PROTECTIVE MIMICRY. 231 



be entitled to be called seeing ; but that, as the larger develop- 

 ment of the compound eye permits the simultaneous perception 

 of movement, its direction, and of light and shades over a 

 certain area, a dragon-fly may pursue and capture another 

 insect without seeing it, in our sense of the word seeing." 



Cases of Mimicry in which the Mimicking Form is equally abundant 



with the Model. 



One of the essentials of true mimicry is that the mimicking 

 form should be scarce as compared with the model which it 

 imitates. The mimicking Pieridre comply with this requisite, 

 and so also do the Wasp and Hornet Clearwings. This very 

 fact has been used as an objection to the theory of mimicry, by 

 Mr. A. W. Bennett.* The whole object of mimicry is obviously 

 the perpetuation of the mimicking species. Defenceless insects 

 have found out this way of escaping annihilation ; and having* 

 been directed into this safe path, we may fairly inquire, with 

 Mr. Bennett, how it is that the mimicking insects continue to 

 be rare in spite of their advantages. 



Curators of museums, and other persons who purchase 

 butterflies, know perfectly well that the mimicking insect 

 often costs as many guineas as its model does shillings ; the 

 obvious inference is that mimicry does not seem to be of much 

 use ; but as a matter of fact the mimicking species are not 

 always so rare as has been supposed. Fritz Miiller states 

 that the mimicked species is not always more abundant than 

 its counterfeit ; the proportions between the two vary very 

 much in different localities; sometimes one and sometimes the 

 other preponderates. 



There is one very striking example of a resemblance between 

 two insects belonging to different orders, usually quoted as a 

 * American Naturalist, 1877, p. 3. 



