186 



Illinois Natural History Survey Bulletin 



Vol. 23, Art. 1 



3. Cerci with a deep lateral incision di- 



viding them into long dorsal and 

 ventral lobes, fig. 653. . .ornatus, p. 189 

 Cerci with posterior margin slightly 

 or not at all incised 4 



4. Cerci very large, long and wide, dwarf- 



ing the other parts of the genitalia, 

 especially the minute tenth tergite, 



fig. 654 rhombicus, p. 190 



Cerci either small, fig. 655, or less than 

 twice length of tenth tergite, fig. 

 659 . 5 



5. Cerci short, either widened at apex 



646 



648 





649 



Fig. 646. — Limnephilus consocius larva, 

 head and thorax. 



Fig. 647. — Limnephilus submonilijer larva, 

 head and thorax. 



Fig. 648. — Limnephilus rhombicus larva, 

 head and thorax. 



Fig. 649. — Limnephilus indivisus larva, 

 head and thorax. 



Fig. 650. — Limnephilus submonilijer larva, 

 first abdominal tergite. 



Fig. 651. — Limnephilus rhombicus larva, 

 first abdominal tergite. 



and spatulate, or with apical margin 



incised, figs. 655-658 6 



Cerci long and rounded or pointed at 

 apex, figs. 659-661 9 



6. Claspers reduced to a small, sharp 



triangle; processes of tenth tergite 

 narrow and sharp, projecting below 

 level of cerci, fig. 655. . .sericeus, p. 192 

 Claspers large, fig. 656, or projecting 

 as finger-like processes, fig. 657; 

 processes of tenth tergite projecting 

 between cerci and at least partially 

 hidden by them in lateral view. ... 7 



7. Cerci with apical margin uniformly 



black and heavily sclerotized, emar- 

 ginate, forming a produced dorsal 

 lobe, fig. 656; mesal face of cerci 

 without row of teeth near base. . . . 



consocius, p. 190 



Cerci with apical margin not black 

 but with mesal, sclerotized teeth 

 black; apical margin nearly straight, 

 with the dorsal corner rounded, figs. 

 657, 658; mesal face of cerci with a 

 row of black, sclerotized teeth near 

 base, fig. 658 8 



8. Claspers broad, nearly as broad as 



cerci; lateral arms of aedeagus end- 

 ing in a membranous, diamond- 

 shaped lobe with a dense brush of 



spines, fig. 657 hyalinus, p. 191 



Claspers finger-like, much narrower 

 than cerci; lateral arms of aedeagus 

 bladelike and with a dorsal angula- 

 tion, bearing a definite dorsal row of 

 setae, fig. 658 indivisus, p. 191 



9. Claspers small and platelike, without 



any projecting parts, fig. 659 



moestus, p. 191 



Claspers with a long, pointed apical 

 portion, fig. 660 10 



10. Cerci longer, more slender at tip and 



curved slightly ventrad, fig. 660. . . 



sordidus, p. 1 89 



Cerci shorter and stouter, straight and 

 tapered at tip to a point, fig. 661 . . . 

 bimaculatus, p. 189 



11. Cerci represented only as slight swell- 



ings at base of tenth tergite, which 



forms a simple tube, fig. 662 



submonilifer, p. 192 



Cerci present as distinct processes 

 above or beside tenth tergite, figs. 

 663-671 12 



12. Tenth segment very short and broad, 



cerci long; ninth tergite broad and 



bandlike, fig. 663 ornatus, p. 189 



Tenth segment more than half length 

 of cerci, fig. 665, usually as long as 

 or longer than cerci, fig. 666 13 



13. Dorsal portion of tenth segment pro- 



duced into a long, thin spatula 



