2S?; DIPTERA OF NORTH AMERICA. [PART II. 



hairs, its usual black bristles of a very moderate length. Thorax, 

 scutellum and abdomen with a slight yellowish dust, which 

 moderates the lustre of these parts. The black bristles of the 

 thorax of moderate length. The scutellum has only the pair of 

 bristles at the tip, which is of a considerable length ; immediately 

 near each bristle of this pair a much shorter black hair is inserted 

 towards the outside. Pleura? black with a green reflection and with 

 a grayish-white dust ; their hind margin gray or at least only in 

 part yellowish. Abdomen green, towards its end genei'ally some- 

 what gilded ; the first segment yellowish, at its basis blackish, on 

 the hind margin metallic-green ; on the second segment the ante- 

 rior margin and corner, sometimes also the lateral margin, yellow ; 

 the third segment has generally, on the anterior part of the lateral 

 margin, an elongated yellowish spot. The scattered pubescence 

 of the abdomen is rather delicate and long ; upon the upper side 

 it is black, whitish only upon the first segment ; the pubescence 

 of the venter is whitish near its basis, but becomes gradually 

 darker towards the end. The black bristles before the incisures 

 of the abdomen of a very moderate length. The external append- 

 ages of the hypopygium small and very narrow, brownish-yellow. 

 Fore and hind coxae pale yellow, the former with a shorter and more 

 delicate whitish pubescence and with a few light-yellowish bris- 

 tles ; middle coxae gray with pale-yellowish tip. Feet yellowish. 

 Femora slender, upon the "under side sparely fringed with exceed- 

 ingly short, minute whitish hairs ; besides, upon the second half 

 of the under side of the middle femora there is a sparse row of 

 minute black hairs. Tibias slender and long ; the usual black 

 pubescence of the fore and hind tibiae is very short and appressed, 

 that of the middle tibiae somewhat longer and more erect, there- 

 fore almost fringe-like. The fore tibiae, with the only exception 

 of a rather small minute black bristle, inserted upon their outside, 

 near the basis, are entirely without bristles. The middle tibhe 

 bear no bristles whatever, distinguished from the other pubescence. 

 Hind tibiae upon the front side, not far from the basis, with a rather 

 apparent little bristle, whilst those upon the upper and under side 

 are less numerous, extremely small and therefore more difficult to 

 perceive. Fore tarsi slender, nearly twice as long as the tibia? ; 

 their first joint for itself alone somewhat longer than the tibia, 

 the following ones of decreasing length, the last one brown. Mid- 

 dle tarsi slender, about once and a half the length of the tibiae ; 



