204 



THE MAMMALIA. 



the bones of the middle foot 

 have also become shortened, and 

 are on the way of becoming 

 rudimentary. In Hipparion the 

 adaptation of an animal once 

 accustomed to marshy ground, 

 to one which lived on firmer 

 ground with extensive meadow 

 lands has become completed; 

 we have, in fact, the transforma- 

 tion from a slowly-moving into 

 a swift animal. It ranged from 

 Central Europe as far as Central 

 Asia, and in both countries lived 

 in enormous herds, as we learn 

 from Gaudry's graphic picture of 

 the Miocene uplands of Pikermi. 

 The transition from Hip- 

 parion to the Horse is a very 

 natural one. The two side toes 

 which are no longer of use to 

 the organism, and 

 yet had to be 



Fio. 36.- Left hind-foot 

 of the Anchitherium. 

 One-half nat. size. 

 After Kowalewsky. 



