378 SEXUAL SELECTION. [Par r II. 



upper surface of the female is of a dull uniform brown. 

 Our common little English blue butterflies, of the genus 

 Lycama, illustrate the various differences in color between 

 the sexes, almost as well, though not in so striking a man- 

 ner, as the above exotic genera. In JOyccena agestis both 

 sexes have wings of a brown color, bordered with small 

 ocellated orange spots, and are consequently alike. In L. 

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

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

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

 Lastly, in JO. avion both sexes are of a blue color and 

 nearly alike, though in the female the edges of the wings 

 are rather duskier, with 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 show, 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 color- 

 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 colored 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 gra- 

 dation from no difference in color to so great a difference 

 that it was long before the two were placed by entomolo- 

 gists in the same genus. In the third place, we have seen 

 that, when the sexes nearly resemble each other, this ap- 

 parently may be due either to the male having transferred 

 his colors to the female, or to the male having retained, 

 or perhaps recovered, the primordial colors of the genus 

 to which the species belongs. It also deserves notice that 



