464 



UNGULATES. 



side of both the upper and lower jaw there are seven cheek-teeth ; but the last molar 



in the upper jaw differs from the rest in having its hinder ridge more or less 



aborted, so that the form of the crown is generally triangular. 



As regards their front teeth, the 



different species of rhinoceros present 



a considerable amount of variation, 



some of them having such teeth in 



both jaws, while in others they are 



totally absent ; but there are never 



any canine teeth or tusks in the upper 



jaw, and the number of upper incisor 



teeth never exceeds two pairs. In 



the lower jaw there may be a pair 



of large pointed and nearly horizontal 



tusks, and between them a small pair 



of incisor teeth. 



All the living: rhin- 

 Form. . ° 



oceroses are animals or 



large size and heavy build, with the 

 legs comparatively short and stout, 

 although less so than in the hippo- 

 potamus. Each of the toes is furnished 

 with a relatively small, but broad and 

 well-defined hoof -like nail. The head 

 is large and elongated, with a concave 

 profile, and the erect oval ears placed 

 very far back. The eyes are very 

 small in proportion to the size of the 

 head ; and the upper lip is generally, 

 although not invariably, prehensile, 

 and prolonged beyond the extremity 

 of the lower one. The thick skin is 

 either naked, or but sparsely clad with 

 hair, and may be thrown in certain 

 parts of the body into a series of deep 

 folds. The tail is thin and of moderate 

 length. 



The horns, which 

 form the characteristic 

 feature of the physiognomy of the 

 living species, are composed of a 

 closely-packed mass of horny fibres, 

 growing from the skin, and having no connection with the bones of the 

 skull, although there are prominences on the latter beneath each horn. The 

 skull, as shown in the figure of that of an extinct species given in the sequel, 

 is characterised by its elevated occipital region, long curved profile, the absence of 



LEFT UPPER MOLAR TEETH OF TWO EXTINCT SPECIES 

 OF RHINOCEROS. 



Both considerably worn by use. 



