236 DLPTERA OF NORTH AMERICA. [PAftT II. 



gradually upon the posterior segments into golden-green, and the 

 last segment is usually entirely, or at least partially, of a steel- 

 blue color. In the male there is, near the basis of each of the 

 abdominal segments, a narrow, but distinct black band ; in the 

 female these black bands are still narrower and less striking. The 

 black hair upon the abdomen and the black bristles before the 

 posterior margin of each of the segments are of considerable 

 length. The hypopygium is rather small, its appendages are not 

 sufficiently well preserved in the described male specimens, to re- 

 cognize their structure accurately ; I perceive only that they are 

 of middling length, rather broad, of a dusky brown, and at the tip 

 of a more black color. Coxae black, covered with a thin whitish 

 dust ; the anterior coxae with comparatively long white hairs and 

 towards the tip with a few black bristles. Femora black, on the 

 under side with long erect hairs, which are white near the basis 

 and black at the tip, and are much longer in the male than in the 

 female. Fore tibiae and fore tarsi brownish-yellow, the latter 

 blackened near the extreme tip ; the fore tibiae have on the upper 

 side a row of five or six very long black bristles, which is inter- 

 rupted long before its end, and of which the last one is the longest 

 and somewhat longer in the female than in the male ; I perceive 

 in the male on the under side of the fore tibiae, in the neighbor- 

 hood of the root, a rather long, but very fine bristle ; in the female 

 this bristle is much shorter, and besides, there are two small bris- 

 tles inserted at equal distances. The- fore tarsi in both sexes are 

 slender and of a plain structure ; in the male a little over one and 

 a half, in the female one and a half the length of the tibia ; they 

 are beset only with the usual black short hair, nevertheless, in the 

 female, there are on the under side of its very elongated first joint 

 four very short bristles, inserted at equal distances and wanting 

 in the male. Middle tibiae and middle tarsi black in the described 

 male ; dark pitch-brown in the female ; the middle tibiae have, be- 

 sides the bristles at the tip, four black bristles on the upper side, 

 which are rather long in the male, but still longer in the female ; 

 on their under side there is in the male only one long black bris- 

 tle, which is very near the root ; in the female there are on the 

 under side, besides the bristles at the tip, three bristles of conside- 

 rable length, of which that which is nearest to the root is also the 

 longest. The middle tarsi are of moderate length, beset only with 

 the usual black hairs, though there are in both sexes on the under 



