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 limbs are 

 susceptible. 



The free limbs undergo greater and more numerous modifications than 

 their related girdles ; and the probability that thjs 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 foetus 

 and child, only giving place to the definitive 

 proportion with advancing age. (Similar 

 variation with age is found in the fore-leg, cf. 

 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, e.g. natives of South Africa, and FIG. 54. RIGHT HUM- 

 , , , -, . ,, i T -.j , ERUS OF A NEC;RO, 



has been observed in the Veddahs in as many SHOWING PERFORA- 



as 58 per cent, in skeletons belonging to the TION OF THE LE - 



., . , . CRANOX FOSSA. (All- 



stone-age, in the Anthropoids (Gorilla and terior aspect.) 

 Orang), and in the lower Apes. 



On the ulnar side of the lower end of the humerus, a few 



