58 ILLIXOIS BIOLOGICAL MONOGRAPHS [58 



usually bearing a pair of seoli 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. 



LYMNADIDAE 



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 seoli usually present. 

 NYMPHALIDAE 



