RHINOCEROS TICHORHINUS. 307 
summits by attrition, is not so soon blended into one con- 
tinuous tract as in the Paleothere (fig. 116), but long 
remains insulated by a complete boundary ridge of enamel 
in each lobe, as shown in the lower molar tooth of the 
Rhinoceros tichorhinus (fig. 127). This tooth was discovered 
in the drift gravel, over-lying the Fig. 127. 
London clay, during the opera- 
tions of digging the Regent’s Canal, 
and is now in the British Museum. 
It shows also the deeper internal 
excavation, and the unequal height 
of the two crescentic lobes, which 
distinguish the lower molars of the 
Rhinoceros from those of the 
largest Palecothere. 
In the lower jaw of the Rhino- 
ceros tichorhinus, represented im 
figures 123 and 124, five molar 
P 3 Fifth molar, right side, lower 
teeth are shown in situ, and the jaw, nat. size ; Rhinoceros tichor- 
socket of a small premolar in front." P"" oe 
The lower jaw, discovered at Montpellier, figured by M. 
Christol in his Memoir on the species of fossil Rhinoceros, 
in the ‘ Annales des Sciences’ for 1835, pl. ii. figs. 1 and 2, 
and referred by that author to the Rhinoceros tichorhinus, 
is described (p. 46) as having all its molars, ‘“‘munie de 
toutes ses molaires,” of which teeth the figures exhibit six, 
corresponding in number with those of the specimen from 
Wirksworth. I have, however, obtained good evidence, 
from British specimens, of the accuracy of M. Adrien 
Camper's statement, cited by Cuvier, ‘ Ossemens Fossiles,” 
1822, tom. ii. pt. 1. p. 61, that the tichorhine Rhinoceros 
had seven molar teeth on each side of the lower jaw, like 
the existing species; and that the smaller number in the 
Z 
