132 DIPTERA OF NORTH AMERICA. 



of which have, without exception, an antenual bristle with long 

 pectinations on the upper side. 



Division 1. The costal vein reaches to the third longitudinal vein, 

 f Abdominal extremity of the male with elongated bristles. 



DICHAETA Meig. 

 j Abdominal extremity of the male without elongated bristles. 



NOTIPHILA Fall. 



Division 2. The costal vein reaches to the fourth longitudinal vein. 

 , ( Upper side of the intermediate tibiae with some long bristles. 2 



I Upper side of the intermediate tibise without long bristles. 3 



f Wings with a costal spine, posterior transverse vein perpendicular, legs 

 not prolonged, clypeus very prominent. PARALIMNA Loew. 



2 ! Wings without costal spine, posterior transverse vein oblique, legs pro- 

 longed, clypeus hardly projecting beyond the oral margin. 



|^ CORYTHOPHORA Lo6W. 



Abdomen sharply edged, apparently three-jointed in both sexes on 

 account of the minuteness of the first and fifth segments. 



TRIMERINA Macq. 



\ Abdomen not sharply edged, fifth segment not so strikingly short- 



(. ened, or only so in the males. 4 



4 f Abdomen broad. DISCOMYZA Meig. 



\ Abdomen not broad. 5 



{Superior half of the face not carinated, third joint of the antennae 

 more or less oblong. PSILOPA Fall. 



Superior half of the face distinctly carinated. 6 



SEyes oblong, cheeks not descending much beneath the eyes. 

 DISCOCERINA Macq. 

 Eyes rounded, cheeks descending very much beneath the eyes. 7 

 7 f Clypeus very prominent beyond the oral margin. ATHYROGLOSSA Loew. 

 \ Clypeus projecting very little beyond the oral margin. HECAMEDE Hal. 



Of the enumerated genera I know Dichceta, Notiphila, Paralimna, 

 Discomyza, Psilopa, andDiscocerina as occurring in North America. 



Gen. I. DICHAETA MEIG. 



This genus is closely related to the genus Notiphila. Both are 

 distinguished by the remarkable stout spine of the second joint of 

 the antennae ; the face is perpendicular and only moderately con- 

 vex, the clypeus small and scarcely prominent beyond the border 

 of the mouth; moreover, in both, the intermediate tibia? are beset 

 on the upper side with some long and stout bristles, and the thick- 

 ened costal vein terminates already at the tip of the third longi- 

 tudinal vein. The characters distinguishing both genera from each 



