63 
Abdomen wholly shining and destitute of pollen ; front in 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, antennas 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, 1 mm. BiscayneBay, 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- 
ehaetae, third joint of antennae three times as long as wide; 
length, .'>..") mm. St. Augustine, Fla. (Proceedings Acad. Xat. 
Sci. rhila., p. 313; Sept., 1895.) 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 
macroeha t;c: 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. Xews, Vol. 
Ill, p. 131 ; June, 1892 : Myothyria.) vanderwulpi Town. 
Genus DIDYMA v. d. W. 
Dichjma van der Wulp, Biologia Cent.-Amor., 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 tibia' on the outer side ciliate with short 
bristles: 
1. Second, or at least the third, abdominal segment bearing discal 
macrochaetae 2. 
Second and third, ablominal segments destitute of discal macro- 
cha^ta*, palpi yellow, hind crossvein slightly curved, nearer to 
the bend of the fourth vein than to the small crossvein; length, 
6 mm. Lake Worth, Fla. (Biol. Cent.-Amer., Dipt., Vol. II, 
p. 163; June, 1890.) inconspiam v. d. W. 
2. Hind crossvein curved S-shape, nearer to the bend of the fourth 
vein than to the small crossvein, palpi j^ellow; length, 1.5 mm. 
Kirkwood, Mo. (Biol. Cent.-Amer., Dipt., Vol. II, p. 100; June, 
1890.) exigua v. d. W. 
Hind crossvein almost straight, midway between the small and the 
bend, palpi black: length, 5 mm. District of Columbia. (Biol. 
Cent.-Amer., Dipt., Vol. II, p. 161; June, 1890.) . . ti inula v. d. W. 
