RHINOCEROS LEPTORHINUS. 369 
nasal horn. We may therefore infer, from the latter 
character, that the second horn was smaller in the 
leptorhine than in the tichorhine Rhinoceros, and con- 
nect in physiological relationship with this indication 
the non-extension of the bony supporting wall beneath 
the second platform.* Another distinction is the nar- 
rower interspace between the curved ridges (¢ ¢) which 
indicate the extent of origin of the temporal muscles 
upon the sides of the cranium: and this is not due 
to any difference of age; for the skull of the ticho- 
rhine Rhinoceros, with which I compared the Clacton 
specimen, belonged to an old individual, and yet 
exhibited the same superior width between the tem- 
poral ridges as is shown in the Cuvierian figure above 
referred to. The plane of the occiput is less inclined 
from below upwards and backwards than in the Rh. 
tichorhinus, and this region of the skull of the lepto- 
rhine species differs more strik- 
ingly in its form (fig. 140) : it is Fiy. 140. 
narrower in proportion to the 
length of the skull, and especially 
at the upper part, which gives it 
a triangular figure with the apex 
cut off. In the Lh. tichorhinus 
it is more square-shaped, and the 
upper overhanging ridge is thicker 
and more rugged, indicating more — Oeciput of Rhinoceros leplo- 
A rhinus. + nat. size. Clacton. 
powerful ligamentous and muscu- 
* The existing species of two-horned Rhinoceroses of Africa present the same 
difference in the proportions of their horns, as was manifested by the two extinct 
European species above compared. The #h, Keitloa of Dr. Smith has both horns 
of equal length ; the Ah, simus has the frontal horm much shorter than the 
nasal one. 
