128 THE GENERAL ANATOMY OF THE CERCOPITHECIDAE [SECT. A 



directed ridges. The palmar surface in the Cynocephalous apes 

 seems to be distinguished in a somewhat similar manner. It 

 is impossible to avoid the 

 impression that this pecu- 

 liarity is associated with the 

 eminently terrestrial habits /~ ^^-F^Oc 



of most of the members of 

 this group of monkeys.) 



-Sinus Calcis 



' R 13a 



R9/s 



E. The Skeleton. The 

 Skull (Fig. 80). The brain- 

 case has increased in size, 

 particularly in its vertical 

 diameter. The face pro- 

 trudes less than in the 

 Lemurs, but more than in 

 Tarsius. In males (especially 

 in aged animals) the temporal 

 ridges are often prominent, 

 and there may be prominent 

 supra-orbital ridges. The 

 snout-like projection of the 

 facial bones is pronounced in 

 the Dog-faced monkeys, but 

 is much diminished in the 

 Cercopitheci. A wall bounds 



the orbit posteriorly, and the nasal duct opens within the margin 

 of that cavity. On the inner orbital wall, the lachrymal bone 

 is separated (as in the Lemuridae) from the os planum of the 

 ethmoid, by the interposition of the frontal and maxillary bones 

 which unite along a fronto-maxillary suture which often measures 

 10 mm. in length. The inter-orbital space is very narrow, especially 

 in young individuals, and in its upper portion. 



The infra-orbital canal is not roofed over. In the temporal fossa, 

 the alisphenoid is separated from the parietal by the interposition 

 of the frontal and squamous portion of the temporal bone, which 

 unite along a fronto-squamous suture. The New- World Apes 

 commonly present the Lemuroid feature of a parieto-sphenoid 



Fig. 79. Macacus nemestrinus. Scheme 

 of the cutaneous grooves of the sole of the 

 foot. Special attention is directed to the 

 course of the line marked R V3 a- (From 

 Schlaarinhaufen.) 



