1902.1 HAIR-SLOPE IN MAMMALS. 155 



„ , , From root of tail 



From root to ^^ -^^^ ^^^^^^ 



tip of tail. or end of mane. 



Cobios uncttoos'us 15 inches. 1 8 inches. 



., kob 12 „ 23 „ 



12 „ 25 „ 

 15 „ 



leche (3 specimens) j 9 „ 



10| „ 19^ „ 



,, senegamus (3 specimens) . ^ 8^ ,, 16| „ 



[9 ,, 12i „ 



[ 91 „ 15 „ 



„ w«r(^o?ii (3 specimens) •••'^ ^ " ^^ " 



I 9| „ 15 „ 



„ i/iowasi (2 specimens) ••• i ^3"' 20 



leucotis ' 5) ^^ " 



" . f 19 14 „ 



Cervicapra arundinum (3 speci- K 9 " j-^ 



mens) | ^2 ^ 20 I 



fuivo-rufola (2 speci- J 9 „ 15 „ 



mens) j 8 „ 12 „ (young) 



Felisleo 37 ,, -^O „ 



In the (1) cervical, (2) jjectoral, (3) post-humeral or axillary, 

 and (4) inguinal regions, the changes of hair-slope consequent 

 upon habits of active locomotion are most evident, 



(1) In the lateral and ventral aspects of the neck, whorls are 

 frequently seen in the Horse and seldom in other animals, and 

 these are less uniform in position and degree of development than 

 in other regions. In the strongly- developed muscular neck of a 

 horse, they appear very frequently between the sterno-niastoid 

 and splenius, or the sterno-mastoid and sterno-hyoid, and nr the 

 middle line of the ventral surface. Felis leo and F. parclus show 

 very marked whorl and feathering on the side of the neck, 

 probably from the strongly acting panniculus carnosus. 



(2) The pectoral area is one of the "critical areas" from this 

 dynamical point of view ; and many animals exhibit here marked 

 sio-ns of the degree and range of their locomotive activity in more 

 01^ less persistent whorls, feathering, and crests, lying over the 

 situation where the strong and important pectoral and flexor 

 muscles of the fore-limb diverge. It is unnecessary to mention m 

 detail the various animals in which these appear more or less 

 markedly ^ ; but the cases of the Horse, Ass, and Mule may be 

 more particularly considered, as bearing on the position here 

 maintained, namely, that the range, degree, and constalacy ot 

 muscular habit in the life-history of a species is portrayed m the 

 hairy covering in certain parts of their bodies, where this is 

 possible. 



1 See 'Use-Inheritance,' A. & C. Black, 1901, pp. 18, 19. 



