26 EINAR LONNBEEG, MAMMALS COLLECTED IN CENTRAL AFRICA. 



From this table can be seen that with regard to the capacity of the brain-cavity 

 these Chimpanzees can be arranged in two groups one with smaller, and one with larger 

 brain. One of these groups comprises three females and a male, the other two females 

 and a male. The difference in volume of the brain-cavity is with regard to the females 

 more than 50 ccm., and with regard to the males about 44 ccm., thus in both cases quite 

 considerable. The question presents itself then again, is this difference due to racial 

 distinction, or not? For the elucidation of this it is necessary to investigate, if there 

 exists any correlation between this difference in brain-capacity and the variation of other 

 characteristics which has been discussed above. Such an investigation is facilitated by 

 the table of measurements above. From this we learn that two of the small-brained fe- 

 males (n:o 178 & 224) have small teeth, but this is not at all the case with the third (161). 

 The first two of these small-brained females have raised eyebrow-ridges and thus com- 

 paratively high orbits, the third again (n:o 161) (PI. V, fig. 3) has the superciliary arch 

 very little raised and therefore comparatively low orbits. On the other hand especially 

 one of the large-brained females (n:o 160, PI. V, fig. 4) has raised eyebrow-ridges and 

 very large orbits. 



The breadth and shape of the palate is also very different in the different speci- 

 mens. Two of the small-brained ones (n:o 178 & 224) have a comparatively broad and 

 flat palate with a width inside m^ of about 36,5 mm., but the third (n:o 161) has the 

 narrowest and most vaulted palate of all with a width inside m^ of 28 mm. On the 

 other hand the corresponding measurement of one of the large-brained females (n:o 

 181) is 34,5 mm, but in the other (n:o 160) it is 37,5 mm. The old large-brained and 

 large-toothed male has the palatal breadth inside of m^ 34 mm.; in the comparatively 

 small-toothed and small-brained male the same dimension is almost similar or 34,5 

 mm. In such a case it is evidently impossible to use this character for dividing the 

 present material of Chimpanzees in two racial groups. The longest palate measuring 

 73,7 mm. is found in one of the small-brained (n:o 161), but also the shortest palate, 

 69,5 mm, belongs to a small-brained specimen (n:o 224). 



The greatest width of the interorbital septum is found in one of the large-brained 

 (n:o 181) with 18,3 mm., and one of the small-brained (n:o 161) with 16 mm., next comes 

 in this respect a large-brained (n:o 160) with 14,2 mm., then again two small-brained 

 (n:o 178 & 224) with resp. 13 and 11,6 mm. 



This complete irregularity of the variable characteristics makes it plainly difficult 

 to attribute any racial value to the differences in the size of the brain-cavity as expressed 

 above. This does not exclude that in other cases a difference with regard to the capacity 

 of the brain-cavity may be of racial value as Selenka has proved to be the case with the 

 Orangs. 



Among the collections of the R. Nat. Hist. Museum there are, however, some other 

 Chimpanzee skulls which appear to indicate a considerable variability among these ani- 

 mals even with regard to the brain-case and its capacity. To prove this the following 

 cubic measurements may be quoted concerning some Chimpanzee skulls collected at 

 Cape Debundscha, Cameroon. They are all from the same locality. The male, at least, 

 belongs to the Anthropopithecus caltius group. To the female skulls there are no skins. 



