RHINOCEROSES. 463 



It is further reported that the tapir is not unfrequently successful ; and, in 

 any case, many of these animals are killed with the marks of jaguar's claws 

 on their backs, 

 succession of Before leaving these animals, it may be mentioned that the 



Teets. whole of the four premolar teetli on each side of the upper jaw are 

 preceded by milk-teeth, whereas in the pig and other Even-toed Ungulates the first 

 of these teeth never has a deciduous predecessor, as, indeed, is the case with other 

 groups of Mammals. Some rhinoceroses, however, resemble the tapirs in having 

 the first premolar preceded by a milk-tooth, although this seems to be merely 

 an individual, and not a specific peculiarity. 



The Rhinoceroses. 



Family RlllNOCEROTlDJS. 



Although inferior in length of body, and probably also in weight, to the 

 hippopotamus, the larger species of rhinoceros exceed it in height, and, there- 

 fore, vie with it in claiming the position of being the Mammals next in point 

 of size to the elephants. Unlike the tapirs, the various species of rhinoceros, all 

 of which are now confined to the Old World, differ very markedly from one 

 another in structure — so much so, indeed, that by many writers they are divided 

 into several genera ; and there is also considerable disparity in point of size. In 

 spite, however, of these minor differences, all these animals are so much alike in 

 general appearance, that it seems preferable to include the whole of them in the 

 single genus Rhinoceros. All the existing rhinoceroses differ from tapirs in having 

 but three toes on both fore and hind-feet, but since there are some extinct species 

 with four toes to the front limbs, this point of distinction cannot be regarded as a 

 very important one. The presence of one or two horns in the middle line of the 

 front of the head might at first sight be regarded as a more valuable diagnostic 

 character, but since these appendages are always or frequently absent in the 

 female of one of the living Indian rhinoceroses, and are invariably wanting in 

 certain extinct kinds, it will be obvious that other features must be sought that 

 will distinguish these animals from the tapirs. 



Such characteristics are to be found in the cheek-teeth, of which 

 Teeth. 



two from the upper jaws of certain extinct species are represented 



in the figures on next page. In the molar teeth of the upper jaw the two outer 



columns have completely coalesced so as to form a continuous external wall to 



the crown; this wall being sinuous, and in some cases (as in the upper figure) 



forming a prominent buttress at the front outer angle of the crown. From this 



outer wall proceed two continuous oblique transverse ridges, separated from one 



another by a deep valley, interrupted by projecting processes from one or both 



ridges, and sometimes also from the outer wall. This middle valley is usually 



quite free from cement ; and its form, as likewise the relative height of the whole 



crown, varies considerably in the different species. Instead of having the simple 



transverse ridges found in those of the tapirs, the lower cheek-teeth of the 



rhinoceroses have a pair of crescents, placed one in front of the other. On each 



