1 82 STUDIES IN THE EVOLUTION OF ANIMALS 



the under surfaces of the head, neck, chest and abdomen, and also 

 on the inner aspects of the four legs. 



Then the yellow-bellied Pangolin {Manis Tricuspis), as well as 

 others, has a muzzle wholly destitute of scales, and its under surfaces 

 and paws are hairy instead of scaly. The soles of its hind feet 

 from the heel to the toes are also bare ; and this latter fact 

 will give us a hint why, in certain descendants of armoured animals, 

 such as certain Cats and Dogs, this very surface from heel to toes 

 in these digitigrade descendants is black, and contrasted with the 

 pigment of their adjacent surfaces. 



It is true that these Pangolins still retain scales on the under 

 surface of their huge tails, but if we search further we find that in 

 the little Ant-eater close by {Cyclofums Didactylus) the under sur- 

 face of the tail is hairless, so is that of Horses ; and this may be 

 the reason why, in the innumerable changes of skin coloration 

 which have occurred in mammals, the under surface of the tail is 

 so often contrasted in colour with the upper surface. Indeed, 

 the under surface of the tail is only a continuation of the 

 under surface of the body from the muzzle to the tip of the 

 tail, and the white tip of the tail we see in so many animals 

 may be only a vestige of a more extended whiteness of the under 

 surfaces. 



Then do you mean to say that Dogs, Cats, Asses, Antelopes, etc., 

 which have contrasted upper and under surfaces, are descendants 

 of Pangolins ? 



I mean to say no such thing. The Pangolins, as well as the 

 Armadillos, and these other mammals mentioned, are descendants 

 of a much remoter stock which had their bodies wholly armoured 

 up and down. Armour was first suppressed on the under surfaces, 

 and gradually replaced by hair, and the Pangolins and Armadillos 

 are survivals of that state of things. Other descendants of the 



