CHAP. V] THE CRANIA OF THE SIMIIDAE ( PRIMATES) 



223 



(b) The nasal bones are splayed and wide, though flat. The face is 

 loss markedly depressed, and is described as fratantognathic, as opposed 

 to the ximognatliic form encountered in the Orang-utan. 



(c) The molar teeth bear large cusps. 



(d) The cranial ridges are very large. 



Fig. 148. Mesial section of the skull of an adult male Gorilla 

 (From a specimen in the Liverpool Museum.) 



.', uat. size) 



And the features which differentiate the skulls of the Gorilla and the 

 Chimpanzee are as follows : 



(a') The whole .skull of the Gorilla is larger : the facial part is rela- 

 tively larger : the cranial ridges are very large and prominent. 



(&') The nasal hones are long ; at their inferior margins they 

 expand widely and end at a level well below that of the inferior orbital 

 margins. 



(c') The nasal aperture is ovate rather than pyriform. 



(d') The molar teeth bear very large cusps and are larger than in 

 the Chimpanzee. 



