349 
of Edinburgh^ Session 1864 - 65 . 
external. In the chimpanzee crania the fangs of the premolars 
differed somewhat from those of the gorilla, for though each of the 
first pair possessed three fangs, those of the second had only two 
fangs, an external and an internal ; and in this respect, therefore, 
they presented a closer approximation to the arrangement of the 
fangs of the premolars in man than did the gorilla. 
In the young gorilla the first and second pairs of true molars 
were fully erupted ; each tooth was quadricuspid ; the anterior in- 
ternal was connected to the posterior external cusp by an oblique 
ridge. The third true molars were concealed within their alveoli. 
In the lower jaw of the young gorilla the permanent incisors 
were erupted : the left milk canine was in its socket, and close to 
it, on its lingual side, was a foramen which led into a canal that 
communicated with the crypt containing the permanent canine ; 
the foramen and canal marked the position of the gubernaculum. 
The right milk canine was shed, but the permanent tooth was deep 
in its alveolus, and the bony septum between the socket for the 
milk tooth and the gubernacular canal was still un absorbed. The 
diastema which existed on each side of the canine, but more espe- 
cially on the premolar aspect in the adult crania, had not been de- 
veloped in the young skull. The first pair of premolars was con- 
siderably larger than the second, each tooth possessed an anterior 
and a posterior fang. The first and second pairs of true molars 
were erupted, each tooth was quinquecuspid ; the third pair of true 
molars was still concealed within the jaw. The eruption of the 
permanent canines in the upper jaw precedes, therefore, their ap- 
pearance in the lower jaw ; but in both the upper and lower maxillsB 
the permanent canines follow in their eruption the first and second 
pairs of true molars. 
The internal capacity of the crania was as follows ; — 
Cubic Inches. 
Adult male gorilla, ..... 28* 
Adult female ,, ..... 26’5 
Young female ,, ..... 23* 
Adult male chimpanzee, .... 22- 
Adult female ,, .... 24- 
Younger ,, .... 21* 
