COLORATION 139 



evidence is overwhelming that their coloration, whatever 

 it may be, has no effect whatever as regards their foes or 

 prey. As regards a very few of them, it may have some 

 slight effect, but only to the extent that natural selection 

 may have set wide bounds to the variation, having no effect 

 on the pattern or color developed within these bounds. It 

 can safely be said, therefore, that natural selection has had 

 no effect in producing the present coloration of any of these 

 animals. We wish we were able to give an opinion based on 

 actual observations as to what the cause of the coloration 

 is, but at present all we can say is that no satisfactory 

 explanation has been given. 



Among the big-game animals the countershading has no 

 effect; the animals without it thrive as well as those with it; 

 and those that seek to escape notice almost always crouch, 

 and then the effect of the countershading practically dis- 

 appears. When the white is confined to the belly of any of 

 these big animals it has little more effect than on the belly 

 of a frog or snake — where it has absolutely none and is 

 never seen, and therefore cannot have been developed for 

 concealing purposes. 



We have not in this chapter more than touched on birds 

 and small mammals, both because we have not studied 

 them as we have studied the big game and because of a lack 

 of space. We allude to them now because the conclusions 

 we have drawn as to big game do not apply in anything 

 like such general fashion to birds and smaller mammals. 

 Among small mammals they apply to most members of the 

 squirrel family, for instance; among species with identical 

 habits, and often in the same species, there are found in- 

 stances of markedly advertising coloration and instances 



