TEE ODD-TOBD UNQULATES. 273 



the Holy Land and Arabia, thought to be the coney re- 

 ferred to in the Bible, is the only genus. 



Order 9. Toxodontia. — Of this group, of which no spe- 

 cies are now living, the types are Tuxodon and Nesndon. 

 They are placed by many authors among the odd-toed 

 Ungulates, not far from the tapirs. Their incisors were 

 f or I". Toxodon in its skull bore some resemblance to the 

 Sirenians, and in the teeth were in certain respects like the 

 Edentates. The species lived in South America during 

 the early Tertiary Period. 



Order 10. Ungulata. — Tlie larger proportion of mammals 

 belong to this interesting order, which comprises nearly all 

 those species of mammals useful to man, such as the ox, 

 camel, pig, deer, and horse. They are, in general, charac- 

 terized by walking, so to speak, on their toes, each toe 

 being at the end encased in a horny hoof; not more than 

 four toes being completely developed on a foot. The teeth 

 are usually well developed, with six incisors in each jaw, 

 but these are often, especially in the upper jaw, less in 

 number or entirely absent, as in the sheep, deer, and ox. 

 The collar-bone is absent. The brain still remains small 

 compared with the bulk of the skull, and the intestinal 

 canal is of unusual length compared with that of animals 

 of the previous orders. 



The Ungulates have been divided by Or/en into two sub- 

 orders, according to the odd number of toes {Perisfodartyla) 

 or even number (Artiodactyhc). In the odd-toed Ungu- 

 lates (Perissodactyles) there may be three toes on each foot, 

 as in the rhinoceros, or one, as in the horse; while in the 

 even-toed Ungulates (Artiodactyles) there maybe four toes 

 {Hippopotamus), or two, as in tlie giraffe, or two functional 

 and two rudimental, as in the ox and deer, i.e., most Rumi- 

 nants. The more generalized existing form of Ungulates 

 is the tapir; the most specialized type is the horse, with its 

 single toe on each limb. A lai-ge number of extinct Ter- 

 tiary Ungulates in the Western States and Territories, and 

 the Tertiary basins of Paris and London, more or less allied 



