84 THOMAS SAY FOUNDATION 



Male. Segments 7, 8 and 9 a little elongated ventraliy, 

 9 most so, but hardly scoop-like at the apex. Segment 10 

 divided dorsally as usual but with the rear lobes thus 

 formed laid flat, not hook-like, but triangular and suban- 

 gulate on the end, and covered with hair, almost lacking 

 the usual forwardly directed spicules. Between these 

 lobes projects the long pointed, tapering upturned tip of 

 the U-shaped supra-anal process, with a pair of acute- 

 angled paragenital plates projecting rearward beside it. 



Female. The subgenital plate is nearly as broad as the 

 abdomen, well marked off on the 8th sternite by a pair of 

 oblique grooves ; its free margin is ovately rounded, thinly 

 hairy and overlaps well across the 9th sternite. 



Distribution. — Rock Island, 111. ; Elkhart, Ind., June 

 (R. J. Weith) ; Lake Geneva, Wis., May 9, 1892, "Fontana 

 Park: crawling on leaves — small stream." No. 27257, 111. 

 State Lab. Nat. Hist. (S. A. Forbes) ; Riley Co., Kan., "K. 

 S. A. C. 244" (G. A. Dean) ; Port Huron, Mich.; St. Paul, 

 Minn. 



Perla hastata Banks. 



(Plate 11, fig. 2; plate 17, figs. 1, 2, 3.) 

 1920. Isogenus hastatus Banks, Bull. Mus. Comp. Zool., 64:314. 



Color fuscous marked with yellow. Top of head mostly 

 black with a crown spot of yellow between the ocelli, nar- 

 rowly connected with apex of an occipital triangle of the 

 same color, whose base spreads laterally across the hind 

 margin of the head. The M-line before the middle ocellus 

 is narrowly yellow and its two apices connect with a dif- 

 fuse spot of the same color upon the side of the clypeus. 

 Labrum yellowish ; antennae and palpi fuscous. 



Prothorax blackish with a middle yellow stripe that 

 slowly widens to rearward, and that suddenly spreads out 

 laterally on the flaring front margin. A mid-dorsal tri- 

 angle of yellow on front of mesothorax points with its 

 apex to rearward and there are other pale spots about 

 the wing roots. Wings smoky hyaline with heavy dark 

 brown veins. Legs fuscous, with pale knee caps. Venter 

 of head and thorax mostly pale, with irregular narrow 

 markings of fuscous that are median on the sternella, and 

 broadly spread across the sterna of meso- and meta- 

 thorax. Venter of abdomen obscure. Segment 10 and 

 genitalia yellowish. Tails brown. 



Some specimens show paired spots of yellow within 

 the brown of the prothoracic dorsum toward the front, 

 and smaller dashes of yellow across the frontal tubercles 

 within the large brown area on the top of the head. 



