RESEMBLANCES AMONG- ANIMALS. S3 



it inhabited ; and the results of his observations arc 

 embodied in a paper published in the Linnean Trans- 

 actions, in which he first explained the phenomena of 

 " mimicry " as the result of natural selection, and 

 showed its identity in cause and purpose with protec- 

 tive resemblance to vegetable or inorganic forms. 



The imitation of the HeliconidaB by the Leptalides 

 is carried out to a wonderful degree in form as well as 

 in colouring. The wings have become elongated to the 

 same extent, and the antenna? and abdomen have both 

 become lengthened, to correspond with the unusual 

 condition in which they exist in the former family. 

 In colouration there are several types in the different 

 genera of Heliconid^e. The genus Mechanitis is gene- 

 rally of a rich semi-transparent brown, banded with 

 black and yellow ; Methona is of large size, the wings 

 transparent like horn, and with black transverse bands ; 

 while the delicate Ithomias are all more or less trans- 

 parent, with black veins and borders, and often with 

 marginal and transverse bands of orange red. These 

 different forms are all copied by the various species 

 of Leptalis, every band and spot and tint of colour, 

 and the various degrees of transparency, being exactly 

 reproduced. As if to derive all the benefit possible 

 from this protective mimicry, the habits have become 

 so modified that the Leptalides generally frequent the 

 very same spots as their models, and have the same 

 mode of flight; and as they are always very scarce 

 (Mr. Bates estimating their numbers at about one to a 

 thousand of the group they resemble), there is hardly a 



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