148 



NATURAL HISTORY. 



out at an early period. Though the number of species included in this section is very considerable 

 (about fifty, according to Mr. Wallace's estimate), it includes only two families, and each of these 

 contains only a single genus. We will commence with that which includes the best-known forms, the 

 Hares and Rabbits. 



FAMILY XYII. LEPORID^E (HARES AND RABBITS). 



The general appearance of these animals hardly needs to be described, and we may, therefore, indi- 

 cate mei'ely the structural peculiarities which serve to define the family. These consist in the presence 

 of six rootless molars on each side in the upper, and five in the lower jaw (see figure on p. 82), each 

 molar being divided into lobes by transverse folds of enamel; in the compressed form of the skull and 

 the presence of wing-like post-orbital processes of the frontal bones ; in the imperfect condition of the 

 clavicles ; the greater development of the hind limbs ; and the presence of a short, bushy, upturned 

 tail. The ears are long ; the inner surface of the cheeks is more or less clothed with shoi"t hairs ; the 

 fore-limbs have five, and the hind-limbs only four toes; and the soles of the feet are hairy throughout. 

 In all these characters, however they may differ in some respects, all the true Hares and Rabbits 

 agree. The representatives of this family occur in nearly all parts of the world, but chiefly in the 

 northern hemisphere, and the few species which pass down within the tropics are generally found 

 only in mountainous regions. In the north they reach the Arctic regions in both continents. In 

 the Old World a few species are scattered over India and Further India, and four or five occur in 

 Africa, but chiefly in the southern part of the continent. In North America the species are 

 numerous, and some of them range southward into Central America ; but South America has only 

 a single species, which occurs in the mountains of Brazil and upon the Andes. 



