• 346 Proceedings of the Boyal Society 
The anterior nostrils in the gorilla in form approached a four- 
sided figure, with the angles rounded off. The boundary between 
the nostril inferiorly, and the alveolar part of the premaxillae was 
not very sharply defined. In the young gorilla, also, the lateral 
boundaries formed by the ascending processes of the premaxillae 
were much more rounded than in the adult. In the chimpanzee the 
anterior nares were triangular in form. The difference in shape in 
these two species of anthropoid apes was due to the different mode 
of termination of the ascending processes of the premaxillae supe- 
riorly ; and as this is a character on which Professor Owen has laid 
great stress, it is as well to note, that in all these gorilla’s crania, 
as in those which he has described, the upper end of the ascending 
process of each premaxilla was intercalated as a triangular plate of 
bone between the nasal and superior maxilla. This could be readily 
traced both in the young skull and in that of the adult male, in 
which the naso- and maxillo-premaxillary sutures were visible, and 
in the adult female though the sutures were ossified, for lines on 
the bones indicated their original position. In the skull of the 
younger chimpanzee, in which alone the sutures persisted, and that, 
too, only at the ascending part of the premaxilla, the upper pointed 
end of that bone articulated with the lower end of the nasal, and 
was not intercalated between it and the superior maxilla."^ 
In the gorillas’ crania the nasal bones were narrow, compressed, 
and projecting superiorly, and raised along their line of coalescence 
into a crest. In the young animal it could be seen that they pro- 
jected upwards into the interorbital process of the frontal ; and 
in this specimen a line, looking at first like a suture, but really 
only a groove, probably for an artery or a nerve, seemed to cut off 
^ In the crania of the orangs and of the gibbons an arrangement of the upper 
end of the premaxillse, closely similar to that described in the chimpanzee, 
was seen. In only one skull of the orang did a linear process of the premaxilla 
pass upwards for of an inch between the nasal and superior maxilla. 
Hence the intercalated triangular plate at the upper end of the premaxilla of 
the gorilla is valuable as a diagnostic character to distinguish the skull of that 
animal not only from the skull of the chimpanzee, but from those of the other 
anthropoid apes. In the mode of termination, however, of its premaxillse 
superiorly the gorilla closely corresponds with the arrangement seen in the 
skulls of many of the tailed apes, e. g., Cynocephalus, Semnopithecus, Cerco- 
pithecus. 
