416 ANALOGICAL RESEMBLANCES. 



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 essen- 

 tial 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 mocking 

 and mocked species, belonging to the same two genera, 

 equally close in their resemblance, may be found. Alto- 

 gether 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 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 butterflies and even a moth are found all closely resem- 

 bling 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 mim- 

 icked 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 assigned 

 for certain butterflies and moths so often assuming the 

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

 plexity 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 



