116 DIPTERA OF NORTH AMERICA. [PART II. 



its covering with whitish dust does not entirely conceal the blue- 

 green ground-color ; the usual transverse swelling lies, as in most 

 of the other species, usually rather far below its middle ; palpi for 

 a female of moderate size, yellowish and blackish at the root. The 

 third joint of the antennae comparatively not large, rather rounded. 

 Front metallic-green, with thin dust and towards the vertex a lit- 

 tle enlarged. Upper side of the thorax only with thin, brownish- 

 yellow dust. Coxae and hind femora black with metallic-green 

 lustre, which is most distinctly seen on the latter. The tip of the 

 fore coxae yellow ; fore feet yellow ; femora on the upper side with 

 a black longitudinal stripe, the tarsi infuscated from the tip of the 

 first joint ; middle feet entirely yellow ; the tarsi infuscated only 

 from the tip of the first joint ; on the hind feet the extreme tip of 

 the femora, the tibiae and the greater part of the first joint of the 

 tarsi are of a pale color. The hair upon the feet is short and 

 rather delicate, the bristles only few, though the little bristles on 

 the hind tibiae are rather long. The pale hairs on the cilia of 

 the tegulae seem to have, in some directions, a dark appearance. 

 Wings only slightly tinged with gray, with dark brown veins. 

 The posterior transverse vein approaches but little the root of 

 the wing, and is somewhat farther from it than in most of the 

 other species. 



Hab. Middle States. (Osten-Sacken.) 



b. Ground color of the palpi blackish. 

 1. Cilia of the tegulse black. 



4. C. o"bliquus Loew. % and 9 . — Viridis, nitens, tegularum ciliis 

 nigris, femoribus nigris viridi-micantibus, summo anteriorum apice 

 fiavo. 



% . Oculis contiguis, tertio antennarum articulo obliquo, tibiis anteriori- 

 bus flavis. 



9 • Tibiis omnibus flavis. 



Shining-green ; cilia of the tegulse black ; femora black, with green lustre ; 



the extreme tip of the four anterior femora yellow. 

 % . The eyes contiguous ; the third joint of the antenna? oblique ; the four 



anterior tibiae yellow. 

 9. All the tibiae yellow. Long. corp. 0.09—0.10. Long. al. 0.09—0.10. 

 Syn. Chrysotus obliquus Loew, Neue Beitr. VIII, 63, 3. 



Male. Eyes completely contiguous upon the face ; the small 

 triangular spot between them, immediately below the antennae, is 



