326 THE CANADIAN ENTOMOLOGIST. 



3. Many cross-veins between radius and radial sector, as well as between 



branches of radial sector Perlodes. 



Rarely more than one cross-vein between radius and radial sector, and 

 not many between branches of radial sector 4. 



4. Several cross-veins in middle part of fore wing, between branches of 



radial sector Acroneuria. 



Few, if any, cross-veins in middle part of fore wing, between branches 

 of the radial sector 5. 



5. Ocellar triangle more than twice as broad as long ; usually one cross- 



vein between radius and radial sector near end of latter ; a dark 



spot near pterostigma Isoganis. 



Ocellar triangle not twice as broad as long ; only abnormally a 

 cross-vein between radius and radial sector near tip of latter 6. 



6. But two ocelli, and setae very short ; the pronotum broader than 



head Peltoperla. 



With three ocelli 7. 



7. From the anal eel] of fore wings there extend below two simple veins, 



or one simple and one forked 8. 



From the anal cell of fore wings there extends below but one vein, 

 which soon forks 9. 



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



one near tip ; small greenish or yellowish species Isoperla. 



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

 sector of fore wings usually twice forked Per/a. 



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



fore wings forked twice Paraperla. 



No series of cross-veins in cubital area of hind wings, only one near 

 base, and one near tip ; small greenish or yellowish 

 species Alloperla. 



10. Anal setse obscure or absent ; one branched vein from anal cell of 



fore wings ; a series of cross-veins in median and cubital areas of 



fore wings ^^Nemourini) 1 1 . 



Anal set^ distinct; one simple vein from anal cell of tore wings ; no 

 series of cross-veins in median and cubital areas of 

 fore wings (Capnini) 1 4. 



11. Second joint of tarsi subequal to first; no oblique cross-vein beyond 



end of subcosta Tcetiiopteryx. 



Second joint of tarsi much shorter than first , 12, 



