347 
of Edinburgh, Session 1864-65. 
the more expanded interorbital part from the narrower crest-like 
portion.* In the chimpanzee the nasal region was much flattened. 
The interorhital region was in the gorilla wider near the floor 
than the roof of the orbit, and the fossa for the lachrymal sac was 
directed forwards. In the chimpanzee there was little difference 
in the width of the interorhital region at the floor and at the roof, 
the fossa for the lachrymal sac was directed outwards, and was con- 
cealed by the sharp edge of the inner end of the lower margin of 
the orbit. In the gorilla the os planum of the ethmoid was an 
elongated triangular plate of bone : in the young skull its apex did 
not reach the lachrymal bone, so that the orbital plate of the 
superior maxilla articulated with the frontal. In the adult crania 
the ossa plana articulated with the lachrymal bones. f 
In all the crania of the gorillas the infra-orbital canals, as was 
first noticed by Agassiz, shallowed, and almost disappeared as they 
approached the spheno-maxillary Assures ; in the chimpanzee they 
remained deep throughout, and in the male were quite, and in the 
younger animal almost, bridged over by a plate of bone posteriorly. 
Owing to the comparative straightness of the alveolar portion of 
the premaxillse, and the more elevated and elongated nasal bones 
of the gorilla, the profile outline of its face may be represented by 
a much more direct line than is possible in the chimpanzee, in 
which the deep nasal depression, lying between the interorhital 
and alveolar projections, gives a deeply concave character to the 
profile outline. In the profile view of all these gorillas’ crania, not 
only was the outline of the nasal bones visible, but the lachr3^mal 
fossa, and a portion of the inner wall of the orbit behind the fossa. 
In the skulls of the gorilla the emarginate form of the posterior 
ii:- Dr Wyman states that in the crania he has examined there are indica- 
tions of a suture separating the lower part of the nasals from the inter-orbital 
part, the latter of which he looks upon as an additional osseous element in- 
tercalated between the frontals. May not such a groove as the one described 
in the text have been regarded as a suture ? 
t So far as could be judged from the skull of the younger chimpanzee, in 
that animal the ethmoid did not articulate with the lachrymal by its anterio 
margin, the superior maxillary and frontal having processes intercalated 
between. In the orangs and gibbons, again, the ossa plana were quadrilateral 
plates, and articulated by their anterior margins with the posterior margins 
of the lachrymal bones. 
