MAMMALS WITH CONTRASTED COLOURS 151 



over, that is, dorsally and ventrally, like the extinct Ganoids and 

 existing Crocodiles ; and that in dispensing with their armour they 

 first lost it on their ventral aspect, and second, and much later, on 

 their dorsal aspect also. 



At the risk of seeming tedious, I repeat that this, in my opinion, 

 is the reason why so many mammals present a distinct contrast 

 between the coloration of their dorsal and ventral aspects with a 

 sharp line of demarcation between the two. Of course later on 

 there may have been z. fusion of the two distinct colorations, and 

 all traces of demarcation wholly obliterated. Examples of this 

 obliteration are seen every day among Horses, Dogs, etc. 



