58 ILLINOIS BIOLOGICAL MONOGRAPHS [58 



usually bearing a pair of scoli or pointed prominences ; 

 crochets usually triordinal. 

 h. Crochets arranged in a circle, usually triordinal, lat- 

 eral crochets about as well developed as mesal; sec- 

 ondary setae small or absent on dorsal half of body, 

 never long and never borne on scoli. 

 i. Head much larger than prothorax; body largest at 

 middle distinctly tapering toward both ends. 



HESPERIIDAE 

 ii. Head partially retractile, smaller than prothorax; 

 body cylindrical. MEGATHYMIDAE 



hh. Crochets arranged in a mesoseries or pseudocircle, 

 lateral crochets, when present, rudimentary; long 

 setae and scoli sometimes present, 

 i. Prolegs with mesoseries interrupted or reduced at 

 middle and with a narrow spatulate fleshy lobe 

 arising near the interruption (Fig. 102) ; head 

 small, 

 j. Head about half the diameter of the body. 



RIODINIDAE 



jj. Head usually less than half the diameter of the 



body. LYCAENIDAE 



ii. Prolegs without a fleshy lobe near the middle of the 



mesoseries. 



j. Osmaterium wanting. 



k. Scoli (Figs. 73, 74) or fleshy filaments (Fig. 

 92) well developed and conspicuous on body; 

 • when reduced, large scoli present on head. 



I. Mesothorax and sometimes a few other seg- 



ments bearing fleshy filaments; secondary 

 setae short and confined to prolegs. 



LYMNADIDAB^U^'L'^ 



II. Fleshy filaments never present. 



m. Scoli at least twelve times as long as wide, 

 those of abdomen as long as metathorax 

 is wide ; each abdominal segment bearing 

 three scoli on each side, none on dorso- 

 meson. HELICONIIDAE 



mm. Scoli when present not so slender; those 

 of abdomen not as long as metathorax is 

 wide ; mediodorsal scoli usually present. 

 NYMPHALIDAE 



