380 SEXUAL SELECTION. [Part II. 



most all the kinds when resting raise their wings verti- 

 cally over their backs, so that the lower sides alone are 

 exposed to view. Hence it is this side which in many 

 cases is obviously colored so as to imitate the surfaces on 

 which these insects commonly rest. Dr. Rossler, I be- 

 lieve, first noticed the similarity of the closed wings of 

 certain Vanessae 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 6 

 of a common Indian and Sumatran butterfly (Kallinia), 

 which disappears like magic when it settles in a bush ; 

 for it hides its head and antennae between its closed 

 wings, and these, in form, color, and veining, cannot be 

 distinguished from a withered leaf together with the 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 resemble the young leaves of the bramble, on 

 which this butterfly in the spring may often be seen 

 seated. 



Although the obscure tints of the upper or under sur- 

 face of many butterflies no doubt serve to conceal them, 

 yet we cannot possibly extend this view to the brilliant 

 and conspicuous colors of many kinds, such as our admiral 

 and peacock Vanessa?, our white cabbage-butterflies (Pie- 

 ris), or the great swallow-tail Papilio which haunts the 

 open fens — for these butterflies are thus rendered visible 

 to every living creature. With these species both sexes 

 are alike; but in the common brimstone butterfly (Go- 

 nepteryx rhamni) the male is of an intense yellow, while 

 the female is much paler ; and in the orange-tip (Antho- 

 charis cardamines) the males alone have the bright 



6 See the interesting article in the ' Westminster Review,' July, 1867, 

 p. 10. A woodcut of the Kallima is given by Mr. Wallace in ' Hard- 

 wicke's Science Gossip,' Sept., 1867, p. 196. 



