PLECOPTERA OF NORTH AMERICA 



197 



Rs and M of forewing originate from a common 

 point of the radial base Perlomyia 



Rs of forewing originates from radius apart from 

 M Leuctra 



Genus NEMOURA Latreille. 



1796. Nemoura Latreille, Precis, 101. 



1832." Nemoura Pictet, Ann. Sci. Nat. (Reprint.) 



1842. Nemoura Pictet, Pedicles, 335 and 382. 



1S42. Nemoura Ranibur, Ins. Neurop., 459. 



1861. Nemoura Hagen, Syn. Neurop. N. A., 36. 



1S94. Nemoura Morton, Trans. Ent. Soc. Lond., 500. 



1S98. Nemoura Kempny, Verh. k. k. Zool. bot. Gesell. Wien, p. 13. 

 reprint. 



1902. Nemoura Ris, Mitt. Schweiz. Ent. Gesell., 10:378-406 (Re- 

 vision). 



1909. Nemoura Klapalek, Snesswasserf. Deutsckl., 8:69. 



Size small, mostly under 15 mm. 

 in length ; color brown or blackish ; 

 veins of the pterostigmas in the 

 form of an X; tails absent; second 

 tarsal segment short. 



Head as wide as or wider than 

 prothorax; three ocelli, the hind 

 ocelli closer to the eyes than to each 

 other ; usually a shallow depression 

 between or just back of hind ocelli. 

 Prothorax usually wider than 

 long; surface not very rugose; 

 brown or blackish. Legs brown, in 

 some species distinctly banded with 

 yellow; first and third tarsal seg- 

 ments subequal, second tarsal seg- 

 ment short. Wings lie flat on body 

 at rest; anal area of hind wings 

 quite large ; the tip of subcosta, the 

 radio-medial crossveins and the 

 base of R4 and R5 together with 

 the radial crossveins form a large 

 X in the pterostigma ; there are no 

 crossveins beyond Sc2; radial sec- 

 tor forked but once; Cul without accessory branches. 



Abdomen brown; cerci composed of a single segment, 

 either membranous or modified into chitinized accessory 

 copulatory organs. 



Fig. 25. Nemoura vallicu- 

 laris Wu. 



