202 



NORTH AMERICAN DIPTERA 



KEY TO GENERA 



1. Eyes bare 3 



Eyes densely pilose; proboscis short and thick 2 



2. Three submarginal cells, both sexes holoptic (3, 4) .Hyrmophloeba Rondani 

 Two submarginal cells *Hirinoneura Meigen 



3. Three submarginal cells 4 



Two submarginal cells; proboscis short and thick (text figure). 



Neohirmoneura Bequaert 



4. Proboscis very small, hardly visible, without fleshy labellae; alula 



rudimentary (1, 2) Parasymmictus Bigot 



Proboscis elongate and protruding; alula broad (5 6). 



Neorhynchocephalus Lichtwardt 



* No North American species are at present known. 



Nemestrinidie. — 1, 2, Parasymmyctus clausa O. S. : 3, 4, Hirmophloeba texana ; 

 Neorhynchocephalus volaticus, a third submarginal cell, b-f posterior cells. 



