THE DIPTEROUS GENUS DOLICHOPUS IN NORTH AMERICA. 121 



tip of first vein; last section of fourth vein scarcely bent, still with 

 the suggestion of a bend before its middle, nearly parallel with third 

 vein; hind margin of wing a little indented at tip of fifth vein, beyond 

 which there is a small but distinct flattened lobe; anal angle rather 

 prominent. Wing with a prominent blackish spot at tip, starting 

 at tip of second vein, and extending back of fourth vein. 



Redescribed from 2 male type specimens from Illinois. 



Types. — In Museum of Comparative Zoology, Cambridge, Massa- 

 chusetts. 



No. 77. DOLICHOPUS OBSOLETUS, new species. 



JiiaZg.— Length, 4.5 mm.; of wing, 3.5 mm. Face moderately wide 

 and long, silvery white. Front shining blue green. Antennae black; 

 first joint scarcely paler below; third joint rather large, short conical, 

 about as long as wide, a little pointed at tip; proboscis and palpi 

 black. Lateral and inferior orbital cilia whitish, the black cilia de- 

 scend a little below the upper corner of the eye. 



Thorax dark but shining green; pleurae dulled with white pollen. 

 Abdomen dark green, shining, its incisures narrowly black; the white 

 pollen on its sides abundant and extending upon the dorsum. Hy- 

 popygium black; its lamellae of moderate size, somewhat oval in 

 outline, but tapering into the stem, only a little longer than wide, 

 white with black border, jagged and bristly on apical margin, fringed 

 with dark hairs above. 



Fore coxae yellow, blackened a little at base, anterior surface with 

 two rows of minute black hairs along inner edge, otherwise with pale 

 hairs, covered with white pollen. Middle and hind coxae black with 

 yellow tips. Femora and tibae yellow. Middle and hind femora each 

 with one preapical bristle, the latter blackened above at tip as far 

 as the preapical bristle, ciliated on the central half of lower edge 

 with about ten yellow hairs which are longer than the width of the 

 femora. Posterior tibiae a little thickened, black at tip for nearly 

 one-third their length, brownish and glabrous for two-thirds their 

 length on inner surface, sometimes the brown extends nearly to the 

 base. Fore tarsi about one and a fourth times as long as their 

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

 three following joints taken together. Middle tarsi black from the 

 tip of the first joint, which is sometimes darkened almost to its base; 

 it is without a bristle above. Hind tarsi wholly black. Middle 

 tibiae with one bristle below. Calypters and halteres yeljow, the 

 former with black cilia. 



Wings (fig. 77) grayish, scarcely darker in front of third vein; 

 costa with a very small knot-like enlargement at tip of first vein; 

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

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

 anal angle not being developed. 



