1C8 DIPTERA OF NORTH AMERICA. [PART III. 



is rounded in such a manner that the apex is equidistant from 

 the anterior and the posterior margins ; the second longitudinal 

 vein, the course of which is rather wavy, has its strongest sinu- 

 osity only little beyond the small crossvein ; the anterior end of 

 the latter is nearer to the root of the wing than its posterior end, 

 so that its position is entirely oblique ; the posterior crossvein 

 is oblique in the opposite direction, as its anterior end is nearer 

 to the apex of the wing than the posterior. The coloring of the 

 surface of the wing is a brown of unequal intensity ; the design 

 consists of the three hyaline bands usual in this genus ; the por- 

 tion of the surface of the wing beyond the third band is dark 

 brown, with a large yellowish-brown spot, which leaves in the 

 submarginal cell only a dark brown border along the margin of 

 the wing, and, so far as it extends in this cell, also somewhat 

 crosses the third longitudinal vein ; the interval between the 

 second and third bands, which has the shape of a crossbaud, is 

 yellowish-brown, margined with dark brown on each side, and 

 also dark brown at the end ; the interval between the second 

 and first crossbands is dark brown, with a large yellowish-brown 

 spot, which fills up the basis of the submarginal cell, and, to a 

 great extent, that of the first basal cell, so that in the former 

 almost nothing is left of the dark brown color, in the latter only 

 a border ; the root of the wing is tinged with yellowish-brown 

 as far as a little beyond the humeral crossvein ; towards the 

 place of insertion of the wing, however, the dark brown color 

 appears again ; the posterior angle of the wing, lying behind 

 the first crossband, is only tinged with gray. The hyaline 

 crossbands are distinctly broader than in T. flexa, and the last 

 of them is much nearer the apex, so that the dark coloring of 

 the latter assumes the shape of a broad crossband. The first 

 hyaline crossband is so oblique that it almost assumes the 

 appearance of a longitudinal stripe ; it starts, as in T. flexa, 

 from the basis of the third posterior cell, but is broader than in 

 that species, and does not diverge from the fifth vein; gradually 

 becoming more pointed, it ends some distance from the margin 

 of the wing, and differs but little in intensity of coloring from 

 the gray posterior angle of the wing; the second pale crossband, 

 which has a very oblique position and is only gently curved, runs 

 from the tip of the costal cell to the posterior corner of the discal 

 cell; however, the tip of the costal cell itself is hyaline to a 



