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Proceedings of the Royal Society 
margin of the hard palate was well seen. In the male gorilla, the 
depth of the posterior nares was almost twice as great as the breadth ; 
in the female the vertical diameter was not so great as the trans- 
verse. In the young, one diameter almost equalled the other. In 
the adult male, and younger chimpanzee, the breadth exceeded the 
depth ; in the female the two diameters were equal. The ratio of 
depth to breadth at these orifices was not, therefore, so definite as in 
the skulls described by Professors Owen and Wyman. 
In the lower jaws the following leading characters were noted : — 
Absence of chin ; backward and downward slope of jaw from its 
incisive margin ; presence of a strong buttress of hone on the inner 
aspect of symphysis ; passage of horizontal into ascending ramus 
by a gentle curve ; alveolar margins for molar and premolar teeth 
almost parallel ; long axes of condyles almost transverse. 
In the skull of the young gorilla various points illustrating pecu- 
liarities in the dentition were noticed. In the upper jaw the per- 
manent incisors had emerged, the central pair being larger than 
the lateral pair. The milk canines were shed, hut the apices of the 
permanent canines had only reached the orifices of their alveoli, the 
teeth being still buried in the jaw ; the septum originally situated 
between the sockets for the temporary and permanent canines was 
in a great measure absorbed : the diastema between the lateral in- 
cisor and canine, so strongly marked in the adult male and female, 
but more especially in the former, had not yet originated ; the 
septum between the sockets for those teeth was but little thicker 
than that between the alveoli for the lateral and central incisor, 
and the maxillo-premaxillary suture passed along the middle line 
of this septum.* The premolars had each two cusps, the external 
of the anterior, and the internal of the posterior being the larger : 
each premolar had three fangs, a larger internal and two smaller 
In the formation of the diastema in the crania of some apes, it would 
appear as if the preraaxilla and the canine portion of the superior maxillar}^ 
hone participated in an equal degree, for the maxillo-premaxillary suture was 
mostly situated, in the adult jaw, about midway between the canine and 
lateral incisor teeth. In others, however, e. g., several cynocephali, the suture 
was placed much nearer the canine tooth, and the interval was occasioned b}^ 
an increased growth of the premaxilla between that suture and the socket for 
the lateral incisor, 
