106 BULLETIN 116, UNITED STATES NATIONAL MUSEUM. 



moderate size, somewhat oval in outline, yellowish wdth a black 

 border on the apical and upper margins, the rounded apex jagged 

 and bristly, fringed above wdth bristle-like hairs, below with delicate 

 yellow hairs. 



Coxae black with yellow tips; anterior pair wdth green reflections, 

 white pollen and rather long black hairs on the front surface. Fore 

 femora black on basal two-thirds or three-fourths, yellow at tip. 

 Middle and hind femora yellow, usually a little blackened at base 

 below, the former with one preapical bristle, the latter with a row of 

 three or four bristles of increasing length, ending in the usual pre- 

 apical bristle, nearly bare below. Tibiae yellow; fore and middle 

 ones sometimes a little darkened at tip, the former with four large 

 bristles on lower outer edge, the latter with two large bristles below; 

 posterior tibiae black at tip for one-fifth to one-fourth their length, a 

 little thickened and wdth a row of about five bristles below, which 

 are nearly as large as those above. Fore tarsi a little longer than 

 their tibiae, blackened from the tip of the first joint, which is" as long 

 as the three succeeding joints taken together. Middle tarsi only a 

 little longer than their tibiae, first two joints yellow, last three black, 

 still the third is sometimes yellow for half its length ; middle basitarsi 

 without a bristle above. Hind tarsi black, sometimes wdth the 

 extreme base of the first joint yellowish. Calypters and halteres 

 yellow, the former with black cilia. 



Wings dark grayish, tinged with yellowish gray in front of third 

 vein and narrowly along all the posterior veins; costa scarcely 

 enlarged at tip of first vein; last section of fourth vein sharply bent 

 before its middle, its tip a considerable distance before the apex of 

 the wing; third vein bent backward so that it runs nearly parallel 

 with the costa and forms a very acute angle with it at its tip, which 

 is close to the tip of fourth vein; hind margin of wang indented at 

 tip of fifth vein, and with a small sinus before the anal angle, which 

 is prominent. 



Female. — Face wider than in the male and more grayish; wings 

 more evenly rounded on the hind margin; third vein not bent back- 

 ward quite so much at tip, anal angle not quite so prominent and 

 without the sinus before it, leaving the anal angle rounded, while in 

 the male it is almost lobe-like; bristles of the legs and feet about as 

 in the male. 



Redescribed from 10 males and 15 females in the collection of 

 J. M. Aldrich and taken at the following locations: Wells, Nevada, 

 July 12; Oxford, Idaho, July 12 (Aldrich), and Pine Lake, southern 

 California. 



Type locality. — North Park, Colorado. J. M. Aldrich reports it 

 from Cache County, Utah. 



The above description agrees with the type specimen in the Ameri- 

 can Museum in New York, which is a female. 



