3 8 NATUEE STUDIES. 



More extraordinary still are the " leaf insects " ; 

 near allies, indeed, of the "walking-sticks." Here 

 " mimicry " of the plant proceeds so far as to fully 

 justify the eminent naturalist's remarks, that it is 

 strange to find the animal assuming a mimetic dis- 

 guise and apeing the actor's art. The wings in the 

 " leaf insects " exactly imitate leaves. The venation, 

 or arrangement of the veins in the leaf, is clearly seen, 

 and in one form (Pltyllium) even the chest and legs of 

 the animal assume leaf-like characters. When such 

 an insect rests amid foliage, the value of such a close 

 resemblance to its plant surroundings as a means of 

 protection can be readily understood. In some " leaf 

 insects " all of which are tropical species the wings 

 resemble leaves that are dried and withered. In 

 others, the minute fungi that attack leaves are 

 imitated. Mr. A. K. Wallace tells us that one of the 

 " walking-sticks " obtained by him in Borneo " was 

 covered over with foliaceous excrescences of a clear 

 olive-green colour, so as exactly, to resemble a stick 

 grown over by a creeping moss or Jungermannia. 

 The Dyak who brought it me assured me it was 

 grown over with moss, though alive, and it -was only 

 after a most minute examination that I could convince 

 myself that it was not so." 



Lastly, there may be noticed in connexion with 

 these curious traits of animal life, the fact that certain 

 animals, themselves harmless and inoffensive, may 

 assume the exact appearance of offensive neighbours. 

 In this respect, certain butterflies are facile principc- 



