XVI INTRODUCTION. 



Lyccenidce, and especially in the latter family, where the terminal 

 appendages of the fore legs are nearly or quite lost in the males, and 

 are as conspicuous as on the other legs in the female. I have not 

 discovered that the differences in the leg-joints follow any general 

 law, although there are few of our butterflies whose sexes do not vary 

 in this particular ; this form of antigeny is also most conspicuous in 

 the Lycenidce. The males of certain Chrysophanidi (Chrysophanus etc.), 

 also present another curious feature in the tumid swelling of the basal 

 joint of the middle and hind tarsi. Finally the fore legs of the males 

 of Nymphalidce are frequently furnished with a spreading brush of 

 hairs ; or, in other butterflies, the thighs and shanks of the middle 

 and hind legs are supplied with curious pencils or fringes of stiff hair, 

 which appear to have the same significance as similar adornments in 

 higher animals " (pp. 873-874). There is also the excessive difference 

 in the legs of apterous species of the nature of Orgyia and the Psychidce 

 (not Nyssia, Hybernia etc.), in which there appears to be no need to 

 walk, and in which nature certainly has expended no waste energy in 

 providing them with legs suitable for the purpose. 



(10). COLOUR. By far the most striking secondary sexual 

 character found in lepidoptera is that of colour. It is, of course, par- 

 ticularly noticeable in, but by no means confined to, the day-flying 

 species. Many species have the males brilliantly coloured in com- 

 parison with the females, but frequently both sexes are equally brilliant 

 or the reverse, but I cannot call to mind a single instance in which 

 the female is more brilliantly tinted than the male, although Scudder 

 mentions a South American genus where this is so. According to 

 Darwin, this excessive beauty on the part of the males in those species 

 in which it occurs is due to " sexual selection," the females having " by 

 a long selection of the more attractive males, added to their beauty or 

 other attractive qualities," whilst he further states, that in instances 

 where " the males have acquired their present structure, not from 

 being better fitted to survive in the struggle for existence, but from 

 having gained an advantage over other males, and from having trans- 

 mitted this advantage to their male offspring alone, sexual selection 

 must have come into action." Now we are met on the threshhold with 

 the question Has our study ever exhibited any illustrations that 

 females in any way selected or made a preference in selecting their 

 mates, or that " females select the more attractive males " at all ? I 

 doubt it most positively in the case of moths, and to a large extent even 

 in butterflies. But that there is some little action in particular 

 instances seems very probable, and it is in certain butterflies that this 

 takes place more frequently than in others. In Pieris, one frequently 

 sees a male flutter around a female, fail to win her affections at once, 

 and repeat the operation, and generally fly away altogether. I have 

 generally assumed that in such cases the female has already been 

 fertilised ; but assuming this is not so, I have, even in the common P. 

 rapce, where this is so noticeable, seen a male pair with a female before 

 her wings have become dry. However, it is impossible to deny that 

 some preference may, in some instances, be shown by the female and 

 that " sexual selection " thus occurs. It must be further borne in mind 

 that it is in butterflies especially that the males are more brilliant than 

 the females, running into other colours and even sometimes taking 



