276 NORTH AMERICAN DIPTERA. 



2. Wings dark, with three oblique, more or less arcuated, hyaline 



cross-bands; first basal cell expanded before its end. Tritoxa. 

 Wings not with such markings. ...... 3 



3. Wings broad, with a marked excision on the costa near the end of 



the auxiliary vein; second vein sinuous (3). Camptoneura. 

 Flies not having such wings. ....... 3 



4. Posterior angle of the anal cell retracted (4) . . . Idana. 

 Posterior angle of the anal cell drawn out into a long hole. 



Diacrita. 



The Ortalinae differ from the Platystominae and Cephalinae in the 

 usually small oral opening, the less developed clypeus, more slender 

 proboscis and smaller palpi. The mesonotum is sometimes bristly in 

 the middle anteriorl)', the propleural and mesopleural bristles both 

 present. Female abdomen with ix segments. 



1. Face sharply carinate. ........ 2 



Face not sharply carinate. ....... 3 



2. Third antennal joint circular; hairy species. Tetropismenus. 

 Third antennal joint ending in a sharp point; pollinose flies. 



Tephronota. 

 Antennae nearly as long as face, rounded at tip; mouth large. 



Hiatus.*. 



3. Mesonotum bristly in the middle in front; third antennal joint ex- 



cised above and with a pointed tip (12). . . Melieria. 

 Mesonotum not bristly in the middle in front. ... 4 



4. Third antennal joint distinctly excised above, pointed at the tip; 



fourth longitudinal vein with a marked anterior curvature on its 

 distal part. ....... Anacampta. 



Third antennal joint not excised above; fourth vein not so curved. 5 



5. Tibiae with preapical bristle,. . . . . . Automola. 



Tibiae without such bristle. ..... Tetanops. 



Trypeta-like; coloring nonmetallic; head rather broad, but low, w T ith 

 rather protuberant eyes; face short, perpendicular, excavated in the 

 middle; clypeus but little developed; third antennal joint round or 

 short oval; mesonotum bristly upon the posterior part only; first longi- 

 tudinal vein and auxilary vein remote from each other at tip; poste- 

 rior angle of the anal cell often drawn out into a long lobe. 



* Cresson. Trans. Amer. Ent. Soc. xxxii, 286. 1906. 



