304 Professor Williston on the 



2. Chrysopila atra, n. sp. (PI. X., fig. IShis, wing.) 



$ . Deep black ; wings hyaline, with two dark-brown spots on 

 the costal margin. Length 5 mm. 



Deep black throughout, with black pile. Face cinereous 

 pruinose. Mesonotum and abdomen opaque velvety. Wings 

 hyaline, the apical third in front clouded ; the stigma, a spot across 

 from the costa to the second vein on the distal part of the 

 auxiliary vein, and a cloud on the humeral cross- vein, dark-brown.. 



One specimen. 



ASILID^. 



OiMMATIUS. 



Wiedemann^ Auss. Zw. Ins._, i., 418, 1828. 



1. Ommatius marginelliis. 



Ommatius marginellus (Pabricius), Wiedemann, Auss- 

 Zw. Ins., i., 421 ; Dipt. Exot., i., 223, pi. vi., 

 fig. 5j Macquart, Dipt. Exot., i., 2, 134; Schiner, 

 Verh. zool. bot. Gesellsch, 1866, 682. 



? Ommatius tibialis , Say, Journ. Acad. Phil., iii., 49 j, 

 Compl. Wr., ii., 63; Wiedemann, Auss. Zw. Ins., 

 i., 422; Williston, Trans. Amer. Ent. Soc. xi., 

 PI. ii., fig. 12 and xii., 76. 



Ommatius Saccas, Walker, List, ii., 474. 



Ommatius vitreuSj Bigot, Ann. Soc. Ent. Fr., 245,. 



1875. 



Hah. West Indies ; South America ; ? North America. 



Thirty specimens. The only difference which these 

 specimens present from others, both male and .female, 

 from Brazil, are the yellow bristles of the hind femora. 

 Others in my collection from San Domingo agree in this, 

 respect with the Brazilian ones. That all are of the same 

 species, I have no doubt. That 0. tibialis is the same 

 species, I am not so confident. The distinctive charac- 

 ters pointed out by Schiner, though I do not think that 

 they are of much importance, are present in North 

 American specimens. The posterior part of the meso- 

 notum and the scutellum also seem to be more hairy in 

 0. tibialis. In all the specimens, the colour of the legs 



