AMERICAN DIPTERA. 195 



the frontal orbits and the ocellar tubercle black. Thorax thinly 

 brownish pruinose; the prothorax clothed with dense light pile; the 

 dorsum of the mesothorax with a median geminate dark stripe, not 

 pronounced in all specimens; the pleurae bare, except for a tuft of 

 fine yellow pile on the sternopleurEe. There is no pile or bristles in 

 front of the pale halteres. Bristles on the anterior two-thirds of the 

 thorax short and chiefly black; those on the posterior third longer, 

 and about equally divided between black and fulvous, except for a 

 row of stout bristles in front of the origin of the transverse suture and 

 extending backwards over the posterior callosity, which are wholly 

 fulvous. Bristles of scutellum fulvous. Abdomen polished black, 

 often obscured somewhat in the male, and quite perceptibly in the 

 female, except on the last two segments, by a grayish bloom, but in 

 the male never losing the polished black color. The anterior and pos- 

 terior margins of the segments 1—5 with lighter pruinose cross-bands 

 not at all prominent; entire male abdomen with fulvous pile, which 

 is quite long in the proximal portion, but becoming shorter and de- 

 pressed distally. The pile of the female abdomen is not as pronounced. 

 Male genitalia red, in two specimens black; the last, and often the 

 last two segments of the female abdomen are red, as are also the 

 spines of the ovipositor. Legs deep yellow except the basal thirds of 

 the front and middle and basal three-fourths of the hind femora, which 

 are black; pile and bristles wholly yellow; pulvilli yellow; claws black, 

 yellow at base. Wings with a dark tinge except the proximal portion 

 of the anal cell and the squama in the male, which are milky white; 

 first posterior cell slightly narrowed at the margin, fourth posterior 

 cell wide open; anal cell open. 



Type. — British Museum. Type of obscuriventris is at the 

 M. C. Z. 



Habitat. — Lake Tahoe and Webber Lake, Cal., July 19 

 (Osten Sacken) ; Summit Sierra Nevada, Sisco, Cal., 6,000 ft.; 

 Beaver Creek Hills, Beaver Co., Utah. 



Described from thirteen males and twelve females, seven- 

 teen of which were collected by Baron Osten Sacken and are 

 at the M. C. Z., three at the Am. Ent. Soc. of Phila., three at 

 the Brooklyn Institute, and two at the Massachusetts Agri- 

 cultural College. 



Stenopogon jubatiis. 



Scleropogon jubatus Coquillett, Invertebrata Pacifica, I. 

 (^ Length 20 mm. — Black; the abdomen polished, clothed with com- 

 paratively long and fine hair; thoracic dorsum with sordid white hair 

 and bristles on the sides, but from the pronotum to the scutellum with 



TRANS. AM. ENT. SOC., XXXV. JUNE, 1909. 



