INSECTS. 361 



attracted by those endowed with most vitality. Never- 

 theless, the Bombycidse, though obscurely colored, are 

 often beautiful to our eyes from their elegant and mottled 

 shades. 



I have as yet only referred to the species in which the 

 males are brighter colored than the females, and I have 

 attributed their beauty to the females for many generations 

 having chosen and paired with the more attractive males. 

 But converse cases occur, though rarely, in which the 

 females are more brilliant than the males; and here, as I 

 believe, the males have selected the more beautiful females, 

 and have thus slowly added to their beauty. We do not 

 know why in various classes of animals the males of some 

 few species have selected the more beautiful females instead 

 of having gladly accepted any female, as seems to be the 

 general rule in the animal kingdom; but if, contrary to 

 what generally occurs with the Lepidoptera, the females 

 were much more numerous than the males, the latter would 

 be likely to pick out the more beautiful females. Mr. But- 

 ler showed me several species of Callidryas in the British 

 Museum, in some of which the females equaled, and in 

 others greatly surpassed, the males in beauty ; for the 

 females alone have the borders of their wings suffused with 

 crimson and orange and spotted with black. The plainer 

 males of these species closely resemble each other, showing 

 that here the females have been modified; whereas in those 

 cases, where the males are the more ornate, it is these which 

 have been modified, the females remaining closely alike. 



In England we have some analogous cases, though not so 

 marked. The females alone of two species of Thecla have 

 a bright purple or orange patch on their fore wings. In 

 Hipparchia the sexes do not differ much ; but it is the 

 female of H. janira which has a conspicuous light brown 

 patch on her wings; and the females of some of the other 

 species are brighter colored than their males. Again, 

 the females of Colias edusa and Jiyale have "orange or 

 yellow spots on the black marginal border, represented in 

 the males only by thin streaks;" and in Pieris it is the 

 females which "are ornamented with black spots on the 

 fore wings, and these are only partially present in the 

 males." Now the males of many butterflies are known to 

 support the females during their marriage flight; but in 

 the species just named it is the females which support the 



