196 BULLETIN 116, UIsTITED STATES NATIONAL MUSEUM. 



surface; middle and hind coxae black with extreme tips yellow. 

 Femora and tibiae yellow. Middle and hind femora each with one 

 preapical bristle, the latter ciliated on lower inner edge for about one- 

 fourth their length, leaving the basal half and apical fourth bare, 

 the longest of these hairs are about as long as the width of the femora. 

 Posterior tibiae tliickened, glabrous on inner surface for more than 

 half their length, lower edge with a row of large bristles. Fore tarsi 

 (fig. 13Sa) nearly twice as long as their tibiae, first four joints yellow, 

 fifth black, compressed, a little longer than the fourth, somewhat 

 oval in outline, fringed above with little black hairs; first joint four- 

 fifths as long as the tibiae, second fully half as long as first, third a 

 little shorter than second, fourth slightly more than half as long as 

 tliird. Middle tarsi a little longer than their tibiae, black fromi the 

 tip of the first joint, which has a large bristle near the middle of its 

 upper edge, the middle tibiae have four bristles on lower surface, one 

 pair near apical third and two single bristles preceding the pair. 

 Hind tarsi wholly deep black, constrasting sharply with the wholly 

 yellow tibia. Calypters, their cilia and the halteres yellow. 



Wings (fig. 138) tinged with gray; costa with an elongated enlarge- 

 ment at tip of first vein; last section of fourth vein bent before its 

 middle; third vein bent backward at tip, still its tip rather distant 

 from the tip of fourth vein as the fourth is also bent back a little; 

 hind margin of wing a little indented at tip of fifth vein, somewhat 

 expanded between the tips of fifth and sixth veins; anal angle 

 prominent. 



Female. — Face wide, covered with whitish pollen; third antennal 

 joint nearly round, still slightly pointed at tip; hind tarsi often 

 yellow at base; fore coxae a little less black; bristle on middle basi- 

 tarsus a little nearer the tip than in the male; hind femora without 

 cilia, their tibiae without the glabrous surface on inner side and but 

 little thickened; wings about as in the male, except that the costa 

 is scarcely thickened at tip of first vein and are more yellowish, 



Redescribed from many males and females. In the Aldrich collec- 

 tion are specimens from Polk County, Wisconsin, July, taken by 

 Baker; Custer, South Dakota, and Bottineau, North Dakota, June 20, 

 1918, taken by J. M. AJdrich, Franconia, New Hampshire, taken by 

 Mrs. Slosson; Hanover, New Hampshire, taken by C. M. Weed; and 

 Kukak Bay, Alaska, July 4, 1899, taken by Kincaid. In the United 

 States National Museum are specimens from Colorado, Alaska, and 

 Woodstock, Vhginia, June, 1897, taken by F. C. Pratt. I have 

 taken it at Olean, New York, August 5; Ridgeway, Ontario, Jime 26- 

 July 15; Niagara Falls, Ontario, July 31, 1910; Kearney, Ontario, 

 July 3-9, 1909, and July 26, 1911. 



Type localities. — English River, Canada; and West Point, New 

 York. Melander and Brues report it from Massachusetts and 

 Wisconsin. 



