i66 THE SKULL. [chap. 



ramus the wide semicircular, shallow alveolar border for 

 the incisor teeth. The region of the angle is expanded 

 and compressed, with a thickened rounded border without 

 any process. The condyle is greatly elevated above the 

 alveolar border; its articular surface is very wide trans- 

 versely, and narrow and convex from before backwards. 

 The coronoid process is slender, straight, and inclined 

 backwards. 



The skull of the Rhinoceros resembles that of the Horse 

 in many essential features, but the occipital region is of 

 much greater extent vertically, the form of the cranial cavity 

 being concealed externally by large occipito-paiietal air- 

 cells. There is no postorbital process to the frontal, so 

 that the orbit is not divided from the temporal fossa. 

 There is a conspicuous rough antorbital projection on the 

 lachrymal bone just in front of the lachrymal foramen. 

 The nasals are very large and strong, early ankylosed to- 

 gether, arched from before backwards, and pointed ante- 

 riorly. The most elevated part of their upper surface is 

 roughened, and supports the great median horn which 

 characterizes the genus. In some species a posterior rough, 

 but less elevated, surface indicates the attachment of a 

 second horn. In some of the extinct species the meseth- 

 moid cartilage was ossified nearly as far forwards as the ex- 

 tremity of the nasals, which is not the case with any existing 

 species. The premaxillce are very small, and do not extend 

 anteriorly beyond the level of tlie front end of the nasals. 

 The hinder border of the palate is deeply excavated, the 

 horizontal plates of the palatines being very narrow. The 

 pterygoids are very slender, as in the Horse, but placed more 

 vertically. There is a distinct alisphenoid canal. The 

 squamosal sends down a very long conical, postglenoid pro- 



