264 DIPTERA OP NORTH AMERICA. [PART II. 



upper side, fringed with a row of hair-like bristles, which are 

 alternately of remarkable length, and the last of which much ex- 

 ceeds all the others in length; Middle tibiae with a moderate 

 number of hair-like black bristles, which are also distinguished 

 by their unusual length, especially those upon their upper side. 

 Hind tibiae only upon the upper side with short bristles, which 

 are but little distinguished from the usual minute hairs. 

 Fore tarsi at least, twice the length of the tibia?, very slender ; 

 their first joint somewhat longer than the four following taken 

 together, upon its upper side with a regular row of propor- 

 tionally very long hair-like black bristles ; the following joints of 

 rapidly deci'easing length ; the third, at the upper side of the tip, 

 with a single bristle-like black hair ; the fifth joint blackish-brown. 

 Middle tarsi very slender, about once and a third the length of the 

 tibia?, from the tip of the third joint blackish-brown ; their first 

 joint about over 1^ the length of the four following taken to- 

 gether, the length of which is quickly decreasing ; upon its upper 

 side it is regularly ciliated with bristle-like hairs; this fringe con- 

 tinues over the upper side of the three following joints, but there 

 it is shorter, more delicate, and closer ; the last joint is not ciliated, 

 but has upon its upper side a short, appressed, snow-like pubes- 

 cence, which is not very distinct. Hind tarsi not quite as long 

 as the tibiae ; their first joint yellowish-bro>svn, distinctly longer 

 than the following taken together ; these are blackish-brown and 

 of decreasing length. Halteres yellowish ; tegula? with a broad 

 black margin and long black cilia. Wings somewhat nai'row, 

 hyaline, with blackish-brown veins, not ciliated on the fore mar- 

 gin, the first longitudinal vein reaches nearly to the middle of the 

 fore margin ; the anterior branch of the fourth longitudinal vein 

 diverges at a rather acute angle and turns towards the margin at 

 a rounded right angle, reaching it before the apex, near the tip of 

 the third longitudinal vein ; hind transverse vein very oblique, 

 little sinuated. 



Female. It resembles the male very much. Face somewhat 

 broader. Bristles on the second joint of* the antennae, the arista, 

 the bristles upon the ocellar tubercle, at the upper corner of the eye, 

 upon the upper side of the thorax, and upon the scutellum shorter ; 

 the bristles before the incisures of the abdomen are very consider- 

 ably shorter ; on the venter, as it seems, there are none at all. 

 The black pubescence upon the upper side of the abdomen is less 



