58 



THE MAMMALIAN ORDER PRIMATES [.SECT. A 



Dental formula: as in the preceding family, viz.: 

 i, | ; c, | ; pm, § ; m, f = 32. 



Pollex : opposable. 



Ischial callosities: found in one genus only, viz. Hylobates 

 (the Gibbons). 



External auditory meatus : an osseous tube, as in Family III. 

 (Cf. Figs. 32, 33.) 



Tail : not developed externally. 



Intraparietal sulcus 



Central sulcus 



Sulcus lunafus 



InFerior occipital Sulcus 



Ant. limiting 

 -sulcus of Reil 

 (Pronto-orbital) 



Sup-limiting 

 sulcus of Reil 



Parallel sulcus 



Fissure of Sylvius 

 (post, limb) 



Olf.n. 



Fig. 34. Lateral aspect of the right cerebral hemisphere of a young Gorilla 

 (Simiidae). The olfactory nerves are attenuated in point of size: the cerebral 

 surface is much more convoluted than in the preceding examples and recalls the 

 appearance of the human cerebrum. Cf. with Figs. 23, 24, 25, 44, and p. 46. 



Nasal septum : as in Family III. 



Sternum : flat (lati-sternal type). 



Caecum : vermiform appendix present. 



Os centrale carpi : sometimes united with the os radiate carpi 

 to form the scaphoid bone. 



This family includes the Gibbons (Hylobates), Orang-utans 

 (Simia) 1 , Chimpanzees and Gorillas (Anthropopithecus niger and 

 gorilla). 



Family V. Hominidae. 



The main characters conform so exactly to those of the preceding 

 family that recapitulation is unnecessary. The Hominidae are 

 however distinguished from the Simiidae by several morphological 

 characteristics of which the following are the most important. 

 1 For the latest revision of these names, v. infra p. 158, footnote. 



