370 NORTH AMERICAN DIPTERA 



15. Second antennal segment slender, much longer than the third (16). 



Dictyomyia Cresson 

 Second antennal segment broad, slightly longer than the third (13). 



Euthycera Latreille 



16. Arista practically bare; infrasquamal swellings with bristles. 



Elgiva Meigen 

 Arista with long rays or long pubescent 17 



17. Arista with long, black rays (10) Trypetoptera Hendel 



Arista white pubescent (11, 15) Limnia Desvoidy 



Tetanoceiidfe III. — 19, Oidematops ferruginea; 20. Sciomyza aristalis ; 21, Pteromicra; 

 22, Dyctia nana; 23, Renocera johnsoni ; 24, Tetanocera, middle femur and tibia; 25, 

 Pcecilographa decora; 26, Tetanocera valida; 27, Tetanocera plebeja (10-27 after Cresson). 



