164 THE SKULL. [CHAP. 



Monkeys, but in all the Cebidx and Hapalidtz the inferior 

 surface of the ankylosed periotic and tympanic is somewhat 

 inflated. 



The carotid canal is always very conspicuous, entering 

 the under surface of the periotic near its hinder border. 

 There is often a glenoid foramen, but never an alisphenoid 

 canal. 



The foramen rotundum perforates the alisphenoid, but 

 the foramen ovale is usually a notch on its posterior border, 

 completed by the periotic behind. 



The mandible presents the same general characters as 

 that of Man, but the horizontal portion of the ramus 

 is usually more elongated, and the anterior border slopes 

 upwards and forwards, there being a complete absence of 

 mental protuberance. The condyle is extended trans- 

 versely, the coronoid process well developed and recurved. 

 The posterior or ascending portion of the ramus is broad 

 and flat ; the angle well developed, square, or more or 

 less rounded, but without any special pointed process as in 

 the Dog. 



In the Howling Monkeys (Mycetes) the hinder or ascend- 

 ing portion of the ramus is remarkable for its extent both 

 vertically and an tero- posteriorly, corresponding to a certain 

 extent with the extraordinary development of the vocal 

 organs, which it partially covers and protects. 



The Sim Una are remarkable in never, or very rarely, 

 having an ossified stylohyal ; but on looking closely at the 

 base of the periotic, immediately to the anterior and inner 

 side of the stylomastoid foramen, a very small depression, 

 in which there is sometimes a minute ossified tympano-hyal, 

 can generally be seen. To this the ligament representing 

 the stylohyal is attached. 



In very few of the Old World Monkeys is there any 



