68 
vittie; three postsutural and two sternopleural macrochiete ; scutellum 
bearing three pairs of long marginal macrochietie; abdomen shining, 
a pair of marginal macrochete on the first and second segments and 
a marginal row on the third; genitalia projecting at least twice the 
length of the fourth abdominal segment beyond the latter, curved 
beneath the abdomen; first segment of abdomen in the female greatly 
dilated ventrally; hind tibiz not ciliate with bristles; front pulvilli in 
female one-half as long as, in the male about as long as, the last tarsal 
joint; wings hyaline, a single bristle at base of the third vein, other 
veins bare, apical cell open at the extreme tip of wing, bend of fourth 
vein arcuate, hind crossvein nearly perpendicular, midway between the 
small crossvein and bend of the fourth vein; calypteres white; length, 
4to5mm. Southern Illinois. Two males and one female collected by 
Charles Robertson. Type No. 3559, U.S. National Museum. .atra n. sp. 
Genus LEUCOSTOMA Meig. 
Leucostoma Meigen, in Illiger’s Magazin fiir Insektenkunde, Vol. II, p. 279; 1803. 
Clelia Desvoidy, Kssai sur les Myodaires, p. 255; 1830. 
Psalida Rondani, Dipterologix Italicee Prodromus, Vol. I, p. 76; 1856. 
This synonymy is given by Schiner! and repeated by Brauer and 
Bergenstamm.? Our species are black, the palpi sometimes yellow; 
three sternopleural and usually three postsutural macrochete : 
1. Thorax shining, almost destitute of pollen, frontal vitta at the 
lowest ocellus narrower than either side of the front at the same 
point, scutellum bearing three pairs of marginal macrochiete, 
first two segments of abdomen each bearing a marginal pair, 
palpi yellow: #2 P22 ene ae oe ee ee 2. 
Thorax opaque, densely gray pollinose, frontal vitta of female at the 
lowest ocellus twice as wide as either side of the front, palpi 
black; front of female one and one-third times as wide as either 
eye, two pairs of orbital bristles, cheeks one-sixth as wide as the 
eye-height, antennw two thirds as long as the face, the third 
joint as long as the second, arista thickened on the basal three- 
fifths, the penultimate joint shorter than broad; thorax not dis- 
tinetly vittate, scutellum densely gray pollinose, bearing two 
pairs of long marginal macrochietie, abdomen shining, basal 
haif of the last three segments gray pollinose, first two segments 
destitute of macrochietie, those of the other two segments very 
short, genitalia of female claw-like, curved beneath the body; 
wings hyaline, third vein bearing two or three bristles near the 
base, hind crossvein straight, one and one-third times as long 
as the last section of the third vein, situated midway between 
the small crossvein and the bend; calypteres white; length, 
5mm. Clementon, N. J. A single female specimen collected 
1Fauna Austriaca, Vol. I, p. 542; 1862. 
2 Zweif. Kais. Mus, Wien, VI, Index; 1893. 
