344 RHINOCEROS. 



Mwus the penultimate true molar is smaller than the last ; 

 while in B. leptorhinus the last is smaller than the penul- 

 timate ; the latter species in his view been represented by the 

 Ehinoceros jaws figured by Cuvier, from the Val d'Arno, and 

 by the B. megarhinus of Montpellier. Brandt distinctly 

 mentions, on two occasions, that in B. tichorhinus the last 

 molar is a little larger than the penultimate. On the other 

 hand, Professor Owen, in the table of comparative measure- 

 ments between the teeth of B. leptorhinus and B. tichorhinus, 

 given at p. 364 of the ' British Fossil Mammalia,' makes 

 it appear that in B. tichorhinus the last true molar is smaller 

 than the pemdtimate, the reverse holding with the teeth of 

 the so-called B. leptorhinus, with which he compares them. 

 Bat I entertain grave doubts whether the Cromer specimen, 

 assumed in this instance as an example of B. tichorhinus, 

 really belongs to that species. There are strong reasons to 

 believe otherwise. An undoubted specimen of a lower jaw 

 of B. tichorhinus, 1 from Lawford, is preserved in the Oxford 

 Museum, in which the last true molar is slightly shorter 

 than the penultimate. The dimensions of these teeth are 

 given in the subjoined table of comparative measurements. 



Length of crown of last molar, at apex 

 Length of crown of last molar, below . 

 Length of penultimate, below 

 Length of antepenultimate, below 



In B. hemitozchus, the teeth increase in length, uniformly, 

 although not symmetrically, from the antepenultimate pre- 

 molar to the last true molar, and the last true molar is 

 ordinarily considerably longer than the penultimate. The 

 relative proportions are best exhibited by the worn crowns of 

 PL XX. In B. megarhinus, the ratio of the length of the three 

 true molars to the three posterior premolars is as 6 to 4*5 : 

 and in B. hemitoechus as 6 to 4 ; the length of the whole series 

 being nearly equal in the two species. 



It now remains to compare the teeth of the Gower species 

 with an important series of Rhinoceros remains, occurring 

 in the ' Elephant-Bed ' or ' Submarine Forest ' of the Nor- 

 folk coast, near Happisburgh and Mundesley, which, so far 

 as the evidence goes, constantly present well-marked dif- 

 ferences. The most perfect of these consist of rami of the 

 lower jaws with teeth. Upper molars are comparatively 

 rare, and such of them as have been met with have in most 

 instances been dispersed. No considerable fragment of a 



1 See p. 401.— [Ed.] 2 B. Etruscus. See p. 345.— [Ed.] 



