2W 

 ).MI!YMI>,« L 



Empida: j 



North Amkkican DirricitA. 13 



28. Tliird aiitennal joint without bristle or style; three posterior 



cells; first posterior cell narrowed or closed, tiie fourth lon- 

 gitudinal vein terniinatin};!^ at or before the tip of the winjj. 



SCKNOIMMD.K 



Third antennal joint rarely without terminal style ; four or three 

 posterior cells; the fourth vein terminates beyond the tip of 

 the win.£r 29 



29. Anal cell narrowly open, or closed near the border. Boa 

 Anal cell closed remote from the border. . 



30. Xeuration intricate, the small cross-vein wantinj;; or rudimentary, 



owinpc to the coalescence of the third and fourth veins for a 

 longer or shorter distance ; tibia? without terminal spurs ; em- 

 podia andpulvilli membranous, but frequently minute. 



NKMISriJlXID.E 



Neuration not intricate; the anterior cross-vein always distinct ; 

 labella of proboscis fleshy 31 



31. The posterior branch of the third vein terminates before the tip 



of the wing; male sexual organs prominent. . Apiocerid/E 



The posterior branch of the third vein terminates behind the tip 



of the wing; male sexual organs small. . Therevida: 



32. Antennae with a dorsal arista 38 



Antenna? with a terminal arista or style 33 



33. Wings pointed, no cross-veins in the middle, the fourth longitu- 



dinal furcate and united with the fifth ; small species. 



LONCHOPTERI D^ 



Wings rounded at the tip, not lancet-like. ... 34 



34. Second basal cell confluent with the discal cell, not separated by 



a small vein ; the auxiliary vein does not terminate in the 

 costa; small, mostly brilliant-colored, predaceous flies. 



D0LICI10P0DID.« 



Second basal cell separated from discal cell by a small vein. 35 



35. Antennae with a terminal style. 36 



Antennae with a terminal bristle 37 



36. First posterior closed (Conopidae, pt., Syrphidae, pt.) 41 

 First posterior cell open. Empid.e 



37. Head comparatively small ; the proboscis usually more or less 



elongated; alula; of wings usually rudimentary. Empid.k 



Head as broad as the thorax ; proboscis fleshy ; alula; distinct. 



PLATYPEZIDiE 



29 Anal cell narrowl}' open, or closed near the margin; discal cell 



present (in our genera) Romhylid.i-:. 



Anal cell closed remote from the border, sometimes wanting; if 

 closed near the bonier (IIii.arimorpha), the discal cell want- 

 ing. EM1'1D-E. 



