148 THOMAS SAY FOUNDATION 



rounded ; slightly narrowed behind ; dark brown with a 

 wide median yellow stripe which is somewhat widened 

 posteriorly; sides of the disc quite rugose. Legs brown. 

 Wings lightly to rather heavily infuscated, with a yellow 

 costal margin ; subcosta does not reach the cord ; usually 

 no costal crossveins between the humeral crossvein and 

 the end of subcosta; one costal crossvein beyond the end 

 of subcosta; no cubital crossveins in hind wing. 



Abdomen brown ; tails brown, a little lighter at base, 

 the middle segments 4-5 times as long as wide. 



Male. Ninth abdominal sternite much produced and 

 rounded behind ; eighth sternite with a transverse knob 

 on the hind margin ; subanal lobes slender, sharply 

 pointed, recurved upon the tenth tergite ; supra-anal lobe 

 not developed. 



Female. Subgenital plate of eighth abdominal sternite 

 broad, produced over about half of the ninth sternite and 

 evenly rounded behind. 



Type, male, 11342, Columbus, Ohio, May 9, 1899 (Banks 

 Collection, Mus. Comp. Zool., Cambridge, Mass.). A male 

 and female (paratypes) from the same locality, also in 

 Banks Collection. Ohio, Columbus, April 10, 1920 (A. E. 

 Miller) ; Illinois, Urbana, May 15, 1898 (F. M. McE.). 



Isoperla marlynia, new species. 



(Plate 25, figs. 12, 13, 14.) 



Length to tip of wings, male, 12 mm.; female, 12-13 

 mm. Expanse, male, 21 mm. ; female, 21-23 mm. 



General color dark brown to blackish with a median 

 yellow prothoracic stripe. 



Head a little wider than prothorax; brown, with a yel- 

 lowish spot in the ocellar triangle and with yellowish in 

 front of the anterior ocellus ; ocelli connected by a black- 

 ish V-shaped mark ; occiput with three yellow spots : a 

 V-shaped one in the middle and one beside each compound 

 eye ; frontal ridge and lateral tubercles not very promi- 

 nent ; hind ocelli closer to the eyes than to each other. 

 Antennae blackish. 



Prothorax dark brown, with a broad median yellow 

 stripe ; much wider than long ; front angles angulate ; hind 

 angles rather sharp; sides of the disc with scattered ru- 

 gosities. 



Legs dark brown ; wings subhyaline, with a very slight 

 greenish tinge ; veins brown ; subcosta ends before the 

 cord ; a series of 5-6 costal crossveins before the end of 

 subcosta and one beyond ; hind wing without cubital cross- 



