718 THE BUTTERFLIES OF NEW ENGLAND. 



terfly by another, there may also enter another element ; for it is hardly to 

 be believed that all distasteful butterflies are equally distasteful to all birds, 

 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 diflficulty remains, and this is that, in a few in- 

 stances, an insect has l)een found diflering so peculiarly from its congeners 

 as to leave no doubt in the mind that it differs in the direction of mimicry 

 when no exact prototype 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 livery pecu- 

 liar 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 that the mimicked butterfly has not yet 

 been found, another that it has for some cause become extinct. But with 

 the extinction of the mimicked form we should expect speedy extinction 

 of the mimicking, and it would seem more probable that these were cases 

 of general mimicry in process of formation toward some specific type. At 

 any rate we need to know more definitely about these instances before we 

 can properly discuss them. They have never been collated. 



In support of the general theory of mimicry, it may be said that cases 

 are far more common in the tropics than in temperate regions, even rela- 

 tively ; and so, too, are insectivorous animals. The accounts of travellers 

 in the tropics constantly mention the attacks of birds upon butterflies, while 

 instances of butterflies being seen pursued by birds are vastly more rare 

 in the temperate regions. I have never seen one. In the tropics, more- 

 over, they are aided by a greater number of other insectivorous animals, 

 such as lizards. In our own country, therefore, we should not look for 

 many instances of mimicry of any decided type. The most striking is 

 unquestionably that of Basilarchia archippus, which mimics Anosia plex- 

 ippus, and the closely related case of Basilarchia eros and Tasitia berenice, 

 the last two butterflies largely supplanting the first two on the peninsula 

 of Florida. In both these instances the mimicry is enjoyed by both sexes. 

 A third case is found in the less close but still striking mimicry of Basi- 

 larchia astyanax by the female of Semnopsyche diana, an instance the more 

 remarkable as the mimicked species belongs to the same genus as our two 

 other mimicking forms. 



When wc take a general view of mimicry as exhibited by one butterfly 

 for another, how strange it seems, and what an interesting illustration it is 

 of the adaptability and ])liancy of natural forces, that for the evident pro- 



