



KNOWLEDGE 



[Jaklary, 1903. 



inguinal whorl, and in the case of the former we can 

 explain, from our knowledge of its slowly-moving action 

 and general heaviness, this negative fact. 



Among the Bovidse certain autelopes, gazelles, and sheep 

 exhibit a more or less defined inguinal pedometer, and 

 these are given in more detail elsewhere.* 



The si)ecial instance of an animal pedometer, which has 

 been described at some lengtli, will serve to illustrate 

 others less well known, and among these, as one would 

 expect, the greater numbers are found in the domestic 

 horse. 



Behind the lai'ge mass of the muscles of the shoulder, 

 and in a hollow correspondiag to the inguinal hollow, 

 there is found just below the withers of some horses a 

 whorl which may be counted among the pedometers of 

 that useful creature. Being not a constant phenomenon 

 it is the more significant from one point of view, for it is 

 evidently a pedometer in process of evolutie)n at the present 

 time. It is never so highly developed or so large as the 



Fig. 3. — Front Yien of Horse's Chest, showing the 

 Whorls, Featherings, and Crests. 



inguinal, and out of 2159 horses examined it was found to 

 exist in only 42 cases, or about 2 per cent. In another 

 group of 87 cases in which it existed there were 57 cart- 

 horses, and this singular fact is readily accounted for when 

 one recollects that this hollow is a region where a decidedly 

 less extended range of action occurs than is the case in 

 the inguinal, excei)t in the particular instance of the cart- 

 horse, where it is markedly greater than in any other 

 form. It is sufficient to watch a fine English cart-horse 

 drawing a heavy weight, and to compare with this action 

 even that of the high-stei>ping hackney, to see at once 

 why the preponderating muscular activity of the cart-horse 

 in this area is stamped upon its hairy covering as a whorl, 

 or pedometer. Here again is the degree of locomotive 

 activity registered by tlie frequency and size of a whorl 



and its associated phenomena. This particular post- 

 humeral pedometer is also found in other Ungulates, and 

 the most noticeable specimens are found in the same group 

 of animals as the inguinal whorl, and these are given in 

 detail in the same place.* 



On the pectoral region of certain animals, among which 

 the Ungulates in general and the horse in particular may 

 be mentioned, there is a bilateral symmetrical whorl with 

 feathering and crest, as a rule, associated. Here, again, is 

 a pedometer which registers the general activity of the 

 species and its ancestors, and the individual range and 

 frequency of movement of the great muscles which flex the 

 "elbow "of the animal. In our familiar show-specimen, 

 the horse, it is invariably present and fully developed, 

 varying only to a slight degree in size in differently 

 developed individuals of this convenient species. 



In many wild animals it is present, as in many Bovidse 

 and a few of the larger Carnivores, but never with the 

 uniformity and degree of development that occurs in the 



Fig. -t. — Front Vie* of Superficial Muscles of Horse's 

 Chest. 



horse. Once more the ass and mule deserve special notice 

 as to the degree in which the pectoral pedometer is 

 displayed by them. In the mule it is small, narrow, nearly 

 always present, in the ass it is very rarely present ; indeed, 

 as mentioned above, the present writer has only examined 

 one specimen in which it occurred. The horse has been 

 stated to show the pectoral pedometer invariably, but the 

 importance of this fact does not end with its constancy, 

 for many degrees of its width and length ai'e to be 

 observed, and it is a rule to which no exceptions have lieeu 

 so far founil, that tlie general development of it is in a 

 direct ratio with the action of the horse in question. In 

 cart-horses, powerful carriage horses, and funeral horses 

 it is highly developed, and in shambling ill-bred hackneys, 

 such as one sees in the streets of Italian cities, it is very 



* Proe. Zool. Soe. Land., 1900, ]). 



* Proc. Zool. Soc. Load., 1902, p. 686. 



