182 MK. P. E. BEDDAKD— CONTRIBUTIONS TO- THE 



French Academy of Sciences ^, the author distinguishes this species by the presence of an 

 additional cusp upon the last molar of the lower jaw. In the complete paper, on p. 73, 

 the following statement is made about the 5th molar of the lower jaw : — " Elle a cinq 

 tubercules, comme les deux dents qui la precedent. Ce caractere separe le Troglodytes 

 aubryi du T. niger et du T. tschego, et le rapproche au Gorilla gina." I quote the 

 passage in full in order to leave no room for any doubt of a misunderstanding on my part 

 in case my own statements are questioned. In the lower jaw of Troglodytes niger 

 belonging to the individual mentioned above the last molar of the lower jaw, though 

 smaller than either M. 1 or M. 2, has an identical pattern. I have not been able to 

 compare the corresponding molar of T. calvus. • 



A comparison of these two skulls shows a good many points of difference ; but the 

 series of skulls in the Natural History Museum, comprising animals of various ages and 

 of both sexes, makes it a matter of considerable difficulty to draw up very definite 

 specific distinctions. The examination of a larger series would probably increase these 

 difficulties. On the whole it appeared to me that the prognathism of the face is more 

 marked in T. calvus ; the face in profile shows a very much more concave outline, the 

 interorbital region being vertical or even (in " Sally's " skull) slightly directed back- 

 wai'ds, while in T. niger the line passing from the top of the skull to the extremity of 

 the upper jaw is almost flat or slightly concave ; in an adult skull from Sierra Leone 

 the concavity of the profile outline was fully as marked as in T. calvus. In none of 

 the specimens in the Natural History Museum was it possible to examine the interior 

 of the skull. 



The inside of the skull of " Sally " showed a few points of difference in the two animals. 

 In T. calvus the cribriform plate has a distinct crista galli ; this ridge is wanting in 

 T. niger. The transverse groove for the optic chiasma is decidedly deeper in T. calvus 

 than in T. niger ; the foramen lacerum anterius is also more extensive, the outwardly 

 directed part being wider as well as larger in T. calvus. The orbits as seen from the 

 inside of the skull were rather different in the two Chimpanzees. In the Common 

 Chimpanzee a strong transverse ridge marks the highest part of the convexity formed 

 by these lines. In T. calvus there is no marked ridge, the surfaces sloping gradually, 

 and the concavity for the lodgment of the anterior part of the temporal lobes of the 

 brain being in consequence less deep. On the other hand, in the skull of T. calvus 

 the petrous bone was produced into a much sharper edge, and the excavations for the 

 occipital lobes of the brain were in consequence decidedly deeper. The vomer of 

 T. niger is bifurcate behind, the diverging plates being attached to the pterygoids. In 

 T. calvus the hinder part of the vomer is covered by the pterygoids, the two little 

 plates of bone which cover over the vomer being distinct from the rest of the ptery- 

 goid. The relative length of the basi-occipital and basi-sphenoid is different in the two 



' This is reprinted at the end of the elaborated Memoir abeady referred to. 



