AMERICAN DIPTERA. 287 



It is seldom that the geminate stripe extends from the an- 

 terior margin of the mesonotum to the base of the scutellum 

 or so sharply defined as in this species. 



Cyrtopogon cretaceus. 



Cyrtopogon cretaceus Osten Sacken, West. Dipt., 302, 1877. 

 " 9 • — Length 10.5 mm. — Thoracic dorsum rather evenly clothed with 

 a grayish-white bloom, completely concealing the ground color; the 

 coloring of this bloom is rather uniform, a geminate median stripe is 

 hardly perceptible; posterior callosities black, polished; scutellum 

 black, brownish pruinose at the base; pleurae with dense yellowish- 

 gray bloom. Abdomen polished, black; segments 2-5 each with a 

 moderately broad cross-band of yellowish-white bloom on the hind 

 margins. Face and front densely covered with yellowish-gray pollen; 

 mystax white above, black below above the mouth; vertex and upper 

 part of the occiput with black pile; lower part with long white hair. 

 Third antennal segment red or reddish, the style black. Thorax with 

 fine black erect pile on the front part, and with whitish pile on the back 

 part of the dorsum; the base of the scutellum with whitish pile, the 

 remainder with long black pile. On the pleura? the fan-like fringe of 

 pile in front of the halteres is mixed of white and black hairs; the sub- 

 humeral callosities and the lower part of the pleura? are beset with 

 white hairs; but, in front of the root of the wings there is some black 

 pile. The abdomen on the sides is beset with white pile; it is long and 

 tuft-like at the base, but becomes rather rare beyond the third seg- 

 ment. Legs uniformly deep black, polished; they are much less stout 

 than in C. callipedillus 9 ; the tibia?, especially the front pair, are 

 more straight; front tarsi rather long, the pile and bristles on the 

 four anterior legs are black, except some white pile on the under and 

 hind side of the femora; the hind femora and tibia? are beset with 

 white pile, which is particularly dense on the upper side of the hind 

 tibia?; the bristles, as usual, are black; the first segment of the hind 

 tarsi shows, in a reflected light, some short, white pile; otherwise the 

 tarsi are uniformly black. Claws whitish, with black tips. Wings 

 grayish hyaline; venation normal. 



Type. — M. C. Z. Two female co-types. 



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

 July 22, 1876). 



This species cannot be taken for any other Cyrtopogon now 

 known to me because of the uniformly grayish-white and 

 dense bloom on the face, front and dorsum, where it is very 

 conspicuous. The geminate stripe and other markings are so 

 nearly obsolete that they do not spoil to any degree the wholly 

 grayish-white effect. " This species," says Osten Sacken, " like 



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



