330 RHINOCEROS 



surface of which is similarly broken by a deep valley, 

 (a,) extending from the posterior margin nearly half-way 

 across, and by a deeper and longer valley, 5, commencing 

 from the middle of the inner side of the crown, and 

 expanding and partly dividing into two deep depressions 

 near its opposite extremity. The principal difference by 

 which the upper molars of the Ehinoceros may be dis- 

 tinguished, independently of their greater size, from those 

 of the Palseotherium, is the much inferior depth of the 

 two longitudinal depressions (d d) on the outer side of 

 the tooth, and the feeble development of their boundary 

 ridges. In the Palseotherium, a slight rising may be 

 discerned at the bottom of each of the two deep outer 

 pressions (see fig. 112) : this rising is much increased in 

 the Rhinoceros, and gains the level of the borders of the 

 depressions, giving an undulating character to the outer 

 surface of the tooth. The changes produced by age and 

 progressive wearing away of the grinding surface will be 

 illustrated by subsequent specimens. 



One of the "strange and monstrous bones" exhumed 

 with the teeth at Chartham (fig. 121), is described by 

 Grew* as "part of the far cheek, with both the ends 

 and the sockets of the teeth broken off." He compares 

 it with the corresponding part of the Hippopotamus ; and, 

 finding " that the orbit of the eye is neither so round 

 nor so big, yet the teeth far bigger ;" that the forehead 

 stands higher than the eye, whilst in the Hippopotamus 

 " it lies so low, that it looks like a valley between two 

 hills," he concludes it more likely that it belonged 

 to a Ehinoceros, " for the being whereof in this country 

 we have as much ground to suppose it as of the Hippo- 



* Loc. cit., p. 255. 



