BUTTERFLIES AND MOTHS. 309 



the sexes differ greatly in color on their upper surface, the lower 

 surface is closely similar or identical in both sexes, and serves 

 as a protection.' 



Although the obscure tints both of the upper and under 

 sides of many butterflies no doubt serve to conceal them, yet we 

 cannot extend this view to the brilliant and conspicuous colors 

 on the upper surface of such species as our admiral and peacock 

 Vanessse, our white cabbage-butterflies (Pieris), or the great 

 swallow-tail Papilio which haunts the open fens — for these but- 

 terflies are thus rendered visible to every living creature. In 

 these species both sexes are alike; but in the common brim- 

 stone butterfly (Gonepteryx rhamni), the male is of an intense 

 yellow, whilst the female is much paler; and in the orange-tip 

 (Anthocharis cardamines) the males alone have their wings tipped 

 with bright orange. Both the males and females in these cases 

 are conspicuous, and it is not credible that their difference in 

 color should stand in any relation to ordinary protection. Prof. 

 Weismann remarks." that the female of one of the LycaensB ex- 

 pands her brown wings when she settles on the ground, and is 

 then almost invisible; the male, on the other hand, as if aware of 

 the danger incurred from the bright blue of the upper surface of 

 his wings, rests with them closed; and this shows that the blue 

 color cannot be in any way protective. Nevertheless, it is probable 

 that conspicuous colors are indirectly beneficial to many species, 

 as a warning that they are unpalatable. For in certain other 

 cases, beauty has been gained through the imitation of other 

 beautiful species, which inhabit the same district and enjoy an 

 immunity from attack by being in some way offensive to their 

 enemies; but then we have to account for the beauty of the 

 imitated species. 



As Mr. Walsh has remarked to me, the females of our orange- 

 tip butterfly, above referred to, and of an American species 

 (Anth. genutia) probably show us the primordial colors of the 

 parent-species of the genus; for both sexes of four or five 

 widely-distributed species are colored in nearly the same manner. 

 As in several previous cases, we may here infer that it is the 

 males of Anth. cardamines and genutia which have departed 

 from the usual type of the genus. In the Anth. sara from Cali- 

 fornia, the orange-tips to the wings have been partially de- 

 veloped in the female; but they are paler than in the male, and 

 slightly different in some other respects. In an allied Indian 

 form, the Iphias glaucippe, the orange-tips are fully developed in 

 both sexes. In this Iphias, as pointed out to me by Mr. A. Butler, 

 the under surface of the wings marvelously resembles a pale- 



SMr. G. Fraser, in 'Nature,' April 1871, p. 489. 



" 'Einfluss der Isolirung- auf die Artbildung-,' 1872, p. 58. 



at 



