POSITION AND STRUCTURE OF HORSE 67 



representatives of the group include the wild horse 

 and the animals known as chigetais, kiangs, and 

 onagers, which serve in some degree to connect the 

 former with the ass. The latter, in a wild state, is 

 restricted to North-eastern Africa ; while the east 

 and south of the African continent form the home 

 of the striped members of the family, commonly 

 known as zebras and quaggas. 



During the Prehistoric Stone Ages, as is more 

 fully indicated in later chapters, the range of some 

 of the living Asiatic members of the group ex- 

 tended to Western Europe. At an earlier date 

 (Pliocene and Pleistocene) extinct species of horses 

 roamed over Central and Northern India. And at 

 some period horses doubtless ranged right across 

 Asia to Bering Strait, as remains of a species closely 

 allied to the existing horse occur on the opposite 

 side of the Strait in the frozen soil of Alaska. 



Moreover, throughout the later portion of the 

 Tertiary period numerous extinct representatives of 

 the family inhabited North America, where horses 

 or asses were quite unknown when that continent 

 was discovered by Columbus. Nor is this all, for 

 quite late in the Tertiary period, when South 

 America, which had previously been isolated for a 

 long epoch, became connected by land with North 

 America, members of the family traversed the 

 Isthmus of Darien, and made their way into 

 Argentina and Patagonia, where they developed 



