288 ERNEST A. BACK. 



C. princeps, has the claws whitish, with black tips; both 

 species were found in the same locality; they are too different, 

 however, to be taken, without further evidence, for the sexes 

 of the same species. The other species of Cyrtopogon, de- 

 scribed in this paper (Western Diptera) , have the claws black 

 and more or less brownish or reddish at the base only. C. 

 profusus and nugator are the only species which, in this respect, 

 resemble the two above-mentioned ones." 



Cyrtopogon evidens. 



Cyrtopogon evidens Osten Sacken, West. Dipt., 306, 1876. 

 % 9- — Length % 7-8 mm.; o 10-11 mm. — First abdominal segment 

 with an uninterrupted white cross-band on the posterior margin; stripes 

 on the thorax very distinctly marked, brown; the longitudinal divid- 

 ing line of the geminate stripe is very distinct; the portion of the 

 lateral stripe anterior to the thoracic suture is large, conspicuous, of 

 a rich dark brown; white cross-bands on abdominal segments entire, 

 somewhat interrupted on the fifth segment only, rarely (in the male) 

 on the fourth segment. In the male the brownish tinge of the distal 

 half of the wing is more marked than in C. rejectus, nugator, positivus, 

 or sudator. 



Type. — M. C. Z. Three male and four female specimens. 



Habitat. — Webber Lake, Sierra Nevada, Cal. (July 22-24, 

 Osten Sacken). 



The original description is short, but to the point. I will 

 add the following. Face and front broad, wholly and densely 

 grayish-white pruinose, as is also the occiput. Pile of face 

 and front wholly black, and nowhere so dense as to obscure 

 the dense bloom. Antennae wholly black. Pleurae and scutel- 

 lum grayish pruinose. The two brownish stripes on dorsum 

 and the whitish pruinose stripe separating them are very dis- 

 tinct, and together with the large spots anterior to the trans- 

 verse suture, which are most prominent when viewed from 

 above, and the markings of the abdomen make this an easily 

 recognized species. Pile of thoracic dorsum short, erect, 

 bristles black, as are those on scutellum. Legs wholly black; 

 coxae and under side of all the femora with silky white pile; 

 tibiae with long black bristles. Trichostical pile and that on 

 side of segments 1 and 2 of abdomen fine and white. 



