212 BULLETIN 116, UNITED STATES NATIONAL MUSEUM. 



sides abundant and extending upon the dorsum. Hypopygium 

 black; its lamellae rather large, somewhat oval, about twice as long 

 as wide, whitish with a black border, which is wide on apical, narrow 

 on upper margin, jagged and bristly at apex, fringed above with 

 little black hairs. 



Fore coxae yellow, slightly blackened at extreme base, their an- 

 terior surface covered with conspicuous black hairs. Middle and 

 hind coxae black with yellow tips. Femora and tibiae yellow. Mid- 

 dle and hind femora each with one ])reapical bristle, the latter with- 

 out cilia below, but the black hairs on the sides reach the lower edge. 

 Posterior tibiae a very little thickened, more so on apical half where 

 the hairs on inner surface are longer and denser, sometimes a little 

 darkened on inner side toward the tip. Fore tarsi (fig. 152a) 

 one and a half times as long as the tibiae, first two joints of equal 

 length and taken together about as long as the tibia; first three joints 

 yellow, third scarcely one fourth as along as second, fourth half 

 as long as third, slightly widened, as wide as long, slightly brownish; 

 fifth joint black, four-fifths as long as first, much compressed, some- 

 what oval, nearly as wide as long, fringed above with little black 

 hairs; pulvilli white, conspicuous. Middle tarsi one and a third 

 times as long as their tibiae, infuscated from the tip of the first 

 joint, which has a large bristle above at apical fourth. Hind tarsi 

 wholly black, still the first joint sometimes a little reddish. Calyp- 

 ters and halteres yellow, the former with black cilia. 



Wings (fig. 152) grayish, slightly tinged with yellowish bro-\\ai in 

 front of third vein; costa without an enlargement at tip of first 

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

 hind margin of wing slightly indented at tip ol fifth vein, with a 

 sUght smus each side of the tip of sixth vein, so as to form a shght 

 lobe at tip of sixth vein. and at the anal angle, which is prominent: 

 wings of rather parallel width. 



Female. — Face wide with gray pollen; fore tarei plain, a little longer 

 than their tibiae, iniuscated from the tip of the first joint, but the 

 extreme base of the three following jomts yellow'sh, first joint 

 equal in length to the three following joints taken together, third 

 and fifth of about equal length, fourth a little shorter, but as thick 

 as the others. Wings evenly rounded on the hind margin; anal angle 

 rounded but rather prominent. 



Described from six males and one female. Three males and the 

 female were taken in Colorado, by Baker; two males at Dinwiddle 

 Creek, Wyoming, September 5, 1895 (Wheeler) ; and one male at Lar- 

 amie, Wyoming, August, 1893. All were in the collection of J. M. 

 Aldrich. 



Type.— Male, Cat. No. 23043, U.S.N.M., from Colorado. 



The males of seratus and procerus have the first two joints of the 

 fore tarsi equal in length, but in procerus the third joint is three- 



