192 DIPTERA OF NORTH AMERICA. [PART IT. 



small bristle, which is on their upper side, not far from the root ; 

 the middle tibiae have only a few bristles ; the hind tibiae have a 

 larger number of bristles, but they are mostly very short ; in the 

 male there is one bristle on the under side, not far from the basis, 

 which is remarkable for its length. The fore tarsi have H the 

 length of the tibiae ; in the male the first joint is very much 

 shortened and not as long as the last one, the second is as long as 

 the three following together, and usually a little blackened on the 

 extreme tip, the three last ones are black and very little decreasing 

 in length ; the last one with somewhat shorter hairs than the two 

 preceding ; in the female the fore tarsi are gradually of a darker 

 black-brownish color towards the tip, and their joints are of a de- 

 creasing length", the first somewhat longer than the two following, 

 but not quite so long as the three following together. The mid- 

 dle tarsi of the male but little exceed the tibiae in length ; their 

 first joint is of a plain structure, but almost 1^ the length of the 

 other joints and blackened at its tip ; the last four joints are black ; 

 the second is as long as the last three together, gradually enlarged 

 towards its end, and at the end on the outside, in consequence of 

 the greater length of the appressed black pubescence, elongated 

 into a kind of projection ; the third and fourth joints have on the 

 posterior side a few erect crooked hairs. The middle tarsi of the 

 female are plain, scarcely shorter than those of the male, towards 

 the tip gradually of a darker black-brown color; their joints are of 

 a decreasing length ; the first is longer than the following two, but 

 shorter than the following three together. The hind tarsi are of 

 the same structure in both sexes, shorter than the tibiae ; their last 

 four joints black ; the first joint is scarcely longer than the third, 

 the second at least as long as the third and fourth together. Hal- 

 teres yellowish. Tegulae with a narrow black margin ; their cilia 

 appear yellowish in a reflected light, seen towards the light, however, 

 blackish, in the female even often black. Wings grayish hyaline, 

 in the male with the posterior margin somewhat wavy, and towards 

 the basis much more pointed than in the female ; the fourth longi- 

 tudinal vein is parallel to the third and ends precisely at the tip 

 of the wing ; the posterior transverse vein is perpendicular and 

 lies upon the middle of the wing. 

 Hob. Illinois. (Le Baron.) 



