224 THE CANADIAN ENTOMOLOGIST. 



8. From the anal cell there extends below one vein, which is soon forked; 



the median vein unites with radius near base, usually but one cross- 

 vein beyond the end of subcosta 9. 



From the anal cell there extend below two simple veins ; the median 

 vein near base runs closely parallel to radius for some distance ..11. 



9. No veined anal field in hind wings ; only two cross-veins in cubital 



area of hind wings ; small greenish species Chloroperla. 



A veined and folded anal field to hind wings 10. 



10. A series of cross-veins in cubital area of hind wings ; radial sector of 



fore wings forked twice beyond anastomosis Paraperla. 



No series in cubital area of hind wings, only one near base and one 

 near tip ; small greenish or yellowish species Alloperla. 



11. Hind wings with but two cross-veins in cubital area, one near base, 



one near tip, small greenish or yellowish species Tsoperla. 



Hind wings with a series of cross-veins in cubital area ; radial sector 

 usually twice-forked 12. 



12. Setae longer than abdomen, joints of middle three to five times as 



long as broad, first fork of radial sector much beyond 



anastomosis Perlesta. 



Setae shorter than abdomen, joints of middle only one or two, rarely 

 three, times as long as broad Perla. 



Nemouri7ii. 



1. Second joint of tarsus subequal to first 2. 



Second joint of tarsus much shorter than first 4. 



2. An oblique cross-vein beyond end of subcosta 3. 



No oblique cross-vein beyond end of subcosta Tceiiiopteryx. 



3. Radial sector forked twice beyond anastomosis ; in fore wings the 



cubitus, beyond cross-veins, bends up to form an elongate 



cell Tceniojiema. 



Radial sector forked but once beyond anastomosis ; the cubitus not 

 forming an elongate cell Rhabdiopteryx. 



4. An oblique cross-vein beyond subcosta; wings not mNoXMit . Nemoiira. 

 No cross-vein beyond subcosta ; wings involute Letictra. 



. Capnini. 

 r. Apical submarginal space with cross-veins '. Capnura. 



No such veinlets 2. 



2. 1'he space beyond discal cell longer than discal cell Arsap?iia. 



This space much shorter than discal cell Capnia. 



