January, 1903.] 



KNOWLEDGE, 



" jolt " is much wider than the backward, and marks out 

 most closely the degree of the forward curve taken by the 

 anterior hair-stream, which descends from the crest. In 

 |)assiug, one may note here a very small and unimportant 

 point, but one which is of some interest. During or after 

 a short shower of rain the flank of a horse presents a 



own needs, but for those of higher creatures who have 

 availed themselves of its potentialities provided by nature. 

 These considerations show the domestic horse to be the 

 best specimen which can be found for the study of animal 

 pedometers, and by comparison of this sj>ecies with all 

 other known hairy mammals it is found to be as muck 



Fui. 2.— Side V ew of Horse shoiving chief Suix-rlieial Muscle? 



ciu'ious distribution of the moisture. At a point just 

 where the proper forward stream from the feathering joins 

 the main stream of hair from the thorax and abdomen, a 

 definite line of darker moist hair is seen, and the moist 

 surface is confined closely to the anterior part of the trunk, 

 and separated from that of the hollow of the flank. This 

 line of demarcation very clearly indicates the position 

 where the forward "jolt" in rapid action terminates. 



For the production of these and kindred ])eculiarities in 

 other animals no other than this dynamical explanation is 

 forthcoming, and no other seems to be required. The 

 arrangements of hair described is the best, because the 

 most familiar, of the pedometers displayed by animals on 

 their bodies. 



Attention to the facts of the horse's life and certain 

 related or contrasted facts of the lives of other animals 

 will show the reasons for which such hair-arrangements 

 are looked upon as registers of long-past and present 

 activities of the species in question The domestic horse 

 is the most locomotive of animals, wild or domesticated. 

 It has been produced by man out of a wild plastic stock, 

 with some such ancestors as the wild ( Prejevalsky"s) 

 horses now at the Zoological Society's Gardens, and by a 

 process of selection during many generations, first in its 

 Central Asian cradle, and later all over the civilised world. 

 It has been as much made by man for his purposes of 

 locomotion, draught and traflic, as a locomotive engine 

 has been made by him. The one has been made by the 

 laws of applied physics, and the other by those of biology. 

 Thus the domestic horse is in the unique position of being 

 the locomotive animal mir ccceltence, and that not for its 



better furnished with pedometers of the kind indicated as 

 it is greatly in advance of them as to the frequency and 

 rate of its locomotive activity. 



There are two closely related animals, the domestic ass 

 and mule, which ought to show this inguinal pedometer, 

 if mere heredity or some variation incidental to the grt>up 

 of animals could be fairly invoked to account for it. 

 These also are locomotive animals, but in a degree verj' 

 much less than the horse, and their pace is of a quieter 

 and less free character. What then do we find in them 

 as to the size and persistence of the inguinal pedometer ? 

 In the ass it is absent (the writer has met with one excep- 

 tion), and in the inule it is variable and occupies less than 

 half the area of that in the horse. These facts agree very 

 closely with the hybrid character of the mule and with 

 the differing locomotive activities of horse, mule and ass. 

 Prejevalskv's horses show a whorl and feathering of an 

 oval shape and limited size, very much like that of the 

 mule. The onager (Eiiiins onager), closely resembling 

 these three domestic animals in form, shows an inguinal 

 whorl or pedometer large and well defined, though much 

 less so than in the case of the horse, which is in keejung 

 with its character for remarkable fleetness and activity. 

 Zebras of the three forms. Mountain, G-revy's and 

 Burchell's zebras, show no whorl here at all, in spite of 

 their close resemblance in size and form and power of 

 locomotion lo the horse. Their wild lives, lived only for 

 their own sake and not for that of man. have been only 

 locomotive in the intermittent way which is incidental to 

 all wild life. 



The domestic ox. and most of the Bovidte. show no 



