152 DIPTERA OF NORTH AMERICA. 



border dusted with whitish ; the foremost beginning of a grayish- 

 white middle line is indistinctly indicated. Pleurae dusted with 

 whitish. Scutellum dusted with brown and opaque. Upper side 

 of the abdomen only a little dusted, and therefore a little greener 

 and less opaque. The under side and the part of the upper ab- 

 dominal plates which is turned downwards, covered with white dust ; 

 this dust extends to the upper side of the abdomen on the poste- 

 rior part of each segment. Legs black; first joint of the middl'e 

 and hind tarsi yellowish-red; first joint of the fore tarsi brown at 

 the base. Poisers yellow. Wings hyaline, rather grayish; the 

 second segment of the costal vein distinctly half as long again as 

 the third. This species diifers from H. incana by the pure white 

 dust on the anterior and lateral borders of the thorax, as well as 

 on the pleurae. 



Hab. Middle States. (Osten-Sacken.) 



I 



3. H. ol>scuriceps LOEW. $, . Subsenesceriti-fusca, abdomine magis 

 virescente, anteunis nigris, facie brunneo-nigra, puncto frontal! albido, 

 pleuris cinereis, pedibus ex fusco nigris, tarsis posterioribus in basi 

 nigris. 



Brassy brown, abdomen more greenish, antennse black ; face brownish- 

 black with a whitish frontal dot ; pleurse ashy gray ; legs brownish-black, 

 base of the middle and hind tarsi red. Long. corp. 0.1. Long. al. 0.1. 



Face rather narrow above, a little widening underneath, not 

 keeled, of a brownish-black velvety color; on each side there are 

 three small bristles, one above the other. Palpi yellow. Cheeks 

 descending very little below the eyes. Antennas black, in some 

 directions with a whitish reflection ; antennal bristle in the described 

 specimen with six rays. The dot immediately above the antennae 

 dusted with whitish, but not strikingly so. Front and upper side 

 of the thorax dusted with brown, opaque; anterior and lateral 

 borders of the thorax as well the shoulder without pale dust. 

 Pleura pale ashy gray, more brown above. Scutellum of the same 

 color as the upper side of the thorax. Abdomen brownish metal- 

 lic-green, somewhat glossy; first segment much shortened, second 

 and third of equal length, fourth a little longer, fifth as long as 

 the second and third together, rather broadly truncate at its end, 

 somewhat convex. Legs brownish-black ; first joint of the pos- 

 terior tarsi yellowish-red; the first joint of the foremost tarsi 

 brownish-red only at the base. Poisers yellow. Wings hyaline, a 



