OSTEN SACKED ON WESTERN DIPTERA. 319 



metallic-greenish 5 wings subbyaline, with a double grayish spot on the 

 great cross-vein, and a similar larger spot on the last section of the 

 fourth vein ; anal appendages of the male narrow, white, blackish at 

 the base. Length 3.5-4,5'"". 



Face brownish-yellow, narrow above, broader below ; antennae black ; 

 the ground-color of the frout is concealed under a grayish pollen. 

 Thorax above with a dense gray pollen, almost concealing the coppery 

 ground-color ; tAvo approximate brown lines in its middle stop some dis 

 tance before reaching the scutellum ; between their end and the scutel- 

 lum, an opaque dark brown spot. Pleurae coppery, with greenish re- 

 flections, slightly pruinose. The scutellum, with two bristles, is green- 

 ish, coppery, or purplish. Abdomen (very much shrunken and with- 

 drawn in ray specimens) coppery, pruinose above, brilliant coppery, 

 and greenish on the sides. Anal appendages ribbon-like, white, blackish 

 near the root. Legs metallic-green or coppery, with purple reflections ; 

 tarsi black. The structure of the legs agrees in the main with the de- 

 scription of the legs of 8. filifer Loew (Monogr., ii, p. 210). Halteres 

 whitish. Wings subhyaline, their root yellowish ; costa yellowish- 

 brown before its junction with the first vein ; a double grayish spot on 

 the great cross-vein, and a similar larger spot on the last section of 

 the fourth vein ; the latter is well defined on the proximal, and evanescent 

 on the distal side. 



Kab. — Webber Lake, Sierra Nevada, July 23-24. Three males, 

 found resting on stones on hill-sides. 



This species differs from 8. filifer Loew (Fort Eesolution, Hudson's 

 Bay Territory) in the coloring of the wings, which have no longitudinal 

 gray streaks between the veins, the color of the anal appendages, which 

 are not yellow at the end, etc. Nevertheless, the resemblance between 

 the two species must be very great. 



2. SCELLUS MONSTROSUS n. sp. — Male. — Thorax browoish-gray, with 

 several rows of brown dots, on which the bristles are inserted, and two 

 approximate brown lines; wings tinged with brownish; anal append- 

 ages of the male at least as long as the abdomen, white ; their end 

 brownish-yellow, inverted-spoonshaped. Length 6-7""" (without the 

 appendages). 



Face brownish-ocher-yellow ; antennai black; front dull greenish- 

 gray; inferior orbit beset with yellow hair; the superior with stiff, 

 black spines. Ground-color of the thorax concealed under a thick 

 grayish-brown pollen ; three rows of brown dots, in linear groups of 

 three or four, bear the usual dorsal bristles; on each side of the inter- 

 mediate row, there is an uninterrupted brown line, reaching to the scu- 

 telUim ; the coppery ground-color of the thorax is visible on the dorsum 

 above the wings; a large, coppery, shining spot on the upper part of 

 the pleurae; a smaller one at the foot of the halteres; abdomen copper- 

 colored ; halteres yellow, the extreme root brownish ; tegulae with yel- 

 low cilia. Anal appendages at least as long as the abdomen, ribbon- 



