2 4 o STUDIES IN THE EVOLUTION OF ANIMALS 



the animals that possessed them. And the callosities of the 

 equine family are probably vestiges of similar glands. The 

 equine and the ruminant families of mammals would appear 

 to have branched off from the same stock. In another place I 

 have given reasons for considering these two sets of animals as 

 closely allied. 



In my opinion there cannot be much doubt that Sir W. 

 Flower's suspicion, as to the nature of the callosities of the Horse, 

 is the right one. They 'belong undoubtedly,' he says, 'to the 

 category of glandular surfaces.' They appear to me to be vestiges 

 of skin-glands which once served a useful purpose in past ages, 

 and were not unlike the suborbital glands of some kinds of Deer. 



Innumerable changes may have naturally occurred on the face 

 of the countries their ancestors inhabited ; and the advent of man, 

 of whose antiquity there can be little doubt, has made still further 

 changes which may have rendered those glands useless, if not 

 hurtful should they become injured. 



Mr. Louis Robinson l has stated that whoever discovers the 

 meaning of the Horse callosities ' will become famous among 

 naturalists all the world over.' Their meaning has already been 

 suggested by one who is * famous all the world over ' viz. 

 Professor Sir William Flower. 



1 North American Review, April 1894, p. 483. 



