114 THOMAS SAY FOUNDATION 



14-16 mm.; length to tip of wings, female, 10-11 mm.; ex- 

 panse, female, 18-20 mm. 



General color yellow with dark spots on head, with the 

 margin and rugosities of pronotum dark brown and with 

 abdomen brown. 



Head hardly wider than prothorax; yellowish, with a 

 V-shaped dark mark connecting the ocelli; frontal ridge 

 and lateral tubercles dark and a dark patch behind the 

 eyes. The dark marks on the head are often interrupted 

 so that the head appears to have six or more dark spots. 

 Hind ocelli a little closer to the eyes than to each other; 

 antennae yellowish at the 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. The blackish margin is -usually in- 

 terrupted in the median portion both in front and behind. 

 Legs yellowish, tarsi a little darker. Wings yellowish 

 brown, veins brown. 



Abdomen brown, with darker median dorsal stripe. 

 Cerci yellowish brown. 



Male. Tenth abdominal tergite broadly and deeply 

 cleft ; ninth tergite with a depressed area behind and near 

 the front margin with raised chitinous process which is 

 triangularly notched; supra-anal process recurved, flat- 

 tened above and at the tip with a short, sharply upturned 

 hook; the greatest width (viewed from above) of the 

 supra-anal process equals about half its length; subanal 

 lobes small, unmodified ; penis, when extruded, entirely 

 membranous, without black chitinized lobes or processes ; 

 ninth abdominal sternite produced and truncate behind. 



Female. Subgenital plate of eighth sternite produced 

 somewhat triangularly and broadly truncate behind or 

 even slightly emarginate behind ; center and hind margin 

 of plate beset with stout hairs. 



Distribution. — Type, female No. 113 5 0, Colorado 

 (Banks Coll., Mus. Comp. Zoo!., Cambridge, Mass.) ; two 

 females, Aug. 3, one male, two females, July 29, Tolland, 

 Colo. ; two females, Aug. 22, Boulder, Colo. ; one male, 

 July 25, Bluebird, Colo. ; many males and females, Boul- 

 der, Colo. (G. S. Dodds) ; one male, June 3, 1879, Mani- 

 tou, Colo.; one female, Aug. 3, 1921, Estes Park, Colo. 

 (P. W. Claassen) ; one male, June 20, 1906, Big Blackfoot 

 River, Potomac, Mont. ; two males July 4, 1908, Emerald 

 Lake, Canadian Rockies (J. C. Bradley) ; one female, 

 July 11, Beulah, N. Mex. 



