iQio] A Sirticiural Study of Some Caterpillars 99 



are common to all the caterpillars, and many of which can be 

 homologized with setae occurring in the Trichoptera and Panor- 

 pata; or they are secondary, in larger numbers, and not definitely 

 arranged. The setae are more or less completely carried over into 

 the pupa, with comparatively slight changes in their arrangement. 

 Often in place of the primary hairs there are tufts of hair spring- 

 ing from the same wart. This is the condition spoken of as 

 "with tufted hair." In such caterpillars as Melalopha, this is 

 due to the occurrence of secondary hair on the tubercle of the 

 primary hair, which remains quite distinct, but in the Arctiidae 

 it seems rather to be a reduplication of the primary hair. 



Where the secondary hairs are ver>^ few, like the primaries, 

 they take definite positions, and are then known as subprimaries. 



The arrangement of the primary setae on the meso- and meta- 

 thorax of the typical Frenatae is shown in figure 4, while different 

 arrangements for the abdomen are shown in Figures 5, 33 and 34. 

 The small primaries numbered iiia, ix and x are usually over- 

 looked. The numbering of the others is after Dyar, except that 

 figure 33 is changed to make it agree with the others. 



The prothorax has its arrangement modified by the persist- 

 ence of three sclerites, the cervical shield, with many setae and 

 some punctures, the prespiracular wart, with two or three setae 

 (sometimes fused with the cervical shield) and the subventral 

 wart, with two or three setae. 



Tufted or secondary hair on the body is usually accompanied 

 by secondary hair on the true legs and head. It reaches its great- 

 est development in the Lasiocampidae, where it occurs even on 

 the antennae and palpi, and on the sclerites, a, b, and c of the 

 labium. 



PROLEGS. 



One may take as a typical proleg that of the Tortricidae or 

 higher Tineidae. It is a fleshy, more or less conical projection, 

 the tip of which, the planta, is more or less retractile, and rounded 

 or flat. Around the edge of the planta is a series of hooks or 

 crotchets, each imbedded about two-thirds its length in the 

 skin, but with the tip free and hooked toward the center of the 

 circle. To the center of the planta is attached a muscle, by which 

 it can be completely inverted, even the hooks disappearing from 

 sight. Just above the hooks on the outer side there may be a 

 homy edge, and above that, a larger plate bearing three setae 

 (vii). On the front of the base is a minute seta (sometimes 

 entirely in front of the leg,) and on the inner side another (viii). 



