ANALOGICAL RESEMBLANCES. 443 



to similar habits of life, but has been gained for the sake 

 of protection. I allude to the wonderful manner in which 

 certain butterflies imitate, as first described by Mr. Bates, 

 other and quite distinct species. This excellent observer 

 has shown that in some districts of South America, where, 

 for instance, an Ithomia abounds in gaudy swarms, an- 

 other butterfly, namely, a Leptalis, is often found mingled 

 in the same flock; and the latter so closely resembles the 

 Ithomia in every shade and stripe of color, 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 imi- 

 tates an Ithomia, another mocking and mocked species, be- 

 longing 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 in- 

 habit 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 abounds 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 butter- 

 flies 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 satis- 

 factorily answer 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. 



