MAMMALIA 295 



having soft straight hair, vigorous beard, retreating cheek 

 bones, narrow prominent nose, and small teeth. 



Order 10. Artiodactyla. This large order includes the 

 hoofed animals with an even number of toes. There are 

 many that are of economic importance, seFving-^as- fur or 

 food for man and as his domestic animals. The pigs, 

 peccaries, and hippopotami do not chew a cud, but rumi- 

 nants (camel, deer, giraffe, prong-horn antelopes, and cattle) 

 crop herbage hastily without masticating it enough for 

 digestion and regurgitate it into the mouth later for 

 thorough chewing. A typical ruminant has the stomach 

 divided into four parts, the functions of which are corre- 

 lated with the peculiar habits of feeding. The deer have 

 solid horns which are shed annually ^but the cattle have 

 horns with a vascular bony core and a hard outer sheath.. 

 The prong-horn antelope of Western North America is 

 unique, having horns like cattle but shedding them annu- 

 ally. The descendants of the British Bos taurus are the 

 commonest of the domestic cattle, though the water 

 buffalo, yak, and others are important in certain districts. 



Order 11. Perissodactyla. The odd-toed hoofed ani- 

 mals include the horses (Equidce), tapirs, and rhinoceroses. 

 Though none of the Equidse were found in America when 

 Columbus discovered it, most of the past evolution of the 

 family took place in the United States. The horses show 

 extreme reduction of the pentadactyl limb ; only the middle 

 toe is functional and the terminal hoof represents the toe- 

 nail. At the present time there are over sixty varieties of 

 domesticated horses, all belonging to one species, Equus ca- 

 ballus. The asses, zebras, and quaggas still run wild in 

 Africa and Asia, but several species have been tamed. 



Order 12. Proboscidia. The two living spebies of ele- 

 phants inhabit Africa and India* respectively. Both have 

 five toes on all the feet, the characteristic elongated trun^: 

 with the nostrils opening at its tip, and a thick loose skin 

 (whence the name, " pachyderm"). Elephants have no 

 canine teeth; the tusks are elongated incisors. In rather 



