1900.] 



HAIR-SLOPE IN CERTAIN MAMMALS. 



683 



and with great uniformity, in a raised ridge of hair. The 

 " feathering " diverges on each side, that on the gluteal region 

 merging easily into the general hair-stream of this part, and the 

 stream which passes on to the thorax sweeps more widely forward 

 and curves again to the ventral surface, uniting with the hair- 

 stream of the thorax. 



This character in Horses is universal, and I have found it 

 present, more or less marked, in 25 other forms of Ungulates 

 (see Notes, p. 686). 



B. Post-humeral or axillary. — This whorl, with occasionally a 

 " feathering " arising from it, lies in the hollow between the great 

 mass of extensor muscles of the fore-limb and the muscles of the 

 thorax. It has been found by me in 87 Horses out of a very 

 large number examined. In two of these it was unilateral ; and of 

 these 87, 57 were cart-horses, though the proportion of cart-horses 

 examined was very small. In regard to this fact, it may be noted 

 that in cart-horses the action of the shoulder-joint prepon- 

 derates considerably over that of the carpal and metacarpo- 

 phalangeal joints. One special group of 2159 Horses examined 

 gave 42 cases of this feature, or nearly 2 per cent. I would suggest 

 that this is a specially interesting case of a new character, like the 

 more stable inguinal and pectoral whorls, being developed before 

 our eyes. This whorl has also been noted in 16 other forms of 

 Ungulates. (See Notes, p. 686.) 



Fig. 2. 



View of Horse showing poet-humeral and inguinal whorls with feathering, 

 arrows indicating directions of opposing muscles. 



C. Pectoral.— This whorl (see fig. 3, p. 684) with oval " feather- 

 ing " is bilateral, and extends from a point about at the level of 

 the olecranon process over the mass of the pectoral muscles in a 



