PLECOPTERA OF NORTH AMERICA 251 



lateral tubercles large, flat, polished ; occiput not rugulose ; 

 surface covered with yellowish pile; with only two ocelli, 

 (in the single male specimen the anterior ocellus is faintly 

 indicated by a mere dot under the chitin, but in the 

 eighteen females there is no indication of an anterior 

 ocellus), ocelli at least twice as close to eyes as to each 

 other ; antennae dark brown with about fifty segments. 



Prothorax black, with a yellow or reddish front margin 

 and often a little yellowish at the sides and behind; a 

 little wider than long ; not widened behind ; the sides 

 somewhat convex; angles rounded; surface finely ru- 

 gulose. Legs yellowish brown with variegated dark mark- 

 ings. Wings spotted with fuscous as in the figure ; veins 

 heavy, dark brown. 



Abdomen dark brown, yellow at the tip (ventral view) . 

 Cerci composed of four segments in the male and five in 

 the female. 



Male. Supra-anal process short, erect, enlarged toward 

 the tip where the process is broadly bilobed or bifurcate ; 

 anteriorly the supra-anal process bears a bilobed tubercle, 

 posterior to the supra-anal process is a large, spinulose, 

 bulbose membrane ; subanal lobes greatly modified into 

 asymmetrical processes; just back of each cercus occurs 

 a black, chitinous, inward curved process, below these 

 processes the asymmetrical membranous parts of the sub- 

 anal lobe and below these two upcurved pointed chitinous 

 processes closely beset with long hairs; at the base of 

 each cercus a raised membranous, granulate lobe ; tenth 

 abdominal tergite with two raised chitinous, rearward 

 pointing processes gradually enlarging and at the tip 

 broadly truncate so as to produce a pointed process on 

 each side ; ninth abdominal sternite greatly prolonged 

 into a keel-shaped process, pointed at the lower extremity 

 and with the tip turned up at right angles ; ninth sternite 

 at the base with a thickened area in the form of a ventral 

 lobe, but this is only a heavier chitinization and not an 

 appendage. 



Female. Hind margin of eighth abdominal sternite 

 partially cleft at the genital opening; ninth abdominal 

 sternite produced into a wide, rounded yellow plate which 

 extends beyond the tip of the abdomen. 



Type, No. 11303, female, Mt. Rainier, Wash. (Banks 

 Coll., Mus. Comp. Zool., Cambridge, Mass.) ; one male, 

 fifteen females, July 16-29, Paradise Valley, Mt. Rainier, 

 Wash. (E. C. VanDyke) ; three females, Boulder, Colo. 

 (G. S. Dodds) ; one female, June 30, Kaslo Cr., B. C. (R. 

 P. Currie). 



