48 BULLETIN 31, UNITED STATES NATIONAL MUSEUM. 



subtiiangular expausion; third segment anteriorly with an interrupted 

 metallic greenish cross-baud, nearly half as broad as the segment, but 

 expanded on the sides along the whole lateral margin ; the posterior 

 half of the segment is of a velvet-black, which does not quite reach the 

 lateral margin; the fourth segment is like the third except that the olive 

 green cross-band is not interrupted, or only sub-interrupted, and con- 

 nected by a longitudinal stripe of the same color, cutting through the 

 velvet-black portion, with the narrow hind margin of the segment; thus 

 the velvet-black on this segment forms a broad, interrupted cross-band, 

 narrowly reaching the lateral margin; fifth segment and hypopygium 

 metallic green. Femora metallic green ; knees yellowish brown ; tibiae 

 yellowish brown or brownish yellow at the base, darker toward the tip, 

 especially of the last pair; tarsi black, first joint of the middle tarsi 

 brown; first joint of the hind tarsi incrassate. Wings subhyaline; 

 stigma brownish yellow. 



Six specimens from the Pacific regions, four from Colorado, and three 

 from Arizona, I have examined, and it is a little singular that only males 

 are yet known. 



Melanostoma obscurum. 



Syrphuff ohHcmrus Say, Amer. Eut., i, jtl. xi; Compl. Wr. i, 23; Wiedemann, 



Auss. Zw. lus. ii, 131 (translation from Say). 

 Melanostoina ohficiira Osten Sacken, Cat. Dipt., 121. 



Habitat. — Atlantic States! 



3,9. Length, C to S™'". Head metallic greenish black, shining ; face, 

 except the tubercles and cheeks, thinly covered with grayish pollen, on 

 the sides forming indistinct ripples, through which the ground color 

 shows more plainly ; tubercle not prominent, not jutting so far forwards 

 as the epistoma. Antennae black, third joint brown, more or less red- 

 dish below, or even wholly reddish. Frontal and vertical triangles more 

 shining, with black pile. Thorax shining greenish black, pile blackish 

 on dorsum, on the scutellum intermixed with yellowish, on the pleurjB 

 wholly yellowish. Abdomen velvety black, narrowly oval, the second 

 segment a little broader behind ; first segment metallic, shining ; second 

 segment on the sides with ti semi-oval bronze spot, extending on the 

 lateral margin.s the whole length of the segment ; third and fourth seg- 

 ments each with a large metallic, somewhat coppery, triangular spot oa 

 each side of the base; third segment with a small triangnlar spot in the 

 middle behind, sometimes extending sleiitleriy forward ; fourth segment 

 with a median stripe dilated on the hind margin ; remaining segments 

 shining. Hind legs blackish, the tibite and tip of femora yellowish or 

 brownish ; front and middle legs yellowish red, femora at base, and tip 

 of tarsi, black ; hind metatarsi in the male slightly thickened. Wings 

 nearly hyaline. 



Six specimens : Mount Washington (William Patton, G. Dimmock), 

 Connecticut, and Pennsylvania (Keen). 



