118 THOMAS SAY FOUNDATION 



Alloperla borealis Banks. 



(Plate 14, fig. 1; plate 21, figs. 1, 2, 3.) 

 1895. Chloroperla borealis Banks, Trans. Amer. Hut. Soc, 22:313. 

 1907. Alloperla borealis, Banks, ('an. Ent., 39:329. 

 1907. Alloperla borealis Banks, Cat. Neur., p. 13. 



Length to tip of wings, male, 11-14 mm. ; expanse, male, 

 20-27 mm.; length to tip of wings, female, 13-16 mm.; ex- 

 panse, female, 24-29 mm. 



The largest species of this genus. 



General color yellowish brown with greenish wings. 



Head very little wider than prothorax; vellow with a 

 blackish V-shaped mark over the ocellar triangle, and 

 with a brown or blackish mark in front of the anterior 

 ocellus ; lateral tubercles brown ; a brownish spot behind 

 the eye; hind ocelli a little closer to eyes than to each 

 other ; antennae fuscous, more yellowish at base. 



Prothorax transversely oval, much wider than long; 

 yellowish with a narrow blackish margin which extends 

 around the entire pronotum ; disc of pronotum with dark 

 brown or blackish raised tubercles in the form of broken 

 longitudinal lines, and leaving a broad median yellowish 

 field which is about one-sixth as wide as the entire pro- 

 notum. Legs brown, tarsi darker. Wings greenish yel- 

 low ; veins brown except subcosta which is yellowish ; sub- 

 costa does not reach to the cord ; five to seven costal cross- 

 veins before the end of subcosta and two to four beyond. 



Abdomen brown ; cerci yellowish, darker toward the tip. 



Male. The anterior margin of the ninth abdominal ter- 

 gite with a narrow, transverse, raised tubercle; supra- 

 anal process recurved, slender, tapering to a blunt point 

 and normally with its tip under the tubercle of tergite 

 nine, tenth tergite cleft and each side with long hairs; 

 ninth tergite emarginate behind and clothed with long 

 hairs; subanal lobes small, unmodified; ninth abdominal 

 sternite somewhat produced and rather truncate behind. 



Female. Hind margin of eighth abdominal sternite 

 produced into a triangular subgenital plate with a broad 

 squarish median notch at the tip; median area of eighth 

 sternite raised into a circular ridge which tapers to a 

 point at the notch of the subgenital plate. 



Distribution.— Type, female, No. 11352, March 27, 

 Olympia, Wash., Banks Coll., Mus. Comp. Zool., Cam- 

 bridge, Mass. ; two females April 29, two males May 9, 

 one male May 1, one male May 2, Bon Accord, B. C. ; two 

 females, June 17, 1901, Banff, Alberta; one male, June 22, 

 1901, Port Renfrew, B. C. All these are in Banks Collec- 

 tion. 4 males, 4 females, July, 1923, Waterton Lakes, Al- 



