THE DIPTEKOUS GENUS DOLICHOPUS IN NORTH AMERICA. 177 



times as long as their tibiae; three first joints slender, yellow, some- 

 times the extreme tip of third blackened, second nearly three-fourths, 

 third one- third as long as first ; fourth and fifth joints black, compressed, 

 fourth half as long as third, as wide as long, fifth much widened, as 

 long as second, somewhat oval but narrowed toward the base and 

 straight below, near the apex a little less than half as wide as long. 

 Middle tarsi a little longer than their tibiae, black from the tip of 

 the first joint, which has a bristle above. Hind tarsi one and a 

 fourth times as long as their tibiae, wholly black. Calypters and 

 hal teres yellow, the former with black cilia. 



Wings (fig. 123) grayish, sometimes a little tinged with brown in 

 front of third vein; costa a little thickened at tip of first vein, taper- 

 ing from there to its tip ; last section of fourth vein a little before its 

 middle, its tip far before the apex of the wing; hind margin of wing 

 scarcely indented at tip of fifth vein; wing of rather equal width, the 

 anal angle being prominent. 



Female. — Differs from the male in having the face broad with 

 yellowish gray pollen; the fore tarsi are plain, a little longer than 

 their tibiae, black from the tip of the first joint, which is about as 

 long as the three following joints taken together; hind tibiae less 

 blackened at tip; the wings are a little more tinged with brown; 

 the costa is scarcely at all thicker at tip of first vein ; posterior margin 

 of wing a little more broadly rounded, the anal angle being a little 

 less prominent. 



Described from 5 males and 1 female. One male was taken at 

 Emigration Canyon, Utah, July 27, 1917, and 1 pair at Tennessee 

 Pass, Colorado, July 25, 1917, by J. M. Aldrich; 1 pair was taken by 

 Baker in Colorado; 1 pair at Beaver Creek, Montana, in Aug., 1913, 

 by S. J. Hunter, at an elevation of 6,300 feet ; 1 male was taken by 

 W. M. Mann, at Nigger Hill, Powell County, Montana, in July. 



Ti/pe.— Male, Cat. No. 23032, U.S.N.M., from Tennessee Pass, 

 Colorado. 



No. 124. DOLICHOPUS VIGILANS Aldrich. 



Dolichopus vigilans Aldrich, Kansas Univ. Quart., vol. 2, p. 13, pi. 1 fig. 18. 



Male. — Length 5.2-5.5 mm.; of wing 4.1-4,5 mm. Face rather 

 wide, silvery white, tinged with yellow on upper half or more. Front 

 violet with a narrow border of green above the antennae and along 

 the orbits. Antennae yellow with- the apical haK of third joint 

 black; third joint conical, about as long as wide; arista twice as long 

 as the antennae. Proboscis black; palpi yellow. Lateral and inferior 

 orbital cilia whitish, about six of the upper cilia on each side black. 



Thorax green, scutellum and sometimes the dorsum with blue 

 reflections, usually there is a coppery spot on the sides at the suture; 

 anterior part of the dorsum a little dulled with grayish pollen which 



