PLECOPTERA OF NORTH AMERICA 41 



Female. The entire 8th ventral segment is involved in 

 the formation of a subgenital plate, by division of it 

 deeply into two parts each of which is produced into a flat 

 triangular arcuate flap that extends nearly across the 9th 

 sternite. 



Distribution. — Trenton Falls and Ithaca, N. Y. ; Hud- 

 son Bay to Black Mts., N. C. 



The period of flight as evidenced by our specimens 

 ranges between late May, when specimens were collected 

 at Sunburst, N. C, and late June, when a single male was 

 taken on Mt. Moosilaukee, N. H., by Mr. N. S. Easton. 



Pteronarcys comstocki Smith. 



(Plate 7, fig. 13.) 

 1838. Pteronarcys proteus Newman, (female). Ent. Mag., 5:177. 

 1917. Pteronarcys comstocki Smith, Trans. Amer. Ent. Soc, 43:454. 



Female. Length to wing tips 52 mm. ; expanse, 70 mm. 



Color brown ; an obscure triangular median light spot 

 on the anterior border of the prothorax. Venter of thorax 

 paler and posterior margins of abdominal sternites 1 to 7 

 each bordered with a narrow pale band, the 8th, except 

 at tip, and the 9th entirely of lighter color. 



Head a little narrower than prothorax; the angles of 

 the latter right angles. 



Female. Subgenital plate arising near the middle of 

 the 8th sternite broadly oval or rounded triangular, bear- 

 ing, at its tip, two minute teeth bordering a minute in- 

 conspicuous apical notch. 



Male unknown. 



Distribution.— Trenton Falls and Wilmurt, and Tarbel 

 (near Ithaca) , N. Y. ( Wm. T. Davis) . 



Genus PTERONARCELLA Banks. 



1900. Pteronarcella Banks, Trans. Amer. Ent. Soc., 2fi:242. 

 1917. PteronarceUa Smith, Trans. Amer. Ent. Soc, 43:455. 



Stoneflies of medium size, similar in form to Ptero- 

 narcys, but only half as large and having the same sort of 

 reticulate venation. Crossveins of the wing fewer, en- 

 tirely absent from the radial areas in the middle of the 

 wing ; median vein but two-branched. Color brown ; a 

 squarish black spot on the head covers the ocelli but 

 leaves the large frontal tubercles pale. The quadrangular 

 disk of the prothorax bears a median longitudinal pale 

 line, which is generally continued on the front of the 

 mesothorax. The ninth abdominal segment is elevated in 

 a broad transverse recurved scoop-like lobe and some of 



