120 THOMAS SAY FOUNDATION 



curved, narrowly spatulate, and narrower behind ; sub- 

 anal lobes small, unmodified ; ninth sternite somewhat 

 produced and truncate behind. 



Female. Eighth abdominal sternite with a subgenital 

 plate which is normally produced over about two-thirds 

 of the ninth sternite, bilobed at the tip and between these 

 two lobes usually another small median lobe ; the median 

 area of the plate with a bulge or ridge. 



Distribution.— Type, female, No. 10823, June 24, 1915, 

 Great Alpine Creek, Tahoe, Calif. (Banks Coll. Mus. 

 Comp. Zool., Cambridge, Mass.). A number of males and 

 females, July and Aug., 1923, Moraine Lake, Alberta, Can- 

 ada (J. McDunnough) ; three females, July 6-12, 1923, 

 Waterton Lakes, Alberta, Canada (J. McDunnough) ; one 

 female, Aug. 18, 1916, Mont. Exp. Sta., Crazy Mts., Mont.; 

 three females, one male, July 15, 1913, Gallatin Co., 

 Mont. ; one male, two females, July 12-18, 1908, Carbonate 

 to Prairie Hills, B. C. (J. C. Bradley) ; two females 11-7, 

 1903, Ainsworth, B. C. (R. P. Currie) ; one male, three fe- 

 males, July 19, 1908, Prairie Hills, Selkirk Mts., B. C. 



Very closely allied to borealis. 



Alloperla spatulata, new species. 



(Plate 21, fijjs. 13, 14.) 



Length to tip of wings, male, 8.5-9 mm. ; expanse, male, 

 15-16 mm. ; length to tip of wings, female, 9-10 mm. ; ex- 

 panse, female, 18-21 mm. 



General color pale yellow with broad black lateral mar- 

 gins on prothorax. 



Head a little wider than prothorax, pale yellow with a 

 little black around the ocelli and sometimes an infuscated 

 area on the clypeus ; hind ocelli just a little closer to the 

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

 becoming more infuscated towards the tip. 



Prothorax transversely oval ; wider than long ; yellow, 

 with broad dark brown or black lateral margins ; this dark 

 band extends around the angles and then tapers down to 

 a point ; surface slightly rugose ; legs pale yellow, tarsi a 

 little darker. Wings greenish hyaline ; veins pale. 



Abdomen yellowish with a broad median dark dorsal 

 stripe. Setae pale yellow. 



Male. Supra-anal process recurved, broadly spatulate, 

 tenth tergite broadly cleft ; ninth tergite with a deep me- 

 dian depression in which the supra-anal process normally 



