72 ANTHEOPOID APES. 



ing of which we have spoken (Torus occipitalis 

 transversus) is already developed. The orbits are 

 distinctly detached from the skull; the bridge of 

 the nose is depressed; the crowns of the canine 

 teeth are, in conformity with the still slight develop- 

 ment of the teeth themselves, less marked, and the 

 triangular space enclosed by the teeth is less convex 

 than in older animals. 



The skull of the adult chimpanzee is, in its 

 coronal and occipital parts, more uniformly arched, 

 narrower, and more elongated than in aged males. 

 The transverse occipital ridge usually develops 

 itself in the region of the upper curved lines, or 

 in the bony parts enclosed between these and the 

 central lines. The nasal and upper maxillary region 

 is depressed. That section of the upper jaw which 

 contains the incisor and canine teeth is small. In 

 the skulls of all chimpanzees, of whatever sex or 

 age, the body of the lower jaw is comparatively 

 small, with two low but wide rami, of which the 

 coronoid and condyloid processes are divided from 

 each other by a comparatively wide cleft. The 

 rami of the chimpanzee's lower jaw are still more 

 abruptly retreating than is usually the case in the 

 gorilla. 



The skull of a very young female gorilla is shaped 

 almost like a half-sphere. The orbits are scarcely 

 detached from the forehead ; the want of elevation 

 of the orbital arch, and the slighter prognathism of 

 the jaw, is marked by the deep depression between 

 it and the nose and forehead (Fig. 20). 



The cancellous texture of the bones of the chim- 



