in ANIMAL LIFE IN THE TROPICAL FORESTS 277 



or upon fully exposed leaves. Being uneatable they have no 

 enemies and need no concealment. Day-flying moths of 

 brilliant or conspicuous colours are also comparatively abund- 

 ant in the tropical forests. Most magnificent of all are the 

 Uranias, whose long -tailed green -and -gold powdered wings 

 resemble those of true swallow -tailed butterflies. Many 

 Agaristidae of the East are hardly inferior in splendour, while 

 hosts of beautiful clearwings and ^Egeriidae add greatly to 

 the insect beauty of the equatorial zone. 



The wonderful examples afforded by tropical butterflies of 

 the phenomena of sexual and local variation, of protective 

 modifications, and of mimicry, have been fully discussed 

 elsewhere. For the study of the laws of variation in all its 

 forms, these beautiful creatures are unsurpassed by any class 

 of animals, both on account of their great abundance, and the 

 assiduity with which they have been collected and studied. 

 Perhaps no group exhibits the distinctions of species and 

 genera with such precision and distinctness, due, as Mr. Bates 

 has well observed, to the fact that all the superficial signs of 

 change in the organisation are exaggerated, by their affecting 

 the size, shape, and colour of the wings, and the distribution 

 of the ribs or veins which form their framework. The minute 

 scales or feathers with which the wings are clothed are coloured 

 in regular patterns, which vary in accordance with the slightest 

 change in the conditions to which the species are exposed. 

 These scales are sometimes absent in spots or patches, and 

 sometimes over the greater part of the wings, which then 

 become transparent, relieved only by the dark veins and by 

 delicate shades or small spots of vivid colour, producing a 

 special form of delicate beauty characteristic of many South 

 American butterflies. The following remark by Mr. Bates 

 will fitly conclude our sketch of these lovely insects. "It 

 may be said, therefore, that on these expanded membranes 

 Nature writes, as on a tablet, the story of the modifications of 

 species, so truly do all the changes of the organisation register 

 themselves thereon. And as the laws of Nature must be the 

 same for all beings, the conclusions furnished by this group 

 of insects must be applicable to the whole organic world ; 

 therefore the study of butterflies creatures selected as the 

 types of airiness and frivolity instead of being despised, will 



