376 CLASSIFICATION. [Chap. XIV. 



shade and stripe of colour and even in the shape of its wings, that 

 Mr. Bates, with his eyes sharpened by collecting during eleven 

 years, was, though always on his guard, continually deceived. 

 When the mockers and the mocked are caught and compared, 

 they are found to be very different in essential structure, and to 

 belong not only to distinct genera, but often to distinct families. 

 Had this mimicry occurred in only one or two instances, it might 

 have been passed over as a strange coincidence. But, if we proceed 

 from a district where one Leptalis imitates an Ithomia, another mock- 

 ing and mocked species belonging to the same two genera, equally 

 close in their resemblance, may be found. Altogether no less than 

 ten genera are enumerated, which include species that imitate 

 other butterflies. The mockers and mocked always inhabit the 

 same region; we never find an imitator living remote from the 

 form which it imitates. The mockers are 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 ; whilst 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 satis- 

 factorily answers this question, by showing that the form which 

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

 whilst the counterfeiters have changed their dress and do not 

 resemble their nearest allies. 



We are next led to inquire what reason can be assigned 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 in numbers, must habitually escape destruction 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 mocking forms, on the other hand, that inhabit the same 

 district, are comparatively rare, and belong to rare groups ; hence 

 they must suffer habitually from some danger, for otherwise, from 

 the number of eggs laid by all butterflies, they would in three 01 



