PLECOPTERA OF NORTH AMERICA 109 



Antennae yellow at base, somewhat infuscated towards 

 the tip. 



Prothorax transversely oval, wider than long ; pale yel- 

 lowish with narrow dark lateral margins, the dark line 

 tending to follow completely around the pronotum; 

 slightly rugose. Legs yellow, tarsi a little darker. Wings 

 pale greenish hyaline, veins pale. 



Abdomen yellow with a broad dark median dorsal 

 stripe. Cerci yellow. 



Male. Tenth abdominal tergite broadly cleft; at the 

 base of the cerci an inward pointing finger-like process; 

 supra-anal lobe very short, largely membranous and 

 clothed at the tip with hairs; subanal lobes small, un- 

 modified; ninth sternite somewhat produced and trun- 

 cated behind. 



Female. The hind margin of the eighth abdominal 

 sternite produced into a large, broadly rounded, subgenital 

 plate which extends to the tip of the abdomen. 



Distribution. — Type, female No. 11346, Aug., Beulah, 

 N. Mex. (Banks Coll. Mus. Comp. Zool., Cambridge, 

 Mass.) ; one female, July 18, 1898, Little Beaver, Colo. ; 

 one female, July 25, 1914, Graham Mts., Ariz.; many 

 males and females, Aug., Estes Park, Colo., (P. W. Claas- 

 sen) ; one male, June 30, 1907, Florissant, Colo. (T. D. A. 

 Cockerell) ; one male, Aug., Platte Canyon, Colo. (Oslar) ; 

 males and females, Boulder, Colo. (G. S. Dodds) ; one fe- 

 male, Aug. 19, Eldora, Colo. (T. D. A. C.) ; three males, 

 two females, June, Olympia, Wash. (Kincaid). ; one male, 

 two females, Reno, Nev. (Morrison) ; many males and fe- 

 males, Aug. 1913, Beaver Creek, Mont. (S. J. Hunter) ; one 

 female, Three Rivers, Calif. (Culbertson) ; four females, 

 May and June, Humboldt Co., Calif. (H. S. Barber) ; two 

 males, May 23, 1917, Niles Canyon, Calif. (W. M. Giff- 

 ard) ; one female, May 17, 1908, Marin Co., Calif. (E. C. 

 Van Dyke) ; one female, July 15, 1917, Muir Woods, 

 Marin Co., Calif. (W. M. Giffard) ; one female, June 24, 

 1920, Nanaimo, B. C. (E. C. Van Dyke) ; three females, 

 May 21, 1922, San Antonio Creek, Alameda Co., Calif. (B. 

 C. Cain); two females, Yellowstone Park; two males, 

 three females, July 9-26, 1923, Waterton Lakes, Alberta, 

 Canada (J. McDunnough). 



This is the western representative of marginata. 



