94 



bdoidal ridges ; thus circumscribing the origins of the temporal mus- 

 cles. The lambdoidal and mastoid ridges are broader and more de- 

 veloped than in the Chimpanzpe, but inferior in both respects to 

 those of the Pongo. The inial region of the occiput is almost 

 smooth, and is convex, without the mesial ridge, and strong muscu- 

 lar impressions observable in the Pongo, where a preponderating 

 weight in front calls for the insertion of powerful muscles behind 

 to counterbalance it. 



The temporal bones join the frontal in Simia Mario as in the Tro- 

 glodytes niger; but this structure occasionally is present on one or 

 both sides of the skull in Simia Satyrvs. 



The addilamentum suturte lambdoidalis is present on both sides 

 in the S. Morio, and the beginning of the lambdoidal suture may be 

 faintly traced, but the remainder is obliterated. 



Directing our attention to the base of the skull of S. Morio we 

 observe the occipital /orawc/? to be less posteriorly situated than in 

 the Pongo, but more so than in the Chimpanzee. The plane of the 

 foramen is also less oblique than in the Pongo. The occipital condyles 

 are as far ajjart anteriorly as in the Chimpanzee. The anterior con- 

 dyloid ybrami'na are double on each side as in the Pongo: the carotid 

 and jugular/orffm?«« open within the same depression; they are rela- 

 tively further apart in the Chimpanzee : the petrous portion of the 

 temporal bone, as in the Pongo, is relatively smaller than in the Chim- 

 panzee, and the articular cavity, or surface for the lower jaw, forms 

 a larger proportion of the base of the skull. 



The other characters of the basis cranii correspond with those 

 of the Pongo ; and the smaller size of the meatus uvditorius externus 

 is probably associated in both species with a smaller auricle, as com- 

 pared with the Chimpanzee. 



On the bony palate the relative position of \\\e foramen incisivvm 

 corresjjonds with the development of the incisive teeth, showing the in- 

 termaxillary bones to be of larger size in the S. Morio than in the Chim- 

 panzee : the situation of the sutures joining these bones to the max- 

 illaries is indicated by vascular grooves, but otherwise obliterated ; 

 while in the cranium of a young Pongo of nearly the same size as 

 that of the Si7nia Morio, the intermaxillary sutures still remain, cor- 

 responding to the non-development of the permanent laniarics. It 

 will be interesting to determine at what period these sutures are ob- 

 literated in the more anthropoid Simia Morio. 



The OS nasi is a single narrow long triangular bone, slightly di- 

 lated at its upper end or apex, with the basal margin entire, pre- 

 senting no indications of original separation into two parts, as has 

 been observed in skulls of the Chimpanzee. 



In the contraction of the interorbital space, and the general 

 form of the orbit and its boundaries, the Simia Morio resembles the 

 Simia Satgriis, but the orbital cavitj', as before obsen^ed, is smaller. 

 In the plane of the orbit and straight contour of the upper jaw, the 

 Simiti Morio resembles the Bornean species oi Pongo or Simia Wurmbii, 

 rather than the Simia Abclii or Sumatran Pongo. 



The orbital process of the os make is perforated in the S. Morio 



