8 Dusois—On Pithecanthropus erectus : 
The shape of the condyles in Pithecanthropus is quite human; in Hylobates it is 
entirely simian. 
I described, however, features which, in my opinion, are not found in such a 
degree nor together in Man; the shaft is on the inner side far more round; the 
popliteal space is less developed, convex in its middle, so that at this height the 
shaft is almost round instead of flattened ; the trochanteric line is less raised, and 
simian in its character. A fourth difference from the human femur, the shortness 
of the spiral line may be in connection with the exostosis which exists on the 
bone in this very area. Now, after having compared them with a very great 
number of human femora of different races, and knowing the opinion of many very 
experienced anatomists and zoologists, I still consider the three named characters, 
together, as marks of differentiation from the human femur. Similar characters, 
however, occur as a rule in Hylobates. 
Many have thought that they could easily find these differentiating characters 
in human femora. But they judged especially after my description, which was 
rather too short; they could therefore not know the degree of the differences, or 
they did not compare the fossil femur directly with human thigh-bones. At the 
Leiden Zoological Congress, Dr. Rosenberg, Professor of Anatomy in the Uni- 
versity of Utrecht, said he had found the characters in question as occasional 
varieties in the femur of» Man; but he compared the human bones with my 
short description, and only saw the fossil bone a good deal later. The same 
human femora of the Utrecht Anatomical Institute I compared directly with the 
fossil bone, and I did not find the characters in a corresponding degree on one of 
them. One of the differentiating characters I could never find in human femora 
even separately. I mean the small development of the popliteal space, which is 
in a high degree convex, because in the midst of it, and separated from the lips of 
the linea aspera, extends a kind of swelling until near the lower extremity, which 
is the reason that the lower part of the shaft of the femur has such a round section. 
Again in human thigh-bones the most backward projecting part of that space is in 
the neighbourhood of the outer lip of the linea aspera, whilst in the fossil Java 
femur this lip is situated much beneath (in a forward plane) from the most 
prominent part, this being in the middle.* I quite agree with all who have 
* Dr. Hepburn, of Edinburgh, has pointed out to me that in Hylobates the vastus imternus muscle, 
and the femoral head of the biceps flexor cruris come into close proximity to each other on the lower part 
of the posterior surface of the femur, below the level of the insertion of the adductor magnus muscle. 
They are only separated from each other by a strong ¢ntermuscular septum, which extends to within an 
inch of the knee-joint. By this means the superior part of the popliteal surface of the femur is rendered 
convex, and presents a median longitudinal elevation. An extension of these conditions of muscular attach- 
ment would exactly produce the appearances found in Pithecanthropus erectus. 
