170 THOMAS SAY FOUNDATION 



Peltoperla arcuata Needham. 



(Plate 31, figs. 1, 2, 3.) 



L905. Peltoperla arcuata Needham, Proc. Biol. Sue. Wash., 18:108. 



1907. Peltoperla arcuata Banks, Cat. Neurop., p. 12. 



Length to tip of wings, male, 14-15 mm. ; female, 18 

 mm. Expanse, male, 27-28 mm. ; female, 34 mm. 



General color brown. 



Head brown, a little more obscure over the ocellar area ; 

 much narrower than the prothorax; ocelli large, with a 

 black mark on the inside ; about twice as close to the eyes 

 as to each other ; antennae brown, darker towards the tip. 



Prothorax brown, nearly twice as wide as long ; surface 

 with broad, flat irregular rugosities ; front margin nearly 

 straight ; hind margin convex ; sides nearly straight ; us- 

 ually somewhat narrowed behind ; front angles narrowly 

 rounded ; hind angles angulate and more broadly rounded. 

 Legs yellowish, darker at the joints ; tarsi dark. Wings 

 brownish hyaline; veins brown; subcosta ends much be- 

 fore the cord; 13-16 costal crossveins before the end of 

 sub-costa and 6-8 beyond; radial sector with about four 

 branches. 



Abdomen yellowish, darker towards the tip; setae yel- 

 low, with about 14-15 segments, the basal segment being 

 very long. 



Male. Ninth abdominal sternite somewhat produced, 

 evenly rounded behind and bearing at the base of the seg- 

 ment a rounded knob which is as long as it is wide ; from 

 the base of the knob originate two divergent ridges, the 

 median portion of the ninth sternite being sunken ; tenth 

 tergite partially cleft, each side with a slightly raised, 

 rounded knob ; supra-anal lobe composed of a median, 

 slender, chitinized, upturned process which at the base is 

 partially surrounded by a membranous sheath ; subanal 

 lobes large upturned and rather sharply pointed. 



Female. Hind margin of eighth abdominal sternite 

 produced into a broad, evenly rounded, subgenital plate 

 which covers most of the ninth sternite. 



Distribution. — Type, female, June 1891, Ithaca, N. Y. 

 (R. H. Pettit, in the Cornell University Collection) ; one 

 male, Ithaca, N. Y. ; one male, 3-4 July, 1923, President, 

 Pa. (J. B. Palmer) . 



Peltoperla thyra Needham and Smith. 



(Plate 15, fig. 2; plate 31, figs. 9, 10.) 

 1916. Peltoperla thyra Needham and Smith, Can. Ent., 48:87. 



Length to tip of wings, male, 18 mm.; expanse, male, 

 30 mm. 



