636 
AFRICAN GAME ANIMALS 
to the modern horses, only the remote ancestral forms of 
which were three-toed like the rhinoceros. In shape of 
body the rhinoceros is not very unlike the hippopotamus, 
the body being almost equally long, but the legs are in 
most of the forms decidedly longer, so that the animal is 
capable of travelling at really astonishing speed considering 
its immense size. The skin is very thick, dense in texture, 
and usually quite hairless. The skin of the two African 
genera resembles in general appearance that of the elephant, 
but it is of a very different quality, being much denser and 
more armor-like. The hair is confined in the existing 
species chiefly to the tips of the ears and the tail, but the 
recently extinct woolly rhinoceros, which lived far north in 
Europe and Asia, was clothed by a coat of long hair to pro¬ 
tect it from the cold. In dental characters the various 
genera of rhinoceroses exhibit much diversity, but the cheek¬ 
teeth show a peculiar pattern of folds which are character¬ 
istic of the family. The great bulk of the genera had well- 
developed incisor teeth in both jaws, and some of the very 
ancient types had canine teeth as well, but the living African 
forms lack all indication of either incisor or canine teeth. 
The cheek-teeth usually consist of the full number found 
in mammals, that is, four premolars which have milk pred¬ 
ecessors and three molars. The premolars and molars are 
quite alike in shape and size, except the first premolar 
which is usually small and sometimes wanting. The cheek¬ 
teeth, as a rule, are composed only of dentine and enamel 
and are broad-crowned, the crowns being thrown into two 
transverse folds projecting inward with deep valleys sepa¬ 
rating them. Certain forms, however, such as the white 
rhinoceros of Africa and the woolly rhinoceros of the boreal 
