CONTENTS XI 



Figure Page 



166. Type (lectotype) jaw of Symborodon ioruus ^ 211 



167. Type (holotype) skull of Megaceratops acer 212 



168. Type (holotype) skull of Megaceratops heloceras 213 



169. Type (lectotj'pe) skull of Symborodon bucco 214 



170. Type skulls of Symborodon altirostris, S. bucco, and Megaceratops acer 215 



171. Type (holotype) skull of Symborodon altirostris 216 



172. Type (holotype) skull of Symborodon trigonoceras 217 



173. Type (holotype) skull of Brontolherium ingens 218 



174. Type (lectotype) of Symborodon hypoceras 218 



175. Type (holotype) of Anisacodon montanus 219 



176. Cope's cotypes of Menodus angustigenis 220 



177. Anterior part of skulls of " Megacerops coloradensis," Menodus iichoceras, and Menodus dolichoceras 221 



178. Type (holotype) horns of Menodus platyceras 222 



179. Type (holotype) skeleton of Brontops robustus 222 



180. Type (holotype) lower jaw of Brontops dispar 223 



181. Type (holotype) skull of Menops varians 223 



182. Type (holotype) skull of Titanops curtus 224 



183. Type (holotype) skull of Titanops elatus 224 



184. Type (holotype) skull of Allops serotinus 225 



185. Type of Menodus selwynianus 225 



186. Type of Menodus syceras 226 



187. Type skull of Diploclonus amplus 227 



188. Type of Teleodus avus , 228 



189. Type skull of Allops crassicornis 229 



190. Type (holotype) skull of Brontops validus 230 



191. Type (holotype) skull of Titanops medius ■ 231 



192. Type (holotype) nasofrontal shield of Menodus peltoceras 232 



193. Cotypes of Menodus? rumelicus 232 



194. Type (holotype) skull of Titanotherium ramosum 232 



195. Type skull of Megacerops hrachycephalus 233 



196. Type (holotype) skull and lower jaw of Megacerops bicornutus 234 



197. Type skull of Megacerops marshi 234 



198. Type (holotype) skull of Brontolherium leidyi 235 



199. Upper premolars of type skull of Brontolherium leidyi 235 



200. Type (holotype) skull of Megacerops lyleri 236 



201. Right manus and right hind limb of the type of Megacerops iyleri 237 



202. Type (holotype) skull of Brontolherium haicheri 238 



203. Type (holotype) skull of Symborodon copei 238 



204. Type (holotype) jaw of Megacerops primilivus 239 



205. Type (holotype) jaw of Megacerops assiniboiensis 239 



206. Type of Titanotherium bohemicum 240 



207. Type (holotype) skull of Allops walcotli 241 



208. Type (holotype) jaw of Megacerops riggsi 242 



209. Characteristic basal sections of horns of Oligocene titanotheres 245 



210. Skulls showing different numerical and proportional characters in five separate phyla of titanotheres 253 



211. Standard measurements of Eocene titanothere skulls 255 



212. Unequal elongation of face and cranium in titanotheres and horses 256 



213. Faciocranial flexure, or cyptocephaly 256 



214. Faciocranial flexure in Patoeosyops and Dolichorhinus 256 



215. Cranial proportions of Eocene titanotheres — Palaeosyops, Manteoceras, and Dolichorhinus 257 



216. Cranial proportions in man and in the titanotheres 258 



217. Natural and artificial brachycephaly and dolichocephaly ■ 258 



218. Contra.sting forms of upper teeth in Eocene titanotheres 264 



219. Skulls of Eocene titanotheres of the principal genera 265 



220. Heads of Eocene titanotheres of four phyla 266 



221. Upper and lower molars of bunoselenodont pattern 268 



222. Upper and lower molar patterns of Hyracotherium 268 



223. Bunoselenodont patterns of upper and lower molars in Tertiary perissodactyls 268 



224. Relations of upper and lower molars in Telmatherium cultridens 269 



225. Dental mechanism of titanotheres 269 



226. Grinding teeth of a titanothere and an insectivore 270 



227. Contrast of braohyodont and semihypsodont molars in titanotheres 270 



228. Cross sections through second upper and lower molars of Lambdotherium and Menodus 270 



229. Upper premolar-molar teeth of the earliest and latest known titanotheres 271 



230. Reconstructed skeletons and restorations of Lambdotherium popoagicum and Eotitanops borealis 277 



231. Lower jaws of Lambdotherium, Eotitanops, and Tapirus 278 



232. Restored contours of skulls of Lambdotherium and Eotitanops . 278 



233. Skull of Lambdotherium popoagicum, reconstructed , 281 



