133 DIPTEItA OF NORTH AMERICA. [PART II. 



so that the first joint, with the exception of its tip, is dark yellow, 

 and the second joint, with the exception of its tip, is brownish- 

 yellow. The hind tarsi are visibly shorter than the hind tibiae, 

 and the first joint is longer than the second. The yellowish tegu- 

 lse have a narrow dark-brown margin and yellowish cilia, which 

 in some directions assume a very dark color. Halteres yellowish. 

 Wings grayish ; the last segment of the fourth longitudinal vein 

 not distinctly inflected ; posterior transverse vein steep. 

 Hab. Middle States. (Osten-Sacken.) 



II. Lower part or the occiput with a strong beard. 



3. S. "barbatus Loew. % . — Viridis, pedibus flavis, femoribus posticis 

 viridibus. 



Green, feet yellow, bind femora green. Long. corp. 0.12 — 0.13. Long. 



al. 0.12. 

 Syn. Synarthrus barbatus Loew, Neue Beitr. VIII, 48, 2. 



Shining metallic-green. Face green, and dull on account of a 

 moderately thick yellowish-white dust, which however does not 

 conceal the ground color. Palpi a little larger than those of the 

 males of Synarthrus in general ; they have also a more disengaged 

 position, a bright yellow color, and are beset with a few black 

 little hairs: Antennas black ; the second joint reaching only a 

 little on the inside of the third, almost of transverse form ; the 

 rather strikingly hairy third joint is broad only about the basis 

 and becomes elongated into a narrow and very long point; the 

 arista is entirely apical and only half the length of the third joint. 

 Front metallic-green, little shining. Cilia of the upper orbit 

 black, short and delicate ; cilia of the lateral and inferior orbits 

 very long, white ; they form with the hair on the lower part of the 

 occiput a striking beard. Thorax and scutellum metallic-green, 

 the former less shining on account of a cover of pale dust, the lat- 

 ter sometimes more bluish-green. Abdomen metallic-green. The 

 last segments assume in some directions a rather black-green 

 color. The small imbedded hypopygium black ; its outer append- 

 ages have the form of small lamella? and are of a brownish color ; 

 the inner appendages are not distinctly perceptible. Fore coxa? 

 blackish, on the front side greenish-blue ; their delicate hairs are 

 principally white, but towards the basis of the coxa? there are also 

 some black hairs ; on the tip are black bristles. Middle and hind 



