Chap. XL] BUTTERFLIES AND MOTHS. 399 



standing how the first steps in the process of mimicry 

 could have been effected through natural selection, it may 

 be well to remark that the process probably has never 

 commenced with forms widely dissimilar in color. But, 

 with two species moderately like each other, the closest 

 resemblance, if beneficial to either form, could readily be 

 thus gained ; and, if the imitated form was subsequently 

 and gradually modified through sexual selection or any 

 other means, the imitating form would be led along the 

 same track, and thus be modified to almost any extent, so 

 that it might ultimately assume an appearance or coloring 

 wholly unlike that of the other members of the group to 

 which it belonged. As extremely slight variations in col- 

 or would not in many cases suffice to render a species so 

 like another protected species as to lead to its preserva- 

 tion, it should be remembered that many species of Lepi- 

 doptera are liable to considerable and abrupt variations in 

 color. A few instances have been given in this chapter ; 

 but under this point of view Mr.. Bates's original paper 

 on mimicry, as well as Mr. Wallace's papers, should be 

 consulted. 



In the foregoing cases both sexes of the imitating spe- 

 cies resemble the imitated; but occasionally the female 

 alone mocks a brilliantly-colored and protected species 

 inhabiting the same district. Consequently the female 

 differs in color from her own male, and, which is a rare and 

 anomalous circumstance, is the more brightly-colored of the 

 two. In all the few species of Pieridse, in which the female 

 is more conspicuously colored than the male, she imitates, 



ural Selection," in the ' Month,' 1869. The writer strangely supposes 

 that I attribute the variations in color of the Lepidoptera, by which cer- 

 tain species belonging to distinct families have come to resemble others, 

 to reversion to a common progenitor ; but there is no more reason to 

 attribute these variations to reversion than in the case of any ordinary 

 variation. 



