34 THE HORSE. 



either become extinct or undergone extensive modi- 

 fication. In the structure of their feet they scarce- 

 ly differ from Hyracotherium. They are, in fact, 

 typical old conservatives, which have scarcely de- 

 parted in any way from the manners, customs, or 

 structure of their ancestors. They appear to be ani- 

 mals tending to extinction, for, though formerly 

 having a wide range of distribution through the con- 

 tinents of America, Europe, and Asia, they are now- 

 only found at two rather isolated parts of the 

 world — i.e., South and Central America and the 

 Malay region — and they are by no means numerous 

 either in species or individuals. 



A second branch of the group can be traced 

 through such forms as Hyracodon, Aceratherkim, 

 and Aphelops to the modern rhinoceroses, which 

 in many respects are more specialized than the 

 tapirs. They have but three toes upon each foot, 

 and the teeth have been considerably changed, 

 some species having lost all the incisors or cutting 

 teeth of the front of the mouth. They have, more- 

 over, acquired the peculiarity of wearing one or 

 two large horns upon their noses, which the early 

 species of the family did not possess. 



Somewhat allied to the rhinoceroses were some 

 remarkable animals which flourished in the early 

 Miocene time in North America, to various modifi- 



