174 STUDIES IN THE EVOLUTION OF ANIMALS 



frontal and face marks for which I have been endeavouring to 

 discover an explanation. The same nerve-centre habit of action 

 which, in ancestral forms, gave rise to horns, now that the Horse no 

 longer has horns, may display itself by producing a change of pig- 

 ment of the skin in the places once occupied by horns. 



There is another feature in Horses for which I have been 

 endeavouring to discover an explanation. 



When Horses change colour, it is only down to the ankle and 

 wrist that they usually do so ; only rarely does the body colour 

 continue to the hoof ; so that we see bay, dun, roan, and dark grey 

 Horses with their hands and feet black ; strawberry roans with 

 these parts bay or chestnut ; l and we see Horses of various colours 

 and even black Horses, with white hands and feet. What can be 

 the cause of this ? Why should there be so frequently such a 

 distinction between the coloration of the hands and feet of Horses 

 and that of their bodies ? It is only in pure whites, pure chestnuts, 

 pure blacks, that the hands and feet are usually of the same colour 

 as the body, but in the duns, or sponge-coloured horses, the black 

 hands and feet form a strange contrast to the colour of the body. 



If we make investigations among other animals in the Natural 

 History Museum we find that the Ruffed Lemur has long hair 

 down to its ankles and wrists, and on its hands and feet the hair 

 becomes short, and of a different colour, so that this animal looks 

 as if it had jet black gloves and socks. 



The Alpaca has a brown body with long hair, and then suddenly 

 its hands and feet become short-haired and jet black. 



The Gaur (Bibos gaurus) and its congener the Javan Ox, have 

 white hands and feet, although the former has a black and the 

 latter a tan or dun-coloured body ; so also the Gayal (Bos frontalis}. 



1 Many roans when clipped are of a blackish grey, and strawberry roans either 

 bay or chestnut. 



