Sept. 7. 1876] 



NATURE 



405 



But it is among islands that we f.nd some of the most striking 

 examples of the influence of locality on colour, generally in the 

 direction of paler, but sometimes of darker and more brilliant 

 hues, and often accompanied by an unusual increase of size. 

 Thus, in the Moluccas and New Guinea we have several Papilios 

 (/'. euchenor, P. ormenus, and/*, tydms), distinguished from their 

 alii s by a much paler colour, especially in the females, which 

 are almost white. Many species of Danais (forming the sub- 

 genus Ideopsh) are also very pale. Eut the most curious are the 

 Euplaeas, which, in the larger islands, are usually of rich dark 

 colours, while in the small islands of Banda, Ke, and Matabello 

 at least three species not nearly related to each other {^E. hoppferi, 

 E. euripon, and E. assiviilata) are all broadly banded or suffused 

 with white, their allies in the larger islands being all very much 

 darker. Again, in the genus Diadema, belonging to a distinct 

 family, three species from the small Aru and Ke islands (Z>. deois, 

 D. hewitsonii, and D. polymena) are all more conspicuously 

 white-marked than their representatives in the larger islands. 

 In the beautiful genus Cethosia, a species from the small island 

 of Waigiou (C cyrene), is the whitest of the genus. Frothoe is 

 represented by a blue species in the continental island of Java, 

 while those inhabiting the ancient insular groups of the Moluccas 

 and New Guinea are all pale yellow or white. The genus 

 Dntsilla, almost confined to these islands, comprises many 

 species which are all very pale ; while in the small island of 

 Waigiou is found a very distinct genus, Hyantis, which, though 

 differing completely in the neuration of the wings, has exactly 

 the same pale colours and large ocellated spots as Drusilla. 

 Equally remarkable is the fact that the small island of Amboina 

 produces larger-sized butterflies than any of the larger islands 

 which surround it. This is the case with at least a dozen butter- 

 flies belonging to many distinct genera,^ so that it is impossible 

 to attribute it to other than some local influence. In Celebes, 

 as I have elsewhere pointed out,^ we have a peculiar form of 

 wing and much larger size running through a whole series of 

 distinct butterflies, and this seems to take the place of any 

 specialty in colour. 



From the Fiji Islands we have comparatively few butterflies, 

 but there are several species of Diadema of unusually pale 

 colours, some almost white. 



The Philippine Islands seem to have the peculiarity of deve- 

 loping metallic colours. We find there at least three species of 

 Euplcea ^ not closely related, and all of more intense metallic 

 lustre than their allies in other islands. Here also we have one 

 of the large yellow Ornithopterse ( O. magellamis), whose hind 

 wings glow with an intense opaline lustre not found in any other 

 species of the entire group ; and an Adolias* is larger and of 

 more brilliant metallic colouring than any other species in the 

 Archipelago. In these islands also we find the extensive and 

 wonderful genus of weevils, Pachyrhynchtis, which in their bril- 

 liant metallic colouring suipass anything found in the whole 

 eastern hemisphere, if not in the whole world. 



In the Andaman Islands, in the Bay of Bengal, there are a 

 considerable number of peculiar species of butterflies differing 

 slightly from those on the continent, and generally in the direc- 

 tion of paler or more conspicuous colouring. Thus, two species 

 of Papilw, which on the continent have the tails black, in their 

 Andaman representatives have them either red- or white-tipped.^ 

 Another species ® is richly blue-banded where its allies are black; 

 while three species of distinct genera of NymphalidDe^ all differ 

 from their allies on the continent in being of excessively pale 

 colours, as well as of somewhat larger size. 



In Madagascar we have the very large and singularly white- 

 spotted Papilio aiitenoy, while species of three other genera * are 

 very white or conspicuous, compared with their continental 

 allies. 



Passing to the West Indian Islands and Central America 

 (which latter country has formed a group of islands in very 

 recent times), we have similar indications. One of the largest of 

 the Papilios inhabits Jamaica,** while another, the largest of its 



' Oriiithoptera priamus, O. Jielena, Papilio deiphobus, P. ulysses, P. 

 gambrisuts, P. codrus, Iphias leucippe, Euplcea prothoe, Hestia idea, 

 Athy7na jocoiie, Diadema pandarus, Nyniplialis pyrrhus, N. euryaliis, 

 Drusilla jairus. 



» " Contributions to the Theory of Natural Selection," pp. 168-173. 



3 Euplcea hewitsonii, E. diocletiana, E. latijica, E. duprsnii. 



^ Adolias callipJwt 71s. 



5 Papilio rlwdi/er (near P. doubledayi) and Papilio chariclcs (near P. 

 mevinoii). 



6 Papilio viayo. 



7 Eupltea andamanensis, Cethosia biblis,'Cyresiis codes. 



8 Danais uossima, Melaiiitis massoura, Diadema dexithea. 



9 Papilio homer Hs. 



group, is found in Mexico. ^ Cuba has two of the same genus 

 whose colours are of surpassing brilliancy ; * while the fine genus 

 Clothilda — confined to the Antilles and Central America — is 

 remarkable for its rich and showy colouring. 



Persons who are not acquainted with the important structural 

 diff'erences that distinguish these various genera of butterflies, 

 can hardly realise the importance and the significance of such 

 facts as I have now detailed. It may be well, therefore, to 

 illustrate them by supposing parallel cases to occur among the 

 mammalia. We might have, for example, in Africa, the gnus, 

 the elands, and the buffaloes aU coloured and marked like 

 zebras, stripe for stripe over the whole body exactly correspond- 

 ing. So the hares, marmots, and squirrels of Europe might be 

 all red, with black feet, while the corresponding species of 

 Central Asia were all yellow, with black heads. Inr North 

 America we might have raccoons, squirrels, and opossums in 

 parti-coloured livery of white and black, so as exactly to resemble 

 the skunk of the same country ; while in South America they 

 might be black, with a yellow throat patch, so as to resemble 

 with equal closeness the tayra of the Brazilian forests. Were 

 such resemblances to occur in anything like the number, and 

 with the wonderful accuracy of imitation met with among the 

 Lepidoptera, they would certainly attract universal attention 

 among naturalists, and would lead to the exhaustive study of 

 the influence of local causes in producing such startling results. 



One somewhat similar case does indeed occur among the 

 Mammalia, two singular African animals, the Aard-wolf {Prc- 

 teles) and the Hyasna-dog (Pycaon), both Jstrikingly resembling 

 hyjenas in their general lorm as well as in their spotted mark- 

 ings. Belonging as they all do to the Carnivora, though to 

 three distinct families, it seems quite an analogous case to those 

 we have imagined ; but as the Aard-wolf and the hysena-dog 

 are both weak animals compared with the hyseaa, the resem- 

 blance may be useful, and in that case would come under thj; 

 head of mimicry. This seems the more probable because, as 

 a rule, the colours of the Mammalia are protective, and are 

 too little varied to allow of the influence of local causes pro- 

 ducing any well-marked effects. 



When we come to birds, however, the case is diff'erent ; for 

 although they do not exhibit such distinct marks of the influence 

 of locality as do butterflies— probably because the causes which 

 determine colour are in their case more complex — yet there are 

 distinct indications of some effect of the kind, and we must 

 devote some little time to their consideration. 



One of the most curious cases is that of the parrots of the 

 West Indian Islands and Central America, several of which have 

 white heads or foreheads, occurring in two distinct genera,* while 

 none of the more numerous parrots of South America are so 

 coloured. In the small island of Dominica we have a very large 

 and richly-coloured parrot {Chrysotis augusta) corr^sponimg to 

 the large and richly-coloured Papilio homerus of Jamaica. 



The Andaman Islands are equally remarkable, at least six of 

 the peculiar birds differing from their continental allies in being 

 much lighter, and sometimes with a large quantity of pure white 

 in the plumage, * exactly corresponding to what occurs among 

 the butterflies. 



In the Philippines this is not so marked a feature, — yet we 

 have here the only known white-breasted Kingcrow (Dicrurus 

 mirabilis),— \hG newly discovered Eurylcemus Steerii, wholly 

 white beneath,— three species of Diceuvi, all white beneath, — 

 several species of Parus, largely white-spotted, — while many of 

 the pigeons have light ashy tints. The birds generally, however, 

 have rich dark colours, similar to those which prevail among the 

 butterflies. 



In Celebes we have a swallow-shrike and a peculiar small 

 crow allied to the jackdaw,' whiter than any of their allies in 

 the surrounding islands, but otherwise the colours of the birds 

 call for no special remark. 



In Timor and Flores we have white-headed pigeons, "^and a 

 long-tailed flycatcher almost entirely white.'^ 



In the small Lord Howe's Island we have the recently extinct 

 white rail {Motornis alba), remarkably contrasting with its allies 

 in the larger islands of New Zealand. 



We cannot, however, lay any stress on isolated examples of 

 white colour, since these occur in most of the great continents, 



1 />. daunus. " P- gundlachianus , P. villiersi. 



3 Pionus albifrons and Chrysotis senilis (C. America), Chrysotis sallai 

 (Hayti). , . , ' . 



* Kittariiicla albiventris, Geocichla albigularts, Sturnta andatnaneusts, 

 Hyloterpe grisola, var., Janthanas palumboides, Osmotrcron chloroptira. 



5 Artamus nionachus, Corviis advefta. 



6 Ptilopus cinctus, P. albocinctus. ' Tchitrca ajptiis, var. 



