274 ERNEST A. BACK. 



interrupted cross-band; on the two following segments, this cross-band 

 is broader and only subinterrupted by a deep emargination; the sixth 

 segment is entirely covered with gray pollen, except a small black 

 triangle in front; hypopygium black, with black pile, and only a small 

 fringe of minute yellowish hairs at the extreme end. Legs black, 

 ornamented as described above; claws whitish, with black tips. Wings 

 uniformly blackish; veins normal; fourth posterior cell hardly co- 

 arctate at all." 



Type. — M. C. Z. A single male specimen. 



Habitat. — Webber Lake, Sierra Nevada, Cal. (Osten Sacken) . 



A pretty species, easily recognized by the long, slender, 

 silvery piled front tibiae and the similar silvery pile of the 

 hind legs. 



Cyrtopogoii piilcher n. sp. 



% — Length 12-13 tnm. — Black, all the tibise and tarsi, except their 

 tips, yellowish-red; the front tibiae on the outer side with fine silky 

 white pile, very sparse and hardly perceptible at the base, but increasing 

 in amount toward the tip; the front tarsi with similar pile much longer 

 on the outside, where it is arranged in tufts corresponding to the 

 tarsal segments. Third antennal segment reddish. Segments 2-5 of 

 abdomen with white pruinose fasciae; segments 1-2 on the sides with 

 long yellowish pile, remaining segments nearly bare. Face, front and 

 occiput, grayish pruinose; middle of gibbosity with golden pile; pile 

 on rest of face, palpi, basal segments of antennae, front, and upper 

 occiput black, that of beard and proboscis white. Third segment of 

 antennas reddish, compressed, sublinear, not coarctate distally nor 

 noticeably constricted proximally; style rather distinct, about one- 

 fourth as long as the third segment tapering to a point. Thoracic 

 dorsum polished black with a bloom ranging from nearly white to a 

 dull olive and black; geminate stripe dull olive, distinct, divided by 

 a fine white pruinose line; viewed from before, there appears two 

 rounded dark spots on each side in front of the transverse suture in- 

 completely surrounded by a nearly white bloom; this whitish bloom, 

 closing the spot behind, crossing the suture, extends backward but 

 does not reach the scutellum, as does the narrow pruinose line dividing 

 the geminate stripe; thus leaving a limited area on the rear of the 

 dorsum glistening black. Pleurae and base of scutellum grayish-white 

 pruinose; the posterior border of the latter polished black. Pile of 

 and bristles of dorsum and long pile on the convex scutellum black; 

 that of the pleurae likewise black, but before the halteres yellow and 

 black mixed. Halteres white. Abdomen polished black, segments 

 2-5 with white pruinose posterior cross-bands interrupted on segments 

 4-5; sides of segments 1-2 with rather long, pale yellow pile which, 

 becoming shorter, extends up onto the tergum, being more noticeable 



