70 Zoological Society. 



in this species occupy an extent of 2 inches 7^ lines (0*06'8), whilst 

 in Troglodytes niger tlieir extent is only 1 inch \0^ lines (0'048). 

 The crown of the canine inclines more outwards in Troglodytes 

 Savagei ; the longitudinal convex ridge on its inner surface is more 

 prominent, the anterior groove bounding that ridge being deeper in 

 Troglodytes Savagei than in Troglodytes niger : the posterior inner 

 groove is continued upon the root of the tooth in Troglodytes 

 Savagei. The last molar is more nearly equal in size to the penul- 

 timate one, and is more complex in structure, than in Troglodytes 

 niger ; it has the posterior outer cusp and particularly the posterior 

 inner cusp more developed, and it has distinctly the connecting 

 cross ridge between the posterior outer and the anterior inner cusp, 

 which ridge is not developed in the last molar of Troglodytes niger. 

 The bony palate is longer in projiortion to its breadth than in 

 Troglodytes niger, in which the breadth of the palate between the 

 canines is absolutely greater than in Troglodytes Savagei. 



The external sutures between the premaxillary and maxillary 

 bones, which disappear so early in the Troglodytes niger, are more 

 or less persistent and traceable in all but the oldest male skull of 

 the Troglodytes Savagei; these sutures show that after the pre- 

 maxillary bone has entered the nose, of which it forms the lateral 

 boundary of the external opening, it again appears upon the exterior 

 surface of the face above the nostril, where its upper extremity forms 

 a triangular or wedge-shaped flattened piece, interposed between 

 the lower half of the os nasi and the os maxillare superius, thus ex- 

 cluding the latter bone from the boundary of the external nostril. 

 One skull of a young Troglodytes niger with deciduous teeth in place, 

 shows by the still persistent upper half of its facial suture, that it 

 terminates in a point a little above the middle of the border of the 

 external nostril, and that a portion of the superior maxillary is in- 

 terposed between it and the nasal : in two other skulls of young 

 Troglodytes niger, the slender pointed summits of the premaxillaries 

 reach the nasals and exclude the maxillaries from the boundary of 

 the nostril, but do not expand into triangular plates as in Troglodytes 

 Savagei : in not any of the skulls of Troglodytes niger with the per- 

 manent dentition does any trace of the suture between the premax- 

 illaries and maxillaries remain*. 



The nasal bones of the Troglodytes Savagei also afforded a re- 

 markable specific character : although the traces of their primary 

 median division were obvious at their lower part, they had coa- 

 lesced with each other as in the smaller species ; but instead of 

 being flat, or slightly and equably convex on the anterior surface, 

 as in Troglodytes niger, they are produced forwards as they incline 

 towards each other, along their upper half, and project there in the 

 form of a slight bony longitudinal ridge, equally dividing the lower 

 half of the interorbital space. This character — the nearest ap])roach 



* M. de Blainville, describing the osteology of the chimpanzee from a young 

 specimen of the Troglodytes niger, says, " Mais les premaxillaires, qm olfrent la 

 particularite de toucher a peine les os du nez et de souder dc fort bon heure avec 

 les raaxillaires," &c. Osteographic, fasc. i. p. 33. 



