PLECOPTERxV OF NORTH AMERICA 



163 



Prothorax wider than 

 long, a little narrowed be- 

 hind; all angles rounded; 

 brown with a broad yellow 

 longitudinal stripe on each 

 disc, leaving a narrow 

 brown median line and 

 brown margins ; surface 

 somewhat rugose. First 

 two tarsal segments very 

 short, subequal ; third tar- 

 sal segment at least twice 

 as long as one and two 

 combined. Wings subhya- 

 line to f umose ; few or no 

 costal crossveins before 

 end of subcosta and one 

 to four beyond ; two to 

 four crossveins between 

 first and second anal veins 

 of forewing; hind wing 

 with a large anal field and 

 a series of cubital cross- 

 veins. 



Abdomen brown, with 

 two long slender cerci, 

 whose middle segments 

 are at least four to five 

 times as long as wide. 

 Ninth abdominal sternite produced and rounded 

 and bearing before the apex a raised, yel- 

 low, transverse knob or hammer; tenth tergite en- 

 tire; subanal lobes modified into slender, fingerlike, re- 

 curved hooks ; supra-anal process not developed. 



Female. Hind margin of eighth abdominal sternite 

 slightly produced and medially broadly and deeply 

 notched. 



Genotype, Isogenus dry mo Newm. 

 Distribution. — East of the Mississippi River. 



Fig. 22. PerlineUa drymo Newm. 



Male 

 behind 



