HISTORY OF THE PERISSODACTYLA 



331 



foot-bones are likewise extremely short and heavy, and the 

 number of digits is three in each foot. Each of the five or 

 more existing species has its skeletal pecu- 

 liarities, every portion of the bony structure 

 showing characteristic features ; but these 

 are only minor modifications of the general 

 plan and may be neglected in any compre- 

 hensive account of the living representa- 

 tives of the family. 



In order to find any American members 

 of this family, it is necessary to go back 

 to the lower Pliocene, where a great abun- 

 dance of them is encountered, representing, 

 according to Osborn's view, four or five 

 phyla; and just as in the case of the 

 horses of the same formation, they were ^^'^- ^'^^- ~ ^^^^ manus 



. of Indian Rhinoceroa 



an assemblage curiously made up of pro- (r. unicornis). 

 gressive and old-fashioned, conservative 

 genera, — some were persistent native stocks, others the de- 

 scendants of immigrants from the Old World, which reached 

 America in the middle Miocene. There was great variety of 

 form, size and proportions among these animals. North America 

 at that time having a larger number of genera and species than 

 Africa and Asia combined have now. Some were quite small, 

 some large, though none equalled the larger modern species. 

 Some of the genera had relatively long legs, but in one genus, 

 \Teleoceras (Fig. 125, p. 230), an Old World type, they were most 

 grotesquely short, the belly almost touching the ground, as in 

 a hippopotamus. Most of these rhinoceroses were hornless, 

 but ^Teleoceras had a small horn on the very tip of the nose. 

 In consequence of the lack of horns, the nasal bones were thin 

 and weak, in marked contrast to the massive, convex nasals 

 of the modern species, and, for the same reason, the upper 

 profile of the skull was nearly straight. Except for minor 

 details, the dentition was in very nearly the modern stage 



