UNGULATA. 361 



frontal appendages. The odontoid process of the axis vertebra 

 retains its primitive conical shape. The ulna and fibula are 

 complete, but some of the carpal and tarsal bones are fused 

 together ; the metapodials nos. in and iv are usually imperfectly 

 united to form a cannon-bone ; while the lateral digits, nos. II 

 and V, even though complete are excessively attenuated. The 

 stomach in the two existing genera is less complex than in the 

 true ruminants, the maniplies being rudimentary. Prodremo- 

 therium, known by the greater part of the skeleton from the 

 Upper Eocene Phosphorites of Quercy, France, is almost identi- 

 cal with the existing Tragulus of the Indo-Malayan region, and 

 exhibits the enlarged upper canines ; but the lateral metapodial 

 bones are reduced to imperfect splints. Tragulus itself seems 

 to have reached its present habitat by the early Pliocene period, 

 so far as can be determin^Bfrom detached teeth found in the 

 Siwalik Formation of India f Gelocus (fig. 195 B, E) from the 

 Upper Eocene and Lo\^^Hocene of France is another extinct 

 ally, in which the later^|Pjtapodial bones are represented only 

 by their upper and lower Atremities. Species of the existing 

 Hyaemoschus or Dorcatherwim (fig. 195 A) of western Africa, 

 seem to have been widely distributed through southern and 

 central Europe during the Miocene, and there is evidence of 

 others in the Lower Pliocene (Siwalik Formation) of India. 

 Allied genera, such as Leptomeryx, also seem to be represented 

 in the Lower Miocene (White River Formation) of Dakota and 

 Nebraska in North America. Since the Miocene period the 

 Tragulidse have been extinct in Europe and North America, 

 and seem to have been restricted to their present geographical 

 range. 



While, however, the Tragulidae are an essentially Old 

 World type, some of their immediate allies in North America 

 during the early part of the Miocene period attained a remark- 

 able degree of specialization in the skull, and exhibited an 

 armature unique among the Artiodactyla. These constitute 

 the family of Protoceratidae, which, like most highly special- 

 ized groups, had only a very restricted range in time and 

 space. The skull, at least in the males, bears two or more 

 pairs of horns or callosities, very suggestive of those of the 



