136 DIPTERA OF NORTH AMERICA. [PART II. 



black bristles, on the posterior margin of the other segments there 

 are only very short bristles. Tenter as far as the tip yellowish. 

 Hypopygium rounded, small, rather imbedded ; its blackish ap- 

 pendages very short and therefore not distinctly perceptible. 

 Coxa? and feet yellowish ; fore coxae only at the tip with a few 

 black bristles, otherwise in front with short and very delicate white 

 hairs. The short hairs upon the feet are black ; under side of the 

 fore femora glabrous ; middle femora upon the under side with a 

 row of short black bristles. Fore tibiae on the upper side with a 

 dense row of black hairs, upon the first quarter of the hind side 

 with a single very small black bristle. Middle and hind tibiae 

 only with a few short black bristles ; the end of the latter is some- 

 what thickened and of a brownish-black color. Fore tarsi plain, 

 from the tip of the first joint blackened ;■ the first joint not quite 

 as long as the other four taken together. The first joint of the 

 middle tarsi nearly as long as the other four taken together, stalk- 

 like, a little thicker at the end and of a whitish color ; the second 

 joint very much flattened, whitish, the apical margin bordered with 

 black ; the third and fourth joints also flattened, and, with the fifth 

 joint, which is not flat, of a deep black color. Hind tarsi as far as 

 the middle of the second joint brown, then black ; the first joint is 

 a little stouter and shorter than the second and has upon the middle 

 of its under side a black bristle which is a little curved backwards. 

 Wings hyaline, tinged with brownish-gray ; the third and fourth 

 longitudinal veins show towards their end a slight convergency. 



Female. The third joint of the antennae rounded-oval, very 

 much shorter than in the male ; the second joint of the antennae 

 overreaches the inner side of the third only by a rounded lobe. 

 Face less dusty than in the male, very broad, by far not reaching 

 the lower corner of the eye ; its lower part is very convex and 

 protrudes in the shape of a roof, whereby the mouth becomes very 

 large. The black palpi considerably larger than in the male. 

 Feet plain, the hind tibiae not thickened at the end and only very 

 slightly infuscated. Fore tarsi from the tip of the first joint gra- 

 dually becoming more infuscated ; middle tarsi from the tip of the 

 first joint blackened, though the root of the second joint is some- 

 what paler ; hind tarsi at the root brown, black towards the end. 

 The little black bristles upon the under side of the middle femora 

 are missing. The rest as in the male. 



Hab. Sitka. (Sahlberg.) 



