CLASS MAMMALIA 



671 



— "^NS^ 



^ Rt-M 



(1) the wild boar, Sus scrofa, of Europe; (2) the wart hog, Phaco- 

 chcerus cethiopicus, of Africa; (3) the hippopotamus, Hippopota- 

 mus amphibius, of Africa; (4) the camel, Camelus bactrianus, of 

 Asia; (5) the dromedary, Camelus dromcdarius, of Arabia; (6) the 

 llama, Lama glama, of South 

 America; (7) the chevro tains, 

 Tragulus and Hycemoschus, of 

 India, Malay, and Africa, among 

 the smallest living ruminants; 

 (8) the okapi, Ocapia johnstoni, 

 of the Congo; (9) the giraffe, 

 Girajja camelopardalis, of Africa; 

 (10) the gazelles, Gazella, of 

 Africa and Asia; (11) the cham- 

 ois, Rupicapra, of southern FlG - 537- • - The musk-ox, Ovibos 



moschatus. (From Flower and Lydek- 



Europe and southwestern Asia; ter.) 



(12) the buffaloes, Bubalus, of 



Africa and Asia; and (13) the yak, Poephagus, of the Himalayas 



and Thibet. 



Order Perissodactyla. — Odd-toed Hoofed Mammals. — 

 The horses (Equid^e), tapirs (Tapirid^e), and rhinoceroses 

 (Rhinocerotid^e) belong to this order. They are characterized 

 by the presence of an odd number of hoofed toes; the axis of 

 symmetry passes through the third digit. None of the Perisso- 

 dactyla are native to the United States, but many remains of 

 extinct species have been found. 



The horses, zebras, and asses of the family Equid.e have but 

 one functional toe on each foot, and two lateral splints. The 

 common horse, Equus caballus, of which over sixty domesticated 

 races exist, is not now known in a wild state. There are several 

 species of wild asses in Asia and Africa. The Nubian ass, Equus 

 africanus, is probably the parent of the domestic donkey. The 

 zebras are confined to Africa, and may be divided into several 

 specific types with numerous subspecies. The common zebra 

 is Equus zebra. 



