PLECOPTERA OF NORTH AMERICA 171 



General color yellowish brown. Head obscure, but little 

 darker around the ocelli ; ocelli large, half again as close 

 to the eyes as to each other; antennae yellowish at base, 

 darker towards the tip. 



Prothorax nearly uniformly yellowish brown, somewhat 

 rugose ; not quite twice as wide as long ; narrowed behind ; 

 front angles quite sharp, hind angles broadly but some- 

 what angulately rounded. Legs yellow, with tips of tibiae 

 and tarsi darker. Wings yellowish hyaline; veins amber 

 brown; subcosta reaches almost to the cord; 15-16 costal 

 crossveins before the cord, not counting the humeral 

 crossvein, and 4-5 beyond subcosta; radial sector with 

 three branches. 



Abdomen yellowish, with the apical segments much 

 darker; tails yellowish, basally, darker towards the apex, 

 composed of about 15 segments. 



Male. Ninth abdominal sternite is divided by a U- 

 shaped suture or depressed area, which separates off the 

 upturned posterior lobe from the basal part of the seg- 

 ment, and just before the suture on the midventral line 

 there is a transverse, chitinized, raised knob ; this knob is 

 not elevated upon a stalk, but merely caps the midventral 

 portion of the hind margin of this basal half of the ninth 

 sternite; ninth tergite broadly excavated on the hind 

 margin, a V-shaped notch almost dividing it in two in the 

 median line. The edges of the V are upturned and chiti- 

 nized. Tenth tergite reduced to a very narrow, thinly chiti- 

 nized ring; supra-anal process short, recurved, knobbed 

 at the end and bearing two thinner, wing-like ap- 

 pendages at its sides; the median terminal knob bears at 

 the margin a row of sharp teeth. Within the apex of the 

 ninth segment there are visible a pair of chitinized ap- 

 pendages, the nature of which is unknown. They are con- 

 tiguous at the base and widely divergent at the tips, 

 gradually tapering to a sharp point. 



Female, unknown. 



Distribution. — Holotype male, Nevada, Cornell Univer 

 sity Collection. 



Peltoperla brevis Banks. 



(Plate 15, fig. 1; plate 31, figs. 11, 12, 13.) 

 1907. Peltoperla brevis Banks, Can. Ent., 39:328. 

 1916. Peltoperla brevis Needham and Smith, Can. Ent., 48:80, 82, 85. 



Length to tip of wings, male, 9.5-11 mm. ; female, 10-13 

 mm. Expanse, male, 16-19 mm.; female, 17-23 mm. 

 General color brown to blackish. 

 Head brown to blackish over the middle area, with yel- 



