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, 6, 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 Rhinoceros may be dis- 
tinguished, independently of their greater size, from those 
of the Paleotherium, 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 Paleotherium, 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 lke a valley between two 
hills,” he concludes it more likely that it belonged 
to a Rhinoceros, ‘for the being whereof in this country 
we have as much ground to suppose it as of the Hippo- 
* Loe. cit., p. 255. 
