PLECOPTEBA OF NORTH AMfcKXCA 153 



rowed behind, angles almost sharp. Legs brown, tarsi 

 somewhat darker. Wings with a yellowish greenish 

 tinge ; veins yellowish ; subcosta ends before the cord ; a 

 series of costal crossveins before the end of subcosta and 

 usually two or three beyond. 



Abdomen yellowish brown; tails yellowish at base, 

 darker beyond. 



Male. Ninth abdominal sternite much produced and 

 rounded behind ; eighth sternite with a large transverse 

 knob on the hind margin ; subanal lobes pointed, recurved 

 upon the tenth tergite; supra-anal process not developed. 



Female. Subgenital plate truncate, little or not at all 

 produced. 



Distribution. — Type, female, No. 11338, Los Angeles 

 Co., Calif. (Banks Collection, Mus. Comp Zool., Cam- 

 bridge, Mass.). 



California, Claremont, May 28 ; Chico, Apr. 23, 



1922 (E. P. Van Duzee). 

 Washington, Longmire, Spg., Mt. Rainier, July 26, 

 1919 (C. L. Fox). 



Isoperla marmona Banks. 



(Plate 27, figs. 1, 2, 3.) 

 ]920. Isoperla marmona Banks, Bull. Mus. Comp. Zool., 64:322. 



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

 Expanse, male, 17 mm. ; female, 19 mm. 



General color yellowish brown with greenish hyaline 

 wings. 



Head wider than prothorax ; yellowish brown ; some- 

 what darker over the ocellar triangle and on clypeus and 

 with a blackish spot between the ocelli ; lateral tubercles 

 and frontal ridge not very prominent ; hind ocelli closer 

 to the eyes than to each other. Antennae brown. 



Prothorax wider than long; front and hind margins 

 rounded, sides straight, not narrowed behind ; angles al- 

 most square; a wide yellow median stripe and yellow on 

 the lateral margins ; rugosities rather coarse, chocolate 

 brown upon a yellow background. Legs yellowish brown, 

 tarsi darker. Wings greenish hyaline, veins brown ; sub- 

 costa reaches almost to the cord; several costal crossveins 

 before the end of subcosta and one beyond ; Rs-M stem in 

 hind wing longer than the cell which is formed by the 

 branches of Rs-M before the cord ; no cubital crossveins in 

 hind wing. 



Abdomen light brown ; tails yellow. 



Male. Ninth abdominal sternite much produced and 

 rounded behind ; eighth sternite with a knob on the hind 



