RESEMBLANCES AMONG ANIMALS. 113 



while its companion of sober brown was looked upon 

 as the female. I discovered, however, that the reverse 

 is the case, and that the rich and glossy colours of 

 the female are imitative and protective, since they 

 cause her exactly to resemble the common Euploea 

 midamus of the same regions, a species which has 

 been already mentioned in this essay as mimicked 

 by another butterfly, Papilio paradoxa. I have since 

 named this interesting species Diadema anomala (see 

 the Transactions of the Entomological Society, 1869, 

 p. 285). In this case, and in that of Diadema misippus, 

 there is no difference in the habits of the two sexes, 

 which fly in similar localities; so that the influence 

 of " external conditions " cannot be invoked here as 

 it has been in the case of the South American Pieris 

 pyrrha and allies, where the white males frequent 

 open sunny places, while the Heliconia-like females 

 haunt the shades of the forest. 



We may impute to the same general cause (the 

 greater need of protection for the female, owing to 

 her weaker flight, greater exposure to attack, and 

 supreme importance) the fact of the colours of female 

 insects being so very generally duller and less conspi- 

 cuous than those of the other sex. And that it is 

 chiefly due to this cause rather than to what Mr. 

 Darwin terms " sexual selection " appears to be 

 shown by the otherwise inexplicable fact, that in the 

 groups which have a protection of any kind inde- 

 pendent of concealment, sexual differences of colour 

 are either quite wanting or slightly developed. The 



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