EVIDENCES OF EVOLUTION 27 



ample of those horses that became extinct 

 during the Miocene, leaving no descendants, 

 and Anchitherium, found both in Europe and 

 in America, was probably also on a side 

 branch. Of the Miocene period, Dr. Lull 

 says: "This was a time of continental eleva- 

 tion and great expansion of our western 

 prairies and a consequent diminution of the 

 forest-clad areas." Many forms very per- 

 fect1v_adapted to soft herbage Became ex- 

 tinct, "but the great majority were more 

 plastic and in consequence underwent a 

 remarkable development, during this period 

 reaching the culmination in numbers and 

 kinds." 



In the Pliocene there was a wide repre- 

 sentation of the Old World genus Hipparion. 

 most of the species still three-toed. It was 

 probably derived from the American Neo- 

 hipparion, a swift, deer-like animal, about 

 forty inches in height at the shoulder. "In 

 the Siwalik beds of India is found a one-toed 

 Hipparion, and it has been suggested that 

 thejnodern zebras may b^ the living Hpcu^nH- 

 fl.nta ofjhis genus. It is certainly not in. the 

 line^ to the common horse, Equus caballus, 

 which makes its appearance, however, in the 

 Upper Pliocene beds both of Eurasia and 

 North America the climax of a long evo- 

 lutionary progression." 



