PEOTECTIVE RESEMBLANCES— DIMORPHISM, ETC. 53 



in India, the Malay Archipelago, and Africa. The 

 way in which the insect is concealed has been described 

 by Wallace in his * Malay Archipelago,' and also in 

 the * Essays on Natural Selection.' The tip of the 

 fore-wing is pointed like the apex of a leaf, and the 

 hind- wing has a short tail like a leaf- stalk, while the 

 outline of the folded wings between these extremities 

 is exactly like that of a withered and somewhat 

 shrivelled leaf. At rest the wings are held upright 

 over the back, the head and antennae are concealed 

 between them, while the tails touch the branch to 

 which the insect clings by its almost invisible legs. 

 Along the supposed leaf runs a distinct mark like 

 a mid-rib, with oblique veining on either side. 



But dead and withered leaves are not all alike ; 

 they may be almost any shade of brown, grey, or 

 yellow, while they are often attacked by fungi of dif- 

 ferent colours and in different places. Similarly the 

 under sides of the wings of the butterfly are excessively 

 variable, the different colours and markings only 

 agreeing in that they jlH represent some familiar ap- 

 pearance presented by withered or decayed leaves. 



Dead leaves are often pierced by insect larvae, and 

 a detail of great interest is added to the disguise in 

 the semblance of a small hole. The scales are absent 

 from both sides of a certain spot on each fore- wing, 

 which is therefore only covered by the thin transparent 

 wing membrane. These spots come opposite to each 

 other in the position of rest, and the effect produced 

 4 



