THE SKELETON 77 
weight of the body); and Man, with what was originally a fore- 
foot turned into a hand. 
Before trying to answer the question as to the mode of 
origin and progress of these important differentiations, let us 
consider the structural variations to which the free lmbs are 
susceptible. 
The free limbs undergo greater and more numerous modifications than 
their related girdles ; and the probability that this may be perhaps connected 
with their exposed position and intimate contact with the environment, may 
be worth consideration. 
THE SKELETON OF THE FORE- LIMB 
The fore-limb of the Anthropoids is relatively longer than 
that of Man, and it is therefore specially interesting to note that 
in some of the lower races of Men the arms are relatively much 
longer than in Europeans. In the Veddahs this difference is 
even externally obvious, and when the skeleton is examined, is 
seen to be, as in the Anthropoids, chiefly due to the great 
length of the forearm (radius and ulna). If 
the length of the humerus be taken at 100, \ 
that of the radius is 73 in the male European, 
nearly 80 in the male Veddah, and 90 to 94 
in the Chimpanzee (Sarasins). This great 
development of the forearm is distinctly a 
mark of low organisation, and it is a signifi- 
cant fact that it obtains in the European fcetus 
and child, only giving place to the definitive 
proportion with advancing age. (Similar 
variation with age is found in the fore-leg, ef. 
infra.) 
The occasional perforation of the olecranon 
fossa of the humerus, to form what is known 
as the ent-epicondylar (supra-trochlear) foramen 
(Fig. 55), is undoubtedly to be regarded as 
atavistic. It is often found in the lower races 
of mankind, eg. natives of South Africa, and Fic. 54—RicHr Hun- 
has been observed in the Veddahs in as many  syowrwe pcbnee 
as 58 per cent, in skeletons belonging to the TION oF THE OLE- 
stone-age, in the Anthropoids (Gorilla and ee aay oe 
Orang), and in the lower Apes. 
On the ulnar side of the lower end of the humerus, a few 
