42 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 79 



with defined patches of dense hairs on third and fourth segments, 

 smaller on latter ; genital segments yellow ; inner forceps blackish, in 

 posterior view narrower than usual, tapering from base to an acute 

 apex, feebly keeled on basal half behind ; outer forceps yellow, nearly 

 equal the length of inner ones and also narrower than usual, tips 

 truncate with the anterior corner bearing a minute hook ; fifth sternite 

 deeply incised, the lobes yellow bearing long black hairs on the inner 

 margin. 



Legs black, long, and slender ; mid tibiae with one large bristle on 

 outer front side near middle ; hind tibiae evenly ciliate ; front claws 

 and pulvilli as long as last two tarsal joints, the hind ones somewhat 

 shorter. 



Wings tinged with yellow at base and on costal margin ; venation 

 as usual ; third vein with one to three hairs at base ; no costal spine. 



Female. — Front at vertex 0.282 of the head width (average of 

 five: 0.28; 0.29; 0.27; 0.29; 0.28); uppermost one or two frontals 

 rather stout, reclinate ; verticals and orbitals two pairs ; third anten- 

 nal joint moderately broad, about two and one-fourth times the 

 length of second; palpi noticeably thickened apically; thorax with 

 denser and paler pollen than in male; second abdominal segment 

 bearing a stout pair of median marginals, the fourth with a subdiscal 

 and a marginal row of strong bristles ; hind tibiae ciliate with one or 

 two longer bristles in the row near middle ; claws and pulvilli short. 



Length, 8 to 11 mm. 



ry;?^.— Male, U.S.N.M. No. 43348, from College Station, Tex. 



Described from 39 specimens. In the United States National Mu- 

 seum 9 males as follows : 1, Melrose Highlands, Mass., September 13, 

 1914 (C. H. T. Townsend) ; 1, Cabin John, Md., July 26, 1916 (R. M. 

 Fonts) ; 1, Campinas, Brazil, March, 1924 (F. X. Williams) ; 1, La 

 Providencia, Obispo, Guatemala (J. M. Aldrich) ; 1, Higuito, San 

 Mateo, Costa Rica (Pablo Schild) ; 1, Taboga Island, Panama (A. 

 Busck) ; 3, Posorja, Ecuador (F. Campos), collection J. M. Aldrich. 

 In the American Museum of Natural History : 9 males from Chapada, 

 Brazil (H. H. Smith) ; 1 from Barro Colorado Island, Canal Zone 

 (C. H. Curran). In my collection: 6 males and 14 females from 

 College Station, Tex., April-October, 1919-1930 (H. J. Reinhard). 



(25) WINTHEMIA TRICOLOR van der Wnlp 



Plate 1, Figure 5 



Exorlsta tricolor van deb Wulp, Biologia Dipt., vol. 2, p. 67, pi. 3, fig. 9, 1890. 

 A robust species with the hind tibiae thickly and evenly ciliated ; 

 abdominal segments 2 and 3 shining on posterior half, the sides 

 conspicuously reddish in male only, which has rather small but 

 sharply defined patches of dense hairs on venter of third and fourth 

 tergites ; claws and pulvilli greatly elongated in male, not in female. 



