21 G DIPTERA OF NORTH AMERICA. [PART II 



In Walker's description of H. alboflorens, the brownish-yellow 

 color of the dust upon the face, the color of the halteres and the 

 black color of the hair on the upper side of the abdomen, agree 

 better with H. pirata ; but it is added, that the thorax is covered 

 with brownish-yellow dust, that the dust upon the femora is of the 

 same color, and finally that the pulvilli are of a pale-yellowish 

 color, of all which there is no trace in H. pirata 



3. H. parvus Loew. % . — Olivaceo-aeneus, thorace et scutello cupreo 

 resplendentibus, abdomine obscure viresoente, femoribus tibiisque viridi- 

 bus, tarsis nigris, polline faciei opacae ex fusco ochraceo, pleurarum polline 

 albido, venis alarum ex nigro cinerascentium nigris, longitudinalibus 

 tertia et quarta perfecte parallelis. 



Metallic olive-brown, tliorax and scutellum witb a copper-colored re- 

 flection ; abdomen dark-green, femora and tibiae green, tarsi black, the 

 dust upon the entirely opaque face brownish ochre-yellow, that on the 

 pleurae whitish ; the wings blackish-gray with black veins, the third and 

 fourth longitudinal veins entirely parallel. Long. corp. 0.09—0.10. 

 Long. al. 0.13. 



Syn". Hydrophorus parvus Loew, Berl. Entom. Zeitschr. VI, 214, 67. 



Reslmbles in the structure of the body H. pirata very much, 

 but sufficiently distinct from it by its smaller size, a more blackish 

 color of the wings and the complete parallel course of the third 

 and fourth longitudinal veins. Face with brownish ochre-yellow 

 dust, entirely opaque, very much narrower upwards. Palpi black, 

 antennae also black. Front almost velvet-black, with yellow- 

 brownish dust, which is not distinctly perceptible in every direc- 

 tion. Ground-color of the occiput green, covered above with 

 yellowish, below and on the lateral margin with whitish dust. 

 Cilia of the upper orbit black, of the inferior one white. Upper 

 side of the thorax metallic olive-brown with almost violet and 

 coppery reflections, the latter of which form two indistinct longitu- 

 dinal lines and are more extended near the posterior margin of the 

 thorax. Scutellum shining copper-colored, with four bristles, the 

 lateral bristles much shorter than those which are nearer to the 

 tip. The abdomen is green, rather opaque, upon the middle 

 somewhat coppery, on the lateral margin and on the under side 

 distinctly covered with white dust ; the very short hair upon it is 

 black. Coxa?, femora and tibiae black-green. The fore coxae 

 are fringed on their front side with very delicate whitish Lair 



