144 THOMAS SAY FOUNDATION 



Unknown to us. Redescribed from Hagen's type in the 

 Museum of Comparative Zoology. The small "tubercle" 

 of the subgenital plate, to which Hagen refers in his 

 original description, was caused by shrivelling in drying. 



Clioperla slossonae Banks. 



1911. Perla slossonae Banks, Trans. Am. Ent. Soc, 37:335. 



Length to tip of wings, female, 15.5 mm. ; expanse, 26 

 mm. 



General color black except for the yellowish stripe on 

 prothorax and yellowish spots on the head. Head mostly 

 black; sides of head yellow and front of clypeus yellow- 

 ish; frontal ridge and lateral tubercles black, shining; 

 hind ocelli closer to the eyes than to each other. Anten- 

 nae dark brown to blackish. 



Prothorax black with a wide median yellowish brown 

 stripe ; half again as wide as long ; very slightly widened 

 behind ; angles rounded ; surface only slightly rugose. 

 Legs blackish with yellow tipped femora. Wings uni- 

 formly subhyaline ; veins heavy brown. 



Abdomen and tails black. 



Male, unknown. 



Female. The subgenital plate is very broad, occupying 

 the entire width of the eighth sternite, produced over the 

 ninth sternite and evenly rounded behind. 



Female, type No. 11327, Franconia, N. H. (Banks Col- 

 lection, Mus. Comp. Zool., Cambridge, Mass.). 



Genus ISOPERLA Banks. 



1906. Isoperla Banks, Ent. News., 17:17.1. 



1907. Isoperla Banks, Cat. Neurop., p. 13. 

 1909. Isoperla Enderlein, Zool. An/.., :14 : :'>90. 



Mostly yellowish to greenish species, 6-15 mm. in 

 length ; hind wings without a series of cubital crossveins ; 

 males with a thickened knob on the posterior margin of 

 the eighth abdominal sternite. 



Head usually a little wider than prothorax, yellowish 

 to dark brown usually with darker markings, either over 

 the entire ocellar triangle or connecting the ocelli ; ocelli 

 three, the hind ocelli as close or closer to the eyes than to 

 each other; lateral tubercles and frontal ridge not very 

 prominent. 



Prothorax rectangular, wider than long; mostly with a 

 wide median yellow, longitudinal stripe and with brown 

 rugose discs; rugosities sometimes on a yellow back- 

 ground, angles sharp or narrowly rounded. First tarsal 

 segments about twice as long as second, third segment 

 longer than one and two combined. Wings mostly green- 



