356 NORTH AMERICAN DIPTKRA. 



29. Arista short-haired; posterior cross-vein half way between bend of 



fourth vein and the anterior cross-vein 30 



Arista distinctly plumose; posterior cross-vein near bend of fourth 

 vein. ........... 31 



30. Eyes bare Acronacantha. 



Eyes hairy Morphomyia. 



31. Antennae not reaching middle of face. . . Phasiops. 

 Antennae reaching at least two-thirds the distance to oral margin 



Metadexia. 



32. Eyes small, less in diameter than the width of cheeks. 



Macrometopa. 

 Eyes of greater diameter than width of cheeks. 33 



33. Costa of wings bristly, or at least with a costal spine. . . 34 

 Costa without bristles or spine. ...... 36 



34. Abdomen elongate, nearly cylindrical, twice as long as the thorax; 



segments of equal length. .... Stenodexia. 

 Abdomen short, stout, the first segment somewhat shortened. 35 



35. Sides of face hairy; claws of male elongate (10). Ptilodexia. 

 Sides of face bare. ...... Sardiocera. 



36. Abdomen conical or elongate oval. ..... 37 



Abdomen cvlindrical or elongate-conical, much longer than thorax. 



38 



37. Middle legs of male disproportionately long (16, 17 1. 



Cholomyia. 

 Middle legs but little if any longer than the others. Melaleuca. 



38 Apical cell widely open; wings unicolorous (21). . Euantha. 

 Apical cell narrowly open; wings nearly hyaline. . . 39 



39. Eyes bare (6,7) Leptoda. 



Byes hairy Uramyia. 



40. Abdomen cvlindrical, long and attenuated at base. Cordyligaster 

 Abdomen oval or conical, not petiolate. . . . . 41 



41. Frontal bristles descending below baseof antennse(5). Chaetona. 

 Frontal bristles not descending below base of antennae. . 42 



42. Third vein with a row of bristles. 43 

 Third vein without bristles, save at base. .... 45 



4.V Third antenna! joint four limes the length of the second. 



Thelairodes. 

 Third joint about twice the length of the second. . . 44 



