1.52 THOMAS SAY FOUNDATION 



eral tubercle; lateral tubercles quite prominent, brown- 

 ish ; frontal ridge not very strong ; hind ocelli closer to 

 the eyes than to each other. Antennae brownish. 



Prothorax narrower than head ; wider than long ; little 

 or not at all narrowed behind ; sides straight ; angles rath- 

 er sharp; brown rugosities on a yellowish background. 

 Legs light brown ; tarsi darker. Wings greenish hyaline ; 

 subcosta does not reach to the cord; three or four costal 

 crossveins before the end of subcosta and about two be- 

 yond; at the origin of the radial sector often a portion 

 of a crossvein extending toward media. 



Abdomen yellow, tails yellow, darker towards the tip. 



Male. Ninth abdominal sternite much produced and 

 rounded behind ; eighth sternite with a median knob 

 which is about as wide as long; subanal lobes recurved 

 upon the tenth tergite as slender sharp hooks ; supra-anal 

 lobe not developed. 



Female. Subgenital plate of eighth abdominal sternite 

 normally produced and rounded, with a slight median 

 emargination. 



Type female, No. 11337, Las Vegas, N. Mex., June 9, 

 1901 (T. D. A. Cockerell, Banks Coll. Mus. Comp. Zool., 

 Cambridge, Mass.). 



Distribution. — 



New Mexico. Pecos, July-Aug., 1903 (T. D. A. 



Cockerell). 

 Colorado, Tolland (G. S. Dodds). 

 Newfoundland, Grand Lake, July 28 (Owen 



Bryant). 

 California, Claremont (Theresa Robinson). 



Isoperla sordida Banks. 



(Plate 27, figs. 13, 14, 15.) 

 190fi. Fcrla sordida Banks, Can. Ent., 38:338. 

 1907. Isoperla sordida Banks, Cat. Neurop., p. 13. 



Length to tip of wings, male, 14 mm. ; female, 14-16 

 mm. Expanse, male, 24 mm. ; female, 24-29 mm. 



General color yellowish brown with yellowish hyaline 

 wings. Head wider than prothorax, brown with yellow 

 in front and a little lighter color in the ocellar triangle ; 

 ocelli connected by an indistinct wide darker mark ; lateral 

 tubercles and frontal ridge not prominent ; hind ocelli 

 closer to the eyes than to each other. Antennae yellowish 

 brown, darker toward the tip. 



Prothorax wider than long; brown with a wide median 

 yellow line and usually some yellow on the sides of the 

 disc, which are very rugose ; sides straight hardly nar- 



