SEXUAL SELECTION 



205 



mucli more simple interpretation. For if we consider the 

 fact that the females frequent the forests where the Heli- 

 conidse abound, while the males fly much in the open 

 and assemble in great numbers with other white and 

 yellow butterflies on the banks of rivers ; may it not be 

 possible that the appearance of orange stripes or patches 

 would be as injurious to the male as it is useful to the 

 female, by making him a more easy mark for insecti- 

 vorous birds among his white companions ? This seems 

 a more probable supposition, than the altogether hypo- 

 thetical choice of the female, sometimes exercised in 

 favour of and sometimes against every new variety of 

 colour in her partner. 



A strictly analogous case is that of the glow-worm, 

 whose light, as originally suggested by Mr. Belt, is 

 admitted to be a warning of its uneatability to insecti- 

 vorous nocturnal animals. The male, having wings, 

 does not require this protection. In the tropics the 

 number of nocturnal insectivorous birds and bats is 

 very much greater, hence winged species possess the 

 light, as they would otherwise be eaten by mistake for 

 more savoury insects ; and it may be that the luminous 

 Elateridse of the tropics really mimic the true fireflies 

 (Lampyridse), which are uneatable. This is the more 

 probable as the Elateridae, in the great majority of 

 species, have brown or protective colours, and are 

 therefore certainly palatable to insectivorous anioials. 



Origin of the Ornamental Plumage of Male Birds. — 

 We now come to such wonderful developments of 

 plumage and colour as are exhibited by the peacock 

 and the Argus- pheasant ; and I may here mention that 

 it was the case of the latter bird, as fully discussed by 



