10 Dusois—On Pithecanthropus erectus : 
that this bone could be different from that of man in important characters. In the 
opinion of Manouvrier, Keith, and myself, there might, therefore, exist a form, 
the skull of which had still many simian peculiarities, whilst the femur was to 
be distinguished from the human bone in quite subordinate and mechanically 
unimportant characters only. 
Such an Anthropoid would have the same proportion between the length of the 
femur and the size of the skull as the Pithecanthropus ; for we have only to double 
the length and breadth, both of the thigh-bone and of the skull of a Hy/obates 
syndactylus, to have dimensions exactly corresponding to those of the Java form. 
By doubling all dimensions of a Hylobates we would obtain an tmaginary product 
with a corresponding cranial capacity also. But certainly such an enlarge- 
ment alone would not be adequate to explain i reality the large cranial 
capacity, as, with an enlargement of the size of the body in nearly allied 
species of mammals, we do not find a corresponding enlargement of the cranial 
capacity. The Anthropoid would therefore not only have grown in the size of 
the body, but his brain would have grown faster relatively to the body than we 
are accustomed to see in homogeneal mammal species of different size. This is 
actually what we find to be the case in the remains of Pithecanthropus, and is 
indeed a proof that this fossil form was on the direct road to human development, 
the special morphological character of the genus Homo being the large cranial 
capacity of the skeleton relatively to the size of the body. 
For normal human proportions, the capacity of the cranium is too small 
for the femur, but microcephalic skulls of the class which may be regarded as 
atavistie can be even relatively smaller, whilst the height of the body is more than 
that of the Pithecanthropus, as computed from the length of the femur. Such was 
the case with the microcephalic idiot Joe, described by Professor Cunningham ; 
this was at least 5 cm. taller, but the capacity of his cranium measured only 
620 c.em. Comparing only the lineal dimensions, the length of the cranium of 
Pithecanthropus is certainly not too small for normal human proportions, assuming 
the femur to have belonged to the same individual—I measured many human 
skeletons having the same proportion — but certainly it would not be high 
enough. 
The fossil femur has a large exostosis growing from the inner and back part 
of the shaft below the lesser trochanter. That this pathological formation may 
have greatly changed the normal general form of the femur is, in consideration of 
other similar femora, very improbable. Of those who more closely examined the 
femur after my description, or the bone itself, none have admitted that. The 
celebrated pathological anatomist Virchow declared at the Leiden Zoological 
Congress the exostosis to be the result of a healed caries, which descended from 
the lumbar vertebre along the psoas muscle, and demonstrated a similar human 
