[429] DIPTERA 43 



black, polished, the hairs mixed yellow and black, a whitish pruinose 

 spot on lower part of the sternopleura and metapleura ; abdomen black, 

 somewhat velvety, opaque, the first segment, sides of abdomen except 

 hind angles of the third and fourth segment, also the fifth segment and 

 genitalia, polished and having a brassy tinge, a pair of yellow spots on 

 the second, third, and fourth segments, not touching the front nor lat- 

 eral margin of the segments, those on the second the smallest, nearly 

 circular, on the third segment the largest, elliptical, extending length- 

 wise with the segment, those on the fourth rhomboidal ; front legs 

 yellow, the coxa?, posterior side of the femora except at the apex, and 

 a streak on outer side of the tibiae, black, apices of tibia? and the first 

 tarsal joint except its apex, whitish, tibiae greatly dilated at the apex, 

 on the inner side gradually dilated for three-fourths of its length, then 

 slightly narrowed to the apex, on the outer side rather abruptly dilated 

 on the last third of its length, slightly narrowing to the apex, the outer 

 angle prolonged considerably beyond the inner; tarsi dilated, tapering 

 gradually to the fourth joint, the latter slightly narrower than the fifth, 

 the first joint about two-thirds as wide as broadest part of the tibia?, 

 about one and one-half times as long as broad, femora on the posterior 

 and under sides bearing many rather long black bristly hairs, the tibia? 

 and tarsi destitute of hairs ; middle and hind legs black, the knees and 

 apices of the tibia? yellowish, femora bearing many rather long hairs, 

 the tibia? and tarsi destitute of them ; wings grayish-hyaline, brownish 

 at base and tinged with smoky along the anterior veins, stigma yellow, 

 halteres also yellow. 



Female : Differs from the male as follows : Hairs of head largely 

 yellow, front tinged with bronze, face, except the tubercle, grayish 

 pruinose, extending on sides of front to its middle where it is conically 

 expanded toward the center of the front, thorax and scutellum tinged 

 with bronze, their hairs yellow ; abdomen bronze black, polished, the 

 yellow spots nearly circular ; front tibia? gradually and moderately di- 

 lated, their tarsi noticeably widened, middle femora, their tibiae, and 

 first two joints of their tarsi, yellow, both ends of the hind femora and 

 tibiae also yellow, wings not brown at base nor tinged with smoky. 

 Length 7 mm. One male and two females. 



Habitat. Kukak Bay, July i ; Popof Island, July 8 ; Kadiak, 

 Alaska, July 28. 



Type. Cat. no. 5238, U. S. National Museum. 



Readily recognized by the shortness of the lower part of the head, 

 the remoteness of the abdominal yellow spots from the margins of the 

 segments, the absence of hooked bristles on the front femora of the 



