18 BUTTERFLIES IN DISGUISE 



and it is obvious that the more distasteful the 

 butterfly is to its rapacious foes, by so much more 

 has it the advantage in the struggle for life ; 

 so that mimicry of one distasteful butterfly by 

 another less distasteful is scarcely more surprising 

 than the mimicry of a nauseous butterfly by one 

 that has not this quality. 



Only one further difficulty remains, and this 

 is that, in a few instances, an insect has been 

 found differing so peculiarly from its congeners 

 as to leave no doubt in the mind that it differs 

 in the direction of mimicry when no exact proto- 

 type can be found. For example, the butterfly 

 of one of the Nymphalinae, with normal dark 

 colors and a definite pattern, will vary altogether 

 from that pattern and coloring, to take on the 

 iivery peculiar to the Euploeinae, a group very 

 extensively imitated, when there is found in the 

 regions inhabited by this supposed mimicking 

 species no Euploeid which it in any way specially 

 resembles. In this case but two explanations 

 have been offered : one tl^it the mimicked butter- 

 fly has not yet been found, another that it has 

 for some cause become extinct. But with the 

 extinction of the mimicked form we should ex- 

 pect speedy extinction of the mimicking, and it 



