THE DIPTEROUS GENUS DOLICHOPUS IN NORTH AMERICA. 235 

 No. 171. DOLICHOPUS SLOSSONAE, new species. 



Male. — Length 4.5-5.5 mm, ; of wing the same. Face rather wide, 

 a Httle narrowed below, ocher yellow, more white below in some speci- 

 mens. Front green. Antennae black; first joint yellow below; third 

 joint somewhat orbicular, but slightly pointed at tip. Lateral and 

 infe:-ior orbital cilia whitish, from 8 to 12 of the upper cilia on each 

 side black. 



Thorax green with slight bronze reflections; dorsum with rather 

 abundant gray pollen along the front, which is quite sharply marked 

 posteriorly, the disk being covered with an almost invisible brown 

 pollen; the large bristles are inserted in little black dots; pleurae 

 dulled with a little gray pollen. Abdomen green, sometimes with 

 coppery reflections; the white pollen on its sides not very abundant. 

 Hypopygium black; its lamellae (fig. 171a) rather large, somewhat 

 triangular, white with a narrow apical black border, jagged and 

 bristly on apical margin, fringed with brown hairs on the rounded 

 upper api<^al corner. 



Fore coxae yellow, their anterior sm'face covered with minute black 

 hairs, which are mixed with some yellow ones. Middle and hind 

 coxae black with yellow tips. Femora and tibiae yellow. Middle 

 and hind femora each with one preapical bristle, the latter without 

 cilia below, but with a row of rather conspicuous, very delicate, little 

 yellow hairs on lower inner edge. Posterior tibiae scarcely thickened ; 

 the usual glabrous stripe on upper side narrow and broken, but there 

 is another one on inner surface just inside of the inner row of large 

 bristles; it is wide at base and extends nearly to the tip. Fore and 

 middle tarsi about one and a third, hind tarsi one and a half times 

 as long as their tibiae, black from the tip of the first joint; first joint 

 of fore tarsi a little longer than the three following joints taken 

 together, fifth shorter than fourth; middle basitarsi without a bristle 

 above, their tibiae with one large bristle below. Calypters and 

 halteres yellow, the former with black cilia. 



Wings (fig. 171) grayish, tinged with brown along the front, usually 

 only slightly so; costa with a small knotlike enlargement at tip of 

 first vein; last section of fourth vein bent beyond its basal third; 

 wings rather narrow and of nearly parallel width; hind margin of 

 wing not indented at tip of fifth vein; anal angle prominent. 



Female. — -Face wide, silvery white; wings more evenly rounded on 

 the hind margin, still not very wide; anal angle prominent. 



Described from 7 males and 1 female. J. M. Aldrich has 4 males 

 and 1 female, taken at Franconia, New Hampshire, by Mrs. Annie 

 Trumbull Slosson. I took 1 male at Golden, Erie County, New York, 

 July 12. C. W. Johnson took 2 males, 1 at Mount Ascutney, Ver- 

 mont, July 11, and 1 at Eastport, Maine, July 15. 



