394 ORDERS OF PTILOTA. 



multiplied in the females, so that it furnishes a good charac- 

 ter to distinguish the sexes. From general observations 

 upon the distribution of colours in insects, it is evident that 

 it is in the day-flying species that we are to expect the great- 

 est variety of tints ; and hence it is amongst the butterflies 

 especially, as every one knows, that the most splendid hues 

 and the most beautiful markings exist. M'oreover, it is to be 

 observed that here, as in some tribes of plants, certain tints 

 prevail in particular groups ; thus the Pontice and Pierides 

 are generally white ; Colias and its allies yellow ; Polyom- 

 matus blue ; Argynnis and Melitcea yellow or bufl", spotted 

 with black, &c. : in like manner peculiar markings prevail in 

 certain groups, so that in many cases it is easy, by merely 

 examining a fragment of one of their wings, to ascertain the 

 tribe of which the insect to which it belonged formed part. 

 Thus in Doritis, the centre of the wings has large eyes, 

 with red and black circles. In Colias the centre of the pos- 

 terior wings on the inferior surface has a silvery eyelet ; the 

 species of Danais, Idcea, and Euploea, have the breast and 

 head spotted with white, and in Acrcea the base of the wing 

 is more or less spotted with black. 



The form of the wings is very much varied, preserving, 

 however, in the species of the various groups, a certain re- 

 semblance in form ; but this, however, must not be alone 

 regarded, for amongst the strange freaks of nature, we 

 find many groups widely apart, and belonging in fact to diff"er- 

 ent primary sections in the order, exhibiting so great a resem- 

 blance together, not only in appearance, but even its habitats 

 and habits, that an imaccustomed eye would be tempted to 

 assert that the individuals formed but a single species. Thus 

 Geometra dealhata flies about the footpaths in woods, with 

 Pontia napi. In the woods of Brazil, Acrcea Thalia (a but- 

 terfly) and Castnia acraoides (a moth) fly together ; and in 

 the thick forests of Guiana Castnia linusand Heliconia psidii 



