TABLE OF FAMILIES. 71 



34. For the most part brilliantly colored, predaceous flies; face of male 



usually narrower than that of female; arista dorsal or terminal; 

 hypopygium often enlarged or conspicuous. 



Dolichopodidae, 228 

 Not brilliantly colored, predaceous flies 35 



35. Eyes sometimes contiguous; head small, the proboscis usually 



rigid; arista usually terminal. . . Empididse, pt. 218 



Eyes never contiguoiis; proboscis not rigid; arista almost always 



dorsal. ........ 4 2 



CYCLORRHAPHA. 



A frontal lunnle above the base of the antenna-; third antennal joint 

 always simple, not annulated or complex, with a terminal or dorsal 

 arista, rarely with a terminal style; third vein never furcate; never 

 more than three complete posterior cells present. Empodia never pul- 

 villiform. 



36. Between the third and fourth longitudinal veins and subparallel 



with them a spurious longitudinal vein; or, when rarely absent, 

 the first posterior cell is closed remote from the border; first 

 posterior cell always closed; head never with bristles, which are 

 rarely present elsewhere; males usually holoptic; almost always 

 with a dorsal arista, rarely a terminal style. Usually brightly 



colored flower flies Syrphidae, 246 



No spurious longitudinal vein. ...... 37 



37. Front broad in both sexes; antennae with a terminal style or dor- 



sal arista; face usually with grooves below the antennae; probos- 

 cis elongate and slender, often folding; no bristles anywhere 

 (Conopidcc, 261.) 

 Not such flies; bristles almost invariably present. . . 38 



38. Hind metatarsi enlarged and ornamented, especially in the males, 



males holoptic; arista terminal. . . Platypezidae, 241 

 Hind metatarsi not enlarged nor ornamented. 39 



39. Head large, composed chiefly of the eyes, the front in the males 



narrowed or the eyes contiguous; first posterior cell narrowed; 

 arista dorsal; rather small flies. . . Pipunculidse, 244 

 Head not large, subspherical, the front broad in both sexes, pro- 

 boscis short, not rigid; first posterior cell narrowed; legs elon- 

 gated (Micropezidcc pt. 264) . 



Head small, the front narrowed or eyes contiguous in male; first 

 posterior cell wide open (Empididfg, pt. 218). 



