PRIMATES PEOM MADAGASCAE. 99 



OcGi])ital Region. — The plane of the occiput is somewhat less inclined than in the 

 case of A. majori. The occipital crest is in most specimens very strongly developed, 

 rising up in a flange-like projection nearly 1 cm. in height. It is continued as far as 

 the auditory meatus. In some skulls a raised line connects the occipital crest with the 

 posterior and upper margin of the zygomatic arch in a manner suggestive of the 

 condition seen in Mesopropithecus, though the two bony fl.anges are not confluent as 

 in the latter genus. The position of the occipital condyles does not materially differ 

 from the condition observed in A. majori, though they tend to occupy a larger part 

 of the circumference of the foramen magnum and to be somewhat broader in their 

 upper portion in the larger species. 



Parietal Begion. — In old skulls of A. edwardsi the brain-case has the appearance of 

 being more depressed and relatively less voluminous than in the smaller species, but 

 probably this is in part due to the great development of the sagittal crest and the very 

 prominent frontal convexity which many of these skulls show. A small raised 

 triangular area is present on the supraoccipital, and from the apex of this triangle 

 the sagittal crest runs forward as a prominent blade-like ridge (Plate XVII. ). 



Frontal Begion. — About 1 cm, in front of the coronal suture the edges of the 

 sagittal crest rapidly diverge to form the posterior margins of the prominent frontal 

 convexity above referred to. This feature forms one of the most marked differences 

 between the two species. The central frontal region of A. edwardsi behind and above 

 the orbits is raised far above the level of the brain-case, forming a very prominent 

 " forehead." This feature occurs, as we have seen, in some skulls of Mesopropithecus. 

 The profile of A. edivardsi is thus in this region more steep than that of A. majori. 

 An extensive frontal sinus exists beneath this convexity, though it does not appear 

 to encroach upon the brain-substance as in the case of Megaladapis. The steep 

 backvvardly sloping edges of this frontal convexity accentuate the appearance of 

 extreme narrowness in the postorbital region. Tliis, again, is a feature that occurs in 

 Mesopropitliecus. 



The frontal bone has the appearance in A. edwardsi of extending backwards to a 

 greater extent along the skuU-Avall than in the case of A. majori; but measurements 

 along the sagittal suture show that this is more apparent than real, being due to the 

 anterior position of the frontal convexity to which reference has been made. 



Nasal Begion. — The median frontal suture is obliterated in its upper part, but can 

 be traced even in old skulls in the region between the orbits. The median nasal 

 suture persists in every case, as also does the fronto-nasal suture. The nasal bones of 

 A, edwardsi agi'ee essentially in form and proportionate dimensions with those of 

 A. majori. The upper external contoui-s of the nasals slightly diverge till the fronto- 

 maxillary suture is reached, below this point in some specimens a slight constriction 

 occurs, when the bones gradually broaden out again to meet long narrow upward 

 projections of the premaxillse, the broadest part of the bone being quite near its 

 anterior extremity. The free anterior margins when intact follow first a very short 



VOL. XVIII. — PAKT II. No. 6. — May, 1908. p 



