August, 1944 



Ross: Caddis Flies of Illinois 



31 



no larger than basal one; each man- 

 dible with 2 or 3 inner teeth, fig. 97 



Rhyacophila, p. 32 



Mandibles with inner margin not ser- 

 rate, and with apical inner tooth 



Fig. 102. — Protoptila maculata, front tibia. 



Fig. 103. — Agapetus illini, front tibia. 



Fig. 104. — Rhyacophila vibox, front tibia. 



Fig. 105. — Palaeagapetus celsus, head and 

 pronotum. 



Fig. 106. — Rhyacophila vibox, head and pro- 

 notum. 



Fig. 107, — Agapetus illini, head and prono- 

 tum. 



Fig. 108. — Glossosoma intermedium, head 

 and pronotum. 



Fig. 109. — Agapetus illini, hind wing. 



Fig. 110. — Glossosoma intermedium, wings. 



larger than basal one; each mandible 

 with 2 inner teeth 2 



2. Apical inner tooth of mandibles half 



as long as apical blade and sub- 

 parallel with it, fig. 98; mandibles in 

 repose over-reaching side of head, 

 fig. 101; size small, less than 4 mm. 



Protoptila, p. 41 



Apical inner tooth of mandibles much 

 shorter, fig. 100; mandibles in re- 

 pose not reaching side of head; size 

 larger, over 5 mm 3 



3. Apical inner tooth of mandibles only 



slightly larger than basal one, fig. 99; 

 apical segments of abdomen only 



slightly curled ventrad 



Agapetus, p. 39 



Apical inner tooth of maftdibles many 

 times larger than basal one, fig. 100; 

 apical segments of abdomen curled 



ventrad and slightly forward 



Glossosoma, p. 39 



Adults 



1. Front tibiae with apical spurs absent 



or hairlike, fig. 102 Protoptila, p. 41 



Front tibiae with both apical spurs 

 prominent and sclerotized, fig. 103 2 



2. Front tibiae with a preapical spur, fig. 



104 Rhyacophila, p. 32 



Front tibiae never with preapical spur, 

 fig. 103 3 



3. Pronotum with mesal pair of warts 



nearly touching; posterior warts on 

 head large, arcuate, tapered to a 

 curved, narrowed point, the two 

 nearly meeting on meson, fig. 105. . 



Palaeagapetus, p. 38 



Pronotum with mesal pair of warts 

 well separated by a concave area; 

 posterior warts of head oval or round 

 and widely separated on meson, 

 fig. 108 4 



4. Head with 1 or both pairs of dorsal 



warts connected by sutures running 

 across epicranial stem, fig. 107; hind 

 wings with radial sector apparently 

 2-branched, fig. 109. . . Agapetus, p. 39 

 Head with neither pair of dorsal warts 

 connected by sutures, fig. 108; hind 

 wings with radial sector 4-branched, 

 fig. 110 Glossosoma, p. 39 



RHYACOPHILINAE 



The larva is free living, in all the Illinois 

 species without external gills; it constructs 

 a dome-shaped cocoon of pebbles for pupa- 

 tion. The pupa is formed within an ellipsoid, 

 translucent pupal chamber anchored at each 

 end within the cocoon. The adults have 



