THE DIPTEROUS GENUS DOLICHOPUS IN NORTH AMERICA. 57 



middle; hind margin of wing not indented at tip of fifth vein, not 

 much widened in the middle, the wing being of somewhat equal 

 width; anal angle of wing rather prominent. 



Female. — Face as wide as the front, grayish white, more yellowish 

 above; fore tarsi plain, black; hind femora with a row of rather long 

 hairs on lower edge, but these hairs scarcely long enough to be called 

 cilia; wings a little wider and more rounded on posterior edge; other- 

 wise about as in the male. The middle tibiae with one large bristle 

 on lower side and their basitarsi with a large bristle above. 



Described from 8 males and about 20 females taken by J. M. 

 Aldrich in Colorado, Tennessee Pass, July 25-26, and Marshall Pass, 

 July 28, at 10,856 feet elevation; 2 males in the United States National 

 Museum from Beulah, New Mexico, top of Las Vegas Range, June 28; 

 and 1 male taken at the northwest entrance to Yellowstone Park, 

 Wyoming, Aug. 3, by A. L. Melander. 



r?/pe.— Male, Cat. No. 22986, U.S.N.M., from Marshall Pass. 



This species differs from tetricus Loew in having the orbital cilia 

 wholly black, while in tetricus they are pale yellowish, except a few 

 black above. The form and color of the fore tarsi of the two species 

 are nearly alike, still there is a slight difference, but they could not be 

 separated by the tarsi alone. The difference in the color of the 

 orbital cilia makes it imjiossible to place them under one species. 

 The females differ in the color of the fore tarsi, which are wholly 

 black in manicula, while the second and third joints are yellowish in 

 the female of tetricus. 



No. 20. DOLICHOPUS CORAX Osten Sacken. 



Dolichopus corax Osten Sacken, Western Diptera, 1877, p. 314. 



j¥a?e.— Length 5 mm.; of wing 4.5 mm. Face rather wide, a 

 little narrowed below, dark satiny yellow, almost golden yellow. 

 Front green. Antennae black, third joint more brownish, not longer 

 than wide, somewhat conical in outline, scarcely pointed at tip. 

 Orbital cilia wholly black. 



Thorax dark green with yellowish pollen, which is almost invisible 

 when viewed from above; pleurae with a little grayish pollen- 

 Abdomen dark green. Hypopygium black; its lamellae moderately 

 large, black, only a little yellowish at their base below, somewhat 

 triaDgular in outline, but broadly rounded on apical margin, jagged 

 and bristly at lower apical corner, otherwise fringed with little 

 blackish hairs both above and below. 



Coxae, legs, and feet black, fore tibiae becoming more or less 

 yellowish toward their tips. Fore coxae covered with black hairs. 

 Middle and hind femora each with one preapical bristle, the latter not 

 ciliate; posterior tibiae thickened, their bristles strong, the usual 



