PLECOPTEBA OF NORTH AMERICA 107 



8. Supra-anal process with a median dorsal carina ; 



the lower anterior portion of the supra-anal 

 process with a slender, spine-like process ; penis 

 with two, black, chitinized leaf -like appendages 



above 9 



Supra-anal process flattened above ; at the tip 

 with a very short, upturned hook (wide in side 

 view) ; penis without chitinized leaf-life ap- 

 pendages above coloradensis 



9. Median carina of supra-anal process low; penis 



with a broad, bilobed, black, chitinized 

 process above (this process is usually retracted 

 within the body but can be distinguished 



through the ninth abdominal sternite) Jamba 



Median carina of supra-anal process low ; penis 

 with two long, chitinized leaf-like processes 

 above (these processes are usually not re- 

 tracted entirely within the body and are usually 



seen protruding below the last segment) 



albert ensis 



10. Prothorax with a dark narrow margin and with 



the rugosities blackish ! 11 



Prothorax without dark margin but with a me- 

 dian longitudinal dark stripe; supra-anal proc- 

 ess binodose, attenuate at the tip continua 



11. Ocelli usually connected by a V-shaped dark 



mark ; supra-anal process slender, not much en- 

 larged in the middle and bluntly pointed 



boreal is 



Ocelli usually not connected by a dark mark; su- 

 pra-anal process enlarged in middle (dorsal 

 view) and pointed at the tip fidelis 



12. Pronotum with blackish lateral margins ; supra- 



anal process flattened, dorso-ventrally ; broadly 



spatulate in dorsal view spatulata 



Pronotum without blackish lateral margins; su- 

 pra-anal process not broadly spatulate in dor- 

 sal view 13 



13. Head with a large triangular, blackish, spot over 



the ocellar triangle and another one in front of 

 the anterior ocellus ; pronotum usually with a 

 broad median blackish line, widened at both 



ends; supra-anal process small signata 



Head yellowish without any striking dark marks ; 

 pronotum not with a well defined broad median 

 dark line 14 



