EVIDENCES FROM MORPHOLOGY 161 
second or the third molar of man presents five cusps—in the one case 
following the chimpanzee, in the other the gorilla. These latter varia- 
tions, therefore, may fairly be regarded as reversionary. For these 
facts I am indebted to the kindness of Mr. C. S. Tomes. 
10. Perforations of the humerus.—The peculiarities which we 
have to notice under this heading are two in number. First, the 
supra-condyloid foramen is a normal feature in some of the lower 
Quadrumana (Fig. 34), where it gives passage to the great nerve of 
Fic. 33.—Molar teeth of lower jaw in gorilla, orang, and man. Drawn from 
nature, nat. size. (From Romanes.) 
the forearm, and often also to the great artery. In man, however, 
it is not a normal feature. Yet it occurs in a small percentage of 
cases—viz., according to Sir W. Turner, in about one per cent, and 
therefore is regarded by Darwin as a vestigial character. Secondly, 
there is inter-condyloid foramen, which is also situated near the lower 
end of the humerus, but more in the middle of the bone. This occurs, 
but not constantly, in apes, and also in the human species. From 
the fact that it does so much more frequently in the bones of ancient 
—and also of some savage—races of mankind (viz. in 20 to 30 per cent 
of cases), Darwin is disposed to regard it also as a vestigial feature. 
