ANATOMICAL STRUCTURE OF ANTHROPOID APES. 71 



takes the form of a half-oyal. The mastoid processes 

 are also present ia the chimpanzee. The external 

 occipital crest and the curved lines are generally 

 apparent. The styloid processes are more plainly 

 traced than in the gorilla. In the latter, as well as 

 in the chimpanzee, there is a blunt, tubular process 

 of the temporal bone, opposite to another bony 

 process, issuing from the occipital bone. This has 

 been observed by Virchow, and is termed by him 

 the carotid process {Processus carotiaus). 



The orbits of the chimpanzee are generally more 

 rounded, with a distinctly circular rim, while the 

 nasal bones are as long and narrow as in the gorilla. 

 The region of the jaws is very prognathous ; the 

 external nasal openings are rounder and smaller than 

 in the gorilla. The crowns of the canine teeth pro- 

 ject in the same pillar-shaped form (Fig. 18). The 

 triangular space enclosed by these and by the row 

 of teeth in the upper jaw is often very wide and 

 projecting, even more so than in the gorilla. But 

 whereas in the latter the canine teeth are shaped 

 almost like a three-sided pyramid, in the chim- 

 panzee they are more rounded and conical. In the 

 general structure of the teeth of both species there 

 are certain differences of which we shall . speak 

 presently. 



The brain-pan of a young male chimpanzee is 

 still more arched than it is in aged animals. The 

 temporal ridges are still far apart. The transverse 

 occipital crest displays near the mastoid process 

 well-defined wing-shaped indentations. In the skulls 

 of very young males the transverse occipital swell- 



