LEPIDOPTERA. 711 



In many forms the body of the pupa ends in a projection the 

 cremaster and when the pupa is one which hangs suspended 

 from a twig or leaf the cremaster is provided with a number of 

 minute hooks. Various methods are used for the imago to 

 escape from the cocoon. After emergence it rests for a while 

 for the wings to dry and then flies away. 



The great beauty of the Lepidoptera is due to the scales, which 

 are little flattened sacs of chitin of very various shape. Some 

 contain pigment, which in certain species take the form of urates. 

 Waste nitrogenous matter is not uncommonly utilized as pig- 

 ment, as in the case of a family of Polychaets, the Capitellidae, 

 and perhaps some Tunicates. The white glistening scales are 

 said to contain air. The metallic burnish of some butterflies is. 

 due to the minute ridging of the surface of the scales, which, acting, 

 as diffraction-gratings, splits up the light. 



There are perhaps some 50,000 species described of which 

 some 2,000 are British. 



The division of the Order into Butterflies (Rhopalocera) and 

 Moths (Heterocera) is probably not a natural one, but there is 

 a certain convenience in adopting it. Beyond this the Order 

 is subdivided into more than fifty families. 



Series 1. RHOPALOCERA. Butterflies. 



Antennae clubbed ; the hind-wing has no frenulum, but a shoulder pro- 

 jecting forwards under the base of the fore-wing, 



Fam. 1. Nymphalidae. The anterior legs of both sexes so reduced 

 as to be useless for walking ; in the male but a single tarsal segment. The 

 pupa hangs freely, without a girdle, from some support, and is compara- 

 tively soft-skinned. This is the largest family of butterflies and in it the 

 pupa attains the height of its development. This stage is frequently 

 ornamented with gold or silver 

 bosses. The family is divided into 

 eight sub-families : 



Sub-fam. 1. Danainae. The 



anal (inner margin or sub- 

 median) nervure of the front 



wing forked at its base. Cells 



of hind-wing closed. Front 



feet of female end in corru- 



gated knobs. Larvae smooth F ' G ' 457 ' %*>' Brazih " f 



but with fleshy protuberances. 



Large rather black or purplish butterflies which chiefly live in warm 



climates though they extend far north in America. There are some 



seven genera ; Limnas, Anosia, Danais. 



Sub-fam. 2. Ithomiinae. Front foot of female has a tarsus? 



though a shortened one. The larvae have no long processes. This- 



