OKDERS OF MAMMALIA. 299 



horse is characterized by its massive heavy body, short blunt 

 muzzle, and feet with four hoofed toes each. The Hippopota- 

 mus is found in the rivers of Abyssinia, and throughout the 

 whole of Africa to the south of this. It reaches a length of 

 from eleven to twelve feet, is nocturnal in its habits, and swims 

 and dives with great facility. It lives upon vegetable food, 

 and is tolerably harmless unless attacked or irritated. The 

 Pigs, Peccaries, and Wart-hogs, constitute the family jSuida, 

 and have usually four toes to each foot, though sometimes the 

 hind-feet have only three toes. All the toes are hoofed, but it 

 is only two which support the weight of the body, the remain- 

 ing toe or toes being placed at some elevation on the back of 

 the foot. The snout is truncated and cylindrical, and is ca- 

 pable of extensive movement. The tail is very short, or is 

 represented only by a tubercle. 



Of the Swine the most important and best known is the 

 Wild Boar (Sus scrofa], from which it is probable that all our 

 domestic varieties of swine have sprung. Another form is the 

 Babyroussa or Hog-deer (Sus babyrussa), which inhabits the 

 Indian Archipelago, and is remarkable for the great size and 

 backward curvature of the upper canine teeth. The Wart- 

 hogs (Phacochoerus) are African, and derive their name from 

 the possession of a fleshy wart under each eye. The Peccaries 

 are exclusively American, the best-known species being the 

 Collared Peccary (Dicotyles torquatus). They are not at all 

 unlike small pigs both in appearance and habits, and they are 

 generally found in small flocks. 



The Muminantia form a most natural group of the Ungu- 

 lata, characterized by the structure of the foot, the dentition, 

 and the structure of the stomach. 



The foot is " cloven," consisting of a symmetrical pair of 

 toes, encased in hoofs, and looking as if produced by the cleav- 

 age of a single hoof. In most cases there are also two small 

 supplementary hoofed toes placed on the back of the foot. 



As regards the dentition, the typical state of things is that 

 there should be no incisor nor canine teeth in the upper jaw, 

 but that the lower jaw should have six incisors and two canines, 

 which are all similar in size and form, and constitute a con- 

 tinuous and uninterrupted series of eight teeth placed in the 

 front of the lower jaw. There are six molar teeth on each 

 side of each jaw, and these have grinding surfaces. The typi- 

 cal dental formula, therefore, for a Ruminant is : 



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