August, 1944 



Ross: Caddis Flies of Illinois 



145 



12. Claspers with dark sclerotized eleva- 



tion near lateral margin midway be- 

 tween base and apex, fig. 520 



albicornis, p. 151 



Claspers with dark sclerotized points 

 only along mesal or apical margins, 

 figs. 521-525 13 



13. Spiral process of aedeagus short and 



slender, fig. 521 scolops, p. 152 



Spiral process of aedeagus long and 

 stout, fig. 522 14 



14. Claspers saber shaped, pointed at 



apex, with a dark, sclerotized point 

 bevond middle ot mesal margin, 



figs. 522, 523 15 



Claspers with mesal margin concave 

 and without sclerotized point, apex 

 slightly curled latero-ventrad and 

 bearing a sclerotized point at each 

 corner, figs. 524, 525 16 



15. Apical portion of aedeagus short and 



slender, its extreme apex with only 

 a short curved process, fig. 522. . . . 



angusta, p. 152 



Apical portion of aedeagus longer and 

 stouter, its extreme apex with a 



long, stout process, fig. 523 



consimilis, p. 1 53 



16. Extreme apex of aedeagus bent at a 



right angle to form a narrow, sharp 

 process, fig. 524; tenth tergite with a 



sclerotized, clavate, mesal strip 

 with the lateral areas membranous 



perdita, p. 1 53 



Extreme apex of aedeagus straight, fig. 

 525; tenth tergite divided by mem- 

 branous strips into a mesal and 2 

 lateral sclerotized fingers. . .ajax, p. 153 



17. Apex of eighth sternite formed as in 



fig. 527, with a pair of sharp corners 

 between which arises a truncate 

 tongue bearing about 6 long, stout 



setae xella, p. 148 



Apex of eighth tergite not formed as in 

 fig. 527 18 



18. Apex of eighth sternite with a pair of 



flat, ovate lobes, each bearing 3 



long setae, fig. 528 amoena, p. 1 50 



Apex of eighth sternite without a pair 

 of flat, ovate lobes bearing 3 long 

 setae 19 



19. Eighth sternite bearing a pair of 



transverse, sclerotized bars below 



apex, fig. 529 hamata, p. 149 



Eighth sternite not bearing such a 

 pair of bars 20 



20. Eighth sternite with a group of 6 long 



radiating hairs at apex, figs. 530, 



532 21 



Eighth sternite without a group of 6 

 long radiating hairs at apex, figs. 

 533-539; hairs absent or short. ... 24 



Figs. 524-526. — Hydroptila, male genitalia. A, B, C, respectively lateral, ventral and 

 dorsal aspects; D, aedeagus. 



