Jan., 1905] 



KNOWLEDGE & SCIENTIFIC NEWS. 



is curiously like P. aristolache ; the roniulus form is an 

 equally close mimic of P. hector. 



These wide differences existing between the sexes 

 of a mimicking species seem at first very difficult to 

 understand. It has been suggested that the males, 

 for some reason, are better able to protect themselves 

 than are the females, and do not, therefore, need the 

 protection of a mimetic likeness to a warningly coloured 

 type. In some cases the males certainly seem stronger 

 on the wing, and better able to escape from danger by 

 flight; while it is obvious that the females, when de- 

 positing their eggs upon vegetation, would run more 

 risk of being attacked by birds and other insectivorous 

 creatures than their mates, who are free from pre- 

 occupations likely to detract from their alertness. 



The question as to how such wide differences be- 

 tween the sexes of one species came to be seems, at 

 first, a very perplexing one, especially in cases where 

 two or more mimicking varieties of the female exist. 

 We know that living creatures often exhibit a strong 

 tendency to vary, but these several well-marked forms 

 of one species seem to be something more than the 

 outcome of mere "sports." 



It is possible — at least, in some degree — to show 

 how they have been produced and established. There 

 are two common butterflies of the family A^ymphalidce, 

 known respectively as Hypoliniiias misippiis and 

 H. holina. These species have their headquarters in 

 India, but they have a wide range in the Eastern 

 Hemisphere. They are closely related, and the males 

 are very similar — both having blackish wings, with 



PnpiUo heelm: Papilio pnmnwn ? {miiiihis iorm). 



central areas of white beautifully tinted with shining 

 purple. The females of both species are curiously 

 variable, and are well worth a careful study by those 

 seeking to comprehend the theory of mimicry. Taking 

 first H. misippus, we find that no female at all like the 



male in appearance is known to exist. The common 

 form of female is that shown in the accompanying 

 photograph. It is bright tawny, bordered with black, 

 and has a conspicuous band of white in the fore-wing. 

 In this it is seen to be a wonderfully accurate copy of 



DfinnU chrysippus. Ht/poHmna^ misippti-f ?. Htipolimtian misippus tf. 



that common and much-mimicked Eastern butterfly, 

 Danais chrysippus. This insect [D. chrysippus) is 

 common all over Africa and Southern Asia, and there 

 are a number of closely allied forms — whether constant 

 local varieties or actual species is not definitely 

 known. These forms vary a good deal in colour and 

 marking. For instance, in D. alcippus the hind wings 

 are almost entirely white; in D. kliigi, all the wings are 

 tawny, with black edges, and there are no white bands 

 in the fore-wings. The range of H. misippus is very 

 similar to that of D. chrysippus and its several forms, 

 and wherever a marked difference is seen in the ap- 

 pearance of the latter, it is found to be reproduced 

 upon the wings of the mimicking females of the former, 

 usually in a strikingly close manner. But though the 

 females vary in different districts, the colouring of the 

 males is identical in each locality- 



These facts — the extraordinary difference between 

 the sexes, the various forms of the female, none of 

 which are in the least like the males — are very sur- 

 prising; but in the case of the allied H. holina we find, 

 in measure, a key to the mystery. The females of this 

 butterfly vary in a much more erratic manner than do 

 those of H. misippus, albeit none of them has attained 

 to such striking mimicry. There is a form (shown in 

 the accompanying photograph) which is an imperfect 

 mimic of the common evil-tasting butterfly, Euphva 

 iore : there are also dozens of other forms, all ex- 

 hibiting some marked difference, but few showing any 

 tendency towards a mimetic likeness. The group of 



