88 BULLETIN 116, UNITED STATES NATIONAL MUSEUM. 



Coxae black; anterior pair with gray pollen and black hairs on 

 their front surface. Femora black with yellow tips, the yellow on the 

 middle ones extends toward their base on the upper edge nearly to 

 the middle. Middle and hind femora each with a row of three or four 

 bristles ending in the usual preapical bristle (these are often broken 

 off so as to leave only one or two) ; hind femora ciliated below with 

 delicate brown hairs, the longest of which are fully as long as the 

 width of the femora, these hairs extend the whole length of the lower 

 inner edge but are very short at the base and longest near the tip. 

 Fore and middle tibiae yellow; hind tibiae thickened, black, yellow 

 at base for a distance about equal to half the length of their basi- 

 tarsus and with a yellowish line extending their entire length just 

 inside of the inner row of large bristles, the two rows of bristles on 

 upper surface, although of only ordinary length, are inserted rather 

 close together, there being about 10 or 12 in each row, the glabrous 

 stripe between them distinct. Fore tarsi one and a half times as 

 long as their tibiae, the first two joints taken together about equal to 

 the tibia in length; fifth joint nearly as long as fourth, third a little 

 longer than fourth. Fore and middle tarsi infuscated from their 

 base, becoming black at half their length, the latter about one and a 

 fourth times as long as their tibiae. Hind tarsi wholly black, about 

 one and a half times as long as their tibiae. Calypters and halteres 

 yellow, the former with black cilia. 



Wings (fig. 47) grayish; there are brown clouds along the cross-vein 

 and the adjoining portions of the fourth and fifth veins, on the bend 

 of the last section of fourth vem and a rather well-defined spot extend- 

 ing from a point opposite the cross-vein to tip of third vein and from 

 the costa to the third vein; costa with an elongated enlargement at 

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

 third; hind margin of wing a little indented at tip of fifth vein, widest 

 point of wing just back of this notch; anal angle prominent. 



Female. — Face a little wider than in the male and more brownish; 

 fore tarsi shorter, about one and a fourth times as long as their 

 tibiae ; fore and middle basitarsi more yellow ; hind tibiae not much 

 thickened; hind femora not ciliated, wings brown m front of third 

 vein from the root to the tip of third vein, cross-vein clouded about 

 as in the male; costa not enlarged; otherwise about as in the male. 

 Middle tibiae with one bristle below, their basitarsi without a bristle 

 above. 



Redescribed from 3 males and 1 female from Colorado; 1 of the 

 males was taken by J. M. Aldrich at Marshall Pass, Colorado, July 

 28, at 10,856 feet elevation, the other specimens were taken by C. F. 

 Baker. 



Type locality. — Colorado. 



