284 DIPTERA OF NORTH AMERICA. [PART II. 



B. Fore femora upon the under side with thornlike bristles in both sexes. 

 1. All the coxae entirely yellow. 



20. P. tener Loew. % and 9 • — Laete viridis, proboscide, palpis, 

 priniis duobus antennarum articulis, pleurarum margine postico, abdo- 

 minis basi, coxis pedibusque flavis, ciliis tegularum albicantibus, alarum 

 vena transversa posteriore valde obliqua. 



% . Femora antica setulis subtribus armata ; appendices hypopygii majus- 

 culae flavos. 



P . Femora antica setis quatuor validis armata. 



Light green, proboscis, palpi, the two first joints of the antenna?, the hind 

 margin of the pleurae, the basis of the abdomen, the coxae and feet yel- 

 low ; cilia of the tegulte whitish ; hind transverse vein of the wings very 

 oblique. 



% . Fore femora generally with three minute bristles ; the rather large 

 appendages of the hypopygium yellow. 



2. Fore femora with four stout bristles. Long. corp. 0.16 — 0.17. Long. 

 al. 0.22. 



Syn. Psilopus tener Loew, Berl. Ent. Zeitschr. VI, 217, 71. 



Light metallic-green, rather shining. Proboscis and palpi yel- 

 low, the latter beset with a few minute bristles, which have in the 

 % a whitish, in the 2 a black color. The glabrous face, covered 

 with white dust, is very broad, particularly upon its upper part, 

 which is very convex. Antenna? small, the two first joints yellow, 

 the second beset with a few short, minute black hairs upon the 

 upper side ; upon the under side with a few short, minute white 

 hairs ; the very small third joint is generally blackish, still it has 

 sometimes a much lighter coloring. The front is generally sky- 

 blue, and, besides the usual black bristles, without pubescence. 

 Upper side of the thorax sometimes more blue than green, rather 

 distinctly dusted and beset with but a moderate number of black 

 bristles. Pleurae, in consequence of a close white dust, grayish- 

 green. The scutellum, which has two bristles, is sometimes green, 

 sometimes purplish-blue. Abdomen shining light-green, some- 

 times rather golden-green ; its basis is in the 9 always, in the 

 male generally, colored with yellow ; the black bristles before the 

 hind margin of the single segments are proportionally short. 

 Hypopygium blackish-brown and dusted with white ; its append- 

 ages are pale yellow ; the external ones are narrow lamella? and 

 are fringed with a blackish pubescence, which is somewhat longer 



