ART. 17. FLIES OF THE GENUS TACHYTRECHUS — GREENE. 9 



with a yellowish-white dust; apical edge of each segment narrowly 

 brownish-black. Hypopygium large, brassy or bluish-green coated 

 with a yellowish- white dust; lower edges shiny, black to reddish; 

 lamellae brown, yellowish at base, hairs brownish-black. On the outer 

 lower corner is a finger-like projection. Front coxae yellow, gray on 

 underside ; middle and hind ones grayish-black. Legs and base of all 

 metatarsi 3^ellowish at the base. Tips of fore and hind tibia, bases of 

 the middle and hind femora and the remainder of the tarsi blackish- 

 brown. Front femora decidedly broadened on the basal two-thirds, 

 on the inner side is a large, elliptical bare spot. Wings faintly tinged 

 with brown, edge faintly curved inward before and after the fifth 

 vein ; posterior cross- vein with a deep bend in the middle. Halteres 

 pale yellow. Tegulae pale yellow, fringes long and black. 



Female. — Very much like the male except darker in color and more 

 robust. Face wider, silvery. Front grayish-brown with a whitish 

 dust. Antennae shorter, third joint with more reddish-yellow. Arista 

 black, about three-fourths as long as face, thickened on the basal third. 

 Apical end of fore and middle femora, outer surface of hind femora, 

 basal fifth of middle and hind tibiae, fore tibiae except apical end, and 

 basal half of all the metatarsi reddish-jellow ; balance of the legs in- 

 fuscated with dark brown. All legs dusted lightly with a whitish 

 dust. Wings faintly tinged with brown, broader and not so deeply 

 incised on posterior edge. Posterior cross-vein deeply but more 

 broadly arcuate. 



Length 5 mm. 



Type-locality. — Saratoga, New York, Osten Sacken. 



Type. — In the Museum of Comparative Zoology, Cambridge, Mas- 

 sachusetts. 



Distribution. — Battle Creek, Michigan ; Ira, Summit Countj^, Ohio, 

 September 10, 1894; Lafayette, Indiana, May 22, 1915. Four speci- 

 mens deposited in United States National Museum Collection by J. M. 

 Aldrich. Durham Pond, Morris County, New Jersey, August 18, 

 1901, George M. Greene, collector. 



7. TACHYTRECHUS BIPUNCTATUS, new species. 



Figs. 13, IS. 



Male. — Face twice as wide at each end as it is about one-third the 

 distance below the antennae, densely coated with a yellow dust, dull 

 and slightly shorter than length of eyes. Front deep green, in certain 

 lights with a dark brown area in middle ; ocellar triangle dark green, 

 ocelli very pale yellow. Antennae mostly yellow, first joint quite 

 large, twice the length of the third, slightly infuscated at tip ; second 

 joint very rudimentary, third joint somewhat rounded, brown-black 



