63 
Abdomen wholly shining and destitute of pollen; frontin male three- 
fifths as wide as either eye; wholly black, no orbital bristles in 
male, frontals descending below the arista, facial ridges bristly 
to the lowest frontal bristles, antennie as long as face, the third 
joint six times as long as the second, arista thickened on the 
basal two-fifths; thorax shining, a whitish pollinose vitta in the 
middle in front of the suture, lateral edges also whitish polli- 
nose; wings hyaline, two bristles at base of third vein, calyp- 
teres whitish; length, 4 mm. Biscayne Bay, Florida. <A single 
male specimen collected by Mrs. A. T. Slosson... nitens n. sp. 
10. Front of female only two-thirds as wide as either eye, facial ridges 
bare, scutellum bearing only two pairs of long marginal macro- 
cheetie, third joint of antenne three times as long as wide; 
length, 3.5mm, St. Augustine, Fla. (Proceedings Acad. Nat. 
SCs Masa), Ol ICDs LOOO~\e x22 8 - «eek Soe maculosa Coq. 
Front of female almost as wide as either eye, facial ridges bristly on 
the lower half, scutellum bearing three pairs of long marginal 
macrochetw; basal three-fifths of the last three segments of 
abdomen, except a dorsal vitta on the first two, gray pollinose; 
length, 5 mm. Los Angeles County, Cal. (Entom. News, Vol. 
Il, p. 131; June, 1892: Myothyria.).....=.. vanderwulpt Town, 
Genus DIDYMA v. d. W. 
Didyma van der Wulp, Biologia Cent.-Amer., Diptera, Vol. II, p. 156; June, 1890. 
Our species are black, with at most the palpi and sides of the abdo- 
men partly yellow, hind tibiw on the outer side ciliate with short 
bristles: 
1. Second, or at least the third, abdominal segment bearing discal 
PERCE OS Mast Peet eam ere anne ee re te oe Ar Se 2. 
Second and third, ab:lominal segments destitute of discal macro- 
cheete, palpi yellow, hind crossvein slightly curved, nearer to 
the bend of the fourth vein than to the small crossvein; length, 
6mm. Lake Worth, Fla. (Biol. Cent.-Amer., Dipt., Vol. II, 
ee LGoieimMes NOOO. ek eth Se oS ot inconspicua v. d. W. 
2. Hind crossvein curved S-shape, nearer to the bend of the fourth 
vein than to the small crossvein, palpi yellow; length, 4.5 mm. 
Kirkwood, Mo. (Biol. Cent.-Amer., Dipt., Vol. II, p. 160; June, 
MESO aor es 2 ats. ee PRE EPL Aeris 6 IG tie) ea Rled exigua v. d. W. 
Hind crossvein almost straight, midway between the small and the 
bend, palpi black; length, 5mm, District of Columbia. (Biol. 
Cent.-Amer., Dipt., Vol. I, p.161; June, 1890.).. timidayv.d.W. 
