THE HOOFED MAMMALS. 125 



front-feet, the hind pair having three. They have low-crowned cheek-teeth ; 

 the upper molars having an outer wall formed by the union of two conical 

 tubercles, from the inner side of which a pair of transverse crests run obliquely 

 across the grinding surface of the crown. In the lower molars there is simply 

 a pair of transverse ridges to each ; the total number of teeth being 42. The 

 skin of all the tapirs is sparsely haired ; and in size these animals may be 

 compared to a large donkey. 



The whole of the five living species of tapirs may be included in the single 

 genus Tapirus, to which special interest attaches on account of its remarkable 

 geographical distribution. Thus, whereas one of the five species is found in 

 the Malayan countries, the whole of the other four are restricted to the forest- 

 region of Tropical America, some of the latter ranging high into the Andes. 

 This, however, is by no means all, sinee the Malayan species is much more 

 nearly related to two of the American species than are the latter to their 

 compatriots. Had we the existing forms alone to deal with, this discontinuous 

 distribution would be very difficult to explain ; but we learn from geology 

 that these animals were formerly widely spread over the Northern Hemi- 

 sphere, whence they have migrated southwards to their present isolated 

 habitats. 



The Malayan species (T. indicus), which is the largest of the five, differs 

 from all the others in having the middle of the body white ; the remainder 

 of the skin being uniformly black, as is the whole of that of the American 

 species. In all the five kinds the skin of the young is, however, striped and 

 spotted with white. As regards their mode of life, tapirs are essentially shy, 

 harmless, and nocturnal forest animals, always frequenting the neighbourhood 

 of water, in which they often swim. 



The rhinoceroses, which include by far the largest representatives of the 

 Perissodactyle sub-order, may be best distinguished from the tapirs by the 

 form and number of their teeth. These are always numeri- 

 cally less than 42 in the living species ; and the upper molars The 

 differ from those of the tapirs in that their outer surface forms Rhinoceroses. 

 a continuous wall, undivided into lobes, while the grinding Family 

 surface, although consisting primarily of two oblique trans- Rhinocerotida. 

 verse ridges, presents a much more complicated pattern. In 

 the lower molars, the ridges, instead of being simply transverse, are curved 

 into crescents. Another point of distinction, so far as the existing kinds are 

 concerned, is the presence of only three toes on both the front and hind-feet. 

 Rhinoceroses derive their name from the presence of either one or two horns 

 arising from the middle line of the fore-part and middle of the head ; these 

 horns consisting entirely of an agglutinated mass of hair- like substances, having 

 no connection with the bones of the skull. 



In appearance, rhinoceroses are huge, ungainly brutes, with an enormous 

 head, much elevated and expanded posteriorly, short, massive limbs, large, 

 tubular, upright ears, often fringed with hairs, a moderately long, tapering 

 tail, and very thick skin, which is generally but sparsely covered with hair, 

 and may be thrown into a number of massive folds. They have always 

 the full number of seven pairs of cheek teeth; but canines are wanting, 

 and the incisors, if present at all, are reduced below the typical number of 

 three pairs. 



Rhinoceroses are restricted to the Oriental countries and Africa ; but there 

 is some difference of opinion whether they should be divided into several 

 genera, or all included under the single generic term Rhinoceros. Adopting 



