Vf^ 



63 



Abdomen wholly shining and destitute of pollen ; front iu male three- 

 fifths as wide as either eye; wholly black, no orbital bristles in 

 male, froutals descending below the arista, facial ridges bristly 

 to the lowest frontal bristles, antennae as long as face, the third 



(Iji, 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- ^ ^t^ 



nose; wings hyaliTie, two bristles at base of third vein, calyp- ^ 



teres whitish; length, 4 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, fiicial ridges 



bare, scutellum bearing only two pairs of long marginal macro- 



chffita', third joint of antennee three times as long as wide; 



length, 3.0 mm. St. Augustine, Fla. (Proceedings Acad. Nat. 



Sci. Phila., 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 



macrocha4u'; 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. 



Ill, p. i;^; June, 1892: Myotliyria.) vanclerwulpi Town. 



6 



Genus DIDYMA v. d. W. 



Didijma van der Wnlp, liiologia Cciit.-Amcr., Diptera, A'ol. II, p. 156; June, 1890. 



Our species are black, with at most the palpi and sides of the abdo- 

 men partly yellow, hind tibiie on the outer side ciliate with short 

 bristles : 



1. Second, or at least the third, abdominal segment bearing discal 



macrochictiiB 2. 



Second and third, ab lominal segments destitute of discal macro- 



cha?t;Te, palpi yellow, hind crossvein slightly curved, nearer to - '^ ^^fj^* -^ 

 the bend of the fourth vein than to the small crossvein; length, -^ —^ , 



G mm. Lake Worth, Fla. (Biol. Cent.-Amer., Dipt., Vol. II, 

 p. 163; June, 1890.) 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. 100; June, 



1890.) exifjua 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.) . . timida v. d. W. 



