80 PROCEEDINGS OF THE NATIONAL MUSEUM. vou. 62. 
few black hairs in front of the wing base. Halteres blackish, the 
knob silvery gray pollinose. 
Abdomen black, entirely covered with silvery white or gray pollen, 
the pile white, that on the dorsum reclinate and with a silvery caste. 
Genitalia blackish, largely thin gray pollinose, the ends of upper for- 
ceps reddish and with a tuft of black bristles (fig. 110), the bristlelike 
hairs of hypandrium almost all black, most of the pile of upper for- 
ceps shorter and whitish. femora black, white pilose, tibiae brown- 
ish yellow with darker tips; base of tarsi brownish yellow, the rest 
black. Wings gray hyaline, stigma blackish; veins black, the cross 
veins and fork of Rs clouded brown; cell M-3 wide open. 
Female.—Length 11 to 12 mm. Like the male, but without the 
silvery white pollen and with shorter white pile. Frons much wider 
below than above, the upper half gray pollinose with short whitish 
and black pile, the lower half silvery gray pollinose, between the 
colors on each side a velvety black triangular mark, broad on the 
eye margin, the narrow part not reaching the center of the frons. 
Outside the base of antennae a dark-gray spot. 
The two thoracic vittae are yellowish gray, a faint suggestion of a 
median stripe. Mesonotum with reclinate whitish pile, the erect 
black pile shorter than in male. First abdominal segment gray pol- 
linose, the second and third largely semishining blackish, the lateral 
margins and posterior margins to near the middle gray pollinose; 
base of fourth segment and middle of segments four to seven gray 
black, the sides gray pollinose. Pile of the first three segments recli- 
nate yellowish white and erect white, longer on the first; segments 
four to seven short erect black pilose. Genitalia largely shining black, 
with short, dense, erect black pile. Venter entirely gray pollinose, 
posterior margins of second and third segments yellowish white. 
Wings as in the male. 
Type locality.—California. 
Type.—iIn Kansas University collection. 
Distribution.—The distribution according to 26 males and 14 
females is: 
Washington: Forks, Clallam County, July 2 (E. P. Van Duzee), 
[Cal. Acad. Sci.]; Skykomish River, May 3, 1892 [Cornell]. 
Oregon: Hood River, May 10 to June 6 (Cole), [Cole]. 
California: Lagunitas Creek, April 15 (Osten Sacken), and Marin 
County. (H. Edwards), [M. C. Z.]; Stanford University, April 27 to 
May 10 (Cole), [Cole]. 
Genus TABUDA Walker. 
1852. Tabuda WALKER, Ins. Saund., Dipt., vol. 1, p. 197. 
Walker’s characterization of his genus is as follows: 
Allied to Apatomzya, but there are five posterior areolets; the first is long; the 
second and third short and of equal length; the fourth is about twice the length of the 
