SEXUAL SELECTION 407 



lower surface alone is exposed to view. Hence it is this side 

 which is often colored so as to imitate the objects on which 

 these insects commonly rest. Dr. Rossler, I believe, first 

 noticed the similarity of the closed wings of certain Vanessse 

 and other butterflies to the bark of trees. Many analogous 

 and striking facts could be given. The most interesting one 

 is that recorded by Mr. Wallace' of a common Indian and 

 Sumatran butterfly (Kallima), which disappears like magic 

 • when it settles on a bush; for it hides its head and antennae 

 between its closed wings, which, in form, color, and veining, 

 cannot be distinguished from a withered leaf with its foot- 

 stalk. In some other cases the lower surfaces of the wings 

 are brilliantly colored, and yet are protective; thus in Thecla 

 rubi the wings when closed are of an emerald green, and re- 

 semble the young leaves of the bramble, on which in spring 

 this butterfly may often be seen seated. It is also remark- 

 able that in very many species, in which 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 con- 

 spicuous colors on the upper surface of such species as our 

 admiral and peacock Yanessse, our white cabbage-butterflies 

 (Pieris), or the greater swallow-tail Papilio which haunts the 

 open fens — for these butterflies are thus rendered visible to 

 every living creature. In these species both sexes are alike; 

 but in the common brimstone butterfly {Gonepteryx rhamni) 

 the male is of an intense yellow, while the female is much 

 paler; and in the orange-tip (^Anthocharis cardamines) the 

 males alone have their wings tipped with 'fright orange. 

 Both the males and females in these cases are conspicuous, 



' See a very interesting article in the ""Westminster Review" for July, 1867, 

 p. 10. A woodcut of the Kallima is given by Mr. Wallaoe in "Hardwicke's 

 Science Gossip" for September, 186Y, p. 196. 



8 Mr. G-. Fraser, in "Nature," April, IBVl, p. 489. 



