ABT. 8 REVISION OF THE FLY GENUS BELVOSIA ALDKICH 13 



Abdomen subtranslucent yellow in ground color, except a median 

 dorsal stripe which is black. Second segment when viewed from 

 behind covered with yellow pollen at the base, which thins out pos- 

 teriorly; the third segment has a much denser coating of yellow pol- 

 len, which, however, is not distinctly visible in some angles. The 

 hind margins of the second and third segments are shining in all 

 angles; fourth segment smaller than in most species, densely covered 

 with yellow pollen to the apex. First and second segments with 

 single pair of median marginals, those on the first quite small; third 

 and fourth segments with a marginal row of about eight. Geni- 

 talia a little larger in proportion than in some of the species, outer 

 forceps very slender and straight, blunt at tip; inner forceps broad at 

 base with long hairs on the middle portion which extend forward 

 beyond the apices. 



Legs black ; front pulvilli small, shorter than last tarsal joint. Hind 

 tibia with irregular bristles, one larger at middle. 



Wings decidedly brown, the veins a little yellow toward the base. 



Calypters almost pure white. 



Length, 9-11 mm. 



Redescribed from the single male type, Vieques Island, P. R., Feb- 

 ruary, 1899 (August Busck); and from seven additional males col- 

 lected at Chosica, Peru, 3,000 feet, May 8 and 9, 1913, on flowers of 

 Mikania (C. H. T. Townsend). 



BELVOSIA OCHRrVENTRIS Van der Walp 



Cnephalia ochriventris Van der Wulp, Bio'ogia, Dipt., vol. 2, 1890, p. 47. 



Male. — Front at vertex 0.35 of the head width, not widening very 

 rapidly for a short distance. Parafrontals yellow pollinose, near the 

 vertex showing a darker and subshining ground color. Frontal bris- 

 tles in three irregular rows, with two pairs of proclinate orbitals; face, 

 parafacials, and cheeks silvery with a tinge of yellow; posterior orbits 

 more densely yellow. Antennae reddish about to the arista, remain- 

 der black; third joint rather slender except at base, three times the 

 second. Arista distinctly flattened but the apex acute. Vibrissae 

 considerably above the oral margin, the distance equal to the length 

 of the second antennal joint; facial ridges with about eight bristles 

 extending up almost to the arista. Palpi yellow. Parafacials with 

 pale yellow hairs above in an uncommonly large patch; cheek with 

 hairs of same color, and there are some additional ones on the facial 

 ridges outside the bristles; beard pale yellow. 



Thorax black with dense, yellowish-gray pollen showing only very 

 narrow, longitudinal lines. Scutellum rather yellow in ground color 

 with dense yellow pollen. 



Abdomen red in ground color except in an almost hidden median 

 stripe; first segment subshining at the sides, remainder of the abdo- 



