390 SEXUAL SELECTION. Part II. 



are nearly alike and wonderfully splendid ; in another, 

 the male is coloured in a similarly gorgeous manner, 

 whilst the whole upper surface of the female is of a dull 

 uniform brown. Our common little English blue butter- 

 flies of the genus Lycsena, illustrate the various differ- 

 ences in colour between the sexes, almost as well, 

 though not in so striking a manner, as the above exotic 

 genera. In Lycsena agestis both sexes have wings of a 

 brown colour, bordered with small ocellated orange 

 spots, and are consequently alike. In L. oegon the 

 wings of the male are of a fine blue, bordered with 

 black ; whilst the wings of the female are brown, with 

 a similar border, and closely resemble those of L. agestis. 

 Lastly, in L. avion both sexes are of a blue colour and 

 nearly alike, though in the female the edges of the 

 wings are rather duskier, w 7 ith the black spots plainer ; 

 and in a bright blue Indian species both sexes are still 

 more closely alike. 



I have given the foregoing cases in some detail in 

 order to shew, in the first place, that when the sexes of 

 butterflies differ, the male as a general rule is the most 

 beautiful, and departs most from the usual type of colour- 

 ing of the group to which the species belongs. Hence in 

 most groups the females of the several species resemble 

 each other much more closely than do the males. In 

 some exceptional cases, however, to which I shall here- 

 after allude, the females are coloured more splendidly 

 than the males. In the second place these cases have 

 been given to bring clearly before the mind that within 

 the same genus, the two sexes frequently present every 

 gradation from no difference in colour to so great a dif- 

 ference that it was long before the two were placed by 

 entomologists in the same genus. In the third place, 

 we have seen that when the sexes nearly resemble 

 each other, this apparently may be due either to the 



