NOKTH AmEKICAN Dll'TERA. 27 



Abdoinon sliort, cylindrical. Black, with bright golden opaque 

 pollinose markings on thorax and abdomen. See "Lapar- 

 ns" pictitarsis Bigot. 



28. Large species ; face bare with bristles on the oral margin, in 



profile straight or concave, the oral margin projecting. 29 

 Smaller species, face convex on lower portion, not projecting. 30 



29. Elongate; fourth posterior cell closed, usually a considerable 



distance before the margin Deromyia 



Less elongate; fourth cell open or closed in the margin, rarely 



a little petiolate. Saropogon 



30' Head broad and flat, face not gibbose, third joint of antennae 



slender, elongate 31 



Head only moderately broader than high ; face gibbose below ; 



third joint of antenn;e more or less dilated, style very short ; 



thorax and legs with numerous bristles ; abdomen broadest at 



the base, rather slender, subeylindrical Lestomyia 



31. Abdomen finely punctulate, of nearly equal width ; hind tibiae at 



the tip and their tarsi only a little thickened ; wings hyaline. 



Taracticus 

 Abdomen smooth ; hind tibiae at the tip and their tarsi thick- 

 ened (compare here Nicocles? scitula); antennal style 

 slender, acuminate ; wings variegated 32 



32. Abdomen flattened; in the female a little broader beyond the 



middle ; in the male near the tip, the last two segments of 

 •which conspicuously silvery above. . . . Nicocles 

 Abdomen of nearly equal width throughout, the last segment in 

 the male not silvery, fourth posterior cell narrowed. 



Blacodes 



'^i. Antenna3 without a terminal bristle (Lap hririie). . M 



AntenniB with a terminal bristle (Asilinae). .41 



M. The veins at the distal ends of the discal and fourth posterior 



cells in the same straight line, continuous, or nearly so. 35 



The veins, etc., not in the same straight line, the vein closing 



the fourth posterior cell more or less remote and oblique. 36 



35. First joint of antennae elongate, slender; second posterior cell 



narrowed toward the maftip o/ the wing. . Cerotainia 



First joint of the anttj(li» much shorter than the third; first 



posterior cell narrowed <jr closed, the second wide open. 



Atomosia 



