diametertotemenival yearly === eee ee eee en a 071 Vertical diameter of neural canal (approximate), ____._.....______._-_---_--__- 044 Transverse diameter of anterior face of centrum, .___ .___. ___..--.---.--.--____- .100 Vertical diameter of anterior face of centrum, _______- Say eS eee eae Re =, Se eee (0.2) Diameter of vertebra, across pre-zygapophyses (approximate), _-______ __. 2 ae nO Diameters ofllateralstoramen) eee. -- 8 s=e5s eee a eee ee -022-.034 Antero-posteriordiameteriot jedi elem es ee aes eee eee 026 THe Seventh Verresra. (Plate XXII, figures 6-10.) The seventh 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 characters are shown in Plate XXII, figures 8 and 10. Measurements of Seventh Cervical Vertebra, (Dinoceras mirabile, No. 1255.) hens thiof floorvor neural (cam all.g ae epee eee ae ae eee se 046 ene thiol centrum.ralonosoun den simtace ss se ea a .051 transverseidiameter,o£ mental (cama eens eee ea ee en eee = 0xail Vertical diameter of neural canal (approximate), _..____!22._-___../_22--_____- 046 Transverse diameter of anterior articular face (approximate),-.-.._.-_._._______ .076 Transverse diameter of posterior articular face (approximate), ...-_-.------_-__- .075 JN MUSRO | NOSES KOVED KELME VATE OV MENISOS, — oe = oa oe Soe wees see ses sence -084 Diametersyohanticulation torshics tyros ee = eee ene ee eee -022—.035 Diameter, across transverse processes (approximate),_._-._.--...---.-----.----- 185 Onl Eva il ead Mt aloe Vd THE DORSO-LUMBAR VERTEBRZ. (Plates XXIII, XXIV, XXV, XXVI, LV and LVI.) The trunk vertebrae in the Dinocerata are proportionally 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 Dorsat VERTEBRA. (Woodcuts 95-98, below.) . The first dorsal vertebra in Dinoceras mirabile (number 1255) has a slender, but elevated, neural spine, as shown in figure 95, below. It is distinguished from the adjoining elements of the column by the presence of elevated and oblique pre-zygapophyses, for articulation with the last cervical. 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. he laminz 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 diameter, and imperfectly united to the centrum. ~T (Js) 80 DINOCERATA. D The transverse processes are short, and strongly tuberculated 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 moderate 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. Fie. 96. Figure 95.—First dorsal vertebra of Dinoceras mirabile, Marsh (No. 1212); frout view. FIGURE 96.—The same vertebra; side view. m. neural canal; 7. face for head of rib; 7’. face for tubercle of rib; s. neural spine; z. anterior zygapophysis; 2’. posterior zygapophysis. Both figures are one-fourth natural size. Fig. 97. Fic. 98. FiguRE 97.—First dorsal vertebra of Tinoceras anceps, Marsh (No. 1030); front view. HicCURE 98 —The same vertebra; side view. nc. neural canal; z. anterior zygapophysis; 2’. posterior zygapophysis; s. neural spine. Both figures are one-fourth natural size. ‘ THE DORSAL VERTEBRA, $1 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 T'inoceras, are given below. Measurements of First Dorsal Vertebra. (Dinoceras mirabile, No. 1255.) m. Wencthrorcentrumy aloncm|oorot neuralycanall 22222 ==". 252] -622eee]—-2 2 - Hee 048 Ihengthiof centrum; along inferior surface, 22---.----------=.------.=- See 058 Werticalidiameter(or anterior facerot centrum’ o-2- ..2-=---.2-- 22--=2--+-----=- .072 Mransverse\diameter of anterior face of centrum, =2_----42-22----_---_2-_ ===. 075 Wertical-diameter or posterior face of centrum, .--..-.---2-2-------.+--+------ .073 Transverse diameter of posterior face of centrum, -----------..---------------- .078 Meniicaltdiameter ofmneurall canal ee =s ee ee ee ee Se See ha Ne 046 iransverseadiaine tenon e ualacandlse s96s Ste = “tee ee een 065 Greatest diameter, across transverse JOMOGOIY, ose Medes See soss esos 5 ae ee -210 Miametermorepre-zyCapoply sess saee anes heey oo SE ata Pee 6030 Wastance across pre-zycapophyses, -...-/-. 224. 2.23221 25.2-00. 2-2-2 22-452 2. - 140 Diameter of post-zygapophyses, -.--.--.-------- ----- ey OA 5 yd pe aes ess .031 Distance across, post-ny sapophyses, ©... --.+-.2-222<-----+-<<-----2+--------- 115 Diameters of anterior face for head of rib,_______.______ .____-_-- SRL Shea ae 030-.038 Dramefersiotmosueriontacemormeadiok wiby se) sa2e eee Me sees oe ee 027-037 Diametersioteace torimtulbercle Oismibye 228 Bees een 22 ee ee 2 = 2) 025 =.082 trans versecdiam even Of pedicely em ans a Oo ose oh ce aiee aes oes SoS _ -.044 Antero-posterion diameter of spedicel, 222 --.-2--..- 5. -----2-. ===. - eRe = SS, 2022, Distanceybetweenstacessormheadvotrlibs -seases 505-5 2205 2n es easecss ee Sees e .015 Measurements of First Dorsal Vertebra. (Tinoceras anceps, No. 1030.) m, Menothvoisioorotsnentallcandal swear reen = he ere he ee ew nS 056 Length OlcentrumwalonceInOe LES untae ess ae === ene ee See ne ee .056 Transverse diameter of anterior face of centrum, ---.------____. 32) os eee .070 Vertical diameter of anterior face of centrum (approximate), - fee =e 063 Transverse diameter of posterior face of centrum, -...-------------..--=------- .080 Vertical diameter of posterior face of centrum, --..-.----.--. - Boss Bee 066 iinansverseldiameter Ormmeutalicanaley eee =e see eee ae he ere eee = _ .068 Vertical diameter of neural canall (approximate), ___. _..-.-..-----------------. .037 Diameterstoleanberior capitmlandkace, sass 2a ase — 2 =e eens ose oes eae .031—.035 Wiameterstom posterior capliulantacee === === aaa ney as 22 eee eee .033-.040 ANLeTOspostenon diameteroi pedicel, 2s e2 sacs a4 ee enna eas ane .030 eran syerseaGiam lpi Of, pedicel wore ets= Se pee sy See eee ee ee 2 oe .029 Diameter of vertebra, across transverse processes, --.-..----------------------- .175 11 82 DINOCERATA. Tue Seconp DorsaLu VERTEBRA. (Plate XXIII; and woodcuts 99-100, below.) The second dorsal vertebra in Dinoceras mirabile (number 1255) is especially distinguished from the one last deseribed by the neural spine, which is massive, and more inclined backward. The neural canal is sub-triangular in outline. The 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 transversely. This vertebra is represented in Plate XXIII. The second dorsal vertebra of Dinoceras mirabile (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. Fig. 99. Figure 99.—Second dorsal vertebra of Dinoceras mirable, Marsh (No. 1212); front view. Figure 100.—The same vertebra; side view. n. neural canal; s. neural spine; 2’. posterior zygapophysis. Both figures are one-fourth 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, _._______ ---. -----__- encinvotscentrum=s along aim dersuntaces esses eee ee = 060 [Transverse diameter of anterior face of centrum, __......--_----.-.--------.-- 073 Vertical diameter of anterior face of centrum, —___ __- cfd cs 5 Soap By 5 a 075 Transverse diameter of posterior face of centrum, ___.--.-_-.----.------------- .075 Werticall diameter ot posterior face ot centrum, _9_ 2.2222 .--- -==. =). 3-2-2 2=--- .070 Transverse diameter of neural canal, _._______-.._--.- Bb ot MABE TN ols ieee take 065 Merticalediameteronmeuralicanalwe ses oe he Sete ee 057 Diameters of anterior capitular face, Diameters of posterior capitular face, _. _____.-. Se ao eee let eres .029-,040 AMLEKO-NoOsterlor diameter of pedicel, 922 = 2-- == 2. 9252 - e eee ee ee Ses eese .025 itransyeccerdiameverorpedicels sass s #227042) 2 ea Sete pie ote seule. .040 Diameter of vertebra, across transverse ROCESS CS sr ae er ee Ss5 TEeAlW Diameter of vertebra, across post-zygapophyses, .--.---- ..-.-------------- Pee 080 eustaimansyerserdiameter of neuralspine, 929 22-2 -5 222-2 ee 035 Tue Tairp Dorsat Verresra. (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 length is greater. Fig. 101. : Fie. 162. Figure 101.—Third dorsal vertebra of Uintatheriwm segne, Marsh (No, 1194); front view. Figure 102.—The same vertebra; side view. d. transverse process; nc. neural canal; 7. face for head of rib; 7’. face for tubercle of rib; s. neural spine. . F Both figures are one-fourth natural size. The third dorsal in Uintatheriwn segne (number 1194) shows essentially the same characteristics, and is represented in figures 101 and 102, above. $4 DINOCERATA. Tae Mrpian anp Postertor DorsaL VERTEBRZ. (Plate XXIV; and woodcuts 103-105, below.) In the dorsal vertebree 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 shorter. 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. Fig. 103. Fie. 104. Fie. 105. 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; 7%. face for tubercle of rib; s, neural spine; z. anterior zygapophys.s; 2’. posterior zygapophysis. All the figures are one-fourth natural size. THE LUMBAR VERTEBRA. ioe OL THe Lumpar VERTEBRA. (Plates XXV and XXVI.) ~The last four lumbar vertebree of the type specimen of Dinoceras mirabile (number 1036) are preserved, and are figured in Plates X\XV and XXXVI. 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 vertebrae, which are more nearly circular in section. The keel disappears upon the last lumbar, which 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 yertebree, and especially upon the last lumbar vertebra. The neural canal in all the lumbar vertebrie is large, but has been considerably reduced, in the vertebrie of this specimen, by erushing. The zygapophyses in the lumbar region are strongly articulated together. The pre-zygapophyses present a curved surface, bending around, and firmly grasping, the semi-cylindrical post-zygapophyses, which are inserted into them. his 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 zy gapophyses 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 Lumbar Vertebra from Sacrum. (Dinoceras mirabile, No. 1036.) Length of centrum (anterior epiphysis sweatin 0,) ee eee ess re eee 080 Vertical diametersot centrum) 255 ee a ee PORT Vertical diameteriot posterior face ol centrum, pe sea aes eee 075 Transverse diameter of posterior face of centrum (approximate), --_______ ____- .088 Measurements of Third Lumbar Vertebra from Sacrum. (Dinoceras mirabile, No, 1036.) m. henethrof centrum, = e505 5 Pte se ee Ae ee oe ee See SEG iransversediameteron anterior epiphysis === == ase ean meen anee ener 091 Werticalidiameterotanterlore pip tiys1sse eae eae near a re -080 Transverse diameter of posterior epiphysis, _______ __-- So ee oe a2 = we OO Vertical diameter of posterior epiphysis, ~~~ _____- caked oe ae ees ae es a OTS) Measurements of Second Lumbar Vertebra from Sacrum. (Dinoceras mirabile, No. 1036.) m. iene thvottcenttis eee ae a eee aye a ee ee .086 Transverse diameter of anterior epiphysis (approximate), _.-..._-....-.-._____- .090 WV exticall diameter, ot antenionepiphy sis. eee ee Se ee ee SO Transverse diameter of posterior epiphysis (approximate), --____________- see e095 Werticaliidiameteriotsposteriorepipbiy.siss ase a ee ee -083 Measurements of last Lumbar Vertebra. (Dinoceras mirabile, No. 1036.) m. Length: of eentroms 25203 <2 sents nace i ee .083 Transverse diameter of anterior epiphysis (approximate), _--.__________-_.____- .095 Verticalidiameterlotvantenioriepip hiyisisse sees eee a ae .080 Transverse diameter of posterior epiphysis (approximate), —-_________---__. ___ 105 Viertical diameterjot posterior epiphiysisss == ae ae ee .075 Crear Ti Vid: THE FORE LIMBS. (Plates XXVII-XXXVIII, LV, and LVI) Tue 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 Scaputa. (Plate XXVILI.) 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 85 DINOCERATA. The external surface of the scapula is divided into two unequal fosse. 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-seapular 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 the elephant and mastodon. The post-scapular fossa is strongly roughened near the posterior angle, which is rounded. The glenoid cavity is only 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 the apex. The supra- scapular border is ossified separately from the body of the bone. The coracoid is firmly united to the scapula in Dinoceras 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 Dinoceras mirabile are as follows: Measurements of Left Scupula. (Dinoceras mirabile, No. 1215.) Antero-posterior diameter, of glenoid\ cavity, 2-29) see ee ee Bese) mollis Transverse diameter of olenoid cavity, 22) 244s s sas eee eee ee Noe e090 Greatest vertical diameter of scapula,__ eee ate eee eee, na ses 85 OTE Greatest horizontal diameter, ____ ___- RPE arempentes Sista Re Sh LN pases Lt ene Shay! eee 480 Length of coracoid border, 2225. 222525". - Site Pewee wae ee EDO Length of supra-scapular border, ___ __- ee eae Sas oe ee toe CT. S390 Menothyofsolen ord b ord er eae ot ae eee x 350 Height ot acromionyaboyerclenoid ica yiltiy een aaa ee .120 Greatest diameter of pre-scapular fossa,_________ - Ee ee Pie hie teed (DE Greatest diameter of post-scapular fossa,_._. -__._.2____-___._.._______- a 310 THE FORE LIMBS. 89 THE Humerus. (Plate XXVIII; and woodeuts 106-107, below.) The humerus of Dinoceras 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 smooth 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 radius and ulna into a line with the humerus, but the weight 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 heavy and strongly armed head 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,@) presents a large rounded articular face, or head, more convex antero-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 tle 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 groove, 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 the head of the humerus. It is strongly 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 tuberosity 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 toward 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, nearly 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, apparently for the insertion of the /atissimus dorsi muscle. At the lower end of the humerus, th's ridge THE FORE LIMBS. Sil ends in a large and prominent inner condyle, which does not, however, extend far back of the trochlear surface, as seen in Plate XX VIII, figure 1, 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 the 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. Fie. 106. Fie. 107. FiguRE 106.—Section of humerus of Dinoceras mirabile, Marsh (No. 1215); near proximal eud, FigurE 107.—Section of humerus of Dinoceras mirabile (No. 1208); below middle. Both figures are one-fourth 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,.------_- ----- Fo RG Se RUSE One ap eri Eas 555 FATIUCEO-NOStETIOl GAME lel Ole NAC years ee ae eens eee eae eee a ler 136 nas VerseyCiameven OL heddas = eae llo ene = Meee ee Se Pe eek 2 ih RE ers 20 Greatestidiameter of proximels end sss sje ae eee ee .220 Least antero-posterior diameter of shaft, - -...----------.-------------------- .070 080 Meastutranusvierse diameteron shatt,esee ess soe =e ae i 92 DINOCERATA. m. iransyerse diameter. through condyles seem seers a om =e eee eee es .200 Transyvierserdtamlebersotateo Cla) eer s esti Ce ese SoH 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, .... ....-.----------- ey ONS Thickness of bone between coronoid and anconeal fosse,_-___..___-....---.---- .016 Measurements of Left Humerus. (Dinoceras mirabile, No. 1208.) m. iheast:antero-posterior diameter ofishattje 2: === see soe ae aan 064 transverse rdiametersit iT Oi oli COl Cy] Gy. es eee eee eee me ane eee 184 Transverse diameter of trochlear surface, ____________-____- By | See ae ore 124 Antero-posterior diameter of trochlear surface, ulnar side, ___- ----- Ree .100 Antero-posterior diameter of trochlear surface, radial side, ._-.-...----------- 095 Antero-posterior diameter of trochlear surface, least, --___-_--- - 5 fue Tee See O80) Thickness of bone between coronoid and anconeal fosse, __-_---------.---.-_- .018 Measuremenis of Right Humerus. (Dinoceras mirabile, No. 1212.) m. Wieastanteno-postenlordiame ten Os Halli temas ses na ee eae .058 Mransyersendianeter linn oon come sys s is eee ete nee eee 188 iDransverse: diameter Ormnrochlearisurh aces ee nae ie eee ne ee ee ee 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 anconeal fossw,__-_____-. -----_----- = I! Meusurements of Right Humerus. (Dinoceras mirabile, No. 1215.) m. Antero-posteriorsdiame ter Oh ead yee eee ee 140 Transverse diameter of heads | x. 282 = eet ae ee oe ee .138 Greates th dianre fer otgpy.o xiii ll er cl eee ee ene ae .220 Antero-posterior diameter of trochlear surface, ulnar side, ---- -- es ee ea gy WC} THe Forearm. (Plates LV and LVI.) The two bones of the forearm in the Dinocerata are quite distinct — throughout in all the specimens observed, and, exclusive of the olecranon process of the ulna, 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 backward 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 distinetly with both bones. THE FORK LIMBS. 93 The articular surfaces of the radius and the ulna for each other were nearly parallel with the axes of those bones, and allowed of little else than a slight antero-posterior gliding motion. The roughened and co-adapted surfaces of the bones indicate that, during life, all movements of pronation and supination were prevented by powerful 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 seen-in ‘the rhinoceros and hippopotamus, than that in the elephant. THe Raprus. (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 antero-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 the groove in the distal articular face of the humerus. The proximal surface of the radius differs from that of the elephant in being proportionally much larger, and extending quite across the humeral articular surface. It differs from that of the tapir, and the hippopotamus, 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 -nuch 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 whar 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 Fie. 108. lic. 109, Fiaurs 108.—Section of radius of Dinoceras mirabile, Marsh (No. 1195). Figure 109,.—Section of radius of Dinoceras mirabile, Marsh (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 mirahile, No. 1208.) Antero-posterior diameter of proximal end, --.------------------------. ------ 061 iam tAMCROEe OMA Got ee eb, ee 22 2 2032-053 AMES CI AIL OU-UIBAU CUR, 2588 8 ao a ee SE Slee cweece seen. ee 2102 Antero-posterior diameter of distal end, _---------_--- ---_.--. ---- ee 080 Diameters of articulation for bumerns, ..__-- .---__--____-- ---------- _- .052-.094 Autere-posteriot diameter of {ace for scaphoid, -......------..-- pe vot DOP pxamevetse aisncter Of Stee for SCAPUOIN, ==. 8 oe eee oe 039 Antero-posterior diameter of face for lunar, ---__--_--- ---------------------- 056 Transverse diameter of face for Innar,----_--_--_ _____ cae ae Transverse diameter of distal articular surfaces, ...__-_____-__--------------- OBZ Measurements of Left Radius. (Dinocerus imirabile, 0, 1206) Antero-posterior diameter of proximal end, _--- _-------_--------------- ---- O73 Se ROBT ANE ARR OR ME RRAR Ge oo ee en Se eta awn -WOI- OAL LO TE ee ee nr mmney, |) f | Antes posterior diameter, distal end, ---- 2 ose eee ee ese ses eo | OV Dranictere of axtienlation for lmmerus, _-_-.__. --.- °--- -.-_ 2 = -- --- 060-108 Antero-posterior diameter of articulation for scaphoid, _-_-------------------- 65 Transverse diameter of articulation for scaphoid, _--..---_-------------------- 040 Antero-posterior diameter of articulation for lunar, _----.-_._-----_----------- M65 Transverse diameter of articulation for lunar, --------_-_--_-_------------------ O55 | Measurements of Right Radius. (Dinocerasz, No. 1544.) DESL OY ee ee eS eae Sp ee ee mmm Sane ae CAMEOS OL TROLIMAL OMA 8 82s ne oe eS anes Antero-posterior diameter of proximal end, _-- -------- ------- --------. ---- N70 Meerrmisa wee ee oe 22-22 - --. 068-085 mR AMEE ON CMAN CM ee ee sae a -~n- 108 Antero-posterior diameter of distal end, _-------_-.----------.--------------- 090 Diameters of articulation for humerus, _..-_._-_---_---_--_-----_--_----_----_-_- 066-104 Transverse diameter of articulation for scaphoid, -_---_----------------------- O47 _ Antero-posterior diameter of articulation for lunar, —.- ---------------------- 055 Transverse diameter of articulation for Immar, ------ -. - ------------------ O45 Transverse diameter of distal articular surfaces, --. -.----_------------------ By, » 96 DINOCERATA. Tue Unna. (Plate XXX; and woodcuts 110-111, below.) The ulna in the Dinocerata 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 end 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 directly 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, somewhat 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 ulna is applied to the radius is broadly excavated, and strongly roughened above, where 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. The 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 ulna of the elephant and mastodon. It is so placed on the shaft of the bone as to look almost directly forward, and only very slightly upward, instead of looking nearly upward, as in the mastodon. It forms, comparatively, a much smaller part of the face for the humeral 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 inward, 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 moderately concave, and adapted to the surface of the radius by a narrow face, becoming wider toward each extremity. The 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 many 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 already stated, were strongly fixed, during life, in their relation to each other. 13% 98 DINOCERATA. The inner texture of the shaft of the ulna is similar to that of the radius, as indicated in the sections represented below, figures 110 and 111. Fig. 110. igure 110.—Section of ulna of Dinoceras lucare, Marsh (No. 1038). FIGURE 111.—Section of ulna of Dinoceras mirabile, Marsh (No. 1548). Both figures are one-fourth natural size. The principal dimensions of the ulna in three individuals of Dinoceras are as follows: Measurements of Left Ulna. (Dinoceras mirabile, No. 1206.) m. Motallene thief tulnayeses=.9- enema a as eee eee eee 530 Diametersotqproximall end, Va 22 oess 2228 seen 222 seer eee ease aes .095—140 Transverse diameter of shaft, behind humeral articular face, ...--..---...-_----- 055 Diameter, of shaft, through humeral’ articular face, 222-2 == es —= ee .097 Dramve fers oes brattit smn ect tilve) rani Cl cll) ese esate ae ae ere ae ee .05 7-081 Antero-posterior diameter of shaft, near distallend, _-.--- .-----=. --..--------=- .085 Transverse diameter ot shaft, mear distal end,.--- =----2----=---.2--- Beer 067 Transverse diameter of humeral articulation, greatest, ....---.---.-----2--.---.. .143 Transverse diameter of humeral articulation, least, -..----------------- ee, ew e060 Antero-posterior diameter of humeral articulation, at the middle,_--- _. _______- -085 Antero-posterjor diameter of humeral articulation, inner lobe, —--- ---- - See ees. 088) Antero-posterior diameter of humeral articulation, outer lobe, ~.-----~_-- Be 6) Transverse diameter of distalvarticulansumiace, = 225 (ee ee nee .076 Antero-posterior diameter of distal articular surface,.... ..-. ---..---_-.-----=:- .070 Least and greatest diameters of distal articular surface, .. __-___- - .067=.097 Measurements of Right Uina. (Dinoceras mirabile, No, 1282.) ™m. Total leneth:of ulna,. 2: <2 2Sec ese aoe oan ee een seee ee ee ae Bee 555 Diameters of proximal end, 2-8. 25. Se bseae ee aes ce Sa ee ees 098-130 Transverse diameter of shaft, behind humeral articulation, _--------.--.--------- .065 Diameter of shaft, through humeral articulation, -_-------------- Ee ee eeeO8 Diamvetersiofisbiaht sane ated be) mi Cl Cll espe are eae er = -O06V—sOMut Antero-posterior diameter of shaft, near distal end, --------..---- ._-.----=--=--- .095 Mransverserdiameter Olushaht-pneart Cistalle eras 2 enn .084 Least transverse diameter of humeral articulation,.--- ...__...=--.-- .- ..22s5522 058 Antero-posterior diameter of humeral articulation, at the mane Neen Ne Sra oss .086 THE FORE LIMBS. 99 m. Antero-posterior diameter of humeral articulation, inner lobe, -_~--------------- 066 Mransverseidiameter of distal azticular surface, +22. -22-----.-----=-=----=---- ais Antero-posterior diameter of distal articular surface, __----_-..------------------ .061 Greatest diameter of distal articular surface,--------_------ Deh ea ot eee .090 Measurements of Right Ulna. (Dinocerus lucare, No. 1038.) m Diameters of proximal end of ulna (approximate), _-------.--.--.----------- .070-,103 Diametenor-shatt. behind) humerallarticulations 522-2225 2------------=--=---=--— 052 Diameter ol shatta through humeral articulation, === - === 29. ee een ee .088 Greatest transverse diameter of humeral articulation, _.- — ----- arent ayes See cow ly) Least transverse diameter of humeral articulation,. -..--.... ------------- == Alby Antero-posterior diameter of humeral articulation, at the middle, —- Ee ee 090 Antero-posterior diameter of humeral articulation, inner lobe,-... ._.----------- .062 Antero-posterior diameter of humeral articulation, outer lobe,-_._-. ------------- .038 vn Gade (ac ‘, 107 te See ire Pe ee Ser fe. rth ere oe “ , oe age Lol nase ee aie. ak oo, se & a ee be eo) 6 — oh au) i an | gue om mT ho part +o eae e es ve 55e, 98 ron 8 Chup rER: VIII. THE FORE LIMBS. — (Continued.) (Plates XXXI-XXXVIII, LIV, LV and LVI). The fore foot in all the Dinocerata 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 Dinoceras 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 Carpat Bongs. (Plates XXXI-XXXIV; and woodeuts 112-124, below.) There are eight separate carpal bones in the fore foot of all the Dinocerata, and a ninth, the central bone, may be separate in very young animals, and,- in adults, either lost or consolidated with the seaphoid, or the trapezoid. 101 102 DINOCERATA. THE ScapHorp. (Plate XX XI, 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 seaphoid 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 posterior 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 portion of the radial side, below the rugose surface, a deep and somewhat oblique depression. THE FORE FERT. 103 The scaphoid in two specimens of Dinoceras are represented in the figures below. Fig. 112. Fie. 113 tm Figure 112.—Left seaphoid of Dinocerus ltaticeps, Marsh (1264); side view. Figure 113.—Right seaphoid of Dinoceras mirabile, Marsh (1200); side view. r. face for radius; tm. tace for trapezium; tr. face for trapezoid. 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 mirabiic, No, 1208.) m. Mens phrorloneitudinal axison seaphordsee=e see se-2 2-8 22 ee = aes ee 077 ILemyettla OH CAME ORIE BOOS, conc cseco5 oases aasona oe EERE eee eee eas acid 049-049 Antero-posterior diameter of radial articular surface, _-__------------- =A 051 ihransvetrseraitamererornadialvariicularysuttace:s=222 2225 25sec 4-2 e- aos = = == .045 Antero-posterior diameter of distal articular surface, _-------------------------- O70 iRranswersediameterotidistalvanticularsuctaces = =. 2525 525-5222 e556 —2 5 eee = O44 Measurements of Right Scaphoid. (Dinoceras mirabile, No. 1200.) m. Wenpthvorloneitudinal vaxisiofe Scaphoidjees= ese = es 2s ean = 8 O71 ane thyofauans verse axess =e eee ee eee es Le ee ee eee - .073-.054 Antero-posterior diameter of radial articular surface,__-_ ---.-.. ---- ------ ee 046 Mransverse diameter of radial articular sumiace:-.-...2---=-- ----------------_-- 038 Antero-posterior diameter of distal articular surface, ___--.---- See es 2 ee ee .066 Transverse diameter of distal articular surface, ---- - Ee Py pe sn she eee, 2 SAR .038 Measurements of Left Secaphoid. (Disoceras laticeps, No, 1264.) m. Meng thy oflonettudinall axisiot scaphoid, == 2225.2" 2-2-2 2s ee 086 beng th of transverse axes, ==-=-.=-2222--_=- Bee ea eee ee see 051 060 Antero-posterior diameter of radial articular surface, - --_-----.------- eee 000 ilrankverse diameter of radiallanticular surtace,-2-- 5-2. -2--- 2225s 2 Lee .046 Antero-posterior diameter of distal articular surface, _.. -_--------------------- .082 Transverse diameter of distal articular surface, _.__._-- .----------------------- .050 104 DINOCERATA., Tue Lunar. (Plate XXXI, figures 7-12, Plate LIV, figure 1,7; and woodcuts 114-116, below.) The lunar bone in the Dinocerata (Plate XXXI, figures 7-12) bears some resemblance to the corresponding bone in the elephant, but differs widely from it in having its proximal surface, for articulation with the radius and ulna, convex throughout, instead of being for the 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. The inner angle of the distal end of the lunar in Dinoceras (numbers 1215, 1229, and 1250) 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 species. 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 seaphoid is broader and more flattened than the 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 shown on the same Plate, figure 9, and presents no articular faces. he lateral surface turned toward the THE FORE FEET. 105 pyramidal is shown in figure 10. Two narrow and approximate faces are seen on this surface, becoming somewhat wider, 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 unciform, 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 carried over on each side to join both the scaphoid and the pyramidal frces. Figure 114.—Right lunar of Dinoceras mirabile, Marsh (No. 1250); front view. Figure 115.—Left lunar of Tinoceras ingens, Marsh (No. 1504); bottom view. Figure 116.—Left lunar of Tinoceras ingens (No. 1219); front view. m. face for magnum; p. face for pyramidal; 7. face for radius; s. face for seaphoid; ér. face for trapezoid; un. face for unciform. All the figures are one-half natural size. The distal surface (figure 12) is divided into two articular faces, supporting in part the magnum and the unciform. These faces are confluent, and sometimes hardly to be distinguished in front, but, on the posterior part of the surface, they are separated by a more or less distinct rounded ridge. Both these faces are nearly flat transversely in front, and somewhat coneave behind. In an antero-posterior direction, they are convex in front, and concave behind. 14 106 . DINOCERATA. In the right lunar of Dinoceras mirabile (number 1230), the distal face for articulation with the scaphoid makes less than a right angle with the face for the magnum. instead of an obtuse angle, as in most other specimens. The lunar bone in Tinoceras presents no articular face for the trapezoid, and is much produced posteriorly, thus distinguishing it from the lunar in the genus Dinoceras. Its main features are shown in the woodeuts, 115 and 116, above. The more important measurements of the lunar bone in four individuals of the Dinocerata are as follows: Measurements of Right Lunar. (Dinoceras mirabile, No. 1280.) m. Eeneth.of longitudinal raxisiat) lunar, ese ae oe ee ee .050 Antero-posterion diameteror proximalliend)) 252s eee ee eee .059 iransyverseidiaim et errors pro xan allen dyer ee ee 056 ATitfero=pOsterlon diame erro tueclis tele Ts Cleese ae ge eee 075 Hiransyerseldism'e fer 101 cis tale 11 Cl a mene reper ea eee .046 Measurements of Left Lunar. (Tinoceras ingens, No. 1503.) m. Ihenethvot done itudimaliaxis\of slum arse ee ee se oT ANMIGRO-| NON MOI Chienaneiier Ore jaynOpMUINN NEL 2. oe a se eos asee esas 061 MUA ORS Cliente Ort jor AeA GING 2 = oe se ee ease dee secesous !sscuse= .053 ANMIEELO= OS benLOT aC ianm ef eT; fe Clit alle en Clays see ee 083 MransVErserdiam eters lads taller Came a eee eee 047 In this specimen, the distal face for the Scaphoid is quite large, and encroaches on the face for the magnum. Measurements of Right Lunar. ( Tinoceras ingens, No. 1504.) m. ene hyo tel ong itd allegra 0 fg ea eee ee en 054 ATILETO-POStEELOL Tame Ger LO Pye Osxat el era Clg eye ee eee are ae ee .062 ADA CS) Ghicnnreee Ohi jotopowanell GN. . ees see ee 5 ee Sones JS se se .065 Actero-postenordiameter of Gistalyend sy aee sis = see ee eee 088 EPransVierSevdiain Gber Ot: cis tral Wer Cees eee ae are ee ee ee .050 Measurements of Left Lunar. (Tinocerus ingens, No. 1246.) ™. eng thy oie] ono rel anal Wea xs 31st Un aes ee O61 Antero-posterior diameter of proximal end, _---._-----_--_- ---- 2225 ----- = .066 inansvierse diame ter Ol, proximal mend. meee ae tee eel eee ee 060 Anfero-postenionidiameter:otedistallten dames ys = eee ee nese ere ee 092 Transvierserdiameterotadistalven deo ees eee ree ee een ns 053 THE FORE FEET. 107 THE PYRAMIDAL. (Plate XXXII, figures 1-6, Plate LIV, figure 1, p; and woodcuts 117-118, below.) The pyramidal bone in the Dinocerata bears a_ considerable resemblance to the corresponding bone in the elephant, and has, in general, a similar shape, and similar arrangement of articular faces. Plate XXXII, figure 1, represents the outer, or dermal, surface of the bone, as seen in its natural position in the foot, and shows a portion only of the saddle-shaped articular face for the ulna. The anterior view of the bone (figure 2) shows but little of the articular faces, although, on the side turned toward the lunar, may be seen a short articular face running along the distal portion of the surface. This face is seen more clearly in figure 8, and is confluent with the lower, or distal, face supporting the unciform, but makes a considerable angle with it. In the posterior view of the bone (figure 4), the oblique articulation for the pisiform is shown. This articular face, like most of the lateral ones among the carpal bones, is of variable shape, and often fails to show the deep emargination at the side, seen in the specimen figured. Along the upper margin, where this face is confluent with the ulnar articular face, the two are separated by a nearly straight, prominent, rounded ridge. The proximal surface of the bone (figure 5) shows principally the sub-triangular saddle-shaped face for articulation with the ulna. The distal surface of the bone (figure 6) presents, also, a somewhat triangular and saddle-shaped face, for the support of the unciform bone, and, in the specimen figured, an additional, distinct, oval, and convex face, giving support to the metacarpal of the fifth digit. In other specimens, this face is present, and well developed, but confluent with that supporting the unciform, as shown in the woodcuts below, figures 117 and 118. 108 DINOCERATA. The pyramidal bone in a second specimen of Dinoceras, and in one of Tinoceras, is shown in figures 117 and 118, below. Fig. 117. Fig. 118. _ Ficure 117.—Left pyramidal of Zinoceras ingens, Marsh (No. 1577); distal end. Figure 118.—Left pyramidal of Dinoceras mirabile, Marsh (No. 1230); distal end. meV. face for fifth metacarpal; wn. face for unciform. Both figures are one-half natural size. The following are the more important dimensions of the pyramidal bone in three specimens of Dinoceras and Tinoceras : Measurements of Left Pyramidal. (Dinoceras mirabile, No, 1208.) m. Greatest length of longitudinal axis of pyramidal,_.-_._..-------------.----- oe 045 Motallelen eth¥o fiom ey eee ee ee re eee .098 Least:transverse diameter. 525-..8- 2.2222 62s! eee - = Se eee eee .054 Greatestidiametenoteulmancanticull aris wisi C eae ee eee .073 Antero-posterior diameter of ulnar articular surface, -_.. .-------.------. ---.-- .049 Greatestidiameter oteartren| arsmace nO raul Ci Om Tle ae eee ar .064 Antero-posterior diameter of articular face for unciform, ---- ------------------- 051 Diametersiot tacestorfituhwmre ta caryp allay meee ee ae eee es 018-029 Measurements of Left Pyramidal. (Dinoceras mirabile, No. 1230.) m. Greatest length of longitudinal axis of pyramidal, _-_-.---.--------.------ ----- 042 Gréatest diameter ofsbone: 2225 2020 226 eee eee oe eee Sees ee ee ee .100 east transverse diameter = —222 9-552 5- 5-92 e = S) Se Rees a eee ae -062 @reatest diameter on ular cutie tll clr ticCeey yee ae ere ree 983 Antero-posterior diameter of ulmar articular face, ___-_--- ----------=-.-------- C49 Greatest diameters Of face stor sun GiiiO Tae eee ae ere Speakers 067 Antero-posterior diameter of face for unciform, --_-_.-------.------------------ .057 Diameter of tace mor ati Gham tel Cai (ye ee aetna eee 026 THE FORE FERT. 109 Measurements of Left Pyramidal. (Tinoceras ingens, No. 1577.) Greatest length of longitudinal axis of pyramidal, ---...-_--1_..-.------------- .050 Ghanian chmmaicr On loonie, 22 38 bes SSeS Soc reer See ae a ee 03} LGB UDINE VOSS CERTINAIG, ae ke Ee ee ee oe ee eee .069 Greatest diameter of ulnar articular surface, __._.._ --__.___._- ae See Oey) Antero-posterior diameter of ulnar articular surface, —- Ae eee a ee eee .062 Greatest diameter of articular face for unciform, .__.._...__.___._____ __._-----. .080 Antero-posterior diameter of articular face for unciform, --........-..---------- 066 Tue Pistrorm. (Plate XXXII, figures 7-12.) The pisiform in the Dinocerata is a short, stout bone, presenting, as usual, two confluent articular faces, one for the ulna, and the second for the pyramidal. Plate XXXII, figure 7, represents the surface of the pisiform seen from the side of the skeleton, when the bone is in its natural position, except that the long axis has been placed in a vertical, instead of an oblique, position. Neither of the articular faces can be seen in this figure. The inner side of the bone, or that turned toward the pyramidal (figure 8), shows, at its proximal end, a large and somewhat triangular face, oO flattened, or slightly concave or convex, and extending, in the specimen figured, over more than half the length of the bone, but, in some specimens, it is proportionally shorter. Figure 9, which gives the view opposite to that in figure 7, shows this articular face, seen obliquely. The proximal end of the bone (figure 11) is nearly covered by a triangular articular face for union with the ulna. This face, in the specimen figured, is flat in one direction, and distinctly convex in the other, but another specimen of the same bone has this face distinctly convex in both directions. Distally, the pisiform is strongly roughened and tuberculated, with the end rounded, as shown in figure 12. The principal measurements of two specimens of the pisiform bone in Dinoceras mirabile are giver below. 110 DINOCERATA. Measurements of Right Pisiform. (Dinoceras mirubile, No. 1211.) ak, Length of pisiform bone, --.---_-_------- -----=---==-=---=------------------ 061 (Greatest ti as vies Cul Une fie em .050 Tneast trans verserci ane bela se = ape = eee a ee Greatest diameter of ulnar articular surface, -------- .- AE cs BL ae ees op eee .038 Wueast: diame ter o tena mire searstrve ull eles ie tiea Cos are 021 Greatest) diametersot tracey forester cll) ee a ee -047 beashrdtameter On face ytOTap ya rra Cl all pees tee et ee == O20) Meusurements of Right Pisiform. ‘| Dinoceras mirabile, No. 1520.) m. Ifehayeailey One TOUS INOW), 2 5 2S sees Sse s ses ee eas 5555555 Ss5se5 525 see 2555 065 Greatest transverse Cen e teres ae eet alee cere et eee ey eee ee .045 MUG ASEAt HANS V.CLSCiCUSUEING GOTes ees es ole a a en eee ees .033 Greatest diameter of umlmare am tui airs mist COs ee eee are .042 Meast i dtamet ers oi lancar ereb x Cul ctr Uys CC sees te ee re 021 Greatestidiameterm ort acer tony piysryev eri Cl al yee ee .044 east diameter Olace ory py Cl yee eee en eee .023 Toe T’RAPEZIUM. (Plate XX XIII, figures 1-6, and Plate, LIV, figure 1, tm.) The trapezium in the Dinocerata is well developed, being considerably larger than the trapezoid. It presents at each end a large articular face, and a third smaller and much less regular one, for articulation with the trapezoid, on the side turned toward that bone. The outer, or dermal, surface of the bone (Plate XX XIII, figure 1), when viewed in its natural position in the foot, is rough and tuberculated. The pcsterior view (figure 2), and the anterior view (figure 4), likewise show no articular faces. Figure 3, representing the surface turned toward the trapezoid, presents an irregular, smooth face along the upper margin. This face differs in size and proportions in different specimens, and in life moved upon a corresponding surface on the trapezoid. The proximal end of the bone (figure 5) is almost entirely covered by the articular face for the scaphoid. This face, nearly semi-circular in outline, is flattened in one direction, slightly concave in the other, and confluent along the straight margin with the face for the trapezoid. THE FORE FEET. Halil The distal end (figure 6) presents a semi-oval articular face, not extending quite to the anterior part of the bone, and supporting in life the well developed, short, first metacarpal. This articular face is somewhat saddle-shaped, being convex along its short diameter, and slightly concave lengthwise. The main dimensions of the trapezial bone in two specimens of the Dinocerata are given below. Measurements of Left Trapezium. (Dinoceras mirabile, No. 1208.) Length of longitudinal axis of trapezium,__--..-._._._____- Ee Oa eee 036 Greatestehonizontalediametenmerr es ast ee a Soe ee Ee ee 062 Meastevorizontaladiameteres sees 66 222s. le 8 En per a ea ae BS 033 ihontextidiametenor proxunalvarticnlantaces 329-2585 .6 see ness eo ee L044 iransverse diameter(or proximalvariiewlar tace,.9—- 0222-982. s ees 2282s 8 .026 iongestidiameteronrdistall anticulan face) —_ 222-522 1 ee .048 Mransverse diameteriot distal articular face, .-.. 22.4.2 222 _- 2 22--5-22-22-2-- .026 Measurements of Right Trapezium. (Tinoceras ingens, No. 1219.) m. Menguhvotsongitudinaltasashoitrapeziumy sees 2 y= ee ee .037 reatestrionizontale diameters oe meee wee ee hn ee 2 .068 Measishorizontdleacam eter eenemae eam ee ee) eee ee .031 Greatest diameter of proximal articular face (approximate), _________________. 5 OH) sinankverseqdiametemoimproximalvanti cular taces| sss 2522. 2 ee Se eT e 039 Greatest diameter of distal articular faces... 52. 22025) eee ee .053 iinansverserdiameterondistaleanticularstaces es see eee ee ae eee .030 THe TRAPEZOID. (Plate XX XIII, figures 7-12, Plate LIV, figure 1, ér ; and woodeuts 119-120, below.) The trapezoid is a small bone in the Dinoceraia, beg much the smallest of the carpals, with the exception of the pisiform, and perhaps also of the central, if separate. ‘The general shape of the bone is that of a blunt, nearly square, wedge, the large end being presented to the superior, or anterior, surface of the foot. This end of the bone is represented in Plate XXXIII, figure 7, and shows nearly all that can be seen of it when in its natural position with 112 DINOCERATA., the other bones of the foot. The surface is strongly rugose, and, in this view, nothing can be seen of the articular faces. The lateral surface turned toward the trapezium presents an articular face for union with that bone. An ordinary form of this face is shown in figure 8, but it is of variable form and size. Sometimes it even extends obliquely across the lateral surface of the bone, and becomes more or less widely confluent with the articulation for the metacarpal, along the anterior part of its lateral border, as in woodcut 119 below. Fig. 120. Figure 119.—Lelt trapezoid of Dinoceras mirabile, Marsh (No. 1230); side view. Figure 120.—The same bone; distal end. mcJJ. face for second metacarpal; s. face for seaphoid; ¢m. face for trapezium. Both figures are one-half natural size. The posterior, or palmar, aspect of the bone (figure 9) shows its wedge-like form, but the articular faces visible are seen only obliquely. The side turned toward the magnum (figure 10) has an articular surface extending across the bone. Usually, this surface is near the anterior part of the bone, and sometimes, as in the specimen figured, is more or less interrupted at the middle by a ridge. This surface may also be broadly continued to the posterior, or palmar, end of the scaphoid articular face, as in number 1505. The upper ulnar angle of this specimen is rounded for articulation with the lunar. This portion of the bone may represent the central, coalesced with the trapezoid, as in the existing Dendrohyraz. The proximal articular face (figure 11), joining the scaphoid bone, is narrowly oval in outline, broader in front than behind, and more or less concave in both directions. The distal face is somewhat similar in shape to the proximal, but sometimes shorter and broader, and is slightly convex in one, or both oO o directions. THE FORE FEET. 113 The principal dimensions of the trapezoid bone in two individuals of Dinoceras, and one of Tinoceras, are as follows: Measurements of Left Trapezoid. (Dinoceras mirabile, No. 1208.) m. Greatestayertiealuexcent of trapezoid, --— 22-2 - =. 222. 1 ee 2 SS -2+- 036 Hien hpotevericaluakibeeee a's 20a eis Sele eet elles 2228 Se en adh V2) kqrestesin (antero-posterior) diameters <2" 2-22-22 -<- 5 =e = 2 ae Seek nae .058 Mransperne GianichersMeanimedmadie,: S522 5 5550. ooo Ds aoe een neck .029 Antero-posterior diameter of proximal articular face, ________.___-___---------- 049 ‘Transverse diameter of proximal articular face,....__-...--- ----------------.- .027 Antero-posterior diameter of distal articular face, --_.----__------------------- 051 iransyerse diameter of distal articular face,.2=.-2=-/2------:-2---<-:=-------- +025 Measurements of Left Trapezoid. (Dinoceras mirabile, No. 1230.) n. Greateshweriiedlvextentionm trapezod... =. 9522520 = 2 fee Seok eae 034 stern etevieltiGaleaxinee: 22 See ee Oe ee So eh oe ee A ee cee x 023 Greatest (antero-posterior) diameter, ---._--------------------------- ele 008 CDpringryaiere ce Peerivei ace = 2 BUS See Ee ee ce Se ers 035 Antero-posterior diameter of proximal articular face, ._..-..-..-.-------------- -050 Transverse diameter of proximal articular face,_____...--------------- ------ 029 Antero-posterior diameter of distal articular face,_-_....-.-.-----..---.---1--- 043 aiminnverse diameter of distal aricular face, ---2-5-2- 2-22 2522-2 S222 ee ees .035 Measurements of Right Trapezoid. (Tinoceras ingens, No. 1219.) m. STCALCH A VELUCAl CXCCN GOL UPADCZOIG, 2-6 32 a2 SS eho e ee See oe fo kk ee eee 038 Meneihte i verticalaxibwe se eae Se ee | ey oe eS eee eee a O05 fexpatbents (Aillero-pOsterOr)) GiaAMeLEn., 72 8 = 225 S22 = S225 soe os eae es ==ssaa=- .068 ' Transverse diameter, near the middle, ____________- eee eee ee 055 Antero-posterior diameter of proximal articular face,.-.._.-..../__------------ .048 Wransverse diameter of proximal articular face,-_...=-.+.._....=..:-~----2=-=--- -030 Antero-posterior diameter of distal articular face, ---._---_-------------------- .050 ransverse diameter of distal articular face, $2.22. 52 622526225) 6 2 ese2cse- .029 THe Macnum. (Plate XXXIV, figures 1-6, Plate LIV, figure 1; and woodcuts 121-122, below.) The magnum in the Dinocerata is proportionally a much smaller bone than in the elephant, and has a much greater difference in the length of the vertical axis in the anterior and posterior parts of the bone, than in that animal. 15 114 DINOCERATA, An anterior view cf the magnum, when in its natural position among the other bones of the carpus, is seen in Plate XXXIV, figure 1. The dermal surface is pentagonal in outline, rough and tuberculated, while behind and above it, is seen obliquely a portion of the smooth articular face by which the bone articulates with the lunar and scaphoid bones of the preceding carpal series. The lateral surface of the magnum (figure 2) turned toward the trapezoid varies in the shape and structure of its articular face for that bone. This face is frequently more or less divided, as in the specimen figured, or the articular face may be on the distal part of the bone, not extending across to the scaphoid face. A large proportion of the posterior part of the face for the scaphoid is seen in the same figure. his face is strongly saddle-shaped. In the same view, is seen a third articular face, for the support, in part, of the second metacarpal. This face is narrow, and elongated from before backward, and, in the natural position of the bone, is directed obliquely downward, toward the radial side of the foot. The posterior, or palmar, surface of the magnum (figure 3) is rough, but rounded over, and shows at the upper, or proximal, end a portion of the articular face for the lunar, carried well over on the posterior face of the bone. The lateral surface (figure 4) turned toward the unciform presents a considerable, but varying, articular surface for union with that bone. In the specimen figured (number 1208), there is a large area extending along the entire length of the proximal, or lunar, articular face, contracting near the middle, but expanding anteriorly, so as to extend nearly, or quite, across the lateral surface of the bone. In many specimens (numbers 1195, 1218, 1219, 1230, 1516), this area is confluent with the distal articular face for the third metacarpal. In the specimen figured, however, it is, interrupted by a slight ridge at this point, beyond which, it is continued well along the margin of this articular face posteriorly. This distal backward extension of the articular face is not present in all specimens (numbers 1195, 1230), and is often much narrower than in the specimens figured (numbers 1211, 1219) THE FORE FEET. 115 The proximal surface of the magnum (figure 5), by which it bears upon the scaphoid and lunar bones, is much elevated posteriorly in the region of the face for the lunar, but the two facets are so perfectly confluent as scarcely to be distinguished. The face for the scaphoid is strongly saddle-shaped, and does not extend quite to the anterior margin of the bone. The face for the lunar is nearly flat, or slightly convex from side to side, sigmoid from before backward, and is carried well over to the posterior face of the bone. The variation in the form of this curve is considerable, but the specimen figured on the Plate may be regarded as a fair average, while extreme forms are represented in woodcuts 121 and 122, below. Fig. 121. mel = mel FiguRE 121.—Right magnum of Dinoceras mirabile, Marsh (No. 1211); side view. FIGURE 122.—Right magnum of Dinoceras mirabile, (No. 1230); side view. l. face for lunar; meIII. face for third metacarpal; wn. face for unciform. Both figures are one-half natural size. The cistal face of the magnum (Plate XXXIV, figure 6) is mostly occupied by an elongated articular face for the support, in great part, of the third metacarpal. This face is more or less moderately concave from before backward, slightly convex transversely, and is usually a little broader in front than behind. It is separated by a rounded ridge from the confluent, narrower and oblique, face lying along its radial side, and aiding in the support of the second metacarpal. The dimensions of the magnum bone of four individuals of the Dinocerata are as follows: 116 DINOCERATA. Measurements of Left Magnum. (Dinoceras mirabile, No. 1208.) m. eng thot longitm dinates to fema orm a es ee ee .033-.062 Antero=posterior (diam ete 222 )-.=)yosee = ae ee Se ee eee eS 066 Dvansverse: diameters: = <= 2- oe ese Ses oe as See = ee ee 038 Antero-posterior diameter of proximal articular face,.__ _-__ .-_.---.----_-_--.-- 058 Transverse diameter of proximal articular face; 24222922 2> = assess oe en Os0 Antero-posterior diameter of face for second metacarpal, .-_--.----------------- -046 Transverse diameter of face for second metacarpal, ____-_-_-_-------..----__--- 018 Antero-posterior diameter of face for third metacarpal, _-.-----------. -------- -057 Transverse diameter of face for third metacanpal,.---_--- 5-25-2225 2 == - = 025 Measurements of Right Magnum. (Dinoceras mirabile, No. 1211.) m. Wen'ethivofalon eatrardinall eases coterie cri ern ee 036-.069 Amntero=postetior diameter, 234) eat) ses aes oe ened eee ee ete 080 Transverse diaméter,-.25.2 Scat A+ eee eee eee ee eee .039 Antero-posterior diameter of proximal articular face, --.__..----.---------=---- .078 Mransyerseidiameter ot proximal anuecularace; === sa see see eae -032 Antero-posterior diameter of face for second metacarpal, ___-___---------------- 060 Transverse diameter of face for second metacarpal, .---_-.--------222-- 2=--2-- 020 Antero-posterior diameter of face for third metacarpal, .._ _____---__---------- 064 Transverse diameter of face for third metacarpal,.-..-. .=)-..---=2--2-2-------- 027 Measurements of Right Magnum. (Dinoceras mirabile, No. 1195.) m. ihengthrvotoneitadinallaxes) om aon nnn ee 032-.062 An tero-postenor diameter ss =. csseses a6 e fans 2 = So eee eee ee eer ae 068 MPransvierse: ameter, cas cme See cele aon ae oe ee eee ree Jue §.034 Antero-posterior diameter of proximal articular face, --.-.-----.--..----------- .065 iihjansverseldiameter of proximalranticulartac eg === se === eee eee 027 Antero-posterior diameter of face for second metacarpal, -_-----------------.--- 050 Transverse diameter of face for second metacanpal, -.-.----_.------_--- --_--_- .018 Antero-posterior diameter of face for third metacarpal, .--.-------------.---.-- 055 Transverse diameter of face for third metacarpal, .-..-..--.--------.--.--.----- .022 Measurements of Left Magnum. (Dinoceras mirabile, No. 1218.) m. Bengthiof longitndimal axes’ ot sma pric ee eee ae eee ene 033-.069 Antero-posterior diameter, . sac. se. oe eee See ee ee ee ee .075 Transverse: diameter. 22 3 Sa See ae a te ee ee ee eee .041 Antero-posterior diameter of proximal articular face, --..---..-.---=---.------- .068 Transverseidiameten of proxmalyanticularidia Ce, wees eee a =e eae ere 034 Antero-posterior diameter of face for second metacarpal, ........-----.--.--.--- .049 Transverse diameter of face for second metacarpal, -----.-..-----.---122+------ .018 Antero-posterior diameter of face for third metacarpal, ...._.-..... ----.-------- .063 Transverse diameter of face for third metacarpal, ..-..--..-.. .:--------ss2---- .031 THE FORE FEET. 117 THe UNcIForm. (Plate XXXIV, figures 7-12, Plate LIV, figure 1, wn ; and woodeuts 123-124, below.) The unciform in the Dinocerata is similar, in general shape and proportions, to that of Proboscidians, but is less oblique, and presents three sub-equal articular faces on its distal surface, instead of two, as in the elephant. The exterior, or dermal, surface of the bone (Plate XXXIV, figure 7) is moderately roughened and pitted, and is regularly rounded, in the horizontal direction, through an are but little short of a quadrant. From above downward, the surface is nearly plane. The inner surface (figure 8), or that twmed toward the magnum, is bordered above, in part, and partly below, by a smooth articular face for union with that bone. The amount and disposition of this surface vary in a manner corresponding with the faces for its union with the magnum, as before described. The proximal and anterior portions of this face are the most constant, and may be confluent along the whole margin of the proximal articular face, or may be interrupted near the middle (number 1195). The proximal part of this face may extend quite across, so as to become confluent with the face for the third metacarpal, and may then, as in the specimen figured, border that face throughout its extent, or it may even fail to reach the lower, or distal, margin of the bone at all (numbers 1509, 1525). The posterior, or postero-interior, face of the unciform (figure 9) is quite irregular, and, when not encroached upon by articular faces, is moderately roughened. The outer side of the bone (figure 10) is short from above downward, allowing the articular face for the pyramidal to approach that for the fifth metacarpal, as in the elephant. These faces may even be confluent for a short distance across this surface (number 1211), as in figure 123, below, or may be separated (numbers 1509 and 1525), as in figure 124. 118 DINOCERATA. The proximal face (Plate XXXIV, figure 11) is obliquely saddle- shaped, and presents two confluent, but distinguishable, faces, one for the lunar, and one much larger, for the pyramidal. The face for the lunar lies along the inner, or radial, side of the proximal surface, and is sigmoid from before backwards, and transversely more or less convex. Its posterior half is considerably elevated above the anterior, to fit into a corresponding excavation in the lunar. The face for articulation with the pyramidal is somewhat in the form of a quadrant, one side being confluent with the face for the lunar, the other side running along the outer, or posterior, margin of the bone, while the curve forms the upper limit of the dermal surface. This face is strongly saddle-shaped, concave antero-posteriorly, and convex from side to side. The distal surface of the unciform (figure 12) bears three concave articular faces for the support of the third, fourth, and fifth metacarpals. Of these, the inner is the smallest, triangular in outline, only slightly coneave, and aids the magnum in the support of the middle, or third, metacarpal. The second, or median, articular face is the largest, and is more deeply concave than the first. It extends antero-posteriorly quite across the distal end of the bone, but is much broader in front than behind. It supports the fourth metacarpal. The third articular face, situated upon the outer, or ulnar, side of the distal end of the unciform, is more strongly concave antero-posteriorly than either of the others, and is nearly as broad behind, or on its palmar margin, as in front. It is oblique to the axis of the bone, and, as already mentioned, may even be confluent for a short distance with the proximal face for the pyramidal, as shown in figure 123, below. The unciform bone in two individuals of the Dinocerata is represented in the woodeuts below. The specimens figured show marked differences, but whether these are constant in all the species of the two genera cannot at present be determined. This is the case, also, with other carpal bones. THE FORE FEET. 119 Fig. 124. Fig. 123. FigurRE 123.—Right unciform of Dinoceras mirabile, Marsh (No. 1211); side view. FigurE 124.—Right unciform of Tinocerus ingens, Marsh (No. 1509); side view. meV. face for fifth metacarpal; p. face for pyramidal. Both figures are one-half natural size. Four specimens of the unciform bone from different individuals of Dinocerata have the following dimensions : Measurements of Left Unciform. (Dinoceras mirabile, Xo. 1208.) m. eno uhtotloneitudinal axesor uncitorm sess. 22.26 essen ene oe ae .041=—.068 FAtenOsp OSUCTIOLECIAMC etna setts ay ee le en ee Se Se ae a Sake Aas .068 irannvierseralam Guerre eee ie wee rN ER Te oe Seu Ah teat ale Neate = 086 Antero-posterior diameter of lunar articular face,....-_.. _-.- ---- ---.--=- .=5--+ 062 sknansverse diameters.oh lunarmarticulantace. = 95 = 5-9 ==) see oe ee .020—.024 AMtero-postenonrdiametenior face for pytamidal, 222.2822) 2225-222 222. 2a see .060 Mransyersecdiametenon face tonpycamld ales sess sa ee = oe ee ee .055 Antero-posterior diameter of face for third metacarpal,_-....------------------- 050 Transverse diameter of face for third metacarpal, -.---.2-.2-22- 22222 -22555---- 025 Antero-posterior diameter of face for fourth metacarpal, -_-._..--.--..-....---. .056 Transverse diameters of face for fourth metacarpal, ......---...------------ .021-.043 Antero-posterior diameter of face for fifth metacarpal, .-_._..-.---..----------- .048 Transverse diameters of face for fifth metacarpal,._./..........-..---+----- 020.025 Measurements of Right Uneiform. (Dinoceras mirabile, No. 1195.) m. Menothvors lon gitudimalvaxesvoi mime torm= == 5 = ee ree 038-.065 PNTGEL OS OS TCT OTRO ayn CLC Gye eye rete ante ene eat ee yeaa Sep ence .067 sian VEESe Wala ClCls= eee cae a ee i a Eo ek eee .079 Antero-postenordiametenon face tor lay, == === == = = eee .059 Miransiverse diameter or tace tor lumen es. a5 a= =e eae eee Re ye ete OLS, Antero=postenior diameter of face)for pyramidal, ----- 22-2222) ee ek 2 cee .061 itransverse diametenottace tor py mami dales a = ee = eee ee ee a .068 Antero-posterior diameter of face for third metacarpal (approximate), ------.---- .052 iiransverse! diameter of face fomthird metacarpalys 252-24 5222225522 se 8s ae .026 120 DINOCERATA. m. Antero-posterior diameter of face for fourth metacarpal, --.-..----------------- 055 Transverse diameters of face for fourth metacarpal, ---- ---- . - AR ee _, .0138-.044 Antero-posterior diameter of face for fifth metacarpal, -__. .-.--_-.-----.----.-- 041 Transverse diameter of face for fifth metacarpal, --.=--.----2222222--==-- 023 Measurements of Right Unciform. (Dinoceras mirabile, No, 1247.) m. Length of longttudinallaxes/of wm eitormy) =o eee er .046-.078 A Gero-P Oster uOrmcll erie te Tp ee a .084 Transverse diameter, =-- 2. 4ces5--2 6-2. on eee ee Cee .091 Antero-posterior diameter of face for lumar, ----_---.----------------- Sees LOO) Mransyverse diametertonmace ctor late sete se a eee ee ee .023 Antero-posterior diameter of face for pyramidal, ___-__-___-------=_-___-----=- .073 Transverse diameter of face for pyramidal, -.-.-...---:----------- Kod ee ee OES Antero-posterior diameter of face for third metacarpal (approximate), ____- = A057 Transverse diameter of face for third metacarpal, -_.....=-----------------+--- .029 Antero-posterior diameter of face for fourth MAehaGal; Palys ae eee 070 Transverse diameters of face for fourth metacarpal,.--.----.--.----. ------ .019-.045 Antero-posterior diameter of face for fifth metacarpal, --------.--.---.-----..-. .055 Transverse diameter of face for fifth metacarpal, ........-..--.--.-+-_--.=-.-.-- .025 Measurements of Right Unciform. (Tinoceras ingens, No. 1509.) m,. Length of longitudinal axes of unciform (approximate), -------------------- .051—.085 PAGER O =|) O SUE LOT CUeAIIN C1 Te5 pees ee -080 Tranverse:- diameter, - 2 22.5- 2-225 acc. 0 = Lene eee es See ee ee ees ees .098 Antero-posterior diameter of face for pyramidal (approximate),-__ -______-__--- .070 iransyierse) diameter of tace ton pyramid ally sess ea ee .077 Antero-posterior diameter of face for third metacarpal, ------------------------ .057 Wransverse diameter of face for third metacarpal, = 22 == 25-522 22s. 222 ee eee .027 Antero-posterior diameter of face for fourth metacarpal, -_--------------------- .067 Transverse diameters of face for fourth metacarpal, ......---..----.-------- .016-.055 Antero-posterior diameter of face for fifth metacarpal, ___..__.----------------- .056 Transverse diameter of tace\for fiithmetacanpaly =a —= seas ae ee 030 Tue Meracarpat Bones. (Plates XXXV, XXXVI, XXXVII, and Plate LIV, figure 1.) The metacarpal bones in the Dinocerata are short and robust. They are five in number, and each represents a well developed digit. Their general form and position in the foot of Dinoceras mirabile are shown in Plate LIV, figure 1, and also in the restoration of this species, Plate LV. THE FORE FEET. 121 Tue First Meracarpau. (Plate XXXV, figures 1-6.) The metacarpal bone of the first, or inner, digit, the pollex, is a robust, and usually short bone, proportionally much stronger than in the elephant. In all the specimens preserved, the epiphyses, whether present on one end only, or on both ends, as in the elephant, are firmly codssified with the shaft of the bone. The surface of the bone, as shown in Plate XX XV, figures 1-4, is rough and very irregular. The proximal articular face (figure 5) is nearly elliptical in outline, and is flattened, but elevated, near the middle of the palmar side of the margin. On some specimens, there is a distinct oval face for contact with the second metacarpal. This face is raised upon a large tubercular elevation, and may, or may not, be in contact with the proximal articular face. The distal end (figure 6) presents a flattened, and somewhat concave, face for the phalangeal bone, and two broad, oblique grooves for the sesamoids. Three first metacarpals of Dinoceras have their principal dimensions as follows: Measurements of First Metacarpal. (Dinoceras mirabile, No, 1208.) m. hotaldlenothroishnstymnetacaepaliy ses ser ea te terse 2 eae eens .068 Diameters of proximal articular face (approximate),..._.-._.---..._.---__.- .025-.044 Diametersiof tacefonphalansse 5 eee aee se aee see. e eee S 2 .. .027-.034 Measurements of First, Metacarpal. (Dinoceras mirabile, No. 1211.) m. Total length of first metacarpal, ----.-_.--.-- ee Se eee Sosa .098 Diameters of proximal articular face (approximate),__-_...-.----._.----.---- .030-.050 Wiameterstomtace, tom phalank maaan rs wasn eee A eee S 037-.043 Diameters: of face for second metacarpal)=— 95> - == 222 = 25-2] soe 5 4-52 =~ = .020—.022 Measurements of First Metacarpal. (Dinoceras, No. 1526.) mm. Rotalmlenptht oftinstimetacanpal ves en 2-30 een eee ene eee ese See. .056 Diameters of proximal articular face (approximate),..__. ...__.. ___-_------- -026-.044 DiameteriGfetace tor phalank,. a= — oe eee ee ee ree ee 5 ats .030 16 122 DINOCERATA. Tue Seconp Meracarpau. (Plate XXXV, figures 7-12.) The metacarpal supporting the second digit in the Dinocerata is nearly twice as long as the first, but not greatly wider, nor thicker. The shaft is strongly roughened and tuberculated near each end, as shown in Plate XXXV, figures 7-10, while the middle portion is much smoother. The proximal end of the bone presents three distinct, but confluent, articular faces, of which the first, beginning on the radial side, is the largest. It met the trapezoid, and furnished the principal support of that bone. This face, shown in figure 11, is oblique to the axis of the bone, throwing it, in its natural position, well toward the radial side of the manus. It is a little broader, and more oblique, above than below, and is slightly concave in both directions. A second adjoining face, shorter and smaller, shown also in figure 11, is nearly perpendicular to the axis of the bone, slightly narrowed behind, and convex in both directions. In life, this face articulated with the oblique distal face of the magnum. A third face, on the ulnar side of the bone at the proximal end, shown best in figure 10, articulated with a similar face on the adjoining third metacarpal. The distal end of the bone (figure 12) bears a broadly oval, only slightly convex, articular face for the phalanx. This is encroached upon below, by the broad, shallow grooves for sesamoid bones. The principal dimensions of the second metacarpal represented in Plate XX XV are as follows: Measurements of Second Metacarpal. (Dinoceras mirabile, No. 1208.) m. Motalelenothtor sec om cl rae tierce yo ea ee ee ese eee eo -102 Diametersiof proximaliend, se_ seee see see ee ee eee 039-.065 Diameters of distalliends = a2 esac sas oe eee ee ee ee ee -046-.058 Diameters: oles sitet ee fT a caf PS ge .080-.040 Antero-posterior diameter of face for trapezoid, --22 .------2.-------. -2--=- 050 Mransverseidiameters\of facelton trapezoid ae= 5 sss— =a sees a aeneees eee eee O20 028 Antero-posterior diameter of face for magnum, ------------------=+---=--- .046 Mransverseidiameters ot face tor macnumies = 2) gees 2) ee eee eee .012-.018 Antero-posterior diameter of face for third metacarpal, ------------------.- .040 Diametersrosetace koro lal anaes eee ere oe ee re .025-.041 THE FORE FEET. 123 Tue THirp Metracarpat. (Plate XXXVI, figures 1-6.) The third metacarpal resembles the second in general size and shape, but may be readily distinguished from it by the presence, on the proximal end, of four, instead of three, articular faces. Like that bone, it is rough and tuberculated, especially near the ends. It bears, also, a rugose surface not far above the middle of its shaft on the ulnar side, best shown in Plate XXXVI, figures 1 and 3. Of the four proximal articular faces, the first, beginning on the radial side is almost entirely on the lateral surface of the bone, as represented in figure 2. In life, it moved upon a corresponding face on the adjoining second metacarpal. It is confluent, along its proximal margin, with the second articular face, which is the largest of the four, and articulated with the principal distal face of the magnum. This face, shown in figures 2 and 5, extends with parallel sides across the proximal end of the bone, from before backward. It is concave from side to side, though slightly convex antero-posteriorly, and formed, during life, the principal support of the bone. Its plane is more inclined to the axis of the bone than is that of the third face, which, in life, rested on the unciform. The third face, best shown in figure 5, is large and triangular, the apex of the triangle being turned posteriorly, or toward the palmar surface of the manus. This face articulated with the unciform. It is convex in both directions, and, being more nearly perpendicular to the axis of the metacarpal than is the face for the magnum, must have contributed, during life, nearly as much to its support. The face for the unciform is confluent along its entire outer, or ulnar, margin with a fourth, broad articular face on the side of the bone (figure 4), which, in life, met a corresponding face on the fourth metacarpal. The distal end of the bone (figure 6) supports a moderately convex face for the phalangeal articulation, placed well upon the upper surtace of the bone, and ‘scarcely extending as low as the middle of the distal end. Here, it is met by the broad and shallow grooves, in which a pair of 124 DINOCERATA. sesamoid bones moved during life. The ridge between these grooves is nearly obsolete in front, but well developed posteriorly. The more important measurements of two third metacarpals of Dinoceras are given below. Measurements of Third Metacarpal. (Dinoceras mirabile, No. 1208.) - m. Total lene thot thirdlmetacanp al eee = oes se es eee 114 Diameters) of jproxiumall(end,s == Ssse5 oe soe oe eee ees ee eee .052-,062 Diametersiofidistallend ses] ss -se5 =e lee SL OU Ie oth 5 EY ed ee eee 044-054 Diameterstolpshiatteress9) sere =e a ee Re ey en oe .031-.042 Antero-posterior diameter of Fate. fon second metacarp: hi BAM REALENEA (Pex ine” Ste See O40 Transverse diameter of face for second metacarpal, --—— -- Peat Se er ee .015 Antero-posterior diameter of face for magnum, -_---- ----..-----.---------- oy 2056 UM ehaknrteraso Che neler Oe UEKES Ore MEM sec eas es booe yesces=Seaness see: .022 Antero-posterion diameter of face toriuneitonm, 4255 2822.5 Sees nee .050 Transverse diameter of face for unciform, _. _- __- Se ee, ens 2 .030 Antero-posterior diameter of face for fourth met nan, a fe tee -050 Transverse diameter of face for fourth metacarpal, --.-.----......--.-.-=------ .025 Diameters of face for phalanx, 2255 55 eee eee ee ae ee es ee eevee 2D NOE Measurements of Third Metacarpal. (Dinoceras mirabile, No. 1529.) m. Diameters of proximal end of third metacarpal, ....---..--------------.--- .044-.078 Diameters:of shafts = 2. sof cis eee ere Mace ees ee nl .032-.040 Antero-posterior diameter of face for second metacarpal, .... .--.----- ----..---- 043 Transverse diameter of face for second metacarpal,. ....-...--.---.----.------ 014 Antero-posterior diameter of face for magnum, -- .--- _--- - aie 5 ae ee a0 Mransversendiamieterro fla certo rma omy erate .025 Antero-posterior diameter of face for unciform (approximate) ese. =e ee ODD (ransverseldiameter of tacen ors un Ciio Tria eee ee ee) CF Antero-posterior diameter of face for fourth metacarpal, -__.-_--.----------..-- .059 Transverse diameter of face for fourth metacarpal, .........---------------- -015-.018 Tse FourtH METACARPAL. (Plate XXXVI, figures 7-9, and Plate XXXVII, figures 1-3.) The fourth metacarpal in the Dénocerata is a robust bone, like the second and third of the series. It may be easily distinguished by the broad, sub-triangular, convex articular face, at right angles with the axis of the bone, and covering its entire proximal end. THE FORE FEET. 125 The surface of the bone is roughened towards the ends, but smoother along the shaft, as shown in Plate XXXVI, figures 7 and 8, and Plate XXXVI, figures 1 and 2. It is considerably extended antero-posteriorly near the proximal end, but is constricted at the middle. The proximal end (Plate XXXVII, figure 3) is almost completely covered by the articular face for the unciform bone, by which the fourth metacarpal was entirely supported. This face is convex in both directions, and broad in front. It becomes much narrower behind, or toward the palmar side of the manus, so as to appear triangular, but does not come quite to a point. Along each side, it is confluent with narrow faces, nearly at right angles with the main surface, which joined, during life, corresponding faces on the third and fifth metacarpals. The largest of these lateral faces, shown in Plate XXXVI, figure 8, extends along the entire margin of the unciform face on its radial side, and was adapted to the third metacarpal. On the opposite, or ulnar, side (Plate XX XVII, figure 2), a smaller and shorter face, sometimes, as in the specimen figured, much larger anteriorly, was adapted, during life, to the fifth metacarpal. The distal end of the bone (Plate XXXVI, figure 9) presents a rounded, and but slightly convex, face for the phalanx, and below are shallow grooves for the two sesamoid bones. Measurements of the fourth metacarpal bone in four specimens of the Dinocerata are as follows: Measurements of Fourth Metacarpal. (Dinoceras mirabile, No. 1211.) m. Wotalblenothiot founthimetacanpal,s sss. s see e es eee eho Eines .131 Wiemreterstofapromunal emda sos ese ee ee eyes ape Bee Ob0— 08 DianreterstOuGistalnend ame eet ees epee ete eee ee eee aS Sere eee .052—.044 Wrameters otsshatt (approximate). qsee ees == eee ae ae eee eee eee eee 038— 041 Antero-posterior diameter of face for unciform, -=_.-._...-----/.-.-5.-------.-- .076 iransverse diameters or face! tor uncitormsy, «2. soos 2= 5 eee see eae eee ee .022—.048 Antero-posterior diameter of face for third metacarpal, _..._-....-------------- 062 Transverse diameters of face for third metacarpal, __-_........-.-.-.--------- .013-.022 Antero-posterior diameter of face for fifth metacarpal,.------.-_.---.---------- .052 Transverse diameters of face for fifth metacarpal, ..-. __- 2 See ne eee ee ..060— 022 Diametersion face) for phalanx,—>-- 2 s==5== 9= == === Pa, SEM srr seid .035-.040 126 DINOCERATA. Measurements of Fourth Metacarpal. (Dinoceras lucare, No. 1038.) m. Mortal pera estar ty fo wiret balers fre 5 0 ote ee ee ee alhilty Diameters of proximaliend.<) 45.25 326. =o Se ears Se eee ere eee 047-064 Diameters: of distaliend, s<-2 . .-8 e255. 5 52a ee Oe ee 054-041 Diameters of shaft (approximate), 2.22822 222 eee ee Soeeeee eee aoe OG 0380 Antero-posterior diameter of articular face for unciform (approximate), —_-_------ .060 Transverse diameters of articular face for unciform (approximate),_--____. ___-. 021—.040 Antero-posterior diameter of articular face for third metacarpal (approximat ),--__ .050 Transverse diameters of articular face for third metacarpal (approximate), -. _-.012-.020 Antero-posterior diameter of articular face for fifth metacarpal, ----______- pone A049 Transverse diameters of articular face for fifth metacarpal (approximate),._. _-.080-.018 Diametersiof articular face ton phalanx ss === =e eee ee eee 032-042 Measurements of Fourth Metacarpal. (Dinoceras, No. 1523.) m. Total length of fourth metacarpal, .__----------- fie pote me Pe ane eee .096 Diametersiof proxualltends (approximate) = es eee ee eee 040-061 IDO Glisil Gal ooo soe eese a sce se Bre ee Pe Se Fs 4 045—.034 Diameters onshatte (approximate) yest oe = ae eee OO 0 Os Antero-posterior diameter of articular face for unciform, __--__----_--. - eee ODS Transverse diameter of articular face for unciform, -_.-___.----.--- --- EES He .040 Antero-posterior diameter of articular face for fifth metacarpal, _.-. --____- sac) 2042 Transverse diameters of articular face for fifth metacarpal,.__.___. ___- -.-----. 040-017 Diametersjofanticularstace tor phalanx se ee ene ae .023-.039 Measurements of Fourth Metacarpal. (Tinoceras ingens, No. 1219.) m. Motallenothro£ founthemetacanpal sess =e ee ae eee cela te ten Gall ys iDiameters® of proximal end ye i ee ep Sees et a ee ee UN a 054—.071 Diametersion shat (approximate) 5 esse ee ee ee o2 2. =.028>040 Antero-posterior diameter of articular face for unciform, _.__ __ Pee aoe OO Transverse diameter of articular face for unciform (approximatc’, ________._-.-. .048 Antero-posterior diameter of articular face for third metacarpal, _-_-_-__-_-_- .055 Transverse diameters of articular face for third metacarpal, ____ ._-_________-.. 014-019 Antero-posterior diameter of articular face for fifth metacarpal, ___._..-___- ee OST Transverse diameter of articular face for fifth metacarpal, _-......_.-. -.------ .020 Diametersioianticnlarsacerdt omiphallanic we eee ee eee ae anna -.080—.042 THE FORE FEET. 127 Tue Fiernh Mertacarpar. (Plate XXXVII, figures 4-9.) The specimens of the fifth metacarpal in the Yale Museum are, unfortunately, all more or less distorted by pressure, and hence fail to fully represent this element of the manus. The bone is well developed, scarcely smaller than the third and fourth, and considerably surpasses the first in length. Like the other bones of the metacarpal series, it is rough and tubercular, especially toward the ends. The proximal end (Plate XX XVII, figure 8) presents three articular faces, of which the main and middle one, for the support of the bone upon the unciform, is strongly convex. The convexity is carried through a considerable are in the antero-posterior direction, to correspond with the outer, and most concave facet, on the unciform bone, to which it is adapted. This surface is bordered, on the inner, or radial side, by a face, broadest anteriorly, for motion on the fourth metacarpal. Behind, and on the outer, or ulnar, side of the principal articular face, is a much smaller face, which, in life, moved upon a corresponding articulation on the distal end of the pyramidal. In some specimens, the shape of the unciform, as shown on page 119, figure 124, would seem to make this impossible, and doubtless this face will not be found to be constantly present on the fifth metacarpal. The distal end of the bone (Plate XXXVII, figure 9) presents, as usual, a round, or oval, face for articulation with the phalanx, and shallow erooves below for a pair of sesamoids. The specimens preserved are so much distorted that measurements would be of comparatively little value. THe Puauances. (Plate XX XVIII, and Plate LIV, figure 1.) The phalanges in the fore foot of the Dinocerata are very short, and comparatively small. Their general characters are shown in the Plates cited above, as well as in the restorations given in Plates LV and LVI. 128 DINOCERATA. The proximal phalanges (Plate XX XVIII, figures 1 and 2) are much the largest. The proximal surface has no central groove, and is adapted to the comparatively smooth face on the distal end of the metacarpals. The median phalanges (figures 3 and 4) are much shorter than those described above. Their proximal articular faces are nearly fiat, and the distal ones, smaller, and more concave transversely. The ungual phalanges (figures 5 and 6) are larger than those of the median series, and, with the exception of the small articular face, their surfaces are very rugose. CHEE T ER 1X. THE RIBS AND STERNUM. (Plates XXXIX, XL, LV, and LVI.) The ribs in the Dinocerata present no special characters of importance. Their general features are well shown in the illustrations above cited, especially in the restorations at the end of the volume. Tue First Rip. (Plate XXXIX, figures 1-3.) The first rib in the Dinocerata has a general resemblance to the corresponding bone in the mastodon. It is, however, proportionally shorter, and more flattened at the sternal end. This rib presents a well rounded articular face to the first dorsal vertebra, and, confluent with this, on the anterior side of the head, is another strongly convex face, for articulation with a well developed facet near the posterior margin of the last cervical vertebra. The tubercular articulation is but little elevated above the capitular. It is convex from before backward, concave from side to side, and looks almost perpendicularly upward, being directed but very slightly backward. The tubercle of the rib extends outward beyond the articular face. The shaft is moderately roughened, more especially on its anterior, or outer, surface. The sternal face is so strongly flattened and expanded that the external border of the rib shows only a very moderate degree of curvature. The inner border, however, is strongly curved, mostly in the upper half of the bone. 17 129 150 DINOCERATA, Tur Anrerror Dorsau Riss. (Woodeuts 125-132, below.) The second rib in one species of Uintatherinm is represented in the figures below. Figure 125.—Second rib of Uintatherium latifrons, Marsh (No. 1231); posterior view, Figure 126.—-The same rib; frout view. Figure 127.—The same rib; inner view. FiguRE 128.—The same rib; proximal end. h. head; ¢. tubercle. All the 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 curved. The head remains large, and its articular faces are usually separated from each other, as shown in figures 129-132, below. ad Fig. 129. Fig. 130. Kes ple Figure 129.—Anterior rib of Dinoceras mirabile, Marsh (No. 1212); posterior view. Figure 130.—The same rib; inner view. Figur® 131.—The same rib; front view. FIGURE 132.—The same rib; proximal end. h. head; ¢, tubercle. All the figures are one-fourth natural size, ve 132 DINOCERATA. The main dimensions of the first rib in one individual of Dinoceras mirabile are as follows: Measurements of First Rib. (Dinoceras mirabile, No. 1251.) Total length of riby4 2 so2 2 ea ee eee Oe SOR Sener ene ar .820 Greatest: diameter ot shea d= 5 o> seh ee ere eee nee ee ike Seer .038 ‘Transverse: diameter of head, foo... 2 2s = 2 re ee .032 Diameters onstwoereul arrears cul atoms eer .020-.030 Diametersto sesh atti earth sr cl cll ese so eee eee 021-.040 Diameters otsshalttaratys berm all eri Clee sees a eee eae ee .027—.095 The principal measurements of the second rib of Uintatherium are given below. Measurements of Second Rib. (Uintatherium latifrons, No 1231.) m. AMG tall Leriert bro fypae3 boy nfs tpn atl eee -440 Greatest diameter of head, -------------- SS a2 oo 2 Bias Seen ee eee .055 Mransverse Glam ever Of: ead wees ee eee are ee a ee .030 Diametenon cuberculan articular ess eee =e a ee 024 iDiametersof shatt.necan the md dle: mene ne eee See oe 8 020=1039) Diameters of shaft, at lower end (approximate), .-....----------------- ---- .025-.060 The dimensions of two dorsal ribs of Dinoceras are as follows: Measurements of Anterior Rib. (Dinoceras mirabile, No. 1212.) m. Wotal@leno thy of cil, uals tra ot sles eee eee ee 500 Greatest.diameter of head, 2 2-222 =) en. 8 eee: ee ee ee ee .048 Transverse diameter of heads so a- - |e ee ee ee eee eee .036 Diameter of tubercular articular face (approximate), -.-.. -- -------------- == £0238 Diameters of shaft, near the middless=2ssee== = see ee Bee Pe oe ee 022060) Diameters of shaft, at lower end (approximate), -------- .---.--------------- 025-038 Measurements of Median Rib. (Dinoceras mirabile, No. 1210.) m. Motallleng tho fame stuns trea oY bata see eee 605 Diameters of head: 12.0. 2oc2e. 5222 5. Pc sces aces tee eee See Hee ee 047-058-065 Diameters of neck, .- ae DD se I ee ee 034-.039 Diametersvorshati.e ee eee hee Se ee ae ee ee ne, Soe oes .017-.057 THE RIBS AND STERNUM. 138 Tue Posterior Riss. (Plate XX XIX, 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 Dinoceras mirabile are the following : Measurements of Dorsal Rib. (Dinoceras mirabile, No. 1036.) Motlelencthwo teri ainestrAl ge hinlin ese ee mea eee ae ee eee. eee 530 Greatestidiameveriombeads 9-22 ses—- s---e= 22 2 = ot aS SS eh AS ey efpes $4059 Transverse diameter of head, ---------------- Be ee ee ee a ne eee, OST Wenstriaimevemomshantemieatwthemnid dle were sa. on eee seek eee eee oe = Cone Diameters of shaft, at broadest point,---_- - Se en ne ers Eee eee ot O20—-060 Measurements of Posterior Rib. (Dinoceras mirabile, No. 1036.) m. MotalPlenotikotumbwinestralo htwline ees eee see ses e es) Snes. 22 520 MEGreALeStROlametensOrsn Cada set es oN 2 a ee el ace! sees 2. AUae Tans Verse iamevernnOtneaGs pom aan se ee oe or a ee eee hte es eae .062 Diameterstol shattwatbroadest) polmti-- = == ses ==— 22-2 ee en ee -016-.051 THe STERNUM. (Plate-XL; and woodeut 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 aré shown in the figures, Plate XL. A series in the natural position is represented in the woodcut below. 154 DINOCERATA. The most marked character of these bones in the Dinocerata is that they are flat and horizontal, as in the Artiodactyls, 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, figures 1, 2, and 3. The bones which follow, and compose the meso-sternum, are broad and flat, somewhat constricted near the middle, with the ends more or less convex. he anterior ends are usually strongly convex, while the posterior extremities 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 woodeut below. FIGURE 133.—Sternum of Dinoceras mirabile, Marsh; top view. One-fifth natural size. The last sternal bone of the series, or the xiphi-sternum, is also broad and flat, but has the posterior extremity pointed. This bone is shown in figures 10-12, of the same Plate. The surface of all the sternal bones is quite rugose, and the extremities are deeply pitted for union with the cartilage that held them in position. No indication of clavicles has been observed. CHAP THR, X. THE PELVIC ARCH AND TAIL. (Plates XLI, XLII, XLITI, LV, and LVI.) THE PEtLvis. (Plates XLI-XLII; and woodeuts 134-135, below.) In all the known specimens of the Dinocerata in which the pelvic arch is preserved, the ilium, ischium, and pubis are firmly cobsified with each other, but not with the sacrum. The three pelvic bones on each side unite with each other earlier, 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 X LI. The pelvis of Dinoceras 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-iliae border being very regularly curved, and only moderately thickened near its union with the acetabular border, which it joins at about aright 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 to} 155 136 DINOCERATA. presents a strong union with the transverse processes of the first two sacral vertebre. The ilia are more rounded in outline, and the pubes 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. Tig. 134 FigurE 134.—Pelvis of Tinoceras ingens, Marsh (No. 1497); seen from below. Vie 135. FigurE 135.—The same; front view ; a. acetabulum; f. thyroid foramen; 7. ilium; ¢s. ischium; p. pubis; s. anterior end of sacrum; s’. posterior end of sacrum, Both figures are one-cighth natural size. THE PELVIC ARCH AND TAIL. 137 The pelvic arch in Tinoceras is similar, in its ¢ reneral features, 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 mirabile represented in Plate XLI. The sacrum in Dinoceras differs from that of Mastodon Americanus in having four sacral vertebra 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 specimen of Dinoceras mirabile, and in one individual of Tinoceras ingens, are the following: Measurements of Pelvis. (Dinocerus mirable, No. 1036.) (creates (ransverse Guameterm ACTOSS Ilia.) oes. 2 oes Se See eet eae 1.120 Horizontal diameter of pelvic opening (approximate), ------------------------- .350 Vertical diameter of pelvic opening (approximate),.--_____-_-- .--------------- 250 WD ranveterachOsstaceuabulameens ts. a. fee aa ese es oe eae ee ese sce ais 222 050 Diametersoteacer a bulunitem meus a een eee UW fe, hee e ee -110—.125 Diametersro ta uliyiol Oso GAN CN ser = ee ae ee eo eee ee Oooo fren splot symphysis spUDIN, == a ee ee = ae ek ate .140 Menethiof tou sacral vertebra (approximate), _---_--___-- ---- -=-- #2 ==-2-- == =- 245 Extent of transverse processes of first sacral, -__- -..----- --------------------- -330 Horizontal diameter of anterior face of first sacral, ___-_------. ---------------- 110 Mertical diameter ofantenor face of frst Sacral, =29.2--- 22-5 2222-5 --=-- =. 075 IL@metiln Orr Tras GEGEN OGM, 252 oS sa ooe ee oe See See 82 ee Soe ae ore ae 075 Measurements of Pelvis. (Tinoceras ingens, No. 1497.) m. Grealestitansvierse Glam eter) ACKOSSt tame een o = ae eres ee eere es eee ee 1.180 Horizontal diameter of pelvic opening (approximate),-_-._-___--_--- Ee ae AO) Vertical diameter of pelvic opening (approximate),-._ ___--.---_ -------------- 300 Dirametercacross;acetabpulaese eae a= eae ee ee hs eel nete .700 Dierravetierrss Ore Wayatorel tim. 8 a. 22 Ces ne oa = Se Se See See ee .060—.150 keno thvot symp hiysishpUlOis y= eee eee ee .140 Length of four sacral vertebrae, -___ - E awe Bs lb aa pale See 205) Extent of transverse processes Of first rei eee ee en eS Sate! eS Horizontal diameter of anterior face of first sacral, __--__-._-.----..----- ee Seats 18 138 DINOCERATA. m. Viertical idiameternor anterior face: on first sacral. pe ear ee 072 Weng throt centramanon stirs ti seicrall yes eee eee ae ea a eee .085 eno thot tcenti; amas of secon dese cre ieee eget wee eee eee eee O75 Length of centrum of third sacral,-_.---=--_------_- Lal) See ee: ee ee ee OGD: enptihvof centrum oft out hysecrell ee ee ee -067 THe CaupAaL VERTEBRA. (Plate XLII; and woodeut 136, below.) The anterior caudal vertebrze 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. Fie. 136. VIGURE 136.—Caudal vertebra of Dinoceras laticeps, Marsh (No. 1039). a. proximal end; b. side view; ec. 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. CHEAP THE XT, TELE HIND? DIM BS: (Plates XLIV, XLV, XLVI, LV, and LVI.) The hind limbs 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. Tue 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 DINOCERATA. > 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 curved 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 surface 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 when standing at rest, and in walking. The characteristic elephantine gait must, therefore, have been assumed by the Dinocerata. The inner 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 deep 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 surface, 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 m the femur, the inner texture of the shaft being merely somewhat cancellated, as shown in the woodeuts below. Fig. 137. Fig. 138. FIGURE 137.—Section of femur of Dinoceras mirabile, Marsh (No. 1206). FIGURE 138.—Section of same bone (No. 1210). Both figures are one-fourth natural size The main dimensions of the femur in one specimen of Dinoceras are given below. Measurements of Right Femur. (Dinoceras mirabile, No. 1206. y J . m. Iasi, Ge eUTTIR a. 2 se) ae Se Se PE ey Be SSN See eae eee ee .690 DE TTNECHTOT INGENG |. ee 3 Sek ae Re ee eee eee .123—.126 Distance from summit of head to trochanter mimor,.--.------ -.---------- ee 00) Height of trochanter minor, -__- —--- - Bags SRS eis Se ye eS Pee ee UE: Transverse diameter through great trochanter, _---......_-----+------------.-- PUG Teast diameters of shaft, ....__------ 2 cies BALE a ee eS .067--.093 iiranswersediameten or aistalwendswe:- se 4 2.2 == Se boone se hee 8 TO Greatest antero-posterior diameter of distal end, -----------.------ ------------ .160 east: antero-posterior diameter of distal) end, -------. --.- ---_------.----.--:- 100 Transverse diameter of inner condyle, --_--._.. -------- ---- ea NN clea ee .065 iirans verse diamotenoiiouter condyles = mesa open sk ae eee «OT Tue Trista. (Plate XLV.) The tibia in the Dinocerata is much shorter than the 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 8 a. The inner face is larger in antero-posterior diameter than the outer, and is coneave 142 DINOCERATA. throughout in both directions, except for a very small area near its posterior margin. The outer face is shorter, 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 outer 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 contracted in the middle, but expands below, and has its distal end nearly covered by the broad surtace 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 lengthiof tibia, ..------ -==- SOR Se Sa ee ane Se SNE ee ae eee ee OO) Greatest diameter, proximal end,___--_.-_------- Nit Fat fe SE, ahve) Be. Ee pees 140 NMIEKO-POSbEMLO Ms Ciera e tials mle]. Osyypa ett lll, jee eas een ete .096 Antero-posterior diameter of inner proximal articular surface, - ~~. ~—___- te .080 Transverse diameter of inner proximal articular surface,...._.-.--------.---.-- .062 Antero-posterior diameter of outer proximal articular surface,--------------.--- .070 Transverse diameter of outer proximal articular surface, .--.--.---------------- .075 Greatest diameter of fibular articular surface, .-._...__-__- .._.__-__.- Sie hap eOSS. Iheastidiameter ots wlan amore wares irs C ese ne ae ee ea Pe eee = ROR Least diameters of shaft, .__- . Pe; Sot eh eC awdte ed eg SE sinh PEG a A Metals 8 .052-.057 Gieatestrdiameter.(daustal vend sme an =e eae gaps SE ee ee ee Bees lis Antero-posterior diameter, distal end,.._: -..--------- ake RE oe eae .093 Greatest diameter of astragalar surface (approximate), .__. ..-__.----__. ------= .095 Antero-posterior diameters of astragalar surface, .-...-.----.- Be eee Obi O80 Antero-posterior diameter of distal fibular surface, _-..-_....._-------.---+-.-. -035 east diaimetertotcdistalateb ull aris tira ce sr ceses sees ene ae eee Es Os THE HIND LIMBS. 143 Tue Fisuta. (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 NLVI, figure 4. In some specimens of the Dinocerata, and probably in all, the fibula met the caleaneum, as in Coryphodon, and the Artiodactyls. Measurements of the fibula in two individuals of Dinoceras are as follows: Measurements of Fibula, (Dinoceras mirabile, No. 1208.) m. encthy ot tibulas (approximate) s.=.==22 2 -- 6. 22 --—- ee aie eS ee ese ee A 6350 Diametersiorproxumalvend) S22 525 552.252. 2— : Se es I ee ee .040—.045 Diameters of proximal articular surface, .--. ..-. ------ eed SEE 2 eel Ue BS OLS 27033 Measurements of Kibula. (Dinoceras mirabile, No. 1210.) m. Wiametersiotss ta hte mem ees ese ors A ern Bo aS Se ie se a -._ .028-.020 Diameters of distal end; -...--..----- Se re ee Oe Be yen oe eS 3 OL O=10N0 Diameters of distal articular surface (approximate),....-.-.----------------. 050-045 Tue Paretya. (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, concave 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 LY and LVI. — Cita hi OX EP. THE HIND LIMBS. (Continued.) (Plates XLVII-LVI.) Tue hind feet in the Dinocerata weré 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 mirabile 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. Tor Tarsat Bones. (Plates NV, Plate LIV, figure 2; and woodcuts 139-146, below.) There are seven well developed tarsal bones in the Dinocerata, 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 woodeuts 139-142, below.) The astragalus in the Dinocerata 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, moreover, 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, figure 1. This surface is sub-quadrate in general outline, with rounded angles, but is prolonged 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 bemg 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, ¢ below. This convex facet apparently supported a separate bone, as in the existing Hyrax (figure 155, Chapter XIV). This bone D . too} ’ / ? as Baur has suggested, probably represents the tibiale, or inner tarsal of oe the proximal row. The same bone exists also in Hystrix, and many other Rodents, and is regarded by Flower as a sesamoid. The inferior surface of the astragalus (Plate XLVII, figure 3) articulated with three bones; below, with the upper faces of the caleaneum, and, in front, with the navicular and the cuboid. All these articular faces may be confluent, as in the specimen figured on the Plate, and the mode of union with the caleaneum is subject to considerable variation. ao ae eet THE HIND FEET. 14 In the specimen there figured, the face for the calecaneum 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 specimen figured, this foramen is small and oblique, and no opening is seen through the bone. Along the outer, or fibular, margin of the boue, 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 the face for the cuboid. Another, and more common, form of articulation with the caleaneum is shown in figure 140, below, where the lower surface of the astragalus presents two distinct faces for the caleaneum. 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 posterior part of the bone. The inner portion of the calcaneal face is longer than the outer, and more concave from before backward. [rom 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 strong contrast with the structure of the foot of the elephant, in which the cuboid is supported by the caleaneum, and the navicular which covers the whole 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 bounded 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 XLVII, 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 caleaneum. 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 Dinocerata 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 XLVI, 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 Coryphodon is very similar in form to that in the Dinocerata, but is shorter. It has essentially the same articular faces, and the facet for the tibiale is equally well marked. The hind foot of Coryphodon is shown in figure 151, in Chapter XIV. Its general resemblance to the corresponding foot in Dimoceras 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. Fie. 139. Fie. 140. Figure 139 —Left astragalus of Dinoceras laticeps, Marsh (No. 1197); top view; showing foramen. Figure 140.—The same boue; bottom vier. b. face for fibula; c. and c’. faces for caleaneum; cb, face for cuboid; n. face for navicular; ¢. face for tibia, ¢”. face for tibiale, Fra. 141, Fie. 142, Tigure 141.—Left astragalus of Tinoceras ingens, Marsh (No. 1209); top view. Figure 142.—The same-bone; bottom view. c. and c’. faces for caleaneum; cb. face for cuboid; f. face for fibula; n. face for navicular, ¢, face for tibia. All the figures are oue-half natural size. 150 DINOCERATA. Measurements of the astragalus in four individuals of the Dinocerata te) are as follows: Measurements of the Left Astragalus. (Dinoceras mirabile, No. 1210.) m. Greatest antero-posterior diameter of astragalus, —. ~~ -- .-- SoS Le eee SL Greatestvtransverse/diameéter; 5-2-2525. 2. SS See eae ee oli Greatestvertical diameters=*-..--2- S235 eee 5 Se eee .070 Greatest diameter oreanticular tacemor tibia, == mete is =r enna ee ee .110 Antero posterior diameters of articular face for tibia, ..--------- _... .072=.066—.092 Transverse diameters of articular face for tibia,_-__- ..-- -----.---.---- .076—071—085 Antero-posterior diameter of articular face for fibula,_--.-. ..._--...--------.-- 044 Vertical diameter of articular face for fibula, _..._._-_..---_-. Be = a oa OS 0 Antero-posterior diameter of articular face for caleaneum, ---.------------------ .054 Transverse diameteror articulariacedor Galcaneuins = 92. 95 =e ee -080 Transverse diameter of articular face for caleaneum, outer lobe,___- .__-___---__- .033 Transverse diameter of articular face for caleaneum, inner lobe, ----- -------- -.-- .040 Diameter of band connecting lobes, ---- ---- ---- 2 Ree eee 2 ee amis .018 Antero-posterior diameter of united faces for navicular-and euboid,-.--_..-.----- .056 Transverse diameter of united faces for navicular and cuboid, _----___ -___- ____ __ .107 Diameters otehace to tim ary G ula ese eee ee ee ee .056-.082 Diametersiof facectoricuboidss se 8 es. eee oe ee ee oe er eS -035—.062 Minimum lengthvof neck, 22-2. -o. ess 22 sa 5—08 sass Soe Se me Se ee See ae O14 Measurements of Left Astragalus. (Dinoceras laticeps, No. 1197.) m. Greatest antero-posterior diameter of astragalus, ---- -------------------------- .128 Greatest transverse diameter, -128 Greatest vertical diameter, _._._-.--_-- ae O80) Greatestidiameter ot artieular Laceytomiblbia,- seen on 9 a yee eee ees em llAs/) Antero-posterior diameters of articular face for tibia,-------------. ---- .0S9—.080—105 Transverse diameters of articular face tor tibia,-._-_---------2-.22---- .090-.085-.09 | Antero-posterior diameter of articular face for fibula, _--. --.---------.--------- .055 Wettical diameter of articulanitacelfomibnmla, eat 2s. ee ee es 031 Antero-posterior diameter of outer articular face for caleaneum, ---- ------------- .053 Transverse diameter of outer articular face for caleaneum,--.-.- ---------------- .048 Antero-posterior diameter of inner articular face for caleaneum, --_-----~------- -- -061 Transverse diameter of inner articular face for caleaneum,___-__...-._.__-.----- .085 Distance between inner and outer faces for caleaneum,---- .--------------.--.-- -009 Antero-posterior diameter of united faces for naviculayr and cuboid, ~---------- Pe One Transverse diameter of united faces for navicular and cuboid, ----------.------- 5s} LD Aaa TONE TEKS aKO NAMEN Doses a see e Ss Geos sea See ese oes: .064-.091 ID Shaner nsrOVNureKes IoC NOM ee Se ees 2s ROR ee aS Sec -081—.071 WW Gheybeawewen, Iheyavetilt Oe mee eye oe 8 eee so ee nee ee SESE SO ES oe .016 ‘THE HIND FERT. 151 Measurements of Left Astragalus. (Tinoceras ingens, No. 1209.) Greatest antero-posterior diameter of astragalus, ...-.....--__--.-------=-.---- 122 Creates tminanswersey diameters hapeset.s chess oa eesvags Ses Se cot pee eve coe iL 147 (CHRONOS HERON hGMEITTGIG, A eee © bee Se ne ee eee ee .083 Createsiaimmetemoimarvicular face ton tibta.een === ose see ee es fe LL 125 Antero-posterior diameters of articular face for tibia, -.-.-.. .--------. .091-.082-.104 Mrjansversexuamerers/ of articolan face tomtibia,--—— s2.8-- 922-2 2 ke .094—.096—.095 Antero-posterior diameter of articular face for fibula, .-_.___- ae Pees 6000 Venticuludiameter Oteanticularicestordibulas ==). wee. ses eee oe) le eee .039 Antero-posterior diameter of outer articular face for caleaneum,_-_._-_.--.- ---- .050 Transverse diameter of outer articular face for caleaneum,_ ---- ----_--- ee 050 Antero-posterior diameter of inner articular face for caleaneum,-—--- ~~ ~~ ~~~ -__- .058 Transverse diameters of inner articular face for ealeaneum, —__—_- —__- 083050 Distance between inner and outer faces for caleaneum, -_-- . —-- Br ee Sees eb 918 Antero-posterior diameter of united faces for navicular and cuboid, ~~~ ----—_--- 068 Transverse diameter of united faces for navicular and cuboid, _-___-_.-__.-_____- 130 DiameterstoleacesolmaviGul aise. se ae aie: ese eee Fee. cs. .068-.105 MinmMeterscotelaceslomMmCeunOldses= eer = ky oat safe eee ease nce e cin Sue .042—.077 Minimunaplene thvotene kes sen eee ase mele Se Shae oe e Ce eee .019 Measurements of Right Astragalus. (Dinoceras mirabile, No. 1528.) Greatest antero-posterior diameter of astragalus,.-......---..-....----.----_--- 100 GhReEALCS MURA SVEUSe cal alnle lel = mere ee = = vel eee as Se es eet OS Grearestsyenticalediance Gekrce ees sauear a oat 2 ey eS ee LL ee 065 Greatest diameter, ohvarticular face for tibia,.-=- .52- 22225--5- 55. ---- Bel LOO Antero-posterior diameters of articular face for tibia,._-.-_-___ ._- ___. .070-.060-.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, __-._.__.._..---. Ee ee Ke" 080 Antero-posterior diameter of outer articular face for caleaneum, ___.------ -__-- .035 Transverse diameter of outer articular face for caleaneum, ----_---__-- _-------_- .039 Antero-posterior diameter of inner articular face for caleaneum, ___--.-.-------- .040 Transverse diameter of inner articular face for caleanenm,._._..____-.-_-. ___.-- 040 Antero-posterior diameter of united articular faces for nayicular and cuboid,---__.053 ‘Transverse diameter of united articular faces for navicular and cuboid, —-__-_ ___- .093 Diameters obshaCerho rm aval CUlAls ams) ere yee ee ee ocr ne wee .076-.053 IDianrebarstolehaceston Gl DOldsm seer, Seen see pe tee Ces ene eo a .026—.055 Minimomelen othrobneck: siya tee ae 9 eRe neal ee Dy pet eaN En rte ald 19 8 2 O15 THe CALCANEUM. (Plate XLVIII, Plate LIV, figure 2, c; and A woodeuts 143-144, below.) The caleaneum 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 caleaneum articulated mainly with two bones, the astragalus and the cuboid. Some specimens, and perhaps all, present a small face where the fibula touched this bone. The articulation with the astragalus is, in most specimens, divided into two distinet facets (figures 144, a and a’) by a deep groove. In some cases, however, these facets are coalescent posteriorly, as in Plate XLVIII, figures 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 bone. The great tuberosity for the attachment of the tendo Achillis is very short, proportionally shorter than in the elephant. Fig. 143. Fig. 144, Figure 143.—Caleaneum of Dinoceras mirubile, Marsh (No. 1210); top view. Figure 144.—Caleaneum of Dinoceras mirabile, (No. 1208); top view. a, and a’. faces for astragalus. Both figures are one-half natural size. Two specimens of the caleaneum in different individuals of Dinoceras are represented in the woodeuts above. Measurements of three specimens of the caleaneum in the Dinocerata are as follows: THE HIND FEET. Measurements of Left Calcaneum. (Dinoceras mirabile, No. 1210.) Length of calcaneum, from great tuberosity to face for euboid, ___-_---------_-- SRRPUDEN SPSS GBP ed oe Ses SS ee a ee a wecee Werticaltdiameter mss. 92 == 5-0 == =e oe eee ee Ae ee ee ee Antero-posterior diameter of inner lobe of articulation for astragalus, .---.__--_- Transverse diameter of inner lobe of articulation for astragalus, -__--_-----___.- Antero-posterior diameter of outer lobe of articulation for astragalus, ._--.--.-~- ‘Transverse diameter of outer lobe of articulation for astragalus (approximate), maf Measurements of Right Caleaneum. (Dinoceras mirabile, No. 1225.) Length of calcaneum, from great tuberosity to face for cuboid, _-__. .__-._------ Transverse diameter’ (approximate), ......-..--.-.-.-.-===-.--- $6,350 SES Snee W@niiGell GIRO. 1 sete ke a Bae tect ae ee Antero-posterior diameter of inner face for astragalus, __--__-- -_-- Pee eee Transverse diameter of inner face for astragalus, ------------------------.----- Antero-posterior diameter of outer face for astragalus, --_----------.----------- Transverse diameter of outer face for astragalus (approximate),__----- -- SSS ee Distance between inner and outer faces for astragalus, _-___---_---------------- Measurements of Left Caleaneum. (Dinoceras imirabile, No. 1208.) Length of calcaneum, from great tuberosity to face for cuboid, .--.---.-------.- TS WORND Ghia, Base! slats os See eee See ee a ee ee eee WERHGHLGMinGiGe, 3.55 hae Soe J aoe ee Oe Se ae a Antero-posterior diameter of inner face for astragalus,-.-_.._.-- .----..------ (ransverse diameter of immer face for astragalus,:-_+-222-22.-.---.--------42-- Antero-posterior diameter of outer face for astragalus, 5 foe ES ee = eee a Transverse diameter of outer face for astragalus,....._-.-. -..--.----------+-=-- Wistance benweenttacesiftor astragaluss 222 Ses eee eee ee an transverse diameter Omrace tO CUDOIG, == = eee See ee ee WerticaladinmeterolmacertOlClboldye= ae ae eee nen ee SoS ee THe Cusor. (Plate XLIX, figures 1-6, Plate LIV, figure 2, cb; and woodcuts 145-146, below.) L107 .086 -074 053 .037 -045 037 -V10 m. -098 -086 -074 044 -042 .050 -032 -070 -035 -019 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. 20 154 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 caleaneum on the proximal end, and one for the fifth metatarsal on the distal end. The plantar aspect of the bone (figure 3) presents a single, or bifid, tubercle, and, on the inner face (figure 2), is an elongate articular surface for union with the navicular. This surface is confluent with the face for articulation with 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. his face is, in the specimen figured on the Plate, widely confluent with a smaller oval face for the caleaneum, In figure 146, below, the face for the caleaneum (c) is much less widely confluent with that for the astragalus, being nearly separated from. it. In both specimens, the caleaneal face is slightly convex transversely, and somewhat inclined to the axis of the bone. Fra, 146. FiguRE 145.—Right cuboid of Dinoceras mirabile, Marsh (No. 1528); side view FiGurRE 146,—The same bone ; proximal end. a. face for astragalus; c. face for caleaneum; 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 the 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,..-.---.----_.--- Od MAC AE Sime ad Toe 035 Mransyersepdrameter assess > Se ye - -= CS1 er 5 SME, Se eee et eee .054 Antero-posterior diameter, -.--..-----..--..--- NS iy eee eee ee -_ 060 Antero-posterior diameter of face for astragalus, _-_.._-_ ._.-------- PAE EL ESAS .055 Transverse diameter of face for astragalus, -_-..--- ---.-------- hig aap m cote ey AAS .03 Antero-posterior diameter of face for cuboid, ...--.--------------.--- eee 035 (Rransmersemiameerotmace fOr CUbOld 2. - 2 2.222552, - 222 eee ee eee 020 Antero-posterior diameter of face for fourth metat steal pets ed Le Regs Che ee SE O40) Transverse diameter of face for fourth metatarsal, ...__--. _ . 2s SA ee Bed ep OO) Antero-posterior diameter of face for fifth metatarsal, .... .-._..._.---_-----.--- .035 Transverse diameter of face for fifth metatarsal, __-___ Se aes ees oleae OLD) Measurements of Right Cuboid. (Dinoceras mirabile, No. 1528.) m. ienethyotecuboidsaloncsaxisvol tooimes a) shea oe eee ee ee .037 Transverse diameter, .__-—_~- 32 A eee ee ere Ne aE wee tee be, 066 AMitero-posienlormdiameten mee as = ses ae Seno eet POA SLI ESL gt esti esta Les 1065 Antero-posterior dianoban. of face fon Sauneliae, CY, ESS Rake eee one Le ee eS A .058 Transverse diameter of face for astragalus, -__- ____-- See en Pe sees e056 Antexo-posterior diameter of facetior cuboid, -=-2==- 222222 —2. = 5-5 a= 2s .032 inansverserdiamerenortacemorm cupolas sae— sone sesame. ite epi de yh - .026 Autero-posterior diameter of face for fourth metatarsal, --_._____ Bt RNG (ow 049 Transverse diameter of face for fourth metatarsal, ____ ____ _- = es at fn po .035 Antero-posterior diameter of face for fifth metatarsal, .___________- PA Ce be NAO 39 Mransverse diameteriot face for stth metatarsal, 02. 2.-1-_ 2 2s 5 et .032 THe NaAvicuar. (Plate XLIX, figures 7-12, and Plate LIV, figure 2, x.) The navicular is a short bone in the Dinocerata, strongly flattened vertically, much as in the elephant. It is supported by the astragalus, and does not usually , as in that animal, touch the caleaneum. It supports only the three cuneiform Hones 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 oceupied 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 strong plantar tubercle, which may, however, (number 1218) be much less developed than in the specimen figured. None of the specimens present any indication, on the proximal face, of a surface for articulation with the caleaneum, such as is found on the corresponding bone of the elephant. The distal surface of the navicular (figure 12) presents three 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 indistinet. Usually, it is of considerable size, and elongated from 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 tlie 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 Navicular. (Dinoceras mirabile, Nc. 1247. « © ? ransverserqiametewonmavi culate se Sone ee See eso sons asks Sek .085 Antero-posterior diameters (axial),......-...:__...-=-...----.- soe cecese COUSS O20 diranusyersediameternot tacemomastramalug. = -2=- 52. 62.222) 2. eee ee e-- = 2s -080 Merticalidiametenotstiacestorastracalms, 2) 22292-22252. Bie oslo ete see .060 itransverse. diameter of face for entocuneiorm,. --- ---.- 2-2 .--. 2-2 2s-2 455. 22 -- .020 Vertical diameter of face for entocuneiform, __-. __.-----_-___--- SSS Sa Pen Ta .050 Transverse diameter of face for mesocuneiform, .._. ------------ --- ERAT S oS ae) OOH: Werticalidiameterion face tormesocuneitonm,-----------2.-------.-.2-.-.-.--.-= 045 Transverse Giameter of face tor ectocunelform, .... -......----..=-- 2<--=--.---- .035 Vertical diameter of face for ectocuneiform (approximate), -..-.---.------------ .055 Measurements of Left Navicular. (Dinoceras mirabile, No. 1208.) m. rte VCrReRGIAm lec O Lena CUl ans peace ee ee ee | Se ee 067 Antero-posterior diameters, -22- 225. =.-2- =. 22-222. 23 eS a a4 a) eee ee 015-025 Wertical kdl am clcrwemener rarer ar Ayebi i brane eee, 2 ee ee yy eee ccs .069 ransverserdiamerenotacehonasuramalle see sa ees Seek es ee ee 058 Vertical diameter of face for astragalus, _---__--------------------- b ne Le .051 Transverse diameter of face for entocuneiform, -__----_...._.-------2----.=--- .022 Vertical diameter of face for entocuneiform, _______- Bee ee See ee re See SEE OOS iransverseidiameten on trace tormesocumettorm, 225-2 -) 2 -222---22-------__---, .026 Wertical diameter of face tor mesocunelfonm,---- .---..222-2_- 2 22-2 ee eee .043 Transverse diameter on face tor ectocumeltorm, — .-.---__.. s2-5.-.2-_--=----- = .082 Vertical diameter of face for ectocuneiform, ________ ___-_- aes a one at ee -040 Measurements of Left Navieular. (Dinoceras mirabile, No. 1218.) m. iinansverserdtamerenolniavicn ane = == eee =e eee ee ee SE eS ee .082 ENOGERO=POSLGEION CAM CLEL Ns eer ien sieee eee nae ee eee See _. .015—.022 Wrenticalkdamebensy = sess ne eee ee 6 es Se ai Be oe ee “065 iiransverserdiameterof faceutor astragalus,s=-— 22-6 92-2252 2 oes sone eee ee .065 Vertical diameter of face for astragalus, --_- --- 0 EI ey AERA Ee EE ER) Transverse diameter of face for entocuneiform (approximate),.... -- --------__- .012 Werticalediameteroidacenor entocuneliormy 255 2o2- e222 se eee = 2 4028 Transverse diameter, of face for mesocuneiform, --..-_-._-_---------+.----.----- 029 Vertical diameter ef face for mesocuneiform (approximate), -----.---------.---. .045 Transverse diameter of face for ectocuneiform, ____ __-- Se oe Be oe eed ee ee ee Be 12 97/ Vertical diameter of face for ectocuneiform,-_____ .__- ___. ._ PRE BANS 1 Pati. 4h LR 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, toa great extent, in front of the articular surfaces. These surfaces are, at their nearest pomts, 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 rough 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 confluent 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. Tue MrsocuneiIrorM. (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 corresponding 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 the plantar extremity (figure 9) also presents a rather prominent protuberance. Of the lateral faces, the inner (figure 8), turned toward the entocuneiform, presents, along the proximal part of its margin, a more or less elongated facet, for articulation with 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 with 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 mesocuneitorm. The following measurements give the principal dimensions of this bone in two specimens of Dinoceras mirabile : Measurements of Left Mesoeuneiform. (Dinoceras mirabile, No. 1210. o « © J m. Createstidiamescmotmesocuneltormy esos nee eee ees ee 058 MRE SRN EIASO) COTE ae ee 2 STP eS oe Le SS ee .032 AMTErO-pOsterloks diameters | (aadall) y= sei 29 eee eee oe oe ee 04020 Measurements of Left Mesocuneiform. (Dinoceras mirabile, No. 1208.) m. Greatest grametenot mesocunelonrm- = 22 2= 2525202) 8 8) el eee 053 sliransverse diameter esse =o eee oe eee eras 2a PE STAD A Ue PALA Shy entitary .026 AMILCLO-NOSLELLO RCIA MI CtCE Sy (GLX 5) wees a ee Nee ye ee ee yee eee 014-.018 THe EcrocunrIrorM. (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 D usually has the two distal faces more distinctly marked. It is also proportionally less elongated from the dorsal toward the plantar side of the foot. 160 DINOCERATA. The dorsal, or dermal, face (Plate L, figure 13) is roughened for ligamentary attachment, 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 tuberele 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). Greatest diameter ote LOC um ent rns sees ae eee eee =e 066 Transverse diameter, _____--- --- ahi ay efor tans 2 Ret REE pS Std a NES ek hn ie ee ee AD Antero-posterior diameters, —— —--- --- Tae aS Se pee See Oa nS .014—.026 Dram eters ot joroxam all earcbi cull are Ce eee ee 030-.048 Measurements of Left Ectocuneiform. (Dinoceras laticeps, No. 1202.) m. Greatest diameter of ectocuneiform,-____..___-___ ..-------- 50 Soe toe? wearer OOO Mransverser diameter eae eee ee a eee Pere es ee rn ee te BRS .040 Antero-posterior diameters) 2.22.24 22. See ae ee es eee Dee ee .017-.024 Diametersvon, proximal fartie ul er sia ce es eee see ee ee -033-.050 THE HIND FEET. 161 Measurements of Left Ectocuneiform. (Dinoceras mirabile, No. 1208.) m.,. GrestestadtametertomectocunellOnmlse= sets sea e ne ee ae Sees Socles US eect eels .055 TM RETASKIGIRSE: CUETO ee ae Ses Sel oe ae eS ee ee .035 PATILERO=POSLeLI OF GIAM CLOLS ta. eat as ise ioe ae Sa bees eee aoe .016—.021 Diameterstol proximalearticulartaces jose esa o= see seers sass eee sean 028-039 Measurements of Left Ectocuneiform. (Dinoceras mirabile, No, 1232.) m. Greatestsd tam eterno fectocuneliOnmsse as ern sereeie as eta steers see a oete eee 064 Hinanswersca Clan tCb ewe meme ena ee ees een eee neo Seiaieoscee eek sc oe .044 Antero-postertor diameters (axial). 525 (2252222 Skee eee eee en ee - .014-,022 Diameters omproximal acti cular tace,== == yam eee = ee ee ee eee ashe 032-046 Tue First MErTaTarsat. (Plate LI, figures 1-6, and Plate LIV, figure 2.) The 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 preserved, 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. Tue Seconp 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 21 162 DINOCERATA. roughened at both the proximal and distal ends, but medially it is smoother and constricted, especially below, where a large, and prominent, 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 ectocuneiform. The latter face is also confluent with a lateral facet, where 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. Tur Tarrp 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 distinet 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 fourth metatarsal. THE HIND FEET. 165 The distal end (Plate LII, figure 3) is large and rounded, and, in some specimens, distinctly oblique. It supports 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 both directions. Tue Fourtu Mrrararsau. (Plate LH, figures 4-9, and Plate LIV, figure 2.) The fourth metatarsal is of about the same size as the third, and considerably resembles it in structure This resemblance is mueh greater than in the elephant, where the fourth is decidedly shorter than the third metatarsal. The shaft of the fourth metatarsal is strongly constricted medially, as seen in Plate LI], 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 faces, 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 Firra MeErararsat. (Plate LI, 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 and outer sides, as shown in Plate LI, 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 Dinocerata 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 views of them may be seen in the two restorations on Plates LV and LVI. CHEE WHR ©X 111: RESTORATIONS OF DINOCERAS AND TINOCERAS. (Plates LV and LVI.) Tue preceding chapters of this memoir, and the illustrations given in Plates I-LIV, will make known to anatomists nearly all the important characters 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 represented as walking, and the position of the head, and the feet, has been chosen to show, to the best advantage, these portions of the skeleton as they were in life. In this restoration, only those portions 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 Zinoceras 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, Dinoceras was intermediate between these two existing animals, and in various points of its structure, it resembled the one quite as much as the other. In still other features, Dinoceras resembled the hippopotamus, and its affinities with the groups represented by these three types will be discussed in the sueceeding chapter. In its stature and movements, Dinoceras 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 different 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 the 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, conclusively, by their numerous remains in deposits of this age. That the animals lived in herds is also suggested by the position in which the remains are found. Their favorite resorts would seem to have been around the borders of the great 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 offensive weapons which surmounted 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 (Antilocapra), 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 below 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 vertebrae 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. SS CAC AY XLV. 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 nearly 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 sarge) 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.) Saeral 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.) Epipubie bones. (19.) Acetabular bones. (20.) Femur with third trochanter. (21.) Three bones in first tarsal row. (22.) Astragalus, flat. (23.) Fibula articulating with caleaneum, — - CONCLUSION. ila 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 the Protungulata, the 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.) Vertebrie, flat. (6.) Trunk vertebree, 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 caleaneum. 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 havé continued up to the present day, and be represented by the living Hyrax. Several divergent lines passed off probably from the same stem, and three of these have continued to the present time, the survivors being the Proboscidea, the Artiodactyla, 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 genus Hlephas 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.) Vertebree, 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 Kocene, where it is represented by Diplacodon, and perhaps ended in the extinet Brontotherium, of the lower Miocene, although this line may have been continued somewhat later in the genus Chalicotherium. From the Artiodactyl line, a peculiar group branched off in the early Kocene, 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. CONCLUSION. 173 Another order, also, which may be termed the Amblydactyla, passed off apparently from the main ungulate stem in the Cretaceous, and became extinct in the Eocene. One branch terminated in Coryphodon, 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. ey Feces =] Recent. Quaternary. Pliocene: iS) = | iS} : . | 8 b.| Miocene.| a a cs = ° ES 15 = a] | E —= Eocene. ~ — ay Amblydactyla; sHolodactyla / 5 suey Cretaceous. / S 6 Protungulata Salli i N -— — B i nD S Jurassic. | Triassic. | 7 y : } SSS Permian. 0 Hypotheria Figure 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 the existing Hyraa, and no fossil remains of the group are-known. The principal characters of the order 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 vertebree, convexo-concave. (11.) Trunk vertebrie, 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. (38.) 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, 175 (9.) Vertebree, flat. (10.) (11.) (12.) (13.) (14.) (15.) (16.) (17.) (18.) (19.) (20.) (21.) (22.) Scapula, acuminate. Sternal bones, flat. Tliac bones, transverse. Femur and tibia in line. Ulna and fibula, complete. Femur without third trochanter Feet, plantigrade. Axis of foot through third digit. Five digits in manus and pes. Two bones in first tarsal row. Carpals and tarsals, slightly interlocking. Astragalus, flat. Fibula articulating with caleaneum. The Holodactyla 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.) (2.) (3.) (4.) (.) (6.) (7.) (8.) (0.) (10.) (11.) (12.) (13.) (14.) Brain, moderate in size, and convoluted. Lower canines. Maxillo-turbinal bones. Malar bone forming front of zygomatic arch. Post-glenoid process. Cervical vertebree, more or less convexo-concave. Trunk vertebrie, not more than twenty-three. Scapula, spatulate. Iliac bones, parallel. Femur and tibia not in line. Feet, digitigrade. Carpals and tarsals, strongly interlocking. Central bone, absent. Scaphoid articulating with magnum. (15.) Astragalus, grooved. 176 DINOCERA'TA. Returning now to the Amblydactyla, or the group from which the Dinocerata were evidently derived, and to which they belong, we may safely assign to them general characters as follows: co) to} (1.) Brain, small and smooth. (2.) Teeth, not more than forty-four. Post-glenoid process. Odontoid process, conical. Cervical vertebree, flat. Trunk vertebrz, twenty-three or more. (8.) Feet, plantigrade. (9.) Five digits in manus and in pes. ) ) ) ) (7.) Scapula, acuminate. ) ) ) Axis of foot through third digit. ) Carpal and tarsal bones, somewhat interlocking. (12.) Three bones in first tarsal row. (13.) Astragalus, flat. (14.) Fibula articulating with caleaneum. (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 extinet in the early Eocene. The Dinocerata probably branched off about the same time, and survived to the Middle Kocene, 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 systematicall , y y CONCLUSION. IE TET 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 groups, and their affinities, and await future discoveries. Excluding the aberrant aquatic Sirenians, now regarded as of ungulate ancestry, and leaving out also Towxodon and other little known extinct forms, the Ungulate Mammals may then be arranged in natural groups, as follows: CLASS MAMMALIA. Sub-Class Monope.puHia. Super-Order UnGuuata. (1.) Order Hyracoidea. (2.) Order Proboscidea. (3.) Order Amblydactyla ce : Coryphodontia. Mesaxonia (Perissodactyla). Paraxonia (Artiodactyla). (4.) Order Clinodactyla 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 DINOCERATA. 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 (Hypotheria) 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 (Protungulata), starting off on a particular line from the preceding type, would naturally 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 possessed by the Holodactyla were most of them still the ancestral features, and the Amblydactyla, on the line toward the Dinocerata, shared many of the same characters. The Dinocerata, representing a further 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.) Vertebre, flat. (6.) Odontoid process, conical. (7.) Sternum, flat. (8.) Feet, plantigrade. CONCLUSION. (9.) Five digits in manus and in pes. (10.) Three bones in first tarsal row. 179 (11.) Astragalus, flat. The specialized characters of the Dinocerata, acquired, doubtless, since this line separated from the Protungulata, are as follows: (1.) (2.) (3.) (4.) (5.) (6.) (7.) (8.) Pre-nasal bones. No upper incisors. Canine tusks. Skull surmounted with protuberances. Condyle of lower jaw, posterior. Pendent processes on lower jaw. Iliac bones, transverse. Femur and tibia in line. If we now compare the Dinocerata with the Coryphodontia, we find Y) ) they agree in the following characters : (1.) (2.) (3.) (4.) 5.) (6.) (7.) (8.) (9.) (10.) (11.) (12.) (13.) (14.) Brain, small, and nearly smooth. General form of teeth. Temporal fossee, widely separated. Post-glenoid process. Odontoid process, conical. Vertebre, flat. Scapula, acuminate. Feet, plantigrade. Five digits in manus and in pes. Axis of foot through third digit. Three bones in first tarsal row. Astragalus, flat. Fibula articulating with caleaneum. Cuboid articulating with astragalus. In comparing the Dinocerata 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 these characters are as follows: 180 DINOCERATA. (1.) Alisphenoid canal. (2) Odontoid process, conical. (3.) Vertebree, 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 Proboscidea 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 Dinocerata with the Perissodactyls, we find an agreement in the following characters : (1.) (2.) (3.) (4.) (5 ) (6.) (7.) (8.) (9.) Premolar and molar teeth similar in form. Nasal bones expanding posteriorly. Malar bone forming front of zygomatic arch, Alisphenoid canal. Posterior nares between last molars. Post-glenoid process. Carpal and tarsal bones, more or less interlocking. Axis of foot through third digit. Astragalus articulating with cuboid. With the typical Artiodactyls, the Dinocerata have the following characters in Common : (1.) (2.) (3.) (4.) (5.) (6.) (7.) (8.) (9.) (10). Cranial protuberances in pairs. No upper incisors. Premaxillary bones uniting with maxillaries and nasals. Premaxillaries with palatine plates. Lower incisors and canine in continuous series. Sternal bones, flat. Femur without third trochanter. Carpal and tarsal bones, more or less interlocking. Fibula articulating with calcaneum. Astragalus articulating with cuboid. MopIFICATION OF THE UNGULATE Foor. 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 the present connection, as they mark the stages of development in each eroup 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 Dinocerata 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 Ichthyosawrus. Here, as the author has shown,! 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 would 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 Ungulates (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, ete., American Journal of Science, 1880. CONCLUSION. 183 This type of foot would be somewhat like that swampy ground. represented in figure 149, below. Fie. 149. S Seon "2009006 Figure 148.—Left hind limb of Baptanodon discus, Marsh; seen from below; one-eighth natural size Figure 149.—Right fore foot of Chelydra serpentina, Linneus; front view (after Gegenbaur). F. femur; F’. fibula; 7. intermedium; c. central bone; /. fibulare; m. metatarsals; R. radius; r. radiale; T. tibia; ¢. tibiale; U. ulna; w. 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 Examples of nearly this stage are seen in the fore feet of The them. Coryphodon and Dinoceras, as shown in figures 150 and 152, below. 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 This general type of foot belongs latter row with the metapodials below. to the Holodactyla, and isseen 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 with the plantigrade five-toed foot began, the first digit, being the shortest of the series, soon left the ground, and was gradually lost. Fig. 150. Ficure 150.—Left fore foot of Coryphodon hamatus, Marsh, front view. Figure 151 —Left hind foot of same. Both figures are one-third natural size. Fig. 153. .—Left fore foot of Dinoceras mirabile, Marsh. .—Left hind foot of same. Both figures are one-fifth natural size. FIGURE 1 Figure 1 52 33 The four remaining digits, having to do the work of five, were strengthened by the interlocking already mentioned, and also by coming nearer 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 the middle of the 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 the fore foot of Brontotherium and Rhinoceros, figures 158 and 160, below, while Oreodon and the hippopotamus, figures 162-165, show the latter type. Fre. 155. FiguRE 154.—Left fore foot of JZyrax capensis, Schrebr. FIGURE 155.—Left hind foot of same. c. central bone; cl. entocuneiform; p. pisiform; t. tibiale. Both figures are natural size. kigure 156 —Left fore foot of H’ephas Indicus, Linnzeus, Figure 157.—Left hind foot of same. 7 Both figures are one-eighth natural size. 24 186 DINOCERATA. The position of the 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 Paraxonia and Mesaxonia were proposed by the author, as substitutes, to express the true axial relation. Fig. 159. FiGuRE 158.—Left fore foot of Rhinoceros bicornis, Linnzeus. Figure 159.—-Left hind foot of same. Both figures are one-eighth natural size. Fie. 161. Fra. 160. FicurE 160 —Right fore foot of Brontotherium ingens. Marsh. Figure 161.—Right hind foot of same. Both figures are one-sixtli 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 Fig. 163. Fig. 162. FiGureE 162.—Left fore foot of Eporeodon socialis, Marsh. = Figure 163,—Left hind foot of same. Both figures are one-third natural size. Fig. 165. Fig. 164. Tigure 164.—Left fore foot of Lippopcetamus amphibius, Linueus. ligure 165.—Left hind foot of same. Both figures are one-eighth 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 the chief support of the foot, while 188 DINOCERATA. the outer digits left the ground, ceased to be of use, and were lost, except as splint hones. 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. 167. Fig. 166, Fic. 169. Fig. 168. Figure 166.—Left fore foot of horse (Hquus caballus, Linnzeus). Figure 167,—Left hind foot of same. Both figures are one-eighth natural size. Figure 168.—Left fore foot of goat (Capra hircus, Linnzeus). FiGurRE 169.—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 remaining toes, the third and fourth doing all the work, and thus increasing in size and power. The fifth digit, for the same reasons as in the Perissodactyl foot, first left the ground, 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 the 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 horse, antelope, and’ camel, were gradualty 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 horse, 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, especially as the subject will be fully discussed in a future volume. Extinction oF Large MaAmMALs. 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 and Succession of Vertebrate Life in America, 1877. See also New Equine Mammals, ete., 1874, and Polydactyle Horses Recent and Extinct, 1879. 190 DINOCERATA. clearly the monarchs of the region in which they lived. In the upper Eocene, Diplacodon, 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 Brontotheride, 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 disappearance of each group of these large Tertiary mammals is not difficult 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, with 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 estimating distinctive characters. CONCLUSION. 191 The Dinocerata now known may be placed in three genera: Dinoceras, Tinoceras, and Uintatherium. These may be separated by characters of the skull, vertebre, 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 Tinoceratip#, Marsh. Uintatherium, Leidy. Dinoceras, Marsh. Tinoceras, Marsh. Teeth, thirty-six. Teeth, thirty-four. Teeth, thirty-four. Lower premolars, four. | Lower premolars, three.; Lower premolars, three. Base of canine tusk, |Base of canine tusk, | Base of canine tusk, nearly vertical. nearly vertical. horizontal. Parietal protuberance | Parietal protuberance | Parietal protuberance above post-glenoid above post-glenoid behind post-glenoid process. process. process. Cervical vertebrae of Cervical vertebree less Cervical vertebree short. moderate length. elongate. Lunar articulating with) Lunar articulating with Lunar not articulating trapezoid ? trapezoid. with trapezoid. These three genera clearly represent three stages of development of the Dinocerata, 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 ; Dinoceras is from a somewhat higher stratum; and Tinoceras, the most specialized of all, occurs in the latest deposits. In the Synopsis which follows this chapter, a systematic list of all the species of the Dinocerata 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 Dinocerata. , Yee geane . 7 : : Pa Le eres ng : ; Viatts by abs: aye “etd a dgiiee Bos ites f Shy) is Selene gl ad Vel ocrye aNietn =Te wt rat 5. Tarai 1 ' Fines lictaee : Pui vil ie? 4-22 Behan NEON: 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 import ant 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 ‘placed 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 reéxamined, 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 Amblypoda, and Coryphodontia, for Pantodonta, the names replaced being both essentially pre-occupied. The last term, moreover, has no significance when applied to the group of which Cor yphodoni is the original and characteristic type. The names Protungulata, Holodactyla, and “Clinodactyla, express, respectively, a prominent feature of the groups they represent; and hence have been introduced in the preceding chapter. 25 193 194 DINOCERATA. DINOCERAS, Marsh, 1872. Dinoceras mirabile, Marsh. : (Plates J-VIIJ, 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; 68, 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; 128, p. 119; 129, 130, 181, 132, p. 181; 133, p. 184; 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, Plates I and H, February, 1873; Vol. XI, p. 164, Plates I-IV, February, 1876; Vol. XXII, pp. 31, 32, Plate I, 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. XTi, >. 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. 2685 69, 70, p. 272; 76,77, p. 275; 80, 81, 82, p. 278; 100, p. 2895 sey Wilk ;paeuor 120-123, p. 296; 134, 185, p. 301; 136, p. 302, 1884. Garrod, Journal of Anatomy and Physiology, Vol. VII, pp. 267, 268, June, 1873. The same, Complete Writings, pp. 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 Paleontology, Vol. II, pp. 370-373, figs. 656, 657, 1879. Dana, Manual of Geology, 3d ed., Plate VI, figs. 1-4 (from present volume), 1880. LeConte, Elements of Geology, pp. 525, 526, figs. 845, 845 (from present volume), 1882. Flower, Encyclopedia Britannica, Vol. XV, p. 426, fig. 105, 1883. Cope (Uintatherium mirabile).—Hayden’s Report U. 8. 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. XII, 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. D. 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. \ 5 , ‘ Aeivos, terrible, and xépas, a horn. SYNOPSIS. 195 This specimen consists of a skull, complete except the lower jaws, cervical and lumbar vertebrze, ribs, pelvis, limb bones, ete. Other specimens here referrédl to this species are as follows: Number 1195, collected by Mr. J. W. Chew, near Sage Creek, about twelve miles southeast of Fort Bridger, and over thirty miles west of Green River, Wyoming, and consisting of “onlge of the fore lee and foot. Number 1199, collected by Mr. F. 8. Wicks, in 1873, near Henry’s Fork, about ten miles below Lone Tree, and twenty miles west of Green River, Wyoming, consisting of bones of the feet, ete. Number 1 1200, collected by the author, in August, 1873, at the Divide near Henry’s Fork, nearly twenty miles Sone: ast of Fort Bridger, and thirty miles west of Green River, Wyoming, consisting principally of carpal bones. Number 1206, collected by Mr. O. Harger, in 1873, from the Divide west of Henry’s Fork, and consisting of a ee ulna, foe ete. Number 1208, collected by Mr. J. W. Chew and Mr. B. D. Smith, in 1873, near Sage Creek, about fifteen miles southeast of Fort Bridger, and nearly thirty -five west of Green River , Wyoming, and consisting of bones of the feet, ete. Number 1210, obtained by Mr. J. W. Chew, November, 1874, in Wyoming, and consisting of sternum, femur, patella, tibia, feet bones, ete. Number 1211, collected by Messrs. H. G. Cheney and FAY, Oakes in August, 1873, a Old Hat Mountain, Henry’s Fork, eighteen miles Peuineact oe Fort Bridger, and about thirty- five west a Eien River, Wyoming, and consisting of a fore foot, ete. Number 1212, Ghenaed by Wiecers S. Smith and J. W. Chew, November, 1878, near Sage Creek, Wyoming, and consisting of lower jaws, vertebrie, humerus, ete. Number 1215, collected by Messrs. 8. Smith and J. W. Chew, in 1873, at Cattail Springs, nearly thirty miles east*southeast of Fort Bridger, and about eighteen miles w est. of Green River, W yoming, and consisting of a scapula, “portions of the pelvis, ete. Number 1218, collected by Messrs. S. Smith and 8. Pearson, in October, 1875, about four miles below Lone ‘Tree, on Henry’s Fork, and twenty-five miles west of Green River, Wyoming, and consisting of a large part of a skeleton, especially bones of the feet and legs. Number 1225, collected by Mr. J. W. Chew, near Henry’s Fork, about twenty-five miles west of Green River, Wyoming, consisting of portions of the skull, vertebrae, bones of the feet, ete. Number 1226, collected in 1875, by Messrs. S. Smith, J. W. Chew, and the author; at Big Bone Buttes, Wyoming, and consisting of portions of the skull, ete. Namber 230, polled by Mr. E. S. Lane, in August, 1873, on the Divide west of Henry’s Fork, Wyoming, and consisting of carpal bones. oO 196 DINOCERATA, Number 1232, collected by Mr. J. W. Chew, in 1874, in Wyoming, consisting of parts of a pelvis, and various limb bones. Number 1234, collected by Mr. L. Lamotte, at Camp Springs, Wyoming, in 1873, consisting of limb bones, caudal vertebrie, etc. Number 1245, collected in 1872, by Messrs. B. D. Smith and J. W. Chew, at Big Bone Buttes, Wey: oming, "and conane of a humerus, ete. Number 1247, collected 3 in November, 1873, by Messrs. 8. Smith and J. W. Chew, at Tule Springs, near Sage Creek, Wy oming, and consisting of tarsal bones, ete. Number 1248, collected by Mr. B. D. Smith, in 1871, at Henry’s Fork, Wyoming, and consisting of axis, femur, tibia, ete. Number 1251, collected by Mr. J. Heisey, May, 1876, eight miles south of Dug Chorstaras, near Haystack Mountain, about sixty- -five miles east of Green River, and twenty- -five miles south of the Union Pacific railroad, Wy oming) and consisting of vertebrie, ete: Nambar a 2, collected by Mr. § . Smith, in February, 1875, north of Leavitt's aia om Henry’s Fork about twenty miles west of Green River, Wyoming, consisting of parts of the skull, a tibia, fibula, ete. Number 1255, ‘collected in June, 1874, by Mr. ib, Lamotte, at Big Bone Buttes, and consisting of part of the lower jaws, showing milk incisors in position, cervical and dorsal vertebree, ribs, and limb bones, ete. Number 1490, collected by Mr. L. Lamotte, in Wyoming, and consisting of incisor teeth. Number 1514, collected by Mr. J. Heisey, May, 1876, eight miles south of Dug Springs, Wy oming, and consisting of lower jaws with molars. iraayer 1520, collected by Dr. a. V. A. Carter, in Wyoming consisting of fr: agments of a skull, carpal bones, vertebree, ete. Number 1528, collected by Mr. J. W. Chew, in 1875, near Henry’s Fork, Wyoming, consisting mostly of tarsal bones. Number 1529, collected in Wyoming, by an Indian, called Shoshone John, and consisting of a considerable number of bones from several different skeletons. Number 1548, collected by Messrs. 5S. Senithh and J. W. Chew, in November, 1873, near Sage Creek, Wyoming, consisting of a parietal horn-core, tee bones, ete. The ¢ eological horizon of all these specimens is in the Dinoceras, or Bridger, beds of the Middle E Locene, as shown in the section on page 7. The remains of the specimens here described are preserved in the Museum of Yale College. SYNOPSIS. 197 Dinoceras agreste, Marsh, x. s. Woodeut: 15, p. 19. In this species, the nasals are separated in front by a distinct suture, extending back beyond the anterior projection of the premaxillary bone. They taper to a blunt conical point, which is much roughened, but presents no certain evidence of the attachment of prenasals. The diastema behind the upper canine is nearly straight, and of moderate length (about 7 cm.), and, in this region, the palate is strongly vaulted. The palato-maxillary foramen is opposite the first premolar. The posterior end of the malar bone was received into a shallow pit, in front of the glenoid cavity of the squamosal. The occiput (figure 15, page 19) has the upper angles well rounded, and presents a median tubercle in the line of the vertical ridge. The foramen magnum is broad, and rises somewhat above the level of the condyles. The type specimen (number 1221) of this species was discovered in 1873, by Mr. L. Lamotte, near Spanish John’s Meadow, about thirty miles east- southeast of Fort Bridger, and fifteen miles west of Green River Wyoming This specimen consists of a skull, scapula, ribs, ete. The geological horizon of this species is in the Dinoceras beds of the Middle Eocene. The known remains of this species are preserved in the Yale College Museum. Dinoceras cuneum, Marsh, x. s. Woodcuts 93, 94, p. 77; 170, 171, below. Fre. 170. Figure 170.—Nasals of Dinoceras cuneum, Marsh (No. 1207). a. side view; b. top view; c. front view. c One-fifth natural size. The skull in this species tapers in front, but, in the type-specimen (number 1042), the nasal protuberances are not well preserved. The 198 DINOCERATA. maxillary protuberances are well developed, divergent, and connected by a moderate ridge. The top. of the skull behind this is flattened, and separated from the lateral surface by a more or less prominent ridge, rising well on the front surface of the elevated parietal processes. These processes are over the post-glenoid processes. They are high, and, toward the apex, flattened antero-posteriorly, while they expand in transverse diameter. The ridge connecting them across the surface of the skull is present, but not elevated. The foramen magnum is slightly higher than the occipital condyles. The palate is excavated in the region of the diastema. Fig. 171. Figure 171.—Skull of Dinoceras cunewm, Marsh (No, 1042); seen from above. One-eighth natural size. Another specimen (number 1207, figure 170) has the snout very tapering in front, and the nasal protuberances small, though rather prominent. ‘The median suture is entirely obliterated, and the prenasals, if present, are thoroughly co-ossified with each other, and with the nasal bones. The maxillary prominences are rounded, and not very divergent. The parietal protuberances are connected by a transverse ridge. The zygomatic process of the squamosal is not excavated for the posterior end of the malar. The type specimen (number 1042) of this species was secured in May, 1875, by Messrs. 8. Smith and J. Heisey, near Haystack Mountain, about sixty-five miles east of Green River, Wyoming. The specimen consists of a skull, with a nearly complete series of dorso-lumbar vertebrae, sacrum, pelvis, ete. The second specimen (number 1207), consisting of portions of the skull and vertebrae, was found by J. W. Chew and the author, in 1873, near Big Bone Buttes, Wyoming. The geological horizon is in the Bridger beds of the Middle Eocene. The only known specimens are in the Yale Museum. SYNOPSIS. IONS) Dinoceras distans, Marsh. Woodcuts: 4, p. 13; 8, p. 15; 10, p. 16; 31, p. 29. Marsh, Fifth Annual Report U.S. Geological Survey (figures from the present volume, viz :) fig. 41, p. 258; 45, p. 260; 66, p. 270, 1884, The skull in the type specimen of this species (number 1235) has nearly the same general shape as in the type of Dinoceras mirabile, but is somewhat more robust, though pertaining to a young % animal, as thoi by the generally open sutures. The nasals’ taper in front, and bear a pair of low rounded oblique tubercles, much as in number 1036. They are terminated, as in that specimen, by flattened, nearly vertical, and deeply pitted, since surfaces, from which the prenasals have fallen away. The maxillary elevations are stout and conical, and are connected across the median line of the skull by an elevated ridge. The naso- maxillary suture curves inward between the maxillary protuber ‘ances, and is strongly marked on their inner surfaces. Behind the maxillary protuberances, the top of the skull is flattened, and presents two low oblique ridges, converging behind, along the lines ai the fronto-nasal sutures. At the ales, the superior surface is separated from the lateral by a ridge, which rises nearly to the top of the parietal protuberances. These are well developed, triangular in section, and directed upward and outward, and are situated aloes the post-glenoid processes. The foramen magnum is below the upper margin of the occipital condyles. In the type specimen, the post-glenoid process is robust. The zygomatic process of the squamosal is deeply excavated in front of the glenoid cavity, for the posterior end of the malar bone, which is peculiarly blunt, and rounded behind. The palato-maxillary foramen is rounded, and placed opposite the posterior half of the first premolar. The cavity for the brain is exposed it n this specimen, and shows a nasal septum just in front of the anterior constriction. The short olfactory lobes were bounded in front by thin cribriform plates. The young specimen (number 1601) agrees with the type (number 1235) in the general shape of the skull, in the form of the maxillary protuberances and connecting ridge, in the shape. and position of the parietal protuberances, and in “the position of the palato-maxillary foramen. Also in the deep excavation for the end of the malar bone. The known differences may be attributed to age. The type of this species (number 1235) was collected by Mr. 8. Smith, in 1874, near Lone Tree, on Henry’s Fork, Wyoming. The second specimen (number 1601) was found by Mr. Smith in 1882, near Haystack Mountain, Wyoming. The geological eae. of this species is in the Dinoceras beds. The type specimen of this species is preserved in the Yale Museum, 200 DINOCERATA. Dinoceras laticeps, Marsh. (Plates X-XIV, XLIII.) Woodcuts: 14, p. 19; 22, p. 25; 27, p. 26; 33, p. 30; 47, p. 43; 50, p. 44; 57, 58, p. 54; and 112, p. 108; 136, p. 138; 139, 140, p. 149. Marsh, American Journal of Science and Arts (3), Vol. VI, p. 301, October, 1873; Vol. XI, p. 164, Plate V, February, 1876. Osborn and Speir (Uintatherium laticeps).—American Journal of Science and Arts (3), Vol. XVII, pp. 304, 305, 307, April, 1879. The type of this species possesses the main characters of Dinoceras, but, in the premaxillaries, palate, and brain-cavity, shows an approach to Tinoceras, especially Tinoceras pugnax. It apparently represents a sub-genus of Dinoceras, which may be ealled Paroceras. The type specimen of this species (number 1039) was obtained in August, 1873, by Mr. L. Lamotte and the author, near Spanish John’s Meadow, Wyoming. This specimen consists of a skull, lower jaws, vertebre, ete. A second specimen, a female (number 1202), consisting of a skull and other parts of the skeleton, was found by the author, in August, 1873, near Henry’s Fork, about thirty miles west of Green River, Wyoming. Additional specimens are numbers 1197, 1222, 1239, and 1264. 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. Dinoceras luecare, Marsh. (Plate IX.) Woodeuts: 46, p. 43; 103, 104, 105, p. 84; 110, p. 98; 172, 173, below. Fig. 172. — { FIGURE 172.—Nasals of Dinoceras lucare, Marsh (No. 1038). a. side view; b. top view; c. front view. One-fifth natural size. SYNOPSIS. 201 Fig. 173. FigtrE 173.—Nasals of Dinoceras lucare, Marsh (No. 1568). a. side view; 6. top view; c. front view. One-fifth natural size. Marsh, American Journal of Science and Arts (3), Vol. V, p. 408, May, 1873. Fifth Annual Report of the U. 8. Geol. Survey, (figures from the present volume, viz:) fig. 88, p. 279; 124, 125, p. 296, 1884. Leidy (Uintatherium).—Extinct Vertebrate Fauna, p. 334, 1873. The type specimen of this species (number 1038) was obtained by Messrs. B. D Smith, J. W. Chew and the author, two miles east of Big Bone Buttes, Wyoming, September, 1872, and September, 1873. This specimen consists of a skull, and numerous parts of the skeleton. The geological horizon of this species is in the Bridger Beds of the Middle Eocene. The remains of this specimen are preserved in Yale College Museum. Dinoceras reflexum, Marsh, x. s. Woodeut : 174, below. Figure 174.—Nasals of Dixoceras reflecum, Marsh (No. 1229). a, side view; b. top view; ¢. front view. One-fifth natural size. In the type of this species (number 1229), the nasal protuberances are small, but prominent, and are directed strongly upward. ‘The nasal bones are completely united to the end, but are there terminated by sutural surfaces, looking nearly downward, and indicating the position of the prenasal bones, which have fallen away. The suture between the nasal and the premaxillary is evident, behind and below the nasal protuberance. 26 202 DINOCERATA. The post-glenoid process is large and strong, and the zygomatic process of the squamosal pr esents a pit for the end ae the malar bone just in front of the glenoid cavity. The occipital crest shows a median keel on its posterior Sree. A cervical centrum, from which the epiphyses have nearly separated, shows that these vertebrze were proportionally shorter than in number 1255. ae vertical diameter is to the longitudinal as 1 to .55, while in number 1255 these dimensions are about as i to .6. A py1 pantie bone, accompanying these specimens, has the face for the fifth metacarpal confluent with that for the unciform, as in figures 117 and 118, page 108, instead of distinct, as on Plate XXXII, figure 6. The specimen ae 1229) upon which the species is based was collected in October, 1873, by Messrs. J. W. Chew and §. Smith, at Tule Springs, Wyoming. This specimen consists of fragments of the skull, limb bones, ete. The geological horizon of ihe species is in the Bridger beds of the Middle Riecenen The known remains are preserved in Yale College Museum. TINOCERAS,’ Marsh, 1872. Tinoceras — Marsh. Woodeuts: 97, 98, p. 80; 175, 176, 177, below. > >| Fie. 175. Figure 175.—Nasals of Tinoceras anceps, Marsh (No. 1266). a. side view; b. top view; c. front view. One-fifth natural size. Marsh (Titanotherium ? anceps.)—American Journal of Science and Arts (3), Vol. II, p. 35, July, 1871. (Mastodon anceps.)—American Journal of Science and Arts, Vol. IV, p. 123, note, August, 1872. (Tinoceras anceps.)—American Journal of Science and Arts (8), Vol. IV p. 322, October, 1872. (The name Tinoceras was published in adyance, August 19, 1872, see Bibliography.) Vol. IV, p. 328, October, 1872 fe IV, p. 504, ‘Decem- ber, 1872; Vol. V, pp. , 122, February, 1873; Vol. V,; p- 296, April, 1873. ’ Tiv@, to tear, and xépas, horn, SYNOPSIS. 203 Fig. 177. Fig. 176. Fieure 176.—Left parietal protuberance of Tinoceras anceps, Marsh (No. 1030); side view. FIGURE 177.—The same specimen; front view. a. anterior crest; b. posterior crest. Both figures are one-half natural size. Marsh, American Naturalist, Vol. VII, p. 52, January, 1873; pp. 147, 152, March, 1873; p- 218, April, 1873; Vol. VII, Appendix, p. viii, June, 1873. Proceedings of the American Philosophie al Society, V ol. XII, p. 578, for 1872, 1873; Vol. NOME p- 256, 1873. Cope (Uintatherium anceps.)—Proceedings of the American Philosophical Society, Vol. XIII, p. 61, 1873. The type specimen of this species was of small size, and evidently a female. The occiput is elevated, and has a median vertical ridee. The lateral crests extend from the front nearly to the summit of the parietal protuberances. The latter are connected by a strong ridge passing directly over the brain-cavity. The post-glenoid processes are triangular in horizontal section, with the apex outwar dd. A second specimen (number 1266) has the nasal protuberances of moderate size, and resembling those of Tinoceras grande. ‘The prenasal bones are firmly co-ossified with the nasals. The type specimen (number 1030) was discovered by Lieut. W. N. Wann, in September, 1870, on the Divide near Sage € ‘reek, fifteen miles southeast of Fort Bridger, Wyoming. The remains of this specimen consist of portions of the skull, cervical and dorsal vertebra, and a tibia. The second specimen (number 1266) was found by Messrs. J. W. Chew and L. Lamotte, in August, 1874, in Wyoming. It consists of portions of a skull, and a few other bones. The geological horizon of this species is in the Dinoceras beds of the Middle Eocene, The known remains of this species are preserved in the Yale College Museum. = 204 DINOCERATA. Tinoceras affine, Marsh, ~. s. Woodcuts: 16, p. 19; and 178, 179, below. Fig. 179. Figure 178.—Vertical section through cranium of Zinoceras affine, Marsh (No. 1574). Figure 179.—The same specimen; seen from above. ps. parietal supra-occipital suture; fp. fronto-parietal suture; o. occipital condyle: ol. olfactory lobes of brain; p’. parietal protuberance ; s. supra-occipital crest. Both figures are one-eighth natural size. In the type of this species (number 1574), the snout tapers, and the nasals are divided by a,distinct median suture. The nasals are well preserved, and much resemble those of number 1041, but are more perfect. As in number 1040, they are thoroughly co-ossified to the extreme point, which is directed obliquely downward. ‘The nasal protuberances are placed obliquely, and are flattened on their outer anterior surface. They are directed outward and upward, and are elongate- oval in section, the long axes of the ovals making about a right angle with each other in front of the snout. The maxillary protuberances are elevated, but of moderate size, and are connected across by a rounded ridge. The parietal protuberances present a moderately sharp ridge on their anterior faces, and are somewhat club-shaped. They were connected across the top of the skull by a rounded ridge. The foramen magnum is transversely oval, and rises nearly to the same height as the occipital condyles. ‘The post-glenoid process is robust. The occipital crest bears a rather prominent, but rounded, ridge along the median line, above the foramen magnum. The palate is moderately excavated in front, and the palato-maxillary foramen is opposite the first premolar. The diastema is thick, strong, short, and straight. The vomer is preserved in this specimen, firmly lodged in a groove in the upper surface of the maxillaries ——————E———=— ee SYNOPSIS. 205 The face on the zygomatic process of the squamosal for the malar is broad and flat, and does not end in a pit, for the posterior end of the malar bone. In this species, the brain occupies a very oblique position in the skull, as shown in the accompanying woodcut, figure 178. In the section of the cranium, the sutures defining the anterior and posterior limits of the parietal bones along the median plane of the skull are clearly shown. The fronto-parietal suture also (figure 178) is apparent on the superior surface of the skull, above the anterior part of the cavity for the cerebral hemispheres, as in Dinoceras distans (number 1601). The suture limiting the parietal posteriorly is evident in the same section. It is behind the cerebral cavity, but cannot be traced with certainty on the upper surface of the skull. The type specimen (number 1574) of this species was obtained by Mr. J. Heisey, eight miles south of Dug Springs, Wyoming, in 1876 This specimen consists of a skull, ete. The geological horizon is in the Dinoceras beds of the Middle Eocene. The only known remains of this specimen are in Yale College Museum. Tinoceras annectens. Marsh. - Woodcuts: 6, p. 13; 21, p. 21; 36, 37, p. 36. Marsh, Fifth Annual Report U. 8. Geological Survey, (figures from the present volume, viz:) fig. 48, p. 258; fig. 56, =. 264; fig. 73, 74, p. 274, 1884. The skull in the type of this species (number 1043) agrees generally in size and form, as far as preserved, with that of Tinoceras ingens, “(number 1041). The canine tusk runs somewhat forward in number 1043, and the premaxillaries appear less robust. The palato- -maxillary foramen is near the front premolar, not well in front of it, as in Tinoceras ingens. The upper canine (page 21, figure 21) has, on its outer side, a large, somewhat heart-shaped, worn surface. The lower jaw in this species is slender, and bears a well developed process running downward and forward, and terminating in an oblique, nearly straight margin. The coronoid process is pointed. The first dorsal in this specimen is proportionally shorter than in Tinoceras anceps, with the lateral faces for its ribs more approximate. The length of the floor of the neural canal is to the length of the under surface of the centrum as 3 to 4, and a similar proportion in the adjoining vertebra indicates an upwar T curvature in the neck at this point. 206 DINOCERATA. The pe of this species (number 1043) was found by. Mr. J. Heisey, in May, 1874, near Haystack Mountain, Wyoming. The remains consist of a skull, aie other portions of the skeleton. Che geological horizon is in the Bridger beds of the Middle Eocene. The ‘only “known specimen of this species is in the Yale College Museum. Tinoceras cornutum, Cope, sp. Woodeuts: 180, 181, below. Fie. 180. FIGURE 180.—S8kull of Tinoceras cornutim, Cope, sp.; side view. This figure and the following were photographed on wood from Prof. Cope’s original photographs, for which the author is indebted to the late Prot sbonig Agassiz. ‘These photographs, although both marked 4, are not of the same size. The present figures are copies, both reduced in the same proportion. . The white portion at the base of the tusk is plaster, and the tooth is thus made to appear longer than in nature. The tusk itself belongs on the other side. SYNOPSIS. 207 Fie. 181. FiguRE 181.—Skull of Zinoceras cornutum, Cope, sp.; seen from below. Both figures are about one-eighth natural size. Cope (Lefalophodon dicornutus).—Proceedings of the American Philosophical Society, Vol. XII, p. 515, for 1872. 1873. Telegram from Black Buttes, Wyoming, October, 1872. The same, Paleontological Bulletin, No. 5, Second Edition, 1873. (Eobasileus cornutus.)—Notices of new Vertebrates from the upper waters of Bitter Creek, Wyoming, November, 1872. Proceedings of the American Philosophical Society, Vol. XII, p. 485, for 1872, 1875, The same, Paleontological Bulletin, No, 6, 1873. American Naturalist, Vol. VI, p. 774, December, 1872; Vol. VII, p. 49, January, 1873; Vol. VII, pp. 158, 159, March, 1873. Hayden’s Report of the U. 8. Geological Survey for 1873, p. 457, 1874. (Loxolophodon cornutus.)—Proceedings of the American Philosophical Society, Vol. XII, pp. 488 and 580, for 1872, 1873; Vol. XIII, pp. 45-54, Plates LIV, 1873. American Naturalist, Vol. VII, p. 291, Plates IV, V, May, 1873; Vol. XIII, p. 334, May, 1879; Vol. XVI, Plate XVII (Restoration), December, 1882. Hayden’s Report of the U. 8. Geological Survey for 1872, pp. 568-575, Plates 1-4, 1873. Osborn, Memoir upon Loxolophodon and Uintatherium, pp. 18, 20, 21, 27, 37, 44, 1881. Osborn and Speir, American Journal of Science (3), Vol. XVII, pp. 304-309, Plate I, April, 1879. Leidy (Uintatherium cornutum).—Extinct Vertebrate Fauna, pp. 333, 334, 1873. Marsh (Tinoceras cornutus).—American Journal of Science and Arts (5), Vol. V, pp. 296, 311, April, 1873. (Tinoceras grande.)—American Journal of Science and Arts (3), Vol. V, p. 294, April, 1873. American Naturalist, Vol. VII, p. 217, April, 1873; Vol. VII, p. 306, May, 1873; Vol. VI, Appendix, p. ii, June, 1873. Proceedings of the American Philosophical Society, Vol. XIII, p. 255, 1873. In the restoration of this species as given by Professor Cope in the American Naturalist, Vol. XVI, Plate XVII, the skull used is the male one here figured, with the tusk much elongated. The lower jaw below it belonged to a female, possibly of another genus. The scapula, as restored, is unlike that of any of the known Dinocerata, and the entire fore limb is in a position anatomically impossible. 208 DINOCERATA. The type of the present species was obtained by Prof. E. D. Cope and Mr. S. Smith, in August, 1872, at Haystack Mountain, Wyoming. The remains consist of pone as of a skull, and other parts of the skeleton. : The skull as here figured is in the collection of Prof. Cope. Some other portions of the same skull and skeleton, subsequently collected by Mr. 8. Smith, are in the Yale Museum Tinoceras crassifrons, Marsh. Woodcuts: 30, p. 29; and 182, below. Figure 182.—Nasals of Tinoceras crassifrons, Marsh (No. 1236). a. side view; b. top view; c. front view. ‘ One-fifth natural size. Marsh, Fifth Annual Report of the U. 8. Geological Survey, (figure from the present volume, viz:) fig. 65, p. 270, 1884. The nasals in the type of this species (number 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 the 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 protuberances. These 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. Woodeuts : 183 and 184, below. Fig. 184, Fie. 183. FIGURE 1383.—Nasals of Tinocerus guleatum (after Cope); a. side view; b. top view. FIGURE 184.—Posterior surface of same skull. Both figures are one-eighth natural size. These figures were photographed 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 Philocophical Society, Vol. XLV, Polisi. (Loxolophodon galeatus.)—Hayden’s Report U.S. Geological Survey for 1873, Plate I, 1874. Osborn, Memoir upon Loxolophodon and Uintatherium, pp. 21, 22, 1881. The specimen upon which this species was based was obtained by Prof. E. D. Cope, in 1875, 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. 24 210 DINOCERATA, Tinoceras grande, Marsh. Woodcuts: 20, p. 21; 49, p. 44; 84, 85, 86, p. 71; 87, 88, p. 75; and 185, below. Fie. 185. Figure 185.—Nasals of Tinoceras grande, Marsh (No. 1040). a. side view; . top view; c. front view. One-fifth natural size. Marsh, American Journal of Science, Vol. TV, 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. XIU, p. 256, 1873. Fifth Annual Report of the U. 8S. Geological Survey, (figures from the present volume, viz:) fig. 55, p. 264; 86, p. 2805 113, 114, 115, 118, 119, p. 295, 1884. Cope, Proceedings of the American Philosophical Society, Vol. XIII, pp. 54, 61, 1873. (Loxolophodon cornutus).—Hayden’s Report U. 8. Geological Survey for 1872, p. 575, 1878. The type 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 vertebree. The geological horizon of this species is in the Middle Eocene, in the Dinoceras beds. The known remains are preserved in Yale College Museum. Tinoceras hians, Marsh. Woodecuts: 32, p. 30; and 186, below. Fie. 186. FicurE J86.—Nasals of Tinoceras hians, Marsh (No. 1499). a. side view; b. top view; c. front view. One-fifth natural size. SYNOPSIS. 211 Marsh, Fifth Annual ever of the U. 8. Geological Survey (figure from the present volume), fig. 67, p. 271, 1884. The snout in the 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 separe ated hon the efor surface by a ridge, rising gradually upon the parietal. protuberances, which are connected by a transverse elevation across the skull, 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 than 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 s specimen consist of a skull, vertebrie, ete. 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 ingens, Marsh. (Plates XV-XVIII, LVL) Woodcuts: 9, p. 16; 17, p.19; 28, p. 25; 28, p. 27; 51, p. 45; 59, p. 55; 115, 116, p. 105; 117, p. 108; 124, p. 1195 154, 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, p. 261; 52, p. 263; 58, p. 267; 63, p. 269; 88, p. 281; 96, 97, p. 286; 126, 127, p. 2973 137, p. 302, 1884. The type specimen (number 1041) of this species was collected by Mr. 8. 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 jugum, Marsh. Woodeut: 187, below. Figure 187.—Nasals of Miocene jugum, Marsh (No. 1500). a. side view; b. 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 codssified, and project in front beyond the tubercles. The maxillary protuberances are high, and stronely divergent. They are connected by a high sharp ridge, eihich suggested the specific name. The type of this species (number ile 500) was found by 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 lacustre, Marsh. W oodeut: 188, below. Fig. 188. Figure 188.—Upper molars of Tinoceras lacustre, Marsh (No. 1037) ; seen from below. m. first true molar; pm. first premolar. Three-fourths natural size. Marsh (Dinoceras lacustris).—American Journal of Science and Arts (3), Vol. IV, p. 344, October, 1872. Proceedings of the American Philosophical Society, Vol. XLII, p. 256, 1875. g | Y> } Cope (Uintatherium lacustre).—Hayden’s Report U. S. Gesldaieal 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 1057) 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, x. s. W oodecuts: 189 and 190, below. FIGURE 189.—Nasals of Tinoceras latum, Marsh (No. 1242), a. side view; 0, top view; c. front view. One-fifth natural size. Fie. 190. —S Figore 190.—Nasals of Tinoceras latum. Marsh (No. 1533). a, side view; b, 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 arr oblique sutural surface. The skull presents a transverse ridge above the brain cavity, uniting the parietal protuberances. 214 DINOCERATA. ‘The teeth preserved are but little worn, indicating a fully adult, but not old, animal. Another specimen (number 1535) referred to this species is quite unlike any other in the collection in the form of the nasal bones so far as presery ed, but, unfortunately, the specimen is considerably eroded. The snout, Fase of tapering, expands forward, 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 fie end of those bones, which were thoroughly consolidated, Bal directed somewhat downward, mmdeeneael the broad shelving protuberances. The left maxillary protuberance preserved with this specimen is of large size, and flattened on its outer side. This species, with Tinoceras cornutum, forms a distinct sub-genus of Tinoceras, which may be called Platoceras. 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), Ue aa a very old individual of the same species, was found in May, 1875, by Messrs. 8S. 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. 192. Ficure 191,—Left maxillary protuberance of Tinoceras longiceps, Marsh (No. 1256, female); side view. Fraure 192,—Left parietal protuberance of same skull; side view. The dotted line shows the outline of the cavities (a and b) at the base of each specimen. Both figures are one-fourth natural size. SYNOPSIS. 215 “a 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 are 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 flattened 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 oe elenoid cavity. 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 45). 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 by 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, ete. 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.) Wicodeuts: bsp) ts Sap: 19519. p. 2 245 p. 25; 295 p. 277 ; ’ 52, p. 45; 67, p. 63. Marsh, Fifth Annual Hepext of the U.S. Geological Survey, (figures from the present volume, viz:) fig. 42, p. 258; 53, p. 263; 54, p- 264; 59, Darcie 64. p 269s SO. p- 282; 104, p. 290, 1884. : The type specinien 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 a the diastema. They are robust and recurved. The parietal protuberance es are of moderate height, and transversely compressed at their summits. The premaxillaries are widely separate din 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 XLX, figure 1). This specimen represents a distinct sub-genus of Tinoceras, which may be ealled Laoceras. The type ees (aumber 1044) of this species was found by Mr. S. Smith, May, 1875, at Haystack Mountain, Wyoming. This specimen consists of a skull 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 Speirianum, Osborn, sp. Woodeut: 193, below. Fic. 193. iCURE 193.—Skull of Tinoceras Speirianum, side view (al.er Osborn) One-eighth natural size. Osborn (Loxolophodon Speirianum).—Memoir upon Loxolophodon and Uintatherium, pp. 18, 20, 21, 22, 24, 41, 44, Plate I, 1881. This figure was photographed on wood from the lithographic pe cited above. ‘The restorations of this skull do not allow some of its important features to be determined, but the generic characters are ean 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 i 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. 217 Tinoceras stenops, Marsh. Woodecuts: 53, 54, p. 47; and 194, below. Fig, 194. FieurE 194.—Skull and lower jaw of Tinoceras stenops, Marsh (No. 1567). ¢. condyle of lower jaw; d. diastema; m’. maxillary protuberance; 7’. nasal protuberance ; 9. occipital condyle; p’. parietal protuberance ; pm. premaxillary hove. One-eighth natural size. Marsh, Fifth Annual Report of the U. 8. Geological Survey (figures from the present volume, viz:) figs. 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 protuber: ince 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 lateral 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 the region of the diastema, and the palato- maxillary foramen is just in front of the first premolar, but not so far in front as in 7inoceras ingens (number 1041). The lower jaw is slender, and expands rapidly in the region of the symphysis for the formation a the flanges protecting the canine tusks. When seen from above, the angle at which the rami meet at the symphysis is distinctly vomlel in front, though somewhat less strongly than in Dinoceras luticeps (Plate XII, figure 1). i he type specimen (number 1567) of this species was collected by Mr. 8. Smith, at Haystack Mountain, Wyoming, in May, 1882. The remains of this specimen consist of a skull, w ith lower jaw, ete. The geological horizon of this species is in fhe Dinoceras beds of the Middle EKoe ene. The known remains of this species are in the ‘ale College Museum. Tinoceras vagans, Marsh. W oodeut: 12, p. 17. Marsh, Fifth Annual Report of the U.S. Geological Survey, (figure from the present volume, viz:) fig. 49, p. 262, 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 upward. ‘The nasal bones are united throughout. The maxillary protuberances are slender, but prominent, and anited across by a low rounded ridge. The upper surface of the skull is separated from the lateral surface, above and behind the orbits, by a ridge, which rises upon the parietal protuber: inces. ‘These are prominent, and are flattened antero-posteriorly. ‘They were connecte xd across the top of the skull by a low transverse elevation. The type specimen (number 1241) of this spec ies was discovered by Mr. S. Pearson, at Red Dog Buttes, Wyoming, in July, 1875. This specimen consists of "port ions of the skull, ete. 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 Uintatherium robustum, Leidy. Woodcuts: 61, 62, p. 57; and 195, below. Fig. 195 Ficure 195.—Skull of Uintatherium robustum, Leidy (type specimen); bottom view of back part of skull. /. foramen magnum; /’. occipital foramen; g. stylo-mastoid foramen; h. foramen lacerum ; 7. vascular foramen in basisphenoid. Kd One-fourth natural size. Leidy, Proceedings of the Philadelphia Academy of Natural Sciences, pp- 169, 241 American Journal of Science and Arts (3), Vol. IV, p. 240, September, 1872. Extinct Vertebrate Fauna, pp. 93, 96, 3338, 334, Plate One Plate XXVI, figs. 1-8 Plate XX VII, figs. 80-34, 1873. ; Cope, Proceedings of the P hiladelphia Academy of Natural Sciences, p. 102, March, 1873; p- 295, for 1882, 1883. Hayden’s Re eport U. 8. Geological Survey for Pas 581, 583, 1873 American Naturalist, Vol. V HI, p. 159, March, 1873; Vol. XV I, p- 68, January, 1883. Proceedings of the American Philosophie val Seca. Vol. XIII, pp. 62, 64, 1873. Marsh, American Journal of Science and Arts, Vol. V, p: 296, April, 187 3. American Naturalist, Vol. VII, p. 147, March, 1873. Proceedings of the American Philosophical Society, Vol. XII, p. 578, 1872. Osborn, Scott and Speir, Paleontological Report, 1877, pp. 62, 71, 82, 1878 Osborn, Memoir upon Loxolophodon and Uintatherium, pp. 18, 28, 1881. Leidy (Uintamastix atrox).—Extinct Vertebrate Fauna, pp. 94, 107, 333, 1873. >] ? The type specimen of this species was collected in 1872, by Drs. J. V. A. Carter and_J. K. Corson, fifty miles east of Fort Bridger, 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. *Uintu, Indian name, and 6ypiov, a wild beast. 220 DINOCERATA. Uintatherium fissidens, Cope, sp. Woodeuts: 196 and 197, below. Fig. 196. Fig. 197. Figure 195.—Lower jaw of Uintatherium fissidens (after Cope); top view. Fieurr 197,—The same specimen; front view. Both figures are two-thirds natural size. The above figures were made by a direct transfer from the original woodeuts cited below. Cope (Bathyopsis fissidens).—Bulletin of the U. 8. Geological Survey of the Territories, Vol. VI, No. 1, pp. 194-196, February, 1881. Proceedings of the ewer can P hilosophic al Soe iety, Vv ol. XX, pp. 176, 177, 1882. American Naturalist, Vol. XV, p. 75, January, 1881; Vol. XV I, jos. WHE, Ke 7K 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 cer tainty, but is apparently i in the Bridger beds of the Eocene. The type specimen is preserved i in Prof. Cope’s collection. Uintatherium lJatifrons, Marsh. Woodeuts: 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. 264, 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 forw ard beyond them. The maxillary protuberances are large, and rounded, and are connected by a very low transverse SYNOPSIS. 221 ridge. The 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 1251) 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, ete. 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. Uintatherium Leidianum, Osborn, Scott, and Speir. Woodeut: 198, below. Fig. 198. WN XS FIGURE 198.—Skull of Uintatherium Leidianum (after Osborn, Scott, and Speir); oblique side view. About one-eighth natural size. This figure was photographed on wood from the original heliotype plate, cited below. Osborn, Scott, and Speir, Paleontological 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-ef this species was collected in 1877, near Dry Creek, in Wyoming. bo iw) bo DINOCERATA. This specimen consists of a skull, and portions of the skeleton. The geological horizon of this species is in the Dinoceras beds of the Middle Eocene. The type specimen is preserved in the Princeton Museum. Uintatherium segne, Marsh. Woodcuts: 41, 42, p. 39; 101, 102, p. 88; and 199, 200, below. Fig. 200. Fie. 199. pee FIGURE 199.—Maxillary protuberances of Uintatherium segne, Marsh (No. 1194); seen from above. F1GurRE 200.—The same specimen; seen from in front. m’. maxillary protuberance; nm. nas2l bone. Both figures are one-fourth natural size Marsh, Fifth Annual Report of the U.S. Geological Survey, (figures from the present volume, viz:) figs. 78, 79, p. 276, 1884. The maxillary protuberances of the skull of this specimen are peculiar for their robust form. They are connected by a well developed transverse ridge. The parietal protuberances are massive, and somewhat elub-shaped, and present a ridge in front, as in Dinoceras mirabile and Tinoceras ingens, 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, Wyoming, in October, 1873. The remains of this species consist of a lower jaw, and other parts of the skeleton. 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. SYNOPSIS. Amblypoda, see Amblydactyla. Bathyopsis fissidens, see Uintatherium fissidens. Dinocerea, see Dinocerata. Dinoceras lacustris, see Tinoceras lacustre. Mopasilens cornutus, see Tinoceras cornutum. Eobasileus furcatus, see Tinoceras. Eobasileus galeatus, see Tinoceras galeatum. Eobasiliidee, see Tinoceratide. Lefalophodon bifurcatus, see Tinoceras. Lefalophodon excressicornis, see Tinoceras. Lefalophodon discornutus, see Tinoceras cornutum. Loxolophodon anceps, see Tinoceras anceps. Loxolophodon cornutus, see Tinoceras cornutum. Loxolophodon fureatus, see Tinoceras. Loxolophodon galeatus, see Tinoceras galeatum. Loxolophodon grandis, see Tinoceras grande. Loxolophodon pressicornis, see Tinoceras. Loxolophodon Speirianum, see Tinoceras Speirianum. Mastodon anceps, see Tinoceras anceps. Pantodonta, see Coryphodontia. Titanotherium? anceps, see Tinoceras anceps. Uintamastix atrox, see Uintatherium robustum. Uintatherium cornutum, see Tinoceras cornutum. Uintatherium lacustre, see ‘Tinoceras lacustre. Uintatherium laticeps, see Dinoceras laticeps. Uintatherium princeps, see Uintatherium. Uintatherium lucare, see )inoceras lueare. Uintatherium mirabile, see Dinoceras mirabile. Uintatheride, see Tinoceratide. ae Ree eM EAL AAD ats Kt ." ¢ a, Ee nee ~ = jialy hi wit! erect: ¥" Fas J = 7 SO Oe ERE, ee on Hea Bx Desieatl ag ; =! La) yee Ve perdhd ah ae tata | Ta wien Aas 2 ae i Me eT TL PS eel ae eM ORs cho: Pie te rite be,® — IS} 11S}. Gaudry, Albert.—Les Enchainments du Monde Animal dans les temps Géologiques. Mammiféres Tertiares, 8vo, pp. 1-293, figure 86. aris, 1878. Marsh, Othniel Charles.—Tinoceras.—Johnson’s New Universal Cyclopedia, Vol. IV, pp. 868, 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 Osborn, Henry Fairfield; Scott, William Berryman; Speir, Francis.— Palxontological Report of the Princeton Scientific Expedition of 1877; Contributions from the Museum of Geology and Archeology of Princeton College, No. 1, 8vo, pp- 146, Plate A, and I-X. New York, 1878. Contains (pp. 62-82, Plates VI, VII) first descriptions of Vintatherium 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 Paleontology, 8vo, Vol. II, p. 370-373, figs. 656, 657. Edinburgh and London, 1879. Description of the Dénocerata, with figures of the skull and feet of Dinoceras mirabile, from the present volume. 1880. Dana, James Dwight.—Manual of Geology, Third Edition, 8vo, pp. 504, 508, Plate VII, figs. 1-4; Plate XI, fig. 1. New York, 1880. A reference to the Dinocerata, 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 fissidens. 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, pp. 121-123. London, 1881. Opinion that the Dinocerata belong to a family of the Artiodactyla. Marsh, Othniel Charles.—Restoration of Dinoceras mirabile-—American Journal of Science (3), Vol. XXII, pp. 31, 32, Plate I. New Haven, July, 1881. The same, published in advance, June 14, 1881. First restoration of Dinoceras mirabile, new characters in the skull and sternum, and distinction stated between this genus and Uintatherium. 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 Uintatherium (Two Genera of the Sub-Order Dinocerata).—Contributions from the E. M. Museum of Geology and Archeology of the College of New Jersey, Vol. I, No. 1, 4to, pp. 54, Plates I-IV. Princeton, 1881. A general discussion of the Dinocerata, and first description of Tinoceras Speirianum, with a restoration. The statement on page 17 in regard to the discovery of the Dinoceratu 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 1881.—Proceedings of the American Philosophical Society, number 111, for 1882, pp. 139-197. Philadel- phia, 1882. [Cope, Edward Drinker.|—American Naturalist, Vol. XVI, plate XVII, 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, 8vo, pp. 440. Second Edition, London, 1882. [Dinocerata, pp. 840-342, figure 146. | 18838. Cope, Edward Drinker.—On Uintatherium and Bathmodon.—American Naturalist, Vol. XVI, 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.—Encyclopedia 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. An 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 Uintatherium /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 elsew here. 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. ’ =a a ae ey a | pr t. oe ee | wee #. eel TT : eee ce ‘eh Soap ie : : a oe if ~ ° y « 7 oP. * ted ota or | fpo~Gleat t = .— , ny : F oe D : aed it 191; i =a h MOM: 4 Se a a, e u pty ee OLS a =) 5, Preheat = 7 _ _ me Sos “ihe wa as ‘ Lit . gl Asay “ait a : 7 ‘ } leeeiehr ts. = aee ae Exe as 299 Ty ye 3 ; : - oe mea : a : «, foe oe eas hsicuereae . ; ial oo ot eed ak Site > Nh ele a als . : ; | by : she bane sti = hain ie Aly, We ty pice Ley 2a. AO Re tees tHiee en bight Se . ‘eae : 1 ; j ‘ wh Yre Als bts Fe, 3 F ; ro, ‘ te OF leg ae ibe Dery: “- enh oh ‘of eR) ee , os = A. Page. Amblydactyla, characters of the .--.------..--..--- 176 Amia, occurrence of, with Dinocerata remains. ----. 9 Amynodon advenus, view of skull of ...-...--..--. 64 Anterior dorsal ribs, description of the ....--.--.-- 130-132 Artiodactyla, comparison of, with Dinocerata -----. 181 development of foot in..... .--...-...-. ------ 188, 189 Astragalus, views and description of the (PI. >-TEN ATI) Seed SG RECA Teen ee eee 146-151 | Atlas, views and description of the (Pl. XX)...-.-. 69-71 | Auchenia vicugna, view of skull of.--.....--..----- 67 | Axis, views and description of the (Pl. X XJ) -.---- 72,73 B. Baptanodon discus, view of left hind limb of --.---. 183 Baur, G., acknowledgment of aid of ......-.-..----. XVI Bibliography of Dinocerata ........-....--.-------. 225-237 Brainy description of they. --.-.-s.-.-----.-------=. 53-67 Brain-cast, views and description of the (Pl. VI)... 53-55 Brain-growth, description of........-.....--------- 57-67 Brain-growth in mammals, laws regulating. .--...-. 58-60 IWGP URE WES) ane Smee ASmer Asa eeScSnQOSeees CSS 6 Brontotberium beds, situation of the_..-....-...-.-.. 6 Brontotherium ingens, view of skull of ......--..--. : 61 wiew Of riphtiteetiOf..2s—.-.2--— 5 =-ceanennc=- === 186 C. Caleaneum, views and description of the (Pl. SRSLVPL)) coerce ine aioe io toilemian isin nia esta alsiee 151-153 | Canines; Gcescuptioni ofthe. .2---- 2c. 5- ce oeeaemn, == 48-46 | Capra hircus, view cf left feet of -.....-.....--..--. 188 Carpal bones, description of the .-.-..-....-.-...--- 101 Carter, J. V. A., collection of specimens by .----. .- 196, 219 | Caudal vertebra, views and description of the (PI. RIG TIM) amienissce cm se ese cee ce cece: sectose succes 138 Cervical vertebra, views and description of the (RG SRERaIM) eee Ses ee as 69-78 Cervus Virginianus, view of skull of-....-...-- > 67 Chelydra serpentina, view of right fore foot of... .-- 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 Clinodactyla, characters of the.....-........--.. mh 175 Colonoceras, occurrence of, with Dinocerata remains 9 Colonoceras agrestis, view of skull of... ..--.....-. G4 Gone] nsions juges. so ene eee see ese ee ee eee eet en 169-191 Cope, E. D., Dinocerata collections of .......- a5 4,5 cvllection of specimens by .-..--.-......-- -- 208, 209 publications of, respecting Dinocerata .-....... 226-237 Coryphodon, dentition #f, contrasted with that of Dinbreratarcc cas tay aan ie cee See eee 51 Coryphodon and Dinocerata, comparison 6fastraga- LIVNI. S33 SG acer CRA Aa Sor arc gaee ecec a eie oars 148 Pa INONON DEO Hoo! nese cee ka rs poe eoesl oe cee 5,6 Page. Coryphodon hamatus, views of molar series of .----- 52 view of skull of .....--..----- soce eeotO SES eara 63 MIOWs OmetG feel Olea nas eae) ae eens ola aia 184 Coryphodontia and Dinocerata, characters in com- MOONCO Lets Seen “nai: SARS o! AeeoSIeRSAaS 179 Corson, J. K., collection of specimens by ---. ------- 219 Cramial nerves, description of the... .----..-- ---- 55-57 Cuboid, views and description of the (P]. XLIX)-.- 153-155 Cuneiform. See Pyramidal. D. Dana, J. D., references to Dinocerata in publica- tions Of--235-ss-s- 2+ === Oy Mopreee oe eee 235 Dicotyles torquatus, view of skull of ..--.-..-.-..--- 67 Dinoceras, place of, among Dinocerata --...- 10 variation of premaxillaries in ---.. 24 dentition Ofeesss=--e asset ane ah 41 LOTITO) eee eapSeee ead Sec one 5 56 measurements of first metacarpal of --- 121 measurements of fourth metacarpal of --- 126 characters of the genus......--.....- ------ 2 191 list of species of, with account of specimens --.. 194-202 Dinoceras agreste, view of skull of.--.-.-----.------ 19 description of occiput of 20 description of specimens of ..-...--..-----.----- 197 Dinoceras and Mastodon Americanus, comparison GVEA ae nees ) Secoeeea <2 omeccono 137 Dinoceras and Tinoceras, restorations of.....-.----- 165-168 Dinoceras beds, situation of ...--..---..---...-..--- 3,6 Dinoceras cuneum, views and description of sixth CERVICAL svertenTa OL. oat s=sene meee ee are ee 77 measurements of sixth cervical vertebra of-.-- 78 description of specimens of ---..--.------------- 197, 198 Dinoceras distans, view of nasals of .-.--.-.----..--- 13 Me WIOLe KUO hace: teen costae eee oe Seca e en 15, 16, 29 description of specimens of ..--..--..-----.----- 199 Dinoceras laticeps, view of skull of .. .---. .-.--.19, 26, 30, 54 description of occiput of. ...--..-.-.------------- 20 Wie Ol palate Ofess aaa. q eee aees <= 25 views and descriptions of skull of (Pl. X, XI, 3:11). s55e25) saqnosos- aecono nae aden Cabs estas 26,45 views and descriptions of lower jaw of (P]. XI, S000) ge cckaeseoococticsoes 35, 36 measurements of lower jaw of- 5 40 view of upper canine of ....---.-.----.-------.-- 43, 44 view and measurements of left scaphoid of. --.-- 103 views and descriptions of caudal vertebre of (PI. S.C) 010 0b een te eo em enn ROBES CREE a paococ 138 views of left astragalus of ......-..----..----.-- 149 measurements of left astragalus of..---...--.--. 150 measurements of left ectocuneiform of. .-.--.--- 160 description of specimens of...-.---------------- 200 Dinoceras lucare, maxillary bone in .--.--.-.----- oes 28 views and descriptions of teeth of (Pl. TX) ----.- 43, 45,49 . 239, 240 Page. Dinoceras lucare— Continued. measurement of axis of......-.--.--..---+-----+- 73 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 Ce((H EIEN) cater cootaececso soasnase sotdonoes view of nasals of ....-...-.----- view of skull of -..---- views of lower jaw of. - ‘views of incisors of .<-..-......---------2--.--6- views and descriptions of teeth of (Pl. VU, VWA0 DD) esac cckete bse co gemeronassessssasue=s 46, 48, 49, 50 views and descriptions of brain-castof (Pl. VI)... 53-55 views and description of atlas of (Pl. XX)-.-..-- 69 measurements of atlas of ....----... - ------- val views and description of axis of (PI. XXI).--...- 72 measurements of axis of ...--..----------------- 73 description and measurements of third cervical vertebralOf. oc n= =m sinlee mem iaieg= = a= =i = =m 74 | views and descriptions of cervical vertebre of ((HED-O- ODN) sacs s-ceodoososecs steconensecocs—c— 74,78 measurements of fourth cervical vertebra of. --. vis) views and measurements of fifth cervical verte- LPP} poganaco p soon oscoroscesscecnsEseocesemes 76 views and description of sixth cervical vertebra 77 description and measurements of seventh cervi- cal vertebra of .. 78 measurements of sixth cervical vertebra of -..-. 78 description and views of first dorsal vertebra of 79, 80 measurements of first dorsal vertebra of ..-..--. 81 description and views of second dorsal vertebra () te ee temoccier qubtac posuod ance oa seco asenog 82 views and descriptions of dorsal vertebra of (Pl. >.@, NEED. O:E Bi N)ige senda So= aso nesouSteuocasese as 82, 84 measurements of second dorsal vertebra of -.--- 83 views and descriptions of lumbar vertebra of ((BIEEXSRA Ve eROXGVEL) eieremtete te eieee aletatetitiene eeierela 85 measurements of four lumbar vertebra of-.....- 86 views and descriptions of left scapula of (PI. DOGO) ot eee ae ne oncod peng Sconcfecerccancias 87 measurements of left scapula of --......-..-..-- 88 views and description of humerus of (Pl. EX OVALE yas octets ee eee mek ee eel 89 measurements and views of sectionof humerusof 91, 92 views and descriptions of radius of (Pl. X XIX). 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 (PI. LIV)... .. 101,145 views and descriptions of scaphoid and lunar of (BL RARE) i oe eisee sec ceosey eceosceess 102, 104 view of right and measurements of right and leff:scapboid of). --3.- -A) O-4 i a aeenoe~ sqosecdnp shanessec dace ne Jlph Tin views of right and measurements of right and lefticuboidliaf \ ‘Te ; D ; . fe i > - / = . ‘ t ; ' i i ‘ bel a Y -* a may Car « Te > a a pial lateral views scent tromithenletity es a= ee en ae d a yee Oe aba Ee DINOCERATA. Skull of DinockRAS MIRABILE, Marsh. One-fourth Natural Size. m —Nasal bone. pm—Premaxillary. e —Canine tooth. m —Maxillary bone. m' —Maxillary protuberance. @ —Lachrymal bone. Jf —Frontal. ma—Malar. pl —Palatine. pt —Pterygoid. as —Alisphenoid. s —Post-glenoid process of squamosal. bs —Basisphenoid. bo —Basioccipital. o —Occipital condyle. p —Posterior crest. p' —Posterior protuberance, Page. PERSE ay, sre “ATIGVUIN SVUHO ONTC eo = e 5 ra SGI. Pea AcT),; aah: DINOCERATA., Skull of DINOCERAS MIRABILE, Marsh. One-fourth Natural Size. Page. Skull; front view, --.--.-- oe Sees oe Sea toe ee Sake ase aoe ees See Lee eee eee 11 Norr.—tThe surface covered by oblique bars in this and the following plates indicates portions concealed by the adhering matrix or otherwise obscured. E.Gnsand, lith New Haven F Berger, del Slat 74 a ERAS MIRABILE, M ) OG IN Tr e052 Jeol AAS x x i : | . ae eS ; ae : = \ IP ACT B- IV. DINOCERATA. ~ - Skull of Dinoceras MIRABILE, Marsh, One-fourth Natural Bize: : Skall; superior view,.-----2o2==22—-- ee Nes ee et, alee ee ee ae eS Bee Ps ; e F Berger, del DINOCERAS MIRABILE, Marsh. %. arrears eT E.Crtsand, lith. New Haver «ail ee Ae = Vee DINOCERATA. Skull of DINoOcERAS MIRABILE, Marsh. One-fourth Natural Size, Skulls uo feriorvi Gwe: sie «ee ee Soe koe anes eee ee nm —Nasal bone, pm—Premaxillary. e —Canine tooth. m —Maxillary bone. m’ —Maxillary protuberance. ma—Malar bone. pl —Palatine. pt —Pterygoid. s —Post-glenoid process of squamosal. 0 —Occipital condyle. p —Posterior crest. p' —Posterior protuberance, F Berger, del E. Orisand, lith New Haven DINOCERAS MIRABILE, Marsh “. =f. Ma 4 uu : ® “¥, : 7 Fie. Fie. Fia. Pie AS nh, vale DINOCERATA, Brain-cast of DINOCERAS MIRABILE, Marsh. Three-fourths Natural Size. 1—Cast of Brain-cavity; lateral view, seen from the left, -2_22222---2--22eesee oe eens 2: Mheisames: Superior ave wy eeu: 22 yest ee ae ee ee oe ee ee 3:=The-sames inferior view; 2fes24°: Jota te eee ee eee ee ee eee ol or J—Olfactory lobes. e —Cerebral hemispheres. s —Sylvian fissure. op or IJ—Optic nerves. V —Trigeminal, or fifth, nerve P —Pituitary body. Jf —Flocculus. J’ —Sixth nerve. ch —Cerebellum. cf or XN J7—Condylar foramen for twelfth nerve. me —Medulla. tO XII. DINOCGERAS MIRABILE, Marsh“ Co PLAT E Grisand lith New Haver ee alee ‘ es | | oe 4 4 5 ; i ey EE ACE, Vea: : DINOCERATA. ~ Molars of DINOCERAS MIRABILE, Marsh. ? Natural Size. Fire. 1.—Upper molars; exterior view, from leftiside, «025-2. -2_ 2.2222 5- oe AE ira 9 25M Ws cara es yyy ere Seca Gg 2 im alt= ~ = r, ee a oa oe Jae ie TN) ny) ica) F Berger, del DINOCERAS MIRABILE, Marsh.” (IP Ae ys aloe DINOCERATA. Lower jaw and teeth of DINoOcERAS MIRABILE, Marsh. Fie. 1.—Right lower jaw; lateral view, inner side, one-third natural size, a —First incisor tooth. e —Canine tooth. d —Wiastema. s —Section through symphysis. cp —Process for protection of canine tusk. a Angle of jaw. J —Dental foramen. ed —Condyle. er —Coronoid process. Fic. 2.—Left lower molars; superior view, natural size, Bie. 3'— The samesilateralicyiew. natural pizeyses es eee eee lpm—First premolar. im —First molar. The first and second premolars in figures 2 and 3 are restored from a second specimen. 50 tpm 3 E Crisand. lith New Haven F. Berger, del _~DINOCERAS MIRABILE, Marsh ca TEZIE arse Gs baa tp oe ACP EG) ESS DINOCERATA, Teeth of Dinoceras LUCARE, Marsh. Natural Size. Page. Fie. 1.—Upper molars and canine; type specimen, (No. 1038,) lateral view, seen from the left, 45 Bie. 2.—Upper molars; showing, grinding surface, <2. 2. .....225 <2 ses. aoe 49 e —Canine tooth, d —Diastema, 1p —¥irst premolar. Im—First molar. J —Posterior palatine foramen. Pals J” —Palato-maxillary foramen, F Berger, del DINOGER# a E < ‘a Ay nN Re Pets 4. LA h ct ICARE, Mar PLATE IX see BPD y PF Berger, dei ie “ge ; : iis : - ° * a ie ~ 5 % a) F Aaa DINOCERATA. Skull of Dinoceras Laviceps, Marsh One-fourth Natural Size. Skull; type specimen, (No. 1039,) lateral view, seen from the left, a ee eee ee | Siren > a - “UBACT MON WAIL PUBSLIO YZ PLATE x7 . DINOCERATA. - Skull of Divoceras LATICEPS, Marsh. One-fourth Natural Size. Skull; (No. 1039,) superior view, -_____-.-______- Bee eet aS ae ee ee See ee a, Se 26 1, lith New Haven DINOGERAS. LATICEPS, Marsh. % PLA TBR Xr. DINOCERATA, Lower jaw of Dinoceras Larrcups, Marsh. One-third Natural Size. Page. Fic. 1.—Lower jaw; (No. 1039,) superior WCW yc it eS an acetates aS eee ee ee 35 : 35 Bie. 2;—The:sames, front vilews.2~ = 0a! 257 2e2 2.005 © eee tod a E.Orisand, del DINOGERAS weie ponte ah coe it WJ, : 1 - 4 ® u i. Da ae. r i i Ow ee ; a \ i i 7 mii a3 = pe ‘ .: 2 : 3 7 4 1 Pz ; . “4 = '] ‘ 4 7 4 x * iy i . ba . ¥ F F 5 i : 5 * ' ‘ ‘ > - : =a) 1 ‘ , A f 7 , by eT ine ‘ La ! y ie PLATE Sigs DINOCERATA, Lower jaw of Dinoceras Laticeps, Marsh. One-third Natural Size, Fic. 1.—Lower jaw; (No. 1039;) seenfrom: the léfp.= £2. fe: 2.8.. Fic, 2.—Lower jaw; POStETIOT ave wea =e oe ce —Socket for canine tooth, m—Mental foramen. p —Process for protection of canine tusk. a —Angle of jaw. ed—Condyle. Coronsid process. d —Dental foramen. & —Symphysis, cr PLATE Xi New Haven. h d, lit Tisand, E 1 F Berger, de 3 ’ Marsh. 7 ¢ = i DINOCERAS LATICEP 4 Ee ep alas AS aE ae DINOCERATA. Skull of Dinoceras Lariceps, Marsh, (female.) One-fourth Natural Size. Page. Fie, 1.—Skull; (No. 1202,) lateral vaew, Beenfromitheloft <<. 2. se aoe eee 45 KG? ——The Gale , SUPCTION WCW, Sas 2 2-325. a5 kere eek 5 45 e —Canine tusk. Uy 3 7 m'—Maxillary protuberance. p' —Posterior protuberance. E Ortsand, lith New Haven DINOCGERAS LATICEPS, Marsh. %. eh ey : PLA Seyi nee DINOCERATA. Skull of TINOCERAS INGENS, Marsh. One-fourth Natural Size. Skull; type specimen, (No. 1041,) lateral view, seen from the left, -_--.--.--------------- ees F Berger, del TINOCERAS INGENS, Marsh. /%. “Nis aoe evga a 7 PA oy DINOCERATA. Skull of TINocERAS INGENS, Marsh. One-fourth Natural Size. Skulll-ii@Nio; 104:0)) sfromtivi ce wise se = ee ee are Page. TINOGERAS INGENS, Marsh.“ Pi Awe ev ae DINOCERATA. Skull of TINOCERAS INGENS, Marsh. One-fourth Natural Size. Skull; (No. 1041,) superior view, ---- ---------- (ae nie Ste ae See eeeness ‘YysieW “SNAONI SVHSOONIL Wh, ai op ‘Ia s1 ~ if cl puesup MAAeH MAN TIT ‘ | cal b> P< ica PLATE sore -DINOCERATA. . Teeth of TINOCERAS INGENS, Marsh. ; Natural Size. Fic. 1—Upper molars; (No. 1041,) left side, lateral view, seen from the left, Fig. 2.—The same; showing grinding surface, -_---_..---.----------- Bteenetece sepa sears s PLATE XVIII F Borger, del TINOGERAS INGENS, Marsh. 4. E Orisand, lith New Haven. iu PLATT. 2cEXe DINOCERATA, Lower jaw and teeth of TINOCERAS PUGNAX, Marsh. Fig. 1.—Lower jaw; lateral view, seen from the left, one-third natural size, z —Incisor tooth. e —Canine tooth. ad —Diastema. Jf —Mental foramen, —Process for protection of canine tusk. a —Angle of the jaw. ed —Condyle. ey —Coronoid process. Fic. 2.—Lower molars; superior view, natural size > > ) Fie. 3.—The same; lateral view, natural size, lpm—First premolar Im —First molar. ASE Xe 4 7m ) F. Berger, del I ger, de E Cnsand, lth New Haven TINOCERAS PUGNAX, Marsh. \ “ ce 4 oe ee ee ee 9.— The igamie;infterion-view,, 2222225) o> coset ae 22 eee eee ees eee HIG A Mnveyshiantey NOM Ny 2 = eo eos ce ee see SSE Sane ses Seen esos Se E Grtsand, lith New Haven F Berger, a sl fon i} DINOGERAS MIRABILE, Marsh.“ \ wy Ge ee eee os ee > *, ad _ PLATE, SOx DINOCERATA. Dorsal Vertebra of DINOCERAS MIRABILE, Marsh. One-fourth Natural Size. Fic. 1.—Second dorsal vertebra; lateral view, seen from the left, .-.._..__-..----__-------- Wie. 2.—The same; superior view,---------------.---- eens Rees Sse Se sep ee eee Bie, 33:— The, sames anterioriview, 2.2022 2 a eo ee ee ee ee ee Bie, 4 Theisames interior views 222 2.2 sk ose oe ee nee Riri. ehesames sp OSbEELOLAVi C Wana ee eee ee ee fy td DINOCERAS MIRABILE, Marsh. “4. risand, lith New Haven Bit PH ex 1. Fic. Fic. Fig. Fic. Fie. Fic. Fie. Fie. Fie. Pe Aaa eae ve DINOCERATA. Dorsal Vertebre of DINOCERAS MIRABILE, Marsh. One-fourth Natural Size. 1.—Median dorsal vertebra; lateral view, seen from the left, 2.—The same; anterior view, SAN niGy SNS She ae VALE ee sk ee eS eRe ea eee 2 4.—The same; posterior view, -...----.__- 5.—Last dorsal vertebra; lateral view, seen from the left, ___- 6.—The same; superior view, 7.—The same; anterior view,-- -_-- 8.—The same; inferior view, -_______- Bes 9.—The same; posterior view, - PLATE XXIV F Borger, de! E Grisand, lith. New Haven DINOGERAS -MIRABILE, Marsh “4 — p ; : < > . i ' z 7 , ' ‘ — < ' Posi x XV. ray Nee Ty. 8 i x Wr ad 3 ; e ‘ 220 PLATE, Sxey DINOCERATA. Lumbar Vertebrz of DrNoceRAs MIRABILE, Marsh One-fourth Natural Size, Page. 1.—Lumbar vertebra, fourth from sacrum; lateral VICWS-S22et3- Soon ko 8d 2.—The"same; ‘superior ‘view, + 25. 25.426542 5-04: ae ee 85 3. The Same ;santerior view, - <2 20- sacd. So ee ee 85 4.——Vhe samesinterior-view, ..- 2.25. 2uee 64 oe ee eee 85 b,—= The same;) posterioncview,-.-2-.8c 2c. ee 2 oe ee pe 85 6.—Lumbar vertebra, third from sacrum; lateral VIGWa tac achecee Sac ee ee 85 (.=-Thesame;, supenorivlew, -<8.-c05 sees ee 85 6:==The kame} anterior view, 252.7 eects o as eee ec 85 o-—The same; inferior view, 222.7 +2. sok -oae 6e eee 85 10;— The same} posterior view, .. $.222=c ses Je ee Soe eee 85 r, del DINOCERAS MIRABILE, Marsh. “4 PLATE XXV. E Cnsand, lith New Haver ibee i Xx er. One-fourth Natural Size. 1.—Lumbar vertebra, second from sacrum; lateral view, seen from the left, .._...__.__- PANNE SANT MNOS Va ge a= oo as coe oe Sennen ee Toba ont. ee 3.— The ‘same; /anterior-view, 9:2") =) St ee ee 4,——The same; “indetior view) =.= “22. 22 aR. . s ae ee 5.-—Dhe samey posterior View, 2s. 22805 .t5.725 eee 6.—Last lumbar vertebra; lateral view, seen from the left, Jiabao as ee ee 3 (= The same; superior ‘view, ek 4-25.20 28 ee eee eee &:-— The same; anterior Wwiew,): 9aL.-< 5/2 ee 2 ee ee ee 9.=-The same; inferior view, = c--- 252-5094. 4: op ae ee ee OF Wh elisa) ea) OSten1OT ay clr eee eee 2b aca PS a Se oe PLA XEXevar: DINOCERATA. Lumbar Vertebre of DINOCERAS MIRABILE, Marsh. F Berger, del E.Crsand, lith. New Haven DINOCERAS MIRABILE, Marsh. %. eS OX VE - PAH, TX OxXe Vane: DINOCERATA. Left Scapula of DINOCERAS MIRABILE, Marsh. One-fourth Natural Size. Wie. 1.—Scapula; ‘exterior view,--2- 2-2. /2-2---2-- == "rie, fe Seen ie iene ee ch—Coracoid border. e —Coracoid process. ge—Glenoid cavity. go—Glenoid border. ss --Suprascapular border. nies 92! e) same: simmer wil Wa eee ae ee Bres3:—The same; inferior wiews 225. ee Se ae ee ee ee a —Acromion,. s —Spine. DINOCERAS M BILE, Marsh. %. Vil. PLATE XX\ Vv Ser, DINOGERAS MIRABILE, Marsh % Ales i axe PLAT So wy, , : } PAE Sosy DINOCERATA. oi Humerus of DInoceras MIRABILE, Marsh. : -One-fourth Natural Size. i Hie. “-—Lett Humeras; anterior view,....-s-.ests. Jeo. een la—Distal end. Fic, 2.—The same; inner view, lia. 3.—The same; posterior view, 3¢—Proximal end. PLATE XXvIL. 3a AA Lite BSCE da E.Origand, lith New Haven F. Berger, de! . DINOGERAS MIRABILE, Marsh. 4 PLA xaos DINOCERATA., Radius of Dinocreras MIRABILE, Marsh. One-fourth Natural Size. Page. Fie. 1 Lett Radius; anterior views.) <. 22 <-2_ 2... Sees 4 es, 93 5) t) la—Distal end. Eig: 2: Whe games. inner views. £2s2dee 6. sey ces 5.2 eae ees Se 93 Fic. 3.—The same; posterior view, showing surface applied to‘ulna, 9)... 2-0 93 3a—Proximal end. Wie. 4.—The same; exterior view,..-._____- Enos SE 2 ES oa ee eee es oe eS DINOCERAS MIRABILE, Marsh.“ < > i ‘ - : ¥ i= . . u a * za ‘ ‘ ” ; * P . t . a * + . , ' Fy ' ‘ . $ . > ’ - - Pag AT). ae DINOCERATA. Ulna of DINOCERAS MIRABILE, Marsh. One-fourth Natural Size. Page. Fic. 1.—Left Ulma; anterior view, showing radial surface, -_--..____-____.__--=_=-..._____. 96 la—-Distal end. Hira. 2:—Mhersames inner wiew, =22 28 aa2=65 4s ase Sees ee ee ee eee ee sete 296 H1G.3:— Lhessames posterior wews 2s... 522 aoe sa eee see ee nee ee ee 96 96 Fic. 4.—The same; outer view, ---- ---- DINOCERAS MIRABILE, Marsh. “. ee oeae = PLAT XX XI, DINOCERATA. Scaphoid and Lunar of DINOCERAS MIRABILE, Marsh. 1.—Scaphoid; outer view, 2.—The 3.—The 4,—The 5.—The 6.—The 7.,—Lunar; anterior or outer view, 8.—The 9.—The 10.—The 11.—The 12.—The same; posterior view, same; anterior view, same; lateral view, showing face same; posterior, or palmar, view, One-half Natural Size. same; proximal view, showing face for radius, same; inner view, Showing face adjoining lunar,_---- ---- --- same; lateral view, showing face adjoining pyramidal,_- -__- same; proximal view, showing face for radius, ---- ------- : same; (distal view, showing faces for articulation with magnum and unciform (Left foot.) . 3 : : { ; same; distal view, showing faces for trapezium and trapezoid, ---- ------------ o-- F Berger, del E Crisand, lith New Haven - DINOCERAS MIRABILE, Marsh. ¥2. hui @eane IBGE Fic. Fic. Fic. Fic. Fie. Fic. Ira. Fic. Fic. Fie. Fic. PEATE. Sexes DINOCERATA. Pyramidal and Pisiform of DiNocERAS MIRABILE, MarsH. (Left foot.) One-half Natural Size. Page. iL —-byramidall (or Cuneiform) bones outer vi Cw eee a (iT 2 Mhersames, anterior Wews== =: Gtiee. ne = eee ee a oe Se 107 3.—The same; inner view, showing face adjoiming lumar, ..— __-._--_-----___--_-._-- 107 4.=-The-same’ POStenior WieW sy ==. sea soe oe ae ects ae ee 107 5 —The same; proximal view, showing faces for ulna and pisiform, 22225 {4ne ae 107 6.—The same; distal view, showing faces for unciform and for fifth metacarpal, -_-- __-- 107 7—Pisiforms, anterior We wss.s2..6- see ee oe ae ee ee ee ee 109 8.—The same; inner view, showing articulation with pyramidal,_......-...----.----1- 109 9:= "The same; posterior wiGw; <.2- 6. sc2seceusp oonee Jane Sere eae eee ee ee eee 109 110: —"Thesame’ (outer Wicws. 2-2 Sea See ee ee ee oe Se ee ee 109 11.—The same; proximal view, showing articulation with ulma,----.-...----.----------- 109 1 2:=Thesames distal wiewso- 226 5 ee ee ee ee oe ee ee 109 PLATE XXXII DINOCERAS MIRABILE, Marsh %. eee i XOX X PLL. Fic. Fie. Fie. Fie, Fie. Fie. Fic. Fie. Fic. re. Fic. Fic. PLA Sori: DINOCERATA, Trapezium and Trapezoid of DINOCERAS MIRABILE, Marsh, (Left foot.) One-half Natural Size. Page. 1 ——Prapezium; lateral! yaew, showings outensuriace, === == =e ses = = eae ee 110 2:—"The same}! Posterior Views)2o see ss soo eS 22 eae ae ee eae Se eee = Se eee 5 Je LLG 3.—The same; lateral view, showing inner surface, articulating with trapezoid, -___-___- 110 4—The same} anterior Views... -2cees. sees oh ee a nee eee ete ae ae ee ee = ibe 5.—The same; proximal view, showing articulation with scaphoid, -.------------------ 110 6.—The same; distal view, showing metacarpal articulation, --.---------------------- 110 7-—Urapezoid;, front view, showing external sumtace,=== = 5) es 2s] ase ee aul 8.—The same; lateral view, showing face adjoining trapezium, .-. .-.--------------.-- 111 9:—The' same} posterior Views. 2 2-3 soe sae = Se i ae eee oe eee rolal 10.—The same; lateral view, showing face adjoining magnum, --.----.-.--...-_----.--. 111 11.—The same; proximal view, showing articulation with scaphoid,___..__-----..------ 111 12.—The same; distal view, showing metacarpal articulation, ~-_____-__ eae ee ILI 10 2 ra wo DINOCERAS MIRABILE, Marsh. *%. 2 0 PEA Eee we DINOCERATA. Magnum and Unciform of Dinocrras MIRABILE, Marsh. (Left foot.) One-half Natural Size. 1.—Magnum; front view, showing external suriace;) 22.224. 2 2.—The same; lateral view, showing face adjoining (Crap eZ 01d) ape a 3.—The Balie; Postenor, Ob palivar, WieW,o =< sc. sac. ek. 3 4.—The same; lateral view, showing face adjoining UN CLOT Sane a 5.—The same; superior, or promunial, vidWate aon. .-:250. 92.0 ace eee ee 6.—The same; inferior, or distal, view, showing face for metacarpal articulation, _ 7.—Unceiform; lateral view, showing external surface,.____._.....__.-..._____._ 8.—The same; front view, showing face adjoining TA OCU Bee ae ee 9.—The same; lateral view. showine innier:sunface,:. 25 92!" Ws 40 eee ie ’ to) > 10.—The same; yoste-ior VidWo- : ] td | D DINOCERAS MIRABILE, Marsh. %. PLATE,” SexXsocexe: DINOCERATA. Ribs of DINOCERAS MIRABILE, Marsh. . 1.—First rib; anterior view, . 2,—The same; inner view, - 3..-The same; superior view, showing head and tubercle, 4.—Dorsal rib; posterior view, 5.—The same; inner view, . 6.—The same; superior view 7.—Posterior rib; anterior view, 8.—The same; outer view, 9.—The same; superior view, showing head and tubercle, . -..-.--- .-..------------ One-fourth Natural Size. ; Showing head anditubercle;s: ss = 92 - eee eee esas ea eeee iu P Berger, del DINOCERAS MIRABILE, Marsh Vi -LATEH XXxXIX E.Orisand, lith New Haven Fie. Fic. Fie. Fic. Fie. Fie. Fic. Fic. Fic. Fie. Ices Fic. PEAT i, Se: DINOCERATA, Sternum of DinoceRas MIRABILE, Marsh. One-fourth Natural Size. Page. 1.—First segment; lateral view, seen from the lefts. 2.25 Seis ee 133 2,—Whe same; superior views :... Lip. o-oo ee ee 133 Si The same; inferior wiew;, -t2- 82 hh ts 2a ee, a ne 133 4.—Second segment; lateral view, seen from the Lehi Sees < Sen LS ek eee ee 134 o:— Thewsame; "superior yiewyi.oa5-. 6 oe one aes eee ee, 134 6 Thejsamesinteriot-view,. ou ca2. <4 ee ae Le ee ae ee 134 7.—Third segment; lateral view, seen from the left ett cee 1 k= As a 2 ee 134 B-—Dheysames superior wiew,. 22: 3¢-tn22252 02 et eee ore ee ne 134 2: hel same ;inferionsyiew) <2. Pee a4 aceon ase ee, 134 10.—Last segment; lateral view, seen from the left, ASS. Ose 6a bo eae aoe ee 134 1. The same; superior view; 252.2745... )22 "42. eben 02s ee 134 12.—The same; inferior view, __- 3 PLATE XL DINOCERAS MIRABILE, Marsh. BE. Ortsand, lith. New Haven \ bes ae A o PRAT EH, mw: . DINOCERATA. Pelvis of DINOCERAS MIRABILE, Marsh. One-fourth Natural Size. Ries 1.—Pelvis; anterior view,.-L-.5 52-6252 s-cb es oe Pe eee oe ee oe Fic. 2.—The same; inferior view, a—Acetabulum. J —Obturator foramen. ai—llium. zs —Ischium. p—Pubis. s —Anterior end of sacrum. s' —Posterior end of sacrum. DINOCERAS } \BILE, Marsh.”%. a (an Le mi ~~. =~ E Orsand, lith New Haver DINOCERAS MIR, DINO RABILE, ae iw PLATE NEE, DINOCERATA. Pelvis of DINOCERAS MIRABILE, Marsh One-fourth Natural Size. Page. Fie. 1.—Pelvis; lateral view, seen from the left, .-_-.---___- pe ee eset. Sas Saee: 135 Hic. 2.— The same; lateral vaew. showing, inner sutaces: 22 52-5 ee oe ED Hic, 8.—TDhe same; posterior view, -2--=---- -------=-- iathceestec pi eer eee ee 135 Ries 4——sacrume imtenlon views oss aaa a= Bach seaden Dees ee Ro ee ea a—Acetabulum. J —Obturator foramen. @ —Sacral face for ilium. 2i—Ilium. zs —Ischium. p —Pubis. s —Anterior end of sacrum. s' —Posterior end of sacrum MN erger, del FB DINOGCERAS MIR PLATE Xuil. E.Crisand, lith New Haven ILE, Marsh. “4 _ ee [ ¥> ff = | r : s Sh ~S _ ~* 7 - 7 ; f pad a é i aif s =, oy ™ F Berger, de) wo Ee ~ r ~ ~ DINOCERAS MIRABILE, Marsh 1 PLATE XLiIt E Crisand, lich New Haven PLATE Shaky DINOCERATA. Caudal Vertebre of DinocERAS LATICEPS, Marsh. One-fourth Natural Size. Page. Fig. 1.—First caudal vertebra; lateral view, sseen from the lefts 22. qs aes ee 138 la—Superior view. 16— Anterior view. 1c—Inferior view. 1d—Posterior view. Fra. 2.—Second caudal vertebra; lateral view, Seen trom the left, o22- se =- sane 138 2a—Superior view. 2b—Anterior view. 2e—Inferior view. 2d—Posterior view. Fie. 3.—Third caudal vertebra; lateral view, Seen'from the left, 25: 02) 42. soe 138 3a—Superior view. 36—Anterior view. 3e—Inferior view. 3d—Posterior view. Fic. 4.—Fourth caudal vertebra; superior View ye: ce hed eos s2 Se ee 138 4a—Inferior view. » F Berger, del DINOG ERAS LATIGEPS, Marsh Va, PLATE XbIil E Cnsand, lith New Haven DS As eee DINOCERATA. Femur of DriNockRAS MIRABILE, Marsh, One-fourth Natural Size. Bic. 1.—Left Femur; LLONb Ok 'SUpELlor, VACW poe .s =o ee ey eee t —Great trochanter, t’ —Lesser trochanter. la—Distal end, Fig. 2.—The same; inner View, cs. «ote ae ee ee rr Fie. 3: . 8a—Proximal end. The same; back, or inferior, VieW)a2 4 = 720! gee a 2 ee DINOCERAS MIRABILE, Marsh. %. > — b l ; PP i yt PILATE. SLEW. DINOCERATA., Tibia of DINOCERAS MIRABILE, Marsh. One-fourth Natural Size. Page Fic. 1.—Left Tibia; anterior view, .---- ---- Se et ee ne ie EAA SLA la—Distal end. Hie. 2.—The same; lateral view, inner side, .__..______ 5 oS al eae ee a ae. seeks Sees 141 RIGS ube ancsii OS GEr1 OTIC Wisi eee ne eee ee ne Ot ee eel ELST 38a—Proximal end. Fic. 4.—The same; lateral view, outer side, _._______ si Rf Cee ee 141 Fie. 5.—Section of shaft of Tibia,....-_____ = Sse Se hos Ae eee, PS sees Halil tl bd DINOCERAS MIRABILE, Marsh. “4. PLAT! PLATE XLVI. + Fia. Fic. Fie. Fic. Fic. Fic. Fic. Fie. Deeg) Dee Bi eb OG aU DINOCERATA. Fibula and Patella of DINOCERAS MIRABILE, Marsh. One-fourth Natural Size, Page l—Lett Bibulas; outer View; :-22<2--3 556 =~ oo eee eae oe 143 lau——Distal end, 2:—The'same; posterior view,- << 9-c220 6.2 = 22han eaten Seas a ee 143 S-—Thersames Inner ViGWio2 << Ss sence oo eee ee 143 3a—Proximal end. 4.—"Thevsames-anterior view) Jaici2se 5525 ay become eee ae eee ee 143 5: Left: Patella; frontwviews 2 2< cus sss. ce oo ee eens Soe ee eee 148 6.—The same; lateral view, showing inner side,...---._-..--.---- a2 143 7-—Vhe same; posterior-views 222 582= 0 =-Gs=2 oa. ae ee ee 143 8.—The same; lateral view, showing outer side fp 2S sos eee seee osee F Berger, de 7 DINOGERAS MIRABILE, Marsh. %. PLATE XLVI E.Cnsand, lith New Haven ' ~ Ay & ‘ ’ ‘ « ; : pute. LV, ’ Nia IA . . ‘ rie! = a) Coen / . : ja) a ‘Aigh) ; > 7 7 7 = Fig. Fie. Fic. Fia. Fia. Fic. PE AIS XG varie DINOCERATA. Astragalus of DINoceRAS MIRABILE, Marsh. (Left foot.) One-half Natural Size, 1.—Astragalus; superior view, showing face for articulation with tibia, 2 hersameswlaterall vilewtilo eles 1c eG. ae eee mae ee ne 3. heysamess inter oriviie way an ee ae eee 4.—The same; lateral view, fibular side, 5.—The same; front view, Gish ey sane sep OS CenLOT kvl 6 Wistar PLATE XLVIL. F Berger, del E.Crisand, lith New Haven. DINOCERAS MIRABILE, Marsh ¥%. PLATE Sop ali. DIN OCERATA. Caleaneum of DINOCERAS MIRABILE, Marsh (Left foot.) One-half Natural Size. > Ries 1—Calcaneumssanterions or tronts vile wae ee ee oa eee ee Hires 2! Thevsame sinner view, talbiallside, 5 25) 22 soe ee ee ) ; ’ ? Hire: '3—Whevsames posterior view, ~. 2. =. .-.-tsave-2-e 2d245- een 4 eee Hei —'Dheiswames\ outer view. fibular side.. y= a 2 ee a ee Fig. 5.—The same; superior view, showing face for astragalus, ____.__.. __.--_-..---.- Saeee rcs 6:——hersamesuimiientors Ox plamtars: Vic Wee ae ete see eee nee : 2 : 4 DINOCERAS MIRABILE, Marsh. %. be is | JEN Bigs 2a bs) obi ial Wie Fic. Fic. 1.-—Manus, s L Pp tm ir un I IT PLATE 2 tVy? DINOCERATA. Feet of DINocCERAS MIRABILE, Marsh. or fore foot (left), .._-- —Scaphoid. —lLunar. —Pyramidal. —Trapezium. —Trapezoid. —Unciform. —First digit, or poilex. —Second digit. IiI—Third digit. TV—Fourth digit. V 2.—Pes, or hind foot (left), IT —Fifth digit. —Astragalus. —Calcaneum. —Cuboid. —Navicular. —Entocuneiform. One-half Natural Size. —First digit, or hallux, —Second digit. I1I—Third digit. TiVE V —Fourth digit. —Fifth digit. 2 DINOCERAS MIRABILE, Marsh. 7. —— 4dilV bap ° ive te Aer Cee + t . . , u Piven bi 2 Ae Si Q , $ dns ; “9 “ft i . a jr is rs ‘ - . - ° / i Re ‘ : . ; BE Ae lie eV. hice Xs « 7 a i ; a ss ‘ mn ite %\3 = Me PLATE LV. Ne DINOCERATA, a Restoration of DINOCERAS MIRABILE, Marsh. One-eighth Natural Sizo, @ Berger, del DINOCERAS } PLAT E LV. a nS Se eh BS E.Onsand, lith New Haven 2ABILE, Marsh ~%. - a wd nv? & Te Sey 7u av oO cars ‘a tha ~ PLATE LV. 4 lith New Haven, 4 : AS =; Ga Gn Ge’ ew ene im ro E Crtsani L Marsh % . DINOCERAS Borger, del b EAE de V1. “4 PLATE: iva DINOCERATA. Restoration of Tinoceras INGENS, Marsh. One-sixth Natural Size. - Ah - > Cin bd A ed on Ab; — i +) : bs sea 2 i _ - Me ari; ae e+ i : -* ‘ ‘ PLATE INI. - per det 3 TINOCERAS INGENS, Marsh. % ) ee ae = Siaees sree st F ailice “vais. yy * he yi : t/a iy Py sal Np be i hy 8s Pee: Ne i arora 1) eyes Pie a CoUpyes igh.) 1 + < ON LIBRARIES ih INSTITUT} SMITHSONIAN ~[ | or 8 he ee SeSeatsecatee te ete