August, 1944 



Ross: Caddis Flies of Illinois 



91 



Main body of aedeagus with only the 

 angle at base pronounced, fig. 363. . 8 



8. Lateral arms tipped with an upturned 



spur, fig. 363 recurvata, p. 99 



Lateral arms tipped with no spur or 

 one that is not upturned 9 



9. Spur of lateral arms long, robust and 



hanging down with tip well below 

 ventral margin of aedeagus, figs. 



364, 365 10 



Spur of lateral arms shorter, flat, fig. 

 366, finger-like, fig. 367, or some- 

 times absent 11 



10. Apex of aedeagus with lateral pockets 



scarcely extruded and containing 

 only a few weak spicules, fig. 364. . 



bronta, p. 98 



Apex of aedeagus with lateral pockets 

 extruded to form a sessile flap con- 

 taining a cluster of strong, dark 

 spicules, fig. 365 cheilonis, p. 98 



11. Spur of lateral arms large and flat, as 



in fig. 366 morosa, p. 98 



Spur of lateral arms small and finger- 

 like, fig. 367, sometimes even smaller 

 or absent 12 



12. Apical segment ot clasper with apex 



appearing attenuated, as in fig. 367, 



seen from side bifida, p. 97 



Apical segment of clasper conical, its 

 apex appearing pointed, as seen 

 from side, fig. 363. . . .recurvata, p. 99 



13. Apex of aedeagus round, fig. 369, or 



truncate, fig. 368 14 



Apex of aedeagus produced into a 

 flattened area composed of two 

 lateral processes and a mesal body, 

 figs. 371-383 16 



14. Aedeagus curved at base to form a 



complete semicircle, fig. 368 



betteni, p. 99 



Aedeagus curved not more than 90 

 degrees, fig. 370 15 



15. Vertical cleft at apex of aedeagus deep 



and not containing extruded mesal 



plates, fig. 369 cuanis, p. 100 



Vertical cleft at apex of aedeagus 

 shallower and containing a pair of 

 prominent mesal plates, fig. 370. . . 

 depravata, p. 100 



16. Apex of tenth tergite turned up and 



deeply cleft, fig. 371 17 



Apex of tenth tergite rounded and at 

 most cleft as deeply as shown in 

 fig. 376 18 



17. Apex of aedeagus as wide as stem, 



without an open area between lateral 

 processes, fig. 371. . . . phalerata, p. 102 

 Apex of aedeagus narrower than stem, 

 with an open area between lateral 

 processes, fig. 372 aerata, p. 101 



18. Tenth tergite armed on each side with 



a stout, long spine, fig. 373 



dicantha, p. 102 



Tenth tergite without such a conspicu- 

 ous spine 19 



19. Aedeagus with lateral lobes produced 



far beyond mesal cavity, fig. 374. . . 



hageni, p. 103 



Aedeagus with lateral lobes produced 

 only slightly beyond mesal cavity. . 20 



20. Apical segment of claspers appearing 



obliquely truncate, from side view, 



fig. 375 placoda, p. 103 



Apical segment of claspers appearing 

 sinuate, from side view, fig. 376. . . 21 



21. Apex of aedeagus moniliform, fig. 376 



arinale, p. 104 



Apex ol aedeagus with only one con- 

 striction and that at base 22 



22. Apex of aedeagus robust and sur- 



mounted by a shallow caplike contin- 

 uation ot the basal portion, fig. 377 



simulans, p. 104 



Apex of aedeagus either not sur- 

 mounted by a "cap" or dorso-ven- 

 trally flattened, fig. 380 23 



23. Apex of aedeagus with lateral proc- 



esses thin and long, as in fig. 378. . 



valanis, p. 105 



Apex of aedeagus with lateral processes 

 much more robust 24 



24. Apex of aedeagus with mesal dome 



elevated above level of lateral flange 

 and also above level of stem and 

 forming a distinct angle with it, 



fig. 379 frisoni, p. 105 



Apex of aedeagus with mesal dome 

 either not elevated above level of 

 lateral flange or confluent with dor- 

 sal margin of stem, figs. 380-383. . . 25 



25. Apex of aedeagus with lateral flanges 



wide, the apical portion of each 

 almost as large as the entire mesal 

 cavity; dorso-lateral edge of flange 

 confluent with dorsal line of stem, 



fig. 380 scalaris, p. 106 



Apex of aedeagus with lateral flanges 

 narrow, the mesal cavity occupying 

 all of the apex except narrow lateral 

 and apical portions; dorso-lateral 

 edge of flange various 26 



26. Apex of aedeagus with a long, narrow 



profile, and with two-thirds of mesal 



cavity open ventrad, fig. 381 



incommoda, p. 106 



Apex of aedeagus with a shorter, stock- 

 ier profile and with mesal cavity 

 only one-third open ventrad 27 



27. Apex of aedeagus with apico-lateral 



corners of flange sharp, projecting 

 almost directly posterad and as wide 

 as in fig. 382 bidens, p. 107 



