290 



NORTH AMERICAN DIPTERA. 



2. Metallic black species; front rather narrow (1, 2, 3). Lonchsea. 

 Yellow or yellowish species; front broad (p. So, 15) . Palloptera. 



3. Arista with short and dense plumosity; anterior fronto-orbital bris- 



tles proclinate (1O, 11) . .... Pachycerina. 



Arista bare, pubescent or loosely plumose; anterior fronto-orbital 



bristles reclinate. ........ 4 



4. Face broad, in profile strongly convex below (6, 7) . Physogenua 

 Face receding, flattened or gently arched. ... 5 



5. First posterior cell much narrowed in the margin (12). 



Griphoneura. 

 First posterior cell not or but slightly narrowed in the margin. 6 



6. Shining black species; third joint of antennae more elongate (8,9). 



Lauxania. 



More or less yellow or pollinose species; third joint of antennae less 

 elongate (4, 5). . . . . . . . Sapromyza.* 



* From the description and figures I can discover no differences, 

 save the imperfect anal cell, an unimportant character, to distinguish 

 C/Hztocoslia from those species of Saproniyza having pictured wings. 



a 



Sapromyza, species; enlarged. 



