PLECOPTERA OF NORTH AMERICA 101 



rather low, broad streakings, outcurving to rearward. 

 Praescutum of meso- and metathorax yellow, behind 

 which brown predominates on the dorsum. Legs yellow- 

 ish brown without pattern, but darker near the knees 

 and on the tarsi. Wings abbreviated, especially in the 

 male (covering only about half of the abdomen in that 

 sex) dull brownish, subhyaline, with veins a little deeper 

 brown. Abdomen yellowish, darkening toward the tip 

 in the male, and becoming yellowish in the female, with 

 tails of corresponding colors. 



Male. The 9th abdominal segment is prolonged a little 

 on the ventral side and upcurved, with a pair of narrow 

 longitudinal folds half the depth of the segment marking 

 off the sides of the subgenital scoop thus formed. On the 

 middle of the most convex portion is a circular disc-like 

 cornicle or hammer which is whitish and bare. The 10th 

 segment is widely cleft above, the rear angles beside the 

 cleft are produced into thick, stout genital hooks, that are 

 first tapering and curving inward, and then linear and 

 curving forward, their convergent obtuse tips reaching 

 forward well above the 9th tergite. They are yellowish 

 at the sides and brownish at their tips. 



Female. The subgenital plate is a low, broad, convex 

 extension of the 8th sternite that reaches hardly one- 

 fourth way across the 9th sternite. The eggs are broadly 

 oval with the micropyle at the broad end and a trans- 

 parent, close-fitting micropylar cap covers almost half 

 of the egg surface. 



Distribution. — Holotype male, allotype female, Yellow- 

 stone River, Wyoming, Aug. 5, 1921 (F. M. Sallee, in 

 Cornell University Collection). Paratypes, same locality, 

 many males and females: Troy, Mont., August (J. C. 

 Bradley) ; Beaver Creek, Mont., 6,300 ft., Aug., 1913 (S. 

 J. Hunter). 



Perla sabulosa Banks. 



(Plate 13, fig. 4.) 

 1900. Perla sabulosa Banks, Trans. Amer. Ent. Soc, 2fi:242. 

 1907. Perla sabulosa Banks, Cat. Neurop., p. 12. 

 1907. Perla sabulosa Banks, Can. Ent., 39:328. 



Length to wing tips, female, 33 mm. Expanse, female, 

 58 mm. 



Color pale yellowish brown. Head yellow with a diffuse 

 brownish spot occupying the ocellar triangle and extend- 

 ing laterally around the frontal tubercles. Ocelli and 

 eyes about equidistant. Antennae and palpi brown. 



Prothorax of uniform yellowish brown color, scarcely 

 narrowed behind, front angles sharp, hind angles rounded, 



