THE GREAT CHIMPANZEE. 395 



The processes posterior (p g) and internal (g) to the glenoid articular surface are better 

 developed, especially the internal one in PI. LXIII., than in the TV. niger (PI. LX.) : the 

 ridge which extends from the ecto-pterygoid (25, Pi. LXIII.) along the inner border of 

 the foramen ovale (< r) terminates in Tr. Gorilla by an angle or process answering to tliat 

 called ' styliform' or ' spinous' in Man, but of which there is no trace in the Tr. niger. 



The palate is narrower in proportion to its length in the Tr. Gorilla, but the pre- 

 maxillary portion (22) is relatively longer in Tr. niger. Two anterior palatine foramina, 

 one on each side the almost confluent incisive foramina, are more constant and con- 

 spicuous in Tr. Gorilla : the posterior palatine foramina are nearer the posterior border 

 of the bony palate in the Tr. niger. The pterygoid fossae (24) are relatively deeper and 

 longer in the Tr. niger. The posterior nares are deeper or longer in proportion to their 

 breadth in Tr. Gorilla ; and the posterior border of the bony palate is emarginate at its 

 middle, instead of being produced backwards into a point as in Tr. niger. 



As decisive marks of specific distinction as any of those deducible from the forms, 

 proportions and connections of the bones are presented by the greater relative dimensions 

 of the canine and molar teeth, as compared with the incisors in the Tr. Gorilla, and by 

 the more complex grinding surface of the last molar (m 3, PI. LXIII.), and its equality of 

 size with the first molar (m I) in Tr. Gorilla. The transverse extent of the four incisors 

 of the upper jaw is as great in the Tr. niger as in Tr. Gorilla : the interspace between 

 the right and left canines is even greater, as is also the extent of the diastema between 

 the canines and the incisors of the upper jaw in Tr. niger. The median incisors are, 

 however, larger in proportion to the lateral ones in Tr. Gorilla. 



In one example of a male Tr. Gorilla the antero-posterior extent of the five grinding 

 teeth is 2 inches 8 lines ; in a second male it is 2 inches 9 lines ; in one male Tr. 

 niger the antero-posterior extent of the same teeth measures 1 inch 10 lines ; in an 

 older male it measures only 1 inch 9 lines. 



The crown of the canine is more inclined outwards in Tr. Gorilla ; the anterior inner 

 groove is much deeper ; the base of the posterior trenchant border is more produced ; 

 the ridge between the two inner grooves is more prominent, and the hinder inner groove 

 is continued more decidedly upon the fang in the Tr. Gorilla. The following are the 

 dimensions of the canines in the males of the two species : — 



Total length 



Length of the crown .... 

 Breadth of its base .... 

 Thickness of ditto .... 



The last molar (m 3) of the Tr. Gorilla is more nearly equal to the penultimate one 

 than in Tr. niger, being only slightly narrower across the back part : it has the posterior 

 outer cusp, and particularly the posterior inner cusp, much more distinctly developed, 



