MIMICRY IN INSECTS. 61 



seven of the fifteen cases given only the female is mimetic, and 

 Mr. Wallace suggested that the reason of this is probably that 

 the slower flight of that sex when laden with eggs, and her 

 exposure to attack while ovipositing, render it especially necessary 

 to have a protecting disguise. 



It was my good fortune to be able to supplement the cases 

 brought forward by these distinguished explorers of South 

 America and the Malayan Archipelago by a similar series of 

 mimetic analogies among African butterflies. From the beginning 

 of my collecting in South Africa I had been familiar with one or 

 two striking instances of mimicry, and a visit to Natal in 1867 

 made me acquainted with several others. While in England 

 shortly afterwards I had excellent opportunities of working up 

 the subject, and early in 1868 I read to the Linnean Society a 

 paper (subsequently published in the twenty-sixth volume of its 

 ' Transactions '), describing in detail the eleven cases of mimicry 

 then known to me. It was interesting to be in a position to 

 fortify the conclusions of Messrs. Bates and Wallace by personal 

 observations made in an entirely difl'erent region. I showed how 

 the Danaince and Acrceince of Africa, like their allies elsewhere, 

 were provided with oifensive odours and secretions, and that 

 several of them were accompanied throughout their geographical 

 range by faithful imitators belonging to quite distinct groups. 

 It was further pointed out (1) that the mimicking butterflies 

 invariably occurred in districts inhabited by the species mimicked, 

 and in six cases (South African) are found in the very same 

 localities ; (2) that in eight cases the mimickers are known to be 

 very much scarcer than the species which they copy ; (3) that in 

 five cases, where the Danais or Acrcea presents local forms, or 

 merely slight varieties, even these are mimicked by individuals 

 of the imitating species ; (4) that in three cases, where the sexes 

 of the insect mimicked difl"er remarkably from each other, the 

 sexes of the mimicker present corresponding differences ; and (5) 

 that, in four cases observed by me in Nature, it was next to 

 impossible to distinguish the living mimicker from the species 

 which it imitated. It must be remembered that these extraordinary 

 likenesses are not those of general colouring and pattern alone, 

 but include outline and form, extending to minute reproduction 

 of prominent markings however small ; and that the deception is 

 often further borne out by following closely the kind of flight and 

 mode of resting exhibited by the species copied. 



