30 LEPIDOl'TEKOUS LXSECTS. 



or inlernal edge. The external angle formed by the meeting of the an- 

 terior and of the exterior edge is called the apex., by which name also 

 the adjacent part of the wing is sometimes called. The angle op])osite 

 to this is sometimes called the internal and sometimes the anal angle. 



The exterior edge of each wing is bordered by a row of small 

 hairs which are very serrate, somewhat scaly, and more oi less long, 

 generally more developed and larger m the Heterocerata than in the 

 RhopaloceratS' ; this has been named the fringe. This is sometimes 

 of a diflerent shade from the ground of the wing ; sometimes it is of a 

 uniform hue and sometimes variegated. 



In regard to colors, the wings of Lepidoptera present as great a va- 

 riety as the corollas, of flowers. To tints the most vivid they some- 

 times unite the lustre and brilliancy of metals and the clearness of pearls 

 and precious stones. In no other race of animals has nature been so 

 prodigal of ornament. But it is generally in the tribes that fly by day 

 that the colors have the greatest brilliancy. In the nocturnals they are 

 rather sombre, and the wings of these latter are rather remarkable for 

 tlic originality of their designs than for the variety of their colors. 



Although no general rule can be laid down for the distribution of 

 colors, and they do not constitute a fixed character, yet it is to be re- 

 marked of them as of plants, that certain hues appear to be aflected by 

 certain genera of Lepidoptera. Thus most of the Pleridcs are white ; 

 the ErebiaCf black, etc. 



The design is a more constant character, and in certain circumstances 

 it is more useful for determining the genera than the palpi and the an- 

 tennae. Sometimes it is suflicient to see a mere fragment of the wing 

 to determine, without mistake, to what genus the Lepidopter, of which 

 it is a part, belongs. 



The Legs, as in other insects, are composed of five parts: the 

 liip (coxa), the trochanter, the thigh (fenmr), the shank (tibia)., and 

 the tarsus. Tliis last has always five distinct articulations, without 

 counting the terminal hooks, which sometimes form a decid.ed claw, as 

 ' in the case in the Jlcherontia atropos, or they are so strong as to scratch 

 the skin. In most tribes the six legs are of equal length, but in some 

 the two fore legs are quite short so as to be unfit for walking -, the latter 

 are termed tetrapodes, the former hexapodes. The legs are generally 

 more or less hairy or scaly. 



^he posterior tibiae have sometimes two and sometimes four small 

 acicular points more or less developed, and designated by the iinme of 

 spurs. AVhen there are four, two are placed near the exlreniily, and two 

 near the middle of llic inward side. 



