One word more about Scarlet Tanagers. Their coloration, dividing them 

 as it does into two things, a red thing and a black thing, is clear proof that con- 

 spicuousness is not what is aimed at. Were these birds meant to be con- 

 spicuous, they would, all the more because of inhabiting dense foliage, be 

 monochrome. (The principle which underlies this fact is illustrated by the 

 diagrams of letters in Plate V.) 



The rule seems to hold good that since animals must first of all breed, feed, 

 and drink, their costumes will prove to be pictures of the scenes of these oper- 

 ations. To speak here only of the feeding (the thing that occupies far the 

 largest part, for instance of a male bird's time), there is among birds every 

 degree of peculiarity of feeding-situation, from that of the hawk, which is 

 the least peculiar — being wherever, in all outdoors, he gets a sufficiently good 

 chance at a victim — to that of the macaw, which is one of the most peculiar 

 and unvarying, commonly some tree-top full of luscious fruit, where he has 

 merely to climb about a few feet to sate himself. What more powerful in- 

 fluence toward dangerous relaxation of vigilance could be imagined? What 

 wonder, then, since the macaw's banquet-hall is forever hung with one gor- 

 geous tapestry of fruit and foliage scenes with sky-glimpses between, that his 

 costume proves to be such as marvellously dissolves him into the scene, as he 

 climbs about, burying his head in cluster after cluster of the brilliant fruit? 

 This was just as much to be expected as that the hawk, whose feats take place 

 now in one situation, now in another, should wear the very most generalized 

 of concealment costumes. 



UPPER-SIDE WHITE PATCHES, ETC. 



It is perhaps possible to show still more clearly than we have yet pointed 

 out the paramount function of upper-side white patches in general. 



In imitating, as we have shown that they do, sky-glimpses through inter- 

 stices of the foliage-background, they pass off those parts of their wearer which 

 they cover, for spaces, — more emphatically than spots of any other color could.' 

 The reason of this is that sky, the element which they represent, is the very 



246 



