34 NORTH AMERICAN DIPTERA. 



f). Second siibmarginal cell longer than tlie first. Erioptera Meigen. 



First submarginal cell longer than the second. Molopiiilus Curtis. 



G. First submarginal cell short, not more than lialf tlie length of the 

 second. ........... 7 



First submarginal cell more than half the length of the second. 10 



7. Marginal cross- vein present 8 



Marginal cross- vein absent. . . . Gonomyia Osten Sacken. 



8. Second submarginal cell in contact with the discal cell, the anterior 



cross-vein obsolete. ......... 



Anterior cross-vein present, the first posterior cell intervening between 

 the submarginal and the discal cells. . Empeda Osten Sacken. 



0. Anal cell closed; no empodia (Asia, Africa and West Indies). 



MoNGOMA Westwood. 

 Anal cell open ; empodia present (Central and South America). 



Paratropesa Schiner. 



10. Seventh longitudinal vein conspicuously bisinuate. Symplkcta Meigen. 

 Seventli longitudinal vein straight. 11 



11. Lengtli of the auxiliary vein beyond the cross- vein at least twice that 



of the posterior cross- vein. . . Trimicra Osten Sacken. 



The cross- vein situated near the end of the auxiliary vein. 



Gnopiiomyia Osten Sacken. 



LTMNOPHILINI. 



1. Discal cell open; antennu- apparently 2S-jointcd in the $. 



PoLY'MERA Wiedemann. 

 Discal cell closed 2 



2. Marginal cross-vein wanting. . . Phyllolabis Osten Sacken. 

 Marginal cross-vein present. ........•> 



3. Wings pubescent Ulomorpha Osten Sacken. 



Wings bare 4 



4. Seventh vein very sliort, abru])tly incurved toward the anal angle. 



Trichocera Meigen. 

 Seventli vein not unusual. . 5 



5. A supernumerary cross-vein between the auxiliary vein and the costa. 



Epipiiragma Osten Sacken. 

 No such sui)ernumerary cross-vein. . . Limxophila Mncquart. 



