NOTES ON THE HAIR-SLOPE IN MAN. 319 



which reaches to the inguinal region, but if flexed at all it 

 would not do so. The suggestion is only put forward tenta- 

 tively that the steady pressure of the weight of the limb with 

 necessary frequent shght movements would have some influence 

 on a parting of the kind described. 



On the liinbs of man there are a few departures from the type 

 of slope of hair which would be expected if man inherited this 

 from quadrumanous ancestors. The most significant is that on 

 the extensor surface of the forearm. The hair-streams on the 

 rest of this limb-segment present no peculiar features. 



On the extensor surface, more especially along the line of the 

 posterior border of the ulna, there is a united stream of hair 

 formed by a coalescence of the two which divide on the flexor 

 surface, pass towards the manus at first, then curve round the 

 axial and pre-axial borders respectively till they lie at right 

 angles to the long axis of the limb. At a point varying from 

 one to two inches from the distal end of the ulna commences the 

 reversed curl, which results in a narrow stream passing straight 

 towards the olecranon process, and terminating in a converging 

 whorl on the proximal side of that process. As to this singular 

 direction of a hair-stream, I pointed out in the paper referred 

 to^ that it was not a vestigial character, but that it was a 

 character produced both in man, anthropoid apes, some American 

 monkeys, and carnivores, by the effect of pressure on this exposed 

 surface of the limb in the attitudes common to those diverse 

 creatures. The view that it is due to rain-tracks, either pro- 

 duced by or for running off tropical rain, has been alluded to as 

 quite insufficient to account for it, considering its presence in 

 almost identical form in many Carnivores and in certain Un- 

 gulates, as some antelopes which adopt an attitude like the 

 ' couchant ' attitude of Carnivores. 



On the manus of man the general trend of hair-streams is 

 from the pre-axial to the post-axial border, and it assumes a 

 direction pretty closely at right angles to the long axis of the 

 limb, except along the dorsal aspect of the first metacarpal bone, 

 where a parting, continuous with that on the flexor surface of 

 the forearm and carpus, is found. This leads to a divergence 

 of the streams on the manus, the one scanty and passing to the 



^ Nature, vol. Iv. p. 236. 



