343 
of Edinburgh^ Session 1864 - 65 . 
The massiveness of the supra- and inter-orbital ridges, and their 
greater size even in the female gorilla than in the male chimpanzee, 
and the influence which their great elevation exercised in conceal- 
ing the frontal part of the cranial vault, were pointed out : only 
in the young gorilla, and that very slightly, did the frontal vault 
come into view, when the skull was looked at from before ; in all 
the three chimpanzee crania the frontal vault could be seen from 
that point of view. The sagittal and occipital crests were abso- 
lutely and relatively larger in the adult male than in the female 
gorilla. These three massive ridges mounted up and converged at 
the summit of the posterior end of the cranium. The original 
bilaterality of the sagittal crest was marked in the male by a median 
depression in its anterior third, subdividing it into two parallel 
ridges ; and quite at its posterior end it bifurcated, where it became 
continuous with the two halves of the lambdoidal crest, and when 
seen from the basal aspect, it seemed like a beak in the centre of 
the rounded occipital outline. The great projection of the lambdoidal 
crest rendered the under surface of the occipital bone concave, 
though it was traversed by strong ridges, evidently for the attach- 
ment of powerful muscles. The posterior margin of the foramen 
magnum was 3J inches from the posterior end of the sagittal 
crest. In the female the sagittal crest was very little raised 
above the surface of the conjoined parietals : the lambdoidal crests 
were much smaller than in the male gorilla, but larger than in the 
male chimpanzee ; the occipital outline rounded, but with no central 
projecting beak. In the young gorilla the two temporal ridges did 
not meet in the middle line : at their point of closest approximation 
they were one inch apart ; hence there was no sagittal crest. The 
occipital crest was feeble, and was joined somewhat more than one 
inch to the outer side of the middle line by the faintly-marked 
temporal ridge. Occipital outline rounded, under surface of the bone 
convex, approaching in form to that of the chimpanzee ; posterior 
margin of foramen magnum 1*9 inch from centre of the occipital 
crest. In all the three chimpanzee crania the temporal ridges 
never coalesced : in the adult male, in which they most closely 
approximated, their nearest points were upwards of an inch apart. 
In the adult male and female gorilla the cranial sutures were 
almost entirely obliterated. In the young animal they were all 
