55 
Dr. Wyman by Prof. Agassiz, it is stated that “in the Chimpanzee 
the infraorbital canal forms a deep groove, terminating in the spheno- 
maxillary fissure, its depth remaining uniform to its termination ; but 
in the Engé-ena (Trogl. Gorilla) the canal becomes gradually less 
deep from before backwards, and at the fissure is scarcely obvious.” 
In the skull of the female Trogl. Gorilla (fig. 2) examined by me, 
the infraorbital canal is also shorter and shallower than in the skull 
of a female Trogl. niger, but the varieties observable in the condition 
of this canal in different individuals of the Trogl. niger are more 
marked than those above noticed in the skulls of the two species, and 
induce me therefore to attach less importance to this character as a 
specific one. In two skulls of adult males, e. g. in the College of 
Surgeons, the infraorbital groove as it passes backwards again be- 
comes a canal by the meeting, and in one specimen by the coalescence 
of the two sides of the groove above the canal for an extent of from 
two to three lines before it enters the spheno-maxillary fissure. Dr. 
Wyman indeed notices a similar conformation in an adult cranium 
of the Chimpanzee belonging to Dr. J. C. Warren. Now this is a 
more decided difference from the continuous open groove at the floor 
of the orbit in the adult female Tr. niger than that groove presents 
in comparison with the shorter and shallower one in Trogl. Gorilla. 
I find too that the second character of Trogl. Gorilla pointed out by 
Prof. Agassiz,—‘‘ from the internal walls of the orbits which recede 
from each other in descending towards the floor, thus leaving a large 
pyramidal space for the lodgment of the os ethmoides,’’—is so much 
less marked in the female skull of Tr. Gorilla, as contrasted with that 
of Tr. niger, as to induce me to view it more in the light of a sexual 
than a specific modification. 
The seventh is a good character, and is repeated by each of the 
skulls of Tr. Gorilia examined by me. All the skulls of Tr. niger also 
show the backward projecting point, where the emargination exists 
in Tr. Gorilla. 
8. The minor relative projection of the incisive alveoli beyond the 
line of the rest of the face is as characteristic of the three skulls of 
Tr. Gorilla now in England as of the four in the United States, and 
results from the same comparative shortness of the premaxillary 
hones, between the nasal orifice and the edge of the incisive alveoli. 
But the ossa nasi, besides being more narrow and compressed supe- 
riorly, aye more prominent at that part in Tr. Gorilla than in Tr. niger, 
and they are also more expanded and broader inferiorly, and I cannot 
but regard the most decisive mark of the specific distinction of the 
Troglodytes Gorilla to be the longer persistence of the maxillo-pre- 
maxillary sutures, and the evidence thereby given of the peculiar 
form, development and connexions of the upper portions of the pre- 
maxillary bones. It is remarkable indeed, since these sutures remain 
so distinct in the adult female skull (fig. 2) and the younger adult 
male skull (fig. 1) here described, that no trace of them should have 
been detected in any of the four skulls taken by Dr. Savage to 
America, in which Dr. Wyman describes the ossa nasi as being 
“‘ firmly co-ossified with each other and with the surrounding bones.” 
