SKELETON OF QUADRUMANA. 529 



portional size of the occipital and mastoid. The interorbital space 

 is broader than in Stenops tardigradus. 



In the true Lemurs the facial part of the skull is more pro- 

 duced ; it is formed by the lacrymals, nasals, and maxillaries ; 

 the premaxillaries continuing very minute. In Lemur Macaco 

 the petrosal has a large and deep cerebellar fossa ; a short ten- 

 torial ridge projects anterior to this. There is a low postclinoid 

 ridge. The lateral sinus pierces the petrosal where it joins the 

 parietal and meets a second venous channel traversing the middle 

 fossa of the cranium to terminate at the postglenoid foramen. 

 The foramen ovale is a small fissure between the petrosal and 

 alisphenoid, less than the foramen rotundum, Avhich is close to 

 the foramen lacerum anterius : the outlet of the foramen ovale 

 is in the Eustachian fossa. 



The grey Lemur {^Chirogaleus griseus, fig. 348) has the more 

 common abbreviation of the antorbitai 

 part of the skull, in which the lacry- 

 mal foramen is conspicuous. The 

 malar is perforated by the ' nervus 

 subcutaneus mala).' The coronoid pro- 

 cess of the mandible, well developed 

 in all Lemuridce, is here very high. 



The anterior cornua of the hyoid, 



^, . 1 xl T -J t^i'^J' Lemur, lxix-. 



m (Jlieiromys and other Lemuriacs, are 



longer than the posterior, and include epi- and cerato-hyals, sup- 

 porting a cartilaginous stylo-hyal. 



In the Platyrrhines the cranium is proportionally larger and 

 the jaws less, as the species are smaller in size : they thus ex- 

 emplify the immature characters of the larger species. The 

 cranium is more globular, the occiput more protuberant, the 

 ' foramen magnum ' more advanced in position, and with a more 

 downward aspect, in the Marmosets (Jacchiis), and Ouistitis or 

 Ti-tis ( Callithrix), than in the Howlers {Mycetes). The frontal 

 suture is obliterated in all, and the single bone, thence resulting, 

 is triangular with the apex extending back, between the parietals, 

 in some Capucins {Cebus) as far as the superoccipital (fig. 239, 

 Cehus) : thus repeating a piscine collocation of supra-cranial 

 bones. The entocarotid perforates the back part of the petrosal. 



In all Platyrrhines a division of the lateral cerebral venous 

 sinus excavates the base of the petrosal to terminate at the post- 

 glenoid fossa, as in most Lemurs : the malar is similarly per- 

 forated by a facial nerve : the plate which divides the orbital 

 from the temporal fossa exhibits a small unossified vacuity in 



VOL. II. MM 



