PLECOPTERA OE NORTH AMERICA 83 



tip. These present a very different appearance according 

 to the way they are turned; they may lie flattened to 

 rearward, or be lifted up erect, or even be turned a little 

 forward, as genital hooks. Between them arises the long 

 slender straight acute tip of the U-shaped supra-anal 

 process. 



Female. The subgenital plate is distinctly marked off 

 upon the 8th sternite by oblique grooves and its free edge 

 projects well backward upon the 9th sternite in an ob- 

 tusely triangular lobe. 



Distribution. — McKenzie River, Canada; Harrisburg, 

 Pa., May 1 (H. A. Surface) ; Ft. Montgomery, N. Y.9 May 

 30, 1906 : (wash of fuscous on rear one-half of hind wing) ; 

 Fall Creek, Ithaca, N. Y.,9 16 May, 1921 (J. G. Need- 

 ham) ; Rosslyn, Va.,5 (F. C. Pratt) ; Gt. Falls, Va., May 

 12 ; Potomac River, Va., Apr. 18, 1907 ; Chain Bridge, Md. 

 (H. Barber). 



Perla varians Walsh. 



(Plate 17, figs. 11, 12, and text fig. 3.) 

 1862. Perla varians Walsh, Proe. Acad. Nat. Sci., Philadelphia, p. 364. 

 1907. Perla varians Banks, Cat. Neurop., p. 12. 



Length to wing tips, male, 11 mm.; female, 12 mm. Ex- 

 panse, male, 32 mm. ; female, 34 mm. 



Color blackish, with the usual yellow middorsal stripe 

 and yellow tipped abdomen. Head blackish with a wide 

 yellow triangular spot upon the occiput and some paler 

 indistinct edgings around the mouth and next the eyes. 

 Ocelli about half as far from the eyes as from each other. 

 Antennae brown ; palpi a little paler brown. 



Prothorax wider than long, about as wide as the head, 

 quadrangular, with parallel sides and sharp front angles ; 

 rear a little convex and hind angles a little rounded. Ru- 

 gosities upon the disc rather coarse and closely crowded 

 toward the inner side. The dorsal pale line widens slightly 

 to rearward and disappears upon the mesothorax. Legs 

 brownish except for meager yellow knee cap line, and 

 tarsi black. Wings subhyaline with blackish veins, that 

 usually show a darker spot upon the stigma and in the 

 base of the costal space. The venation is variable as il- 

 lustrated in the introduction, but the closed cell outside 

 the cord between veins R and M is usually present. 



Abdomen dark brown with the extreme apex yellowish, 

 more strongly and extensively so in the female. Tails 

 brown except for a very few of the short basal segments, 

 thickly clad with short hair. 



