116 THOMAS SAY FOUNDATION 



one male, Vesta Pass, Colo. ; males and females, Boulder, 

 Colo. (G. S. Dodds). 



Alloperla albertensis, new species. 



(Plate 22, figs. 6, 7.) 



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

 15-16 mm. Length to tip of wings, female, 9.5-11 mm. ; 

 expanse, female, 17-19 mm. 



General color of head and prothorax yellow with dark 

 markings, abdomen dark brown, wings greenish hyaline. 

 Similar to coloradensis and lamba. Head about as wide as 

 prothorax, yellow, with dark marks at the ocelli (tending 

 to form a V-shaped mark which connects the ocelli) ; lat- 

 eral tubercles, frontal ridge and two spots on clypeus 

 dark ; a dark spot behind the eye ; hind ocelli a little closer 

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

 blackish towards the tip. 



Prothorax transversely oval, almost twice as wide as 

 long ; yellow, with a narrow blackish margin and with the 

 rugosities blackish ; legs yellowish, tarsi a little darker 

 toward the tip. Wings yellowish to greenish hyaline; 

 veins yellowish to light brown. Meso- and metanotum 

 blackish. 



Abdomen blackish ; cerci yellow, somewhat inf uscated 

 towards the tip. 



Male. Tenth abdominal tergite very broadly and deeply 

 cleft, ninth tergite with a large sunken area ; on the front 

 margin of the ninth tergite a raised chitinous tubercle 

 or process narrowly notched behind ; supra-anal process 

 recurved, somewhat concave above with a low median 

 carina, somewhat spatulate at the tip, with a slender 

 slightly upturned, spine-like, process which originates 

 from the lower anterior part of the supra-anal process; 

 penis with two finger-like membranous lobes at the tip 

 and with two smaller lobes below, dorsally near the base 

 of the penis two large, black, longitudinally striated leaf- 

 like appendages; subanal lobes small, unmodified; ninth 

 sternite produced and truncate behind. 



Female. Subgenital plate of eighth abdominal sternite 

 somewhat angulately produced, with the hind margin 

 somewhat truncate and normally extending entirely 

 across the ninth sternite or even partly onto ten. Plate 

 is very similar to subgenital plate in coloradensis but not 

 clothed with such stout hairs. 



Distribution. — Holotype male, allotype female, July 6, 

 1923, Waterton Lakes, Alberta, Canada (J. McDunnough, 



