PLECOPTERA OF NORTH AMERICA 199 



Supra-anal process recurved upon the body; 

 subgenital plate not turned up at a right angle 8 



3. 1st A and 2nd A of forewing united before mar- 



gin of wing 4 



1st A and 2nd A of forewing not united before 

 margin of wing carolinensis 



4. Subanal lobes rather small, in side view flask- 



shaped; subgenital plate in side view broad 



vallicularia 



Subanal lobes large, in side view somewhat boot- 

 shaped; subgenital plate in side view narrow. _ 5 



5. Subanal lobes with a tooth or spine on the upper 



forward corner washingtoniana 



Subanal lobes without a tooth or sharp projec- 

 tion 6 



6. Outer sheaths of supra-anal process with teeth or 



serrations 7 



No outer sheaths with serrations ; the supra-anal 

 process partly membranous; subanal lobes in 

 side view irregularly enlarged at tip producta 



7. Subanal lobes (side view) much constricted in 



the middle and spinulose at the tip interrupta 



Subanal lobes (side view) not constricted in mid- 

 dle and not spinulose at tip nevadensis 



8. Cerci heavily chitinized and variously modified 



into accessory copulatory hooks 9 



Cerci membranous and not modified into copu- 

 latory hooks _\ 12 



9. Cerci on the inside membranous, the chitinous 



portion armed at the tip with spines; subanal 

 lobes very large and not much modified ; sub- 

 genital plate and ventral lobes broad and short 



trispinosa 



Cerci long, completely chitinized and ending in a 

 sharp point; subanal lobes long and quite slen- 

 der 10 



10. Subgenital plate divided at the tip, each half be- 



ing serrate on the outer margin ; subanal lobes 

 long, slender and near the tip armed with two 



spurs serrata 



Subgenital plate entire and smooth ; subanal lobes 

 not armed with spines 11 



11. Subgenital plate broadly truncate at tip; supra- 



anal process recurved and not very complicated 



truncata 



Subgenital plate greatly prolonged into a slender 



