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in ANIMAL LIFE IN THE TROPICAL FORESTS 277or upon fully exposed leaves. Being uneatable they have noenemies and need no concealment.Day-flying moths ofbrilliant or conspicuous colours are also comparatively abundantin the tropical forests. Most magnificent of all are theUranias, whose long -tailed green -and -gold powdered wingsresemble those of true swallow -tailed butterflies.ManyAgaristidae of the East are hardly inferior in splendour, whilehosts of beautiful clearwings and ^Egeriidae add greatly tothe insect beauty of the equatorial zone.The wonderful examples afforded by tropical butterflies ofthe phenomena of sexual and local variation, of protectivemodifications, and of mimicry, have been fully discussedelsewhere. For the study of the laws of variation in all itsforms, these beautiful creatures are unsurpassed by any classof animals, both on account of their great abundance, and theassiduity with which they have been collected and studied.Perhaps no group exhibits the distinctions of species andgenera with such precision and distinctness, due, as Mr. Bateshas well observed, to the fact that all the superficial signs ofchange in the organisation are exaggerated, by their affectingthe size, shape, and colour of the wings, and the distributionof the ribs or veins which form their framework. The minutescales or feathers with which the wings are clothed are colouredin regular patterns, which vary in accordance with the slightestchange in the conditions to which the species are exposed.These scales are sometimes absent in spots or patches, andsometimes over the greater part of the wings, which thenbecome transparent, relieved only by the dark veins and bydelicate shades or small spots of vivid colour, producing aspecial form of delicate beauty characteristic of many SouthAmerican butterflies. The following remark by Mr. Bateswill fitly conclude our sketch of these lovely insects. "Itmay be said, therefore, that on these expanded membranesNature writes, as on a tablet, the story of the modifications ofspecies, so truly do all the changes of the organisation registerthemselves thereon. And as the laws of Nature must be thesame for all beings, the conclusions furnished by this groupof insects must be applicableto the whole organic world ;therefore the study of butterflies creatures selected as thetypes of airiness and frivolity instead of being despised, will