804 



with the same part of that from the Gahoon, we see not only a much greater develop- 

 ment of the lambdoidal and sagittal intermuscular crests, but the superorbital ridge is more 

 produced both upwards and forwards from the plane of the forehead. In comparing the 

 skulls of the two varieties in a direct front view, the malar bones are larger, the lacrymal 

 bones smaller, and the lacrymal fossae and canals much more expanded, than in the Gaboon 

 variety. The nasal aperture is also wider and has more sharply defined lateral borders in 

 that from the river Danger. But the upper jaw below the nostril is not more developed, and 

 in proportion to the rest of the skull is shorter and narrower than in the variety from the 

 Gaboon. The suborbital foramina are two on one side and three on the other in the skull 

 under description, in which, as in the Gaboon variety, there is neither superorbital foramen 

 nor groove. It would at first seem probable that the greater development of the lambdoidal 

 and sagittal cristse, to which the greater extent of the cranial part of the skull depends, in 

 the specimen from the river Danger, might be due to the greater age of the individual and 

 the longer continuance of the stimulus of the action of the muscles concemed in the support 

 of the head, and in the movements of the anteriorly produced and preponderating jaws. But 

 the condition of the grinding surface of the teeth, and more especially that of the sutures, 

 negative the idea of the skull of the Gorilla from the river Danger having belonged to an 

 older animal than those skulls of the Gorilla from the Gaboon with which it has been com- 

 pared. In fact, in no other skull of the adult Troglodytes Gorilla that has hitherto been 

 described, is the course and extent of so many sutures more clearly traceable than in the 

 present specimen. The whole circumference of the partially coalesced nasal bones is shown 

 by a suture which is as wavy or dentated as most of those in the Human cranium. The two 

 nasal bones are quite blended together at their upper or interorbital halves, which form the 

 usual well-marked ridge-like prominence characteristic of the species. Above this ridge the 

 bone expands and again contracts as it ascends, and terminates in a point within three lines 

 of the summit of the superorbital ridge. The remnant of the straight suture which divided 

 the lower halves of the nasals is confined to the anterior surface of those bones. 



The suture of the upper expanded part of the premaxillary, which is wedged between the 

 nasal and maxillary, and forms the upper and lateral boundary of the nostril, is very distinctly 

 marked, and is continued down to within an inch of the alveolar border between the canine 

 and outer incisor : the premaxillary suture on the inner surface of the nostril is continued 

 into the outer one about nine lines below the nasal bone, and so insulates the upper end of 

 the premaxillary. This variety does not exist in the skulls of the Gaboon Gorillas here com- 

 pared, and may be accidental to the individual from the river Danger. 



The squamosal unites with the frontal by a dentated suture more than an inch long, sepa- 

 rating the alisphenoid from the parietal to the same extent. The suture between the squa- 

 mosal and alisphenoid is also dentated ; that between the squamosal and parietal is even and 

 is slightly concave upwards instead of being convex as in Man ; that between the mastoid and 

 parietal is convex upwards and is continued backwards upon the lambdoidal crista, where 

 it bends down to define the mastoid from the superoccipital. The coronal suture becomes 

 obliterated at the base of the fronto-parietal crest at the junction of its middle and anterior 

 thirds, thus indicating the proportion of that crest which is formed by the coalesced frontal 

 bones. 



