TACHYTRECIIUS. 113 



species, broader inferiorly, in both sexes covered with a pale yel- 

 low dust, and without lustre. Palpi small, black. Antennae of the 

 usual form, black. Arista in both sexes plain and bare. Front 

 covered with a dense yellow or brown dust. Cilia of the posterior 

 orbit above black, below white. Upper side of the thorax with a 

 gray-yellowish or brownish-yellow dust upon a metallic-green or 

 partially copper-colored and lustrous ground, very dull. The 

 scutellum has a similar coloring, still its ground color can sonic- 

 times be distinctly recognized. Abdomen green and coppery, 

 dull with a gray-whitish dust. Pleurae and coxae grayish-green; 

 on account of a whitish dust upon green ground. Femora dark 

 metallic-green, thinly pruinose with whitish, their tip brownish- 

 yellow ; hind femora before their tip with a row of four bristles ; 

 tibiae brownish-yellow ; the tip of the fore and hind tibiae blackened, 

 the tip of the middle tibiae usually only brown. Tarsi black, plain 

 also in the male ; the fore tarsi usually brownish-yellow only at the 

 extreme root, the middle tarsi, however, brownish-yellow upon the 

 first half of the first joint. Cilia of the tegulae black. Wings of 

 the male narrow, hyaline, scarcely tinged with gray, at the tip with 

 a small spot, the first two-thirds of which are deep-black, the last 

 third, however, appears snow-white when seen against the light. 

 Wings of the female not quite so narrow as those of the £ , dis- 

 tinctly tinged with gray, with a slight dark shadow around the 

 hind transverse vein. The end of the fourth longitudinal vein in 

 both sexes is less approximate to the end of third longitudinal 

 vein, than in the previous species. The short pedunculated hy- 

 popygium of the J 1 is black, upon the inferior side more greenish- 

 black, but gray from a pale dust ; the lamellae are black, of mode- 

 rate size only, rather rounded, and covered with black hairs. 

 Hah. District Columbia. (Osten-Sacken.) 



3. T. aiisrustipeniiis Loew. % . — Viridis, antennis nigris, pedibus 

 totis ex viriili nigris, alis immaculatis, basim versus attenuatis. 



Green, antennre black ; the whole feet greenish-black ; wings spotless, nar- 

 rower towards the basis. Long. corp. 0.22. Long. al. 0.19. 



Syx. Tachytrechus angustipennis Loew, Berl. Ent. Zeit. VI, 213, G4. 



Green and but little shining, on account of being rather densely 

 covered with a line dust. Palpi black, with a gray-yellowish 

 dust. Face pale, ochre-yellow, dull. The rather small antennae 

 8 



