ILLUSTRATIONS OF EVOLUTION AMONG FOSSIL 



MAMMALS. 



A. — The Horse. 



By W. D. Matthew, Ph.D., 

 Associate Curator, Department of Vertebrate Pala?ontology. 



As a domestic animal the Horse is to be found almost every- 

 where that man can live. He is spread all over the world — 

 from torrid to arctic climates, in all the continents, in remote 

 oceanic islands — he is completely cosmopolitan. But as a wild 

 animal the Horse is at present limited to the Old World, and is 

 found there only in the open arid or desert plains of Central Asia 

 and Africa. There are two species in Asia, the Asiatic Wild Ass 

 {Eqiiiis hemionus), and the little known Przewalsky's Horse {E. 

 przewalskii), while in Africa there are the African Wild Ass {E. 

 asiniis) and the several species of Zebra {E. zebra, E. hurchdli, 

 E. qnagga). In the Americas and i\ustralia there are no true 

 wild horses, the mustangs and broncos of the Western Plains and 

 South America being feral (domesticated animals run wild) and 

 descended from the horses brought over from Europe by the early 

 white settlers. When the Spaniards first explored the New 

 World they found no horses on either continent. The Indians 

 were quite unfamiliar with them and at first regarded the strange 

 animal which the newcomers rode with wonder and terror, 

 like that of the ancient Romans when Pyrrhus and his Greeks 

 brought elephants — "the huge earth-shaking beast"' — to fight 

 against them. 



The Horse is distinguished from all other animals now living 

 by the fact that he has but one toe on each foot. Comparison 

 with other animals shows that this toe is the third or middle 

 digit of the foot. The hoof corresponds to the nail of a man or 

 the claw of a dog or cat, and is broadened out to aflford a firm, 

 strong support on which the whole weight of the animal rests. 

 Behind the "cannon-bone" of the foot are two slender little 



' Macaulav — "The Battle of Lake Rcgillus." 



