252 DIPTEllA OF NORTH AMERICA. [PART II. 



sharply limited transverse bands, which are broader upon the 

 hind segments than upon the anterior ones. Pubescence of the 

 abdomen black, whitish only on the anterior part of the lateral 

 margin and of the venter ; the black bristles before the hind mar- 

 gin of the single segments are of a considerable, but not striking 

 length. The small hypopygium is black with small black lamella?. 

 Coxae and feet black, the fore tibiae only in immature specimens 

 brownish-black ; fore coxae and all femora with a green reflection, 

 the fore coxae have a rather conspicuous white pubescence, among 

 which are inserted some black bristles ; on the under side of the 

 femora there is a long erect pubescence, which has only very near 

 their tip a black, otherwise everywhere a whitish coloring. Tibiae, 

 besides the usual short black pubescence, with a moderate number 

 of black bristles, which may be easily overlooked on the hind tibiae, 

 as they are rather short and to be found only upon their outside. 

 First joint of the fore tarsi extremely elongated, about as long as 

 the tibiae and nearly twice the length of the four following joints 

 taken together ; upon the outside, towards the tip, fringed with 

 black bristles ; the second and third joints are of equal length, both 

 very short, taken together only as long as the fourth joint ; the 

 fifth joint distinctly shorter than the fourth, but longer than the 

 second and third taken singly. Middle tarsi plain, their first 

 joint nearly as long as the tibia and at least If times the length 

 of the four following joints taken together ; upon the front side 

 with a short and delicate fringe-like pubescence of a black color ; 

 the following joints of a gradually decreasing length. Hind tarsi 

 considerably shorter than the tibiae, their first joint hardly once and 

 a half the length of the four following taken together, which gra- 

 dually decrease in length and are not thickened. Halteres black- 

 ish-brown, sometimes more pale dingy -yellow. Tegulae with a broad 

 black margin and with long black cilia. Wings hyaline With the 

 usual siphon-like black picture, both bands, which form this pic- 

 ture, are perpendicular, broad, always connected on the fore mar- 

 gin, and generally upon the fourth longitudinal vein, abbreviated 

 before the hind margin ; the first longitudinal vein reaches nearly 

 to the middle of the fore margin ; the anterior branch of the 

 fourth longitudinal vein diverges from it at an angle of 70 to 80° 

 and turns afterwards at a rounded right angle towards the mar- 

 gin, which it reaches before the extreme apex, near the tip of the 



