THE ORIGIN OF MAN 115 



feature of tlie skeletoD. The occasional existence of a supra- 

 condyloid spur, and even a supracondyloid foramen, in the 

 humerus is a well-known anomaly in Man : it is not a 

 common variation, and yet the spur is so uniform in its 

 manifestations and in its pecuUar relation to the brachial 

 artery and median nerve, that it is obviously a true rever- 

 sionary or atavistic variation. But none of the anthropoids 

 or of the Old World monkeys have this spur or foramen as a 

 normal structure, nor has it, I believe, ever been recorded in 

 any of them as an anomaly. On the other hand, it is a well- 

 known generaUsed reptiUan and primitive mammaKan posses- 

 sion. It is present in generalised Marsupials, Carnivora, 

 Insectivora, Lemurs and American Monkeys, but it is absent 

 altogether in those Primates which are reckoned as the 

 immediate ancestors of Man. 



In dealing with the far more plastic muscular system great 

 caution is necessary to ensure that the results of dissections 

 of the members of the Primate series convey any proper 

 picture of the distinctions of Man. If all the variations that 

 have ever been recorded in all the anthropoid apes be grouped 

 together into one composite picture, then it must be admitted 

 that there are singularly few muscular distinctions that can 

 be claimed for Homo, when all the muscular anomaKes that 

 have been recorded in him are so blended as to form a complex 

 human picture for contrast. On the whole, the total range 

 of variations of the muscular system of Man very closely 

 resembles that of the chimpanzee, and yet the average human 

 subject differs from the majority of chimpanzees (1) by 

 lacking certain speciaUsations which characterise the anthro- 

 poids, (2) by retaining certain very primitive features with 

 great constancy, (3) by exhibiting certain definite hiunan 

 specialisations not present in the anthropoids. The second 

 and third groups are those of most interest from the point of 

 view of the origin of Man. We may note that the constant 

 human retention of the ulnar fascia of the biceps cubiti is a 

 primitive feature, lost in all other members of the Primates. 

 Again, we may point to the normal presence of the primitive 

 pyramidalis and the deep head of the pronator radii teres. 



