74 DIPTERA or NORTH AMERICA. [PART IV. 



Head dark brown, antennae and palpi black. Thorax dark 

 brown, moderately shining and slightly pruinose "n'ith grayish 

 above ; stripes not distinct ; some parts of the pleurae and of the 

 posterior portion of the thorax are reddish or yellowish-brown. 

 Halteres with an infuscated knob ; feet dark "brown, femora 

 tawny, paler at the basis ; coxjb brownish-yellow. Abdomen 

 brown ; forceps paler ; the upper valves of the ovipositor are 

 very narrow^, pointed, and nearly straight. Wings (Tab. I, fig. 

 2) immaculate, somewhat tinged with grayisli ; stigma elliptical, 

 pale brownish ; the apex of the wing is finely and sparsely 

 pubescent ; in the marginal cell this pubescence begins a little 

 before the stigma, and it occupies nearly the whole of the sub- 

 marginal, posterior, and discal cells. The tip of the auxiliary 

 vein is about one length of the stigma beyond the origin of the 

 second longitudinal vein ; the subcostal cross-vein is near its tip. 

 The first longitudinal vein ends in the second, forming a regular 

 arQ of a circle ; the cross-vein connects it with the costa. The 

 discal cell of this species is often open (among twenty specimens 

 caught by me in 1859 in the same locality, five had it open), and 

 in such specimens, it is the anterior branch (and not the posterior 

 one as usual) of the fourth longitudinal vein which is forked ; in 

 other words, the discal cell coalesces with the third, and not with 

 the second posterior cell. 



Hab. Washington, D. C, not rare in April and May; also 

 further north. 



The pubescence in the apical portion of the wing, as well as 

 the forking of the anterior, instead of the posterior branch of the 

 fourth vein are very good distinctive characters of this species. 



17. I>. glolJiltliorax, n. sp. % and 9 • — Brunnea, capite antennisque 

 nigro-fuscis, thorace gibbo ; alis brevioribus, pallide infuscatis, immacu- 

 latis, stigmatis vestigio nullo ; vena longitudinali prima in secundam 

 (non in costam) incurvS, ; vena auxiliari pone prsefurcse initium extensS,. 



Brown, bead and antennae brownish-black ; thorax gibbous, wings rather 

 short, slightly tinged with brownish, without spots ; no vestige of a 

 stigma ; the first longitudinal vein is curved towards the second (not 

 towards the costa) ; auxiliary vein prolonged beyond the origin of the 

 prsefurca. Long. corp. 0.2 — 0.22. 



Head, including the palpi, brownish-black; joints of the flagel- 

 lum short, subglobular, with a short, scattered pubescence. 



