216 THOMAS SAY FOUNDATION 



Subanal lobes entire, greatly enlarged, curved upward 

 and in side view shaped somewhat like a boot ; cerci small, 

 membranous; supra-anal process produced backward and 

 upward, the outer sheaths membranous and finely spinu- 

 lose; subgenital plate much produced and bent upwards; 

 ventral lobe about twice as long as wide. 



Female. Unknown. 



Holotype, male, 1877, Morgantown, N. C. (Morrison, in 

 the Museum of Comparative Zoology, Cambridge, Mass.). 



Nemoura nevadensis Claassen. 



(Plate 38, figs. 8-11.) 

 1923. Nemoura nevadensis Claassen, Can. Ent., 55:286. 



Length to tip of wings, male, 10.5-11 mm.; female, 

 14.5-15 mm. Expanse, male, 17-18 mm.; female, 22-24 

 mm. 



General color dark brown. Head a little wider than pro- 

 thorax ; lateral tubercles large ; hind ocelli closer to eyes 

 than to each other. Prothorax dark brown, somewhat 

 lighter on the lateral and anterior margins; wider than 

 long; somewhat narrowed behind; front angles narrowly 

 rounded, hind angles more broadly rounded. Legs brown. 

 Wings subhyaline, veins heavy, somewhat infuscated at 

 the stigma; 1st and 2nd A of front wings united before 

 the margin ; anal field of hind wings large. Gills absent. 



Male. Subanal lobes very large, upcurved, the tip 

 slightly truncate, cerci very small, membranous; supra- 

 anal process produced backward and upward, the outer 

 sheaths wide and bearing spines on upper and lower mar- 

 gin; inner sheaths slender, unarmed; subgenital plate 

 very long, upcurved, with many transverse ridges before 

 the tip ; ventral lobe large, about twice as long as wide. 



Female. Seventh sternite produced over the entire 

 eighth segment as an evenly rounded subgenital plate; 

 eighth sternite unmodified. 



Distribution. — Holotype, male, allotype, female, 1878, 

 Reno, Nev. (Morrison, in the Museum of Comparative 

 Zoology, Cambridge, Mass.). 



One female, Eureka, Calif., May 22 (H. S. Barber) ; one 

 male, Yosemite Valley, Calif., May 24, 1921 (E. C. Van- 

 Dyke) ; one female, Tenino, Wash. (H. G. Hubbard) ; one 

 female, Sausalito, Calif., May, 1913 (J. C. Thompson). 



