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 a 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. 



