242 BULLETIN 116, UNITED STATES NATIONAL MUSEUM. 



abundant and extending upon the dorsum. Hypopygium black with 

 metalHc reflections; its lamellae (fig. 177a) rather small, somewhat 

 elliptical, one and a half times as long as wide, white with a black 

 border on apical and upper margins, that above verv^ narrow, jagged 

 and bristly at apex, fringed above with a few rather stiff short black 

 hairs. 



Coxae yellow, middle ones blackened on outer surface; fore coxae 

 with minute black hairs along inner edge, anterior surface with 

 silvery pollen and little white hairs, sometimes there are a few black 

 ones intermixed. Femora and tibiae yellow. Middle and hind 

 femora each with one preapical bristle, the latter without cilia below 

 but with a row of very delicate little yellow hairs on lower inner edge. 

 Posterior tibiae a little thickened, their inner surface glabrous from 

 near the base nearly to apical fourth. Fore and middle tarsi about 

 one and a fourth times as long as their tibiae, middle ones black 

 from the tip of the first joint, anterior ones from the middle of third 

 joint; first joint of fore tarsi about as long as the following three taken 

 together, fourth and fifth of nearly equal length. Middle tibiae with 

 three bristles below, one pair at apical third and one bristle at basal 

 third, their basitarsi with one large bristle near apical third of upper 

 side. Hind tarsi black from the tip of the first joint. Calypters 

 and halteres yellow, the former with black cilia. 



Wings (fig. 177) grayish, usually tinged with brownish in front of 

 third vein; costa with a conspicuous elongated enlargement at tip of 

 first vein; tip of third vein bent backward a little; last section of 

 fourth vein bent at right angles near its middle, the bend having a 

 stump of a vein at its first angle and sometimes also one at its upper 

 angle, the vein running nearly straight from upper angle to its tip; 

 hind margin of wing only a little indented at tip of fifth vein; anal 

 angle prominent. 



Female. — Face wider than in the male; fore tarsi but little longer 

 than their tibiae, usually black from the middle of the third joint, 

 sometimes infuscated a little from the tip of the first joint; wing as 

 in the male except that the costa is not enlarged at tip of fifth vein; 

 bristles of middle tibiae and tarsi as in the male. 



Redescribed from many specimens from the following localities: 

 Brookmgs, South Dakota (Aldrich); Lafayette, Indiana, June 8-11; 

 Princeton, New Jersey, July 21; Cuyahoga Falls, Ohio, August 14; 

 Western New York, June 10-October 19; Toronto, Ontario, July 4; 

 Port Credit, Ontario, July 15. 



Type localities. — Chicago, Illinois, and Genesee, New York. Me- 

 lander and Brues rei)ort it from Wisconsin; Chagnon from Mon- 

 treal, Canada. 



Type. — In Museum of Comparative Zoology, Cambridge, Massa- 

 chusetts. 



