Chap. XL BUTTERFLIES AND MOTHS. 389 



is usual with their sex in this genus, for they are gaily 

 decorated in nearly the same manner as the males, but 

 in a somewhat less degree. Hence in these two species 

 the bright colours of the males seem to have been trans- 

 ferred to the females ; whilst the male of the tenth 

 species has either retained or recovered the plain 

 colours of the female as well as of the parent-form of 

 the genus ; the two sexes being thus rendered in both 

 cases, though in an opposite manner, nearly alike. In 

 the allied genus Eubagis, both sexes of some of the 

 species are plain-coloured and nearly alike ; whilst 

 with the greater number the males are decorated with 

 beautiful metallic tints, in a diversified manner, and 

 differ much from their females. The females through- 

 out the genus retain the same general style of colouring, 

 so that they commonly resemble each other much more 

 closely than they resemble their own proper males. 



In the genus Papilio, all the species of the iEneas 

 group are remarkable for their conspicuous and strongly 

 contrasted colours, and they illustrate the frequent ten- 

 dency to gradation in the amount of difference between 

 the sexes. In a few species, for instance in P. ascanius, 

 the males and females are alike ; in others the males 

 are a little or very much more superbly coloured than 

 the females. The genus Junonia allied to our Vanessaa 

 offers a nearly parallel case, for although the sexes of 

 most of the species resemble each other and are desti- 

 tute of rich colours, yet in certain species, as in J. oenone, 

 the male is rather more brightly coloured than the 

 female, and in a few (for instance J. andremiaja) the 

 male is so different from the female that he might be 

 mistaken for an entirely distinct species. 



Another striking case was pointed out to me in the 

 British museum by Mr. A. Butler, namely one of 

 the Tropical American Theclae, in which both sexes 



