has to fear. Since crows are apparently too unappetizing,' as well as per- 

 haps too formidable, to be much bothered by predatory animals, it would 

 seem to be the eggs, and not the parents, that here most need protection.) 



What we know of the concealing-function of such costumes as that of the 

 black-and-red South American Heliconii will bear further elucidating. 

 These insects, in their abundance, and consequent general conspicuousness as 

 a species, are on a par with our common yellow butterfly * here in the North. 

 Both these species, existing in such immense numbers as to be almost con- 

 stantly in sight, record, on the beholder's mind, one cumulative impression of 

 conspicuousness. Yet each is colored for the utmost average concealment, 

 at the very time when it most needs it — its feeding time. Such species are 

 merely further proof of what our book demonstrates, viz.^ that Nature, in 

 carrying out her principle of coloring animals for their most trying circum- 

 stances, sometimes finds herself giving to a species that has one particularly 

 dangerous habit, a coloration which, while it is the utmost imaginable con- 

 cealer in the special situation it fits, looks necessarily more or less conspicuous 

 and out of place everywhere else. 



These brilliant Heliconii, so magically concealed by their colors while they 

 are feeding among red, yellow, or orange flowers, seem to be greatly indebted, 

 during the rest of their day, to the protecting power of their habit of threading, 

 with their rather slow flight, the interstices of dense foliage, where fly-catching 

 birds have but a poor chance to capture them. In this habit of haunting the 

 dense foliage, as well as in their colors, these Heliconii remind one of Scarlet 

 Tanagers — a fact worthy of notice. 



There is no need of going to the tropics to study the concealing-power of 

 the coloration of one of these red-and-black or yellow-and-black Heliconii. 

 Place a dead one, or even an artificial one, on any kind of plant that has 

 either red, yellow, or orange flowers, and not only will you find it wonderfully 

 concealed, but you will perceive that the principle on which this concealment 

 is achieved would always be operant wherever such a butterfly sat among 



such flowers. *Colyas. 



245 



