Chap. XL] BUTTERFLIES AND MOTHS. 391 



the former commonly basking in the sunshine, the latter 

 haunting gloomy forests. It is therefore possible that 

 different conditions of life may have acted directly on the 

 two sexes ; but this is not probable, 31 as in the adult state 

 they are exposed during a very short period to different 

 conditions ; and the larvse of both are exposed to the same 

 conditions. Mr. Wallace believes that the less brilliant 

 colors of the female have been specially gained in all or 

 almost all cases for the sake of protection. On the con- 

 trary, it seems to me more probable that the males alone, 

 in the large majority of cases, have acquired their bright 

 colors through sexual selection, the females having been 

 but little modified. Consequently the females of distinct 

 but allied species ought to resemble each other much 

 more closely than do the males of the same species ; and 

 this is the general rule. The females thus approximately 

 show us the primordial coloring of the parent-species of 

 the group to which they belong. They have, however, 

 almost always been modified to a certain extent by some 

 of the successive steps of variation, through the accumula- 

 tion of which the males were rendered beautiful, having 

 been transferred to them. The males and females of allied 

 though distinct species will also generally have been ex- 

 posed during their prolonged larval state to different con- 

 ditions, and may have been thus indirectly affected ; 

 though with the males any slight change of color thus 

 caused will often have been completely masked by the 

 brilliant tints gained through sexual selection. When we 

 treat of Birds, I shall have to discuss the whole question 

 whether the differences in color between the males and 

 females have been in part specially gained by the latter 

 as a protection ; so that I will here # only give unavoidable 

 details. 



81 On this whole subject, see ' The Variation of Animals and Plants 

 under Domestication,' vol. ii. 1868, chap, xxiii. 



