MIMICRY. 129 



MIMICRY. 



IV. — Historical review of remarks made by various observers as 



TO THE ORIGIN OF LEAF-MARKINGS DISPLAYED BY CERTAIN BUTTERFLIES 

 FOR PROTECTIVE PURPOSES ON THE UNDER SURFACES OF THEIR WINGS. 



By J. W. TUTT , F.E.S. 



It has been suggested that it would be interesting to rehite biietly 

 some of the published remarks relating to those butterflies which, 

 for protective purposes, exhibit on the undersides of their wings the 

 appearance and markings of leaves. 



Most butterflies Avhen at rest close their wings vertically over the 

 back, and then allow the fore-wings to slide back as far as possible into 

 concealment behind the hind-Avings. The area of the wings thus 

 exposed to view consists of the whole of the hind-wings and the apices 

 of the fore-wings. This area is usually so coloured and marbled as 

 to render the butterfly inconspicuous in its resting-place. 



Among the many patterns Avith Avhich the exposed portions of the 

 Avings are provided, there can be no doubt that the " leaf -markings " 

 of the oriental genus Kallma are among the most specialised. These 

 butterflies' are conspicuous objects Avhen flying, but Avhen they alight 

 upon a tAvig, the Avings raised over the back, and the fore-Avings thrown 

 Avell forAvard, the pattern and colour of the under-surface are such 

 that they make a perfect resemblance to a leaf. The mid-rib consists 

 of a coloured stripe crossing both Avings, Avhich, taking its rise at the 

 apex of the fore-Aving, is continued over the hind-Aving, and terminates 

 in a tail-like extension of the latter, the extension just reaching the 

 twig, and thus resembling the pedicel of a leaf. The Nymphalid 

 butterflies of this genus — Kalliiiia — are large, the Indian species — 

 paralckta, inacJiis, a,nd jiliilarchn.'>, being nearly four inches in expanse, 

 whilst the African species, K. riunia, is smaller, nor is the underside 

 resemblance to a leaf so perfect. Butterflies of other genera, hoAve\'er, 

 have very similar protective leaf-markings. 



Kirby and Spence (1815) Avere the first authors to apply the term 

 "mimicry" to the resemblance that insects bore to the objects on 

 Avhich they rested. In the introduction to their treatise on 

 entomology, they Avrite : — " You Avould declare, upon beholding some 

 insects, that they had robbed the trees of their leaves to form for 

 themselves artificial Avings, so exactly do they resemble them in their 

 form, substance, and vascular structure ; some representing green 

 leaves, and others those that are dry and Avithered. Nay, sometimes 

 this mimicry is so exquisite, that you Avould mistake the Avhole insect 

 for a portion of the branching spray of a tree." 



At the meeting of the British Association, 1859, Mr. Andrew 

 Murray read a paper upon the " Disguises of Nature," in AA'hich he 

 showed that the most perfect imitation of inanimate objects occurs, 

 not rarely or exceptionally, but in some groups so commonly, that the 

 Avant of it might be regarded as the exception, and that the conceal- 

 ment of the animal Avas the plain purpose of the disguise. So 

 hopelessly lost Avas he for an explanation, hoAvever, that he could 

 only suggest that the cause of this phenomenon might be found in 

 some force analogous to the great laAV of attraction, that " like draAVS 

 to like, or like begets like." 



The theory of natural selection, however, propounded directly 



