50 VERTKBRA'IES : MAMMALS. 



springs or streams in their course, they used to serve as 

 highways of tra\'el to the explorers of the plains. 



The Buffalo is now nearly extinct. At present there 

 are only a few hundred alive, most of them in Yellow- 

 stone Park. As soon as the railways were built across 

 the continent they were rapidly exterminated, being 

 hunted for their skins. 



Oxen. 



The true Ox is known only as a domesticated animal, 

 although there are some half-wild herds in certain parks 

 in England \\'hich may represent the wild stock from 

 which the Domestic Cattle came. In the time of Caesar, 

 wild Cattle were abundant in the forests of Europe. 



Perhaps the Zebu, or " Sacred Cattle of India," had a 

 different source, as there are several \\ild forms of 

 Cattle in Asia, nearly related to the Domestic Ox. 



Odd-toed Ungulates. 



The Horse, Ass, and Zebra, 



In the Horse and its allies, the weight of the body is 

 carried by the middle toe, the third in each foot. The 

 second and fourth toes are represented by the splint 

 bones. There are incisor teeth in each jaw and the 

 stomach is simple. 



The Horse has been found in a wild state in the high 

 ])lateaus of Central Asia, and perhaps this form repre- 

 sents the ancestor of the Domestic Horse. The wild 

 Horses of America are the offspring of domesticated 

 animals. A great amount of variation has been pro- 

 duced b)- man in the size, structure and habits of the 



