ART 18 DIPTEKA OR TWO- WINGED FLIES ALDRICH 31 



Wings hyaline, third vein with four or five bristles at base; fourth 

 vein rather suddenly bent, almost at a right angle from which it 

 curA'es a little outward reaching the costa considerably before the tip 

 of the wing. 



Length 9 mm. 



Female. — The front has the two large dark, reflecting spots on the 

 parafrontals as in hrasiliensis., but the color of the remaining pollen 

 is gray rather than golden. This with the characters given in the 

 table will readily distinguish the two species. 



Length 7.5 mm. 



Described from three males and one female. The males are from 

 Great Falls, Virginia, August 9, 1923 (Aldrich) : Tupelo, Missis- 

 sippi, September 30, 1921 (H. W. Allen) ; Hope, Arkansas, August 

 21, 1922 (received from C. W. Johnson and returned to him). The 

 single female is from Opelousas, Louisiana, April, 1897 (Pilate). 



r^/^oe.— Male, Cat. No. 26845, U.S.N.M., from Great Falls, Vir- 

 ginia. 



ATACTA ARGENTIFRONS. new species 



Male. — This species is most nearly related to crassiceps, the single 

 male specimen has the front much the same as in hrasiliensis, the 

 parafrontals having very decided silvery color and being less in- 

 flated than in crassiceps. The thoracic stripes are the same in all 

 the species which I have seen, but hrasiliensis is the only one with 

 deep golden pollen on the fourth abdominal segment and without 

 median marginals on the second. The female of this species is un- 

 known. 



Length 9.5 mm. 



Described from a single male collected in May by H. H. Smith 

 at Corumba, Brazil. 



Type in the collection of the American Museum of National His- 

 tory. 



ATACTA CRESCENTIS (Townsend) 



Atactomina crescenhs Townsend, Bull. Amer. Mus. Nat. Hist., vol. 35, 

 1916, p. 15. 



Described from four males and a female in the American Museum. 

 Locality, Chapada, Brazil. One paratype male is in the United 

 States National Museum. The supposed generic characters are very 

 slight except that the parafrontals are quite rapidly widened below, 

 the eye being rather more crescent-shaped than in the other species. 



ATACTA NIGRIPALPIS (Van der Wulp) 



Brachycoma nigripalpis Van der Wulp, Biologia Cent. Amer. Dipt., 



vol. 2, p. 98. 

 Atacta nigripalpis Brauee and Bergenstamm, Zweifl. Kais. Mus., pt. 5, 



1891, p. 365. 



