NouTH American Diptera. 11 



Wings with small cross-veins near the middle, not broad and 

 pointed, the veins hairy and conspicuously fringed along the 

 hind margin ; wings when at rest not roof-shaped. Mosqui- 

 toes CULICID.'E 



12. Third joint of the antenna? complex; basal cells of wings long. 13 

 Antenna? composed of three simple joints, the third not annu- 

 lated or segmentated, with or without a dorsal arista, or ter- 

 minal style or arista. ....... 19 



Ul Kmpodia undeveloped or bristle-like; antenna; elongate, com- 

 posed of four or five joints, without differentiated style or 

 arista; vertex and front hollowed out transversely between 

 the ej'es ; eyes of male never contiguous. ... 26 

 F>mpodia developed pulvilliform ; third antennal joint more or 

 less distinctly segmentated or annulated ; body not bristly 14 



14. Teguhu rather large ; third longitudinal vein furcate ; five pos- 



terior cells always present ; the costal vein encompasses the 

 whole margin of the wing; proboscis of the female adapted 

 for piercing; third joint of antenna; with from three to eight 

 annuli, never with style or bristle. Horseflies. . Tabanid.e 

 Tegulse small or rudimentar}' ; mostly flower-flies. (See No ta- 

 cantha.) 15 



15. Tibia> wholly without terminal spurs; longitudinal veins of the 



wings usually crowded anteriorly, those posteriorly often 

 ■ weak ; the costal vein does not reach beyond the tip of the 

 wing; antennae long or short, with or without a terminal or 

 dorsal arista or terminal style. . . StratiomyidjK 



The middle tibiae at least, with distinct spurs ; the costal vein 

 encompasses the entire wing; third longitudinal vein always 

 furcate, and five posterior cells always present. . . 16 



16. All the tibia; with spurs; third Joint of antennae sometimes di- 



vided into separate divisions. . . . XYLOPHAGiDiE 

 Front tibiae without spurs. 17 



17. Fourth posterior cell of wings closed (Subula). 



Stratiomyid.k, pt. 

 Fourth posterior cell open (Art hrocerina;.)^' . . 18 



18. Face projecting on each side into a rounded conical protuber- 



ance Glutofs 



Face with two diverging furrows. . . Arthroceras 



