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COLOURS OF ANIMALScomparatively rare and not great in amount, whereas amongbirds they are very frequent and very largely developed. Soamong insects, they are abundant in butterflies, while they arecomparatively uncommon in beetles, wasps, and hemiptera.The phenomena of sexual variations of colour, as well as ofcolour generally, are wonderfully similar in the two analogousyet totally unrelated groups of birds and butterflies and as;they both offer ample materials, we shall confine our study ofthe subject chiefly to them. The most common case of differenceof colour between the sexes is for the male to have thesame general hue as the females, but deeper and more intensifiedas in many thrushes, finches, and hawks, and amongbutterflies in the majority of our British species. In caseswhere the male is smaller the intensification of colour isespecially well pronounced as in many of the hawks andfalcons, and in most butterflies and moths in which thecoloration does not materially differ. In another extensiveseries we have spots or patches of vivid colour in the male,which are represented in the female by far less brilliant tintsor are altogether wanting as exemplified in the gold-crestwarbler, the green woodpecker, and most of the orange-tipbutterflies (Anthocharis). Proceeding with our survey, wefind greater and greater differences of colour in the sexes, tillwe arrive at such extreme cases as some of the pheasants, thechatterers, tanagers, and birds-of-paradise,in which the maleis adorned with the most gorgeous and vivid colours, whilethe female is usually dull brown, or olive green, and oftenshows no approximation whatever to the varied tints of herpartner. Similar phenomena occur among butterflies and in;both these groups there are also a considerable number ofcases in which both sexes are highly but differently coloured.Thus many woodpeckers have the head in the male red, inthe female yellow ;while some parrots have red spots in themale, replaced by blue in the female, as in Psittacula diopthalma.In many South American Papilios, green spots onthe male are represented by red on the female ;and in severalspecies of the genus Epicalia, orange bands in the male arereplaced by blue in the female, a similar change of colour tothat in the small parrot above referred to. For fuller detailsof the varieties of sexual coloration we refer our readers to2 A.