308 RHINOCEROS. 
jaws from Montpellier and Wirksworth, is due to the 
age of the individuals to which they belonged. 
The anterior part of the left branch of the lower jaw of 
a younger Rhinoceros (fig. 128), from the drift at Lawford, 
near Rugby, now in Dr. Buckland’s Museum, contains 
four teeth, which demonstrate, by their 
Fig. 128. 
relative position to the broken symphysis, 
a distinctive character of the Rhinoceros 
tichorhinus, and, at the same time, the 
existence of a smaller and more simple 
premolar anterior to that tooth, of which 
the empty socket is shown in fig. 124. 
The third tooth, in the present specimen, 
precisely accords in size and_ confor- 
mation with the second in fig. 124; 
and the fourth premolar with the third 
tooth, in fig. 124: the sole differences 
Portion of lower 
jaw. 4 Nat. size. 
Rhinoceros tichorhi-  yyesent, arise from their having been much 
nus. Drift, Lawford, 
Rugby. more recently acquired; the summits of 
which the teeth in the younger specimen 
the two crescents, composing the crown of the third 
tooth, had only just begun to be used im mastication, 
whilst those of the fourth are entire, and the base of the 
crown is not quite disengaged from the socket. We have 
in this instructive specimen the whole series of premolars, 
or those permanent teeth which succeed and displace the 
four deciduous molars of the still younger Rhinoceros. 
The individual to which the fossil in question belonged, 
must have perished just as it had accomplished this change 
of its dentition. In fig. 124, it may be observed that the 
third tooth in place, which is the first true molar, has been 
more worn than the tooth in advance, from which it is 
separated by the dotted line; the summits of the two 
