August, 1944 



Ross: Caddis Flies of Illinois 



61 



Baso-dorsal lobe of claspers shorter 

 and wide, the mesal point sharp, the 

 entire lobe erect; aedeagus nar- 

 rowed at tip, fig. 248 



centralis, p. 64 



11. Processes of tenth tergite long, scle- 



rotized and arched, fig. 236 12 



Processes of tenth tergite either semi- 

 membranous or short, fig. 239 14 



12. Apex of cerci long and tapering to a 



sharp point, fig. 236 



interruptus, p. 69 



Apex of cerci shorter, rounded at apex, 

 fig. 237 13 



13. Aedeagus and filaments of tenth 



tergite long; claspers with only a 

 short dorso-mesal flap, fig. 237. . . . 



flavus, p. 68 



Aedeagus and filaments of tenth 

 tergite short; claspers with a large, 

 rhomboidal dorso-mesal flap, fig. 

 238 g'.acialis, p. 68 



14. Tenth tergite with a pair of curved. 



hornlike, sclerotized processes, fig. 



239 remotus, p. 67 



Tenth tergite without such processes, 

 fig. 240 15 



15. Claspers with lateral aspect quadrate, 



posterior margin only narrowly in- 

 cised, fig. 240 cinereus, p. 67 



Claspers with lateral aspect expanded 

 at apex, posterior margin deeply 



and widely incised, fig. 241 



nascotius, p. 68 



16. Genital segment long and tapering, 



lateral lobes of eighth sternite with 

 footlike base and stylelike blade on 



meso-apical corner, fig. 249 



crassicornis, p. 64 



Genital segment shorter and broader, 

 lateral lobes of eighth sternite not so 

 shaped, fig. 250 17 



17. Base of eighth sternite with a pointed 



elevation, fig. 250 flavus, p. 68 



Base of eighth sternite without a 

 pointed elevation, fig. 251 18 



244C 



Figs. 242-244. — Polycentropus, male genitalia. A, lateral aspect; 5, ventral aspect; 

 C, baso-dorsal appendage of clasper; D, aedeagus. 



