172 THOMAS SAY FOUNDATION 



lowish lateral margins and often with the hind margin 

 of the occiput yellowish ; lateral tubercles small, shiny ; 

 ocelli a little closer to the eyes than to each other. An- 

 tennae yellowish at base, except the first segment which 

 is brown, brown toward the tip. 



Prothorax dark brown, with the front and hind mar- 

 gin usually a little lighter; nearly twice as wide as long; 

 front margin usually straight, hind margin rounded; 

 front angles quite sharp, hind angles narrowly rounded; 

 somewhat widened behind ; surface somewhat rugose. 

 Legs yellowish brown. Wings somewhat infuscated ; the 

 veins heavy brown ; 13-14 costal crossveins before the end 

 of subcosta and 2 or 3 beyond ; subcosta ends much be- 

 fore the cord ; radial sector with two branches. 



Abdomen brown, a little lighter underneath, especially 

 towards the tip. Tails brown, short, with about 7 to 9 

 segments. 



Male. Ninth abdominal sternite prolonged beyond the 

 tip of the abdomen, evenly rounded behind, with a yel- 

 low transverse knob in the center; from the base of the 

 knob two diagonal grooves extend toward the hind lateral 

 margin; tenth abdominal segment almost wholly with- 

 drawn within the ninth segment ; subanal lobes broadly 

 triangular and not noticeably recurved at the tip; supra- 

 anal lobe largely membranous and in the form of a glo- 

 bose bulb with faint chitinization at the base. 



Female. Eighth abdominal sternite produced into a 

 broad, medially notched subgenital plate which normally 

 reaches almost entirely across the ninth sternite. 



Distribution. — Type, female, No. 11381, Aug. 21, Gla- 

 cier, B. C, and another specimen, July 3, 1901, Port Ren- 

 frew, B. C. (in Banks Collection, Mus. Comp Zool., Cam- 

 bridge, Mass.) ; one male, six females, July 16, 1907, Per- 

 melia L., Mt. Jefferson, Ore. (J, C. Bridwell) ; one female, 

 July 16, 1911, Marv's Peak, Ore.; one female, July 25, 

 1920, Paradise Val., Mt. Ranier, Wash. (E. C. Van Dyke) ; 

 two males, one female, June 27, 1921, Yosemite Val., Cal. 

 (E. C. Van Dyke) ; two males, 7-3-16, Eldorado Co., Calif. 

 (A. C. Browne). 



Peltoperla cora Needham and Smith. 



(Plate 31, figs. 14, 15, 16.) 

 1916. Peltoperla cora Needham and Smith, ('an. Ent., 48:86. 

 Length to tip of wings, male, 18-21 mm. ; female, 23-26 

 mm. Expanse, male, 34-39 mm. ; female, 42-49 mm. 



