2o2 THE ORIGIN OF SPECIES 



remote from the I'onii which it imitates. Tlie mockers 

 arc almost invariably rare insects; the mocked in almost 

 every case abound in swarms. In the same district in 

 which a species of Leptalis closely imitates an Ithomia 

 there are sometimes other Lepidoptera mimicking the 

 same Ithomia: so that in the same place, species of three 

 genera of butterflies and even a moth are found all 

 closely resembling a butterfly belonging to a fourth 

 genus. It deserves especial notice that many of 

 the mimicking forms of the Leptalis, as well as of the 

 mimicked forms, can be shown by a graduated series to 

 be merely varieties of the same species; while others are 

 undoubtedly distinct species. But why, it may be asked, 

 are certain forms treated as the mimicked and others 

 as the mimickers? Mr. Bates satisfactorily answers this 

 question, by showing that the form which is imitated 

 keeps the usual dress of the group to which it belongs, 

 while the counterfeiters have changed their dress and do 

 not resemble their nearest allies. 



We are next led to inquire what reason can be as- 

 signed for certain butterflies and moths so often assuming 

 the dress of another and quite distinct form; why, to the 

 perplexity of naturalists, has nature condescended to 

 the tricks of the stage? Mr. Bates has, no doubt, hit 

 on the true explanation. The mocked forms, which 

 always abound iu numbers, must habitually escape de- 

 struction to a large extent, otherwise they could not 

 exist in such swarms; and a large amount of evidence 

 has now been collected, showing that they are distasteful 

 to birds and other insect-devouring animals. The mock- 

 ing forms, on the other hand, that inhabit the same dis- 

 trict, are comparatively rare, and belong to rare groups; 





