234 



STUDIES IN THE EVOLUTION OF ANIMALS 



another which had them as small as peas on those limbs ; and 

 the foreman of the stables of the London Road Car Co. told me 

 he has seen them as small as the nail of his little ringer. It is 

 therefore not improbable that the ancestors of the Ass and Zebra 

 may have had callosities also on the hind-legs, but from some 



\ 



l 



FIG. 85. (a) Black tuft of hair on fawn-grey hind-leg of Peruvian Roebuck (Coriacus 

 antisiensis] ; (b] dark brown tuft on a dirty white ground hind leg of Elk ; (<:) grey tuft on 

 fawn-coloured leg hock of Virginian Deer (Coriacus Virginianus) from Natural History 

 Museum. 



cause they may have dwindled off and disappeared so completely 

 from those species that they are not reverted to. As far as I am 

 aware, if the Ass and Zebra ever had them on their hind-legs, no 

 trace of them is to be seen there now. 1 



1 It is curious that Equus Grevyi of Fig. 52 does not show a callosity on the fore-leg 

 as in Fig. 53. Grevy's Zebra which I saw at Tring also has its fore-legs 'without them. 



