15(j THOMAS SAY FOUNDATION 



Isoperla longiseta Banks. 



(Plate 26, figs. 15, 16, 17.) 

 1906. Isoperla longiseta Hanks, Tan. Ent., 58:337. 

 L907. Isoperla longiseta Banks, Cat. Neurop., p. 13. 



Length to tip of wings, male, 10 mm.; female, 11-12 

 mm. Expanse, male, 17 mm. ; female, 18-20 mm. 



General color yellowish brown with greenish hyaline 

 wings. 



Head dull yellowish, the ocelli connected by a dark V- 

 shaped mark; clypeus also a little darker; lateral tuber- 

 cles indistinct ; hind ocelli closer to the eyes than to each 

 other. Antennae light at the base, darker towards the tip. 



Prothorax narrower than head ; wider than long ; front 

 and hind margins rounded, sides about straight, slightly 

 narrowed behind ; angles slightly rounded ; brown ru- 

 gosities on a yellow background, leaving a wide median 

 yellow stripe and yellow margins. Legs yellowish brown, 

 tarsi darker. Wings greenish hyaline ; veins light brown, 

 subcosta reaches almost to the cord ; several costal cross- 

 veins before the end of subcosta and one beyond; hind 

 wing without cubital crossveins. 



Abdomen yellowish brown ; tails about twice as long as 

 abdomen ; yellow at base, darker towards the tip ; seg- 

 ments beyond middle about five times as long as wide. 



Male. Ninth abdominal sternite much produced and 

 evenly rounded behind ; eighth sternite with a transverse 

 knob -on the hind margin ; subanal lobes slender, sharp, re- 

 curved upon the tenth tergite ; supra-anal lobe small. 



Female. Subgenital plate of eighth abdominal sternite 

 somewhat produced and evenly rounded behind. 



Distribution. — Type, female, No. 11336, Onaga, Kans. 

 (Banks Coll. M. C. Z., Cambridge, Mass.) ; Kansas, Onaga; 

 Lawrence, June 26, 1919 (P. W. Claassen) ; Indiana. 



Genus PERLESTA Banks. 



1906. Perlesta Banks, Can. Ent., 38:222. 



1907. Perlesta Banks, Cat. Neurop., p. 12. 

 1909. Perlesta Enderlein, Zool. Anz., 34:389. 



Brown stoneflies, 9 to 14 mm. in length, with a yellow 

 costal margin and with long slender tails. 



Head a little wider than prothorax, usually with a 

 blackiish quadrangular spot over the ocellar triangle ; 

 three ocelli, the hind ocelli closer to the eyes than to each 

 other. 



Prothorax wider than long, somewhat narrowed be- 

 hind ; front angles subacute, hind angles rounded ; brown 

 to blackish ; sometimes with a median yellowish stripe ; 



