132 The American Naturalist. . [February, 
the Cebide. In the case of the third trochanter we can hard- 
ly stop short of the lemuroide in spite of the probability that 
‘they and the anthropoide came from a common stem. Fora 
really large para-mastoid process we must go beyond the pri- 
mates altogether. There would be some comfort to be gained 
from the insectivora were we in the least justified in putting 
them among the ancestors of the primates, for several genera 
-have a well-developed para-mastoid process, the supra-condy- 
loid process is general, and the third trochanter is frequently 
represented, still it is neither general nor very prominent. 
For its greatest development we must turn to the odd-toed 
ungulata, and now descent is out of the question. 
It may be opposed to this that we have no right to assume 
that a certain well developed anomalous process in man must 
necessarily be accounted for by inheritance from a form pos- 
sessing an equal large one; that it is enough to show the 
existence of a clearly marked process in a common ancestor 
and to assume that its great-development in the anomaly is an 
accident of no significance. I am quite willing to grant that 
this objection has weight. Still when we account by atavism 
for the supra-condyloid process we must admit that the gulf 
between the structure of man’s body and that of one. of the 
Cebide is so great that this explanation would hardly serve 
were it not absolutely necessary for a theory. 
Another class of anomalies are those, which far from being 
general features, are found in certain highly specialized ani- 
mals which can be included in no possible scheme of descent. 
An instance is the fossa praenasalis, not to be confounded with 
the rounding of the border of the nares which is practically 
universal. It occurs in human skulls of a low order and pre- 
sents a development which is seen in no animal. It is usually 
more or less distinctly marked in the seal tribe. I have seen 
-it poorly marked in the gorilla. Here atavism is wholly at 
fault. The Pronator Quadratus muscle in man very rarely 
‘sends a prolongation downwards to one or more carpal bones 
on the radial side of the wrist. Iam not aware that this is 
normal in any mammal. Whence then does it come? Testut 
would have it the homologue of a muscle which Humphry 
