34 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 83 



third black, five or six times longer than second which is largely 

 yellow ; arista blackish, finely pubescent, thickened on proximal two- 

 fifths, basal segments short; palpi slender, pale yellow, bearing a 

 few long black hairs beneath on apical half ; cheek bare above lower 

 margin, gray pollinose, clothed with pale hairs; eyes distinctly 

 hairy. 



Thorax and scutelliim black, covered with thick gray pollen; 

 mesonotum with four narrow dark stripes, often poorly defined, 

 interrupted at suture and stopping far before base of scutellum; 

 two or three acrostichal bristles usually developed behind the su- 

 ture, other details of chaetotaxy as in validwervis] postscutellum 

 thinly pollinose and membranous above; infrasquamal hairs pres- 

 ent; calypters semitransparent, white with a tawny tinge. 



Abdomen black, largely gray pollinose; hind margins of last 

 three segments black and subshining when viewed from above, but 

 pollinose or subpollinose in most other views, first segment with 

 conspicuous pollen on the sides above ; one pair of median marginal 

 bristles present on first and second segments, the third and fourth 

 each with a marginal row, no discals on dorsal surface of fourth 

 segment; genital segments small, black, retracted; inner forceps 

 united, slender, clothed with brownish hairs behind near base, 

 flattened and shining beyond middle, apex minutely notched ; outer 

 forceps shorter than inner ones, tapering uniformly to a blunt tip, 

 tinged with yellow^; penis simple, short, blackish, apex bearing a 

 short pale membrane. 



Legs black, basal segments and knees yellowish ; mid tibia with 

 a whorl of three bristles near middle, the one on outer front side 

 stout ; hind tibia with a scattering row of irregular bristles on outer 

 posterior edge ; claws and pulvilli elongate. 



Wings subhyaline; veins yellow, bare except third, which has 

 hairs extending almost to small cross vein; fourth vein with a 

 rounded almost rectangular stumpless bend, beyond rather deeply 

 concave to costa; last section of fifth vein about ono-fourth as long 

 as preceding section; apical cell open well before the wing tip; 

 costal spine strong; epaulets red. 



Female. — Front at vertex 0.282 of the head width (average of 

 five: 0.28; 0.28; 0.28; O.ai; 0.2G) ; pollen on para frontals, meso- 

 notum and abdomen with a distinct pale brassy tinge; outer verti- 

 cals developed, orbitals two pairs; antennae shorter than face, 

 third segment slender, j^ellow at base, about four times the length 

 of second; arista short haired to the tip; first abdominaj segment 

 without median marginals, the fourth with discals above; fore 

 tarsal segments compressed and swollen, claws and pulvilli atrophied. 



Length. — G to 8 mm. 



