338 



RHINOCEROS. 



Fig. 128. 



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 

 relative position to the broken symphysis, 

 a distinctive character of the Rhinoceros 

 tic/iorMnus, 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. 1 24. 

 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 

 which the teeth in the younger specimen 

 present, arise from their having been much 

 more recently acquired ; the summits of 

 the two crescents, composing the crown of the third 

 tooth, had only just begun to be used in 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 



Portion of lower 

 jaw. % nat. size. 

 Rhinoceros tichorhi- 

 nus. Drift, Lawford, 

 Rugby. 



