lOG NORTH AMERICAN DIPTERA. 



short; no auxiliary vein; third and fourth longitudinal veins 

 parallel or divergent ; posterior basal united with the discal 

 cell ; anal cell wholly wanting or rudimentary. Legs short ; 

 femora sometimes thickened ; tibite without preapical bristle. 

 This group of flies is always sure to be represented by nu- 

 merous specimens and species in any collection of diptera. 

 The flies are very common and are collected in large numbers 

 by the sweep-net, from rank growing grass and meadowlands. 

 The larvae of several species of Oscinis have been bred from 

 wheat, barley, oats, rye and grass stems and Phraf/mites ; 

 those of Qs^'i'H.is- have similar habits ; larvae of Siphoiiella from 

 Cirslum, etc. The larva? are thick, cylindrical, with stout 

 mouth-hooklets ; abdomen with fleshy protuberances for loco- 

 motion ; the antennas two-jointed. 



TABLE OF GENERA. 



1. Head produced conically in front, the antenna^ elongate. 



EcTECEPHALA Macquart. 

 Head not produced conically ; antennae not elongate. ... 2 



2. The costal vein reaches to the tip of the third longitudinal vein. . 3 

 The costal vein reaches to the tip of tlie fourth longitudinal vein. 5 



;>. No posterior cross-vein ; first three longitudinal veins recurved. 



Ellu'Oneura Loew. 

 Posterior cross-vein present. ........ 4 



4. Hind femora much thickened Meromvza Meigen. 



Hind femora not thickened ; mcsonotum usually with stripes. 



Chlorops Meigen. 



f). Ovipositor horny, suhulate Opetiophora Loew. 



Ovipositor not horny and subulate. ....... 6 



0. Antenna; witli a thickened, porrect, style like arista. 



Elachiptera Macquart. 

 Antennae with the usual bare, pubescent or rarely plumose arista. 7 



7. Oral margin of the face produced ; proboscis often elongate and folded 



back. ....... Siphonella Macquart. 



Oral margin not produced. ........ 8 



8. Third joint of the antenna; reniform, with a subterminal, short-plumose 



arista. . . ...... Gai:rax Loew. 



Third antennal joint rounded or oval. ...... 9 



