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Show 246 DARWINISM 1 CIIAl', Other Examples of llfimicry among Lepidoptem. In tropical Asia, and eastward to the Pacific Islands, the Danaidre take the place of the Heliconidre of America, in their abundance, their conspicuousness, their slow flight, and their being the subjects of mimicry. They exist under three principal forms or genera. The genus Euplrea is the mo11t abundant both in species ancl individuals, and consist. of fino broad-winged butterflies of a glossy or metallic blue -black colour, adorned with pure white, or rich blue, or dusky m:trkings situated round the margins of the wings. Danai. has generally more lengthened wings, of a semitransparent greenish or a rich brown colour, with radial or marginal pale spots ; while the fine Hestias are of enormous size, of a papery or semitransparent white colour, with dusky or black spot awl markings. Each of these groups is mimicked by various ~pe.cie~ of t~e genus ~a_pilio,. usually with such accuracy that It Is Impo Sible to distmgmsh them on the wing.l RoYoral species of Diadema, a genus of butterflies allied to onr Vanessas, also mimic species of Danais, but in thi case tho females only are affected, a subject which will be discw:>sed in another chapter. Another protected group in the Eastern tropics is tlmt of the beautiful day-flying moths forming the family Agaristitl, '. These are usually adorned with the most brilliant colours or conspicuous markings, they fly slowly in fore. ts amon<r the butterflies and other diurnal insects, and their o-rcat almn~Lnce ufficiently indicates their possession of somcb eli tastcfnlness which saves them from attack. Under these conditions we may expect to find other moths which arc not o protected imitating them, and this is the case. One of the common and wide-ranging species (Opthalmis lincea), found in the il'hnds from Amboyna to New Ireland, is mimicked in a wonderful manner by one of the Liparidre (the family to which our common " ~ussock " and " vapourer " moths belong). This is a new species collected at Amboyna during the voyage of the Challenger, and has been named Artaxa . imulans. Both 1 See T1·an.s. Linn. Soc., vol. xxv. Wallace, on Variation of l\Jalayan Papilioni<lre; and, Wallace's Contributions to Natuml &lection, chaps. iii. and iv., where full details are given. IX WARNING COLORATION AND MIMICRY 247 insects arc black, with the apex of the fore wings ochre coloured, and the outer half of the hind wings bright orange. The accompanying woodcuts (for the use of which I am indebted to Mr. John Murray of the Challenge?' Office) well exhibit their striking resemblance to each other. FIG. 24.-0pthnlmis Jinccn (.l.garistiJ.ro). Artaxa. simulans (Liparidr~). In Africa exactly simihr phenomena. recur, specie of Papilio and of Din.dema mimicking Danaidre or Acrreidm with the most curious accuracy. Mr. Trimen, who studied this snhjcct in South Africa, has recorded eight species or v:trictie:; of Diadema, a,nd eight of P:tpilio, which each mimic omc species of Drmais; while eio·ht species or varieties of Pa,110pxa (another genus of N ymphaJiche), three of Melanitis (Eurytelidre), and two of Papilio, r esemble with equal accmacy some species of Acrrea.l He has al o independently ob. erved the main facts on which the explanation of the phenomenon rests,-thc unpleasant orlonr of the Danais and Acrrea, extending to their larvre and pupre ; their great abundance, sl~w flight, and disregard of conccaJmcnt; and he states that while lizards, mantidre, and dra,gonflics all hunt butterflies, and the rejected wings arc to be found abundantly at some of their 1 See Truns. Linn. Soc., vol. xxvi., with two colon red plates illustrating cases of mimicry. |