28 PEOCEEDINGS OF THE NATIONAL MUSEUM vol.66 



second with a small, depressed pair rather far apart in the described 

 specimen; third with a large pair, fourth with a marginal row. 

 Genital segments small, wholly black, with small black hair, the sec- 

 ond segment with two small bristles turned up behind. Forceps 

 minute, black, diverging only at tip, in profile of rather even width, 

 bearing a small tooth at the middle of the blunt tip. Accessory plate 

 yellow, shining, rounded, not much produced apically. Posterior 

 clasper not visible in the specimen, anterior minute, depressed for- 

 ward. Penis small, blackish, distinctly jointed, the distal segment 

 somewhat globose, its main sclerite forming the back and sides has 

 a thick, rounded, transverse rim at apex, in front of which in the 

 middle is a small protuberance. Fifth sternite wholly retracted in 

 the specimen. 



Legs black, middle femur without comb, middle tibia with one 

 bristle on outer front side, hind tibia without villosity; claws and 

 pulvillia large, the latter infuscated. 



Wings hyaline ; third vein with a row of six or eight hairs ; fourth 

 vein ending nearer apex than in most species (less than half the fifth 

 costal segment) ; third costal segment slightly shorter than fifth. 



Length 5 mm. 



Described from a single male, reared by Eay T. Webber from a 

 puparium which he took out of a spider's web at Somerville, New 

 Jersey, on June 23, 1922. 



Type.—MdlQ, Cat. No. 27099, U.S.N.M. 



The nearest relative is davidsoni, Coquillett, which has been reared 

 from spiders' eggs; subaenescens differs from this species in having 

 no anterior acrostichals, thinner pollen, a slight aeneous cast to the 

 color of the abdomen, etc. It is highly probable that subaenescens 

 attacks spiders' eggs. 



Family TACHINIDAE 

 Genus ATACTA Schiner 



Atacta ScHiNEK, Novara Reise, 1868, p. 328. Type and sole species hrasil- 



iensis, new. 

 Atactomima Townsend, Bulletin Amer. Mus. Nat. Hist., vol. 35, 1916, p. 15. 



Type and sole species crescentis, new, from Brazil. 



The characters of Atacta are in brief as follows : Head wider than 

 thorax, subhemispherical ; front in male strikingly narrow above 

 (about twice the ocellar triangle), the eyes diverging at a wide angle 

 to the level of the antennae, parafrontals someAvhat triangular in 

 form, usually silvery, covered with dense hair, frontal stripe only 

 about as wide as ocellar triangle; only one vertical on each side. 

 Female with wide front, the parafrontals slightly inflated, very 

 broad, with a long dark, translucent reflecting spot on each bearing 



