2QO 



NORTH AMERICAN DI1TKRA. 



2. Metallic black species; front rather narrow d, 2, 3i. Lonchaea. 

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



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



tles proclinate (IO, 11) . .... Pachycerina. 



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



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



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

 Face receding. Battened or gently arched. 5 



5. First posterior cell ninch 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 antenna; less 



elongate (4, 5 1 Sapromyza.* 



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

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

 Chestocoelia from those species of Sapromyza having pictured wings. 



Sapromyza, species; enlarged. 



