66 BULLETIN 116, UNITED STATES NATIONAL MUSEUM. 



pointed at tip. Lateral and inferior orbital cilia white, about seven 

 of the upper cilia on each side black. 



Thorax green with bronze reflections, dorsum dulled with grayish 

 pollen on its anterior portion; pleurae dulled with white pollen. 

 Abdomen green with coppery reflections and with a little white pollen 

 on the sides. Hypopygium black, rather short; its lamellae (fig. 27a) 

 of moderate size, oval, white with a narrow black border at tip, only 

 a little jagged on apical margin, fringed with brown hairs, which are 

 stouter on the apical edge. 



Coxae and femora black with yellow tips. Fore coxae with white 

 pollen on their anterior surface, the inner half of which has minute 

 black hairs and the outer side is nearly bare. Middle and hind femora 

 each with one preapical bristle, the latter more or less yellowish at 

 base and on inner side, ciliated with white hairs for nearly their whole 

 length, the longest of these hairs nearly as long as width of femora. 

 Fore and middle tibiae yellow. Hind tibiae black, more or less yellow 

 at base; thickened and a little compressed; the glabrous stripe on 

 upper edge not conspicuous, but extending two thirds their length. 

 Fore tarsi about one and a fourth times as long as their tibiae, black 

 from the tip of the first joint, which is about as long as the three 

 succeeding joints taken together. Middle tarsi one and a third times 

 as long as their tibiae black from the tip of the first joint, still some- 

 times infuscated almost to their base. Hind tarsi wholly black. 

 Calypters and halteres yellow, the former with black cilia, but there 

 is a row of pale hairs back of the cilia and if the latter are broken 

 off these pale hairs would be mistaken for the true cilia. 



Wings grayish (fig. 27) ; costa scarcely enlarged at tip of first vein; 

 last section of fourth vein a little bent before its middle; hind margin 

 of wing scarcely indented at tip of fifth vein, evenly rounded, the 

 anal angle being but little developed. 



Female. — Face wide, silvery white; fore coxae with little black 

 hairs on their entire anterior surface; hind femora more yellowish 

 than in the male, without cilia below, but with a row of delicate, 

 short, pale hairs on lower inner edge; hind tibiae of normal size, 

 yellow with black tips. Otherwise about as in the male. Middle 

 basitarsi without a bristle above. 



Described from 3 males and 8 females, taken by J. M. Aldrich at 

 Market Lake, Idaho, June 18; 1 male by W. M. Wheeler from Little 

 Wind River, Wyoming, Sept. 2; and 1 pair b}" C. F. Baker from 

 Colorado. 



Type.— Male, Cat. No. 22991, U.S.N.M. 



