74 NORTH AMERICAN DIPTERA. 



3. Posterior basal transverse vein, i. e. tlie vein wliich limits the anal cell, 



parallel or nearly parallel with the hind border of the wing. 



VjMviviyjE. 

 Posterior basal transverse vein not parallel with the hind border of the 



wing. ......... IlYBOTIN.iE. 



HILABIMORPHIN^. 



1. Second vein very short, terminating in the first; discal cell present. 



Mythicomyia Coquillett. 

 Tlie second vein terminates in the costa; discal cell wanting. 



niLARiMOKPH.\ Schiner. 



HYBOTIX.E. 



1. Third longitudinal vein furcate; first submarginal cell closed. 



Blephakopkoctus Loew. 

 Tliird longitudinal vein simple. ....... 2 



2. Anal cell shorter than the second basal cell. .... 3 

 Anal cell as long or longer than the second basal cell. ... 4 



0. Third antennal joint conical ; bristle terminal. Leptopeza Macquart. 

 Third antennal joint ovate; bristle subdorsal.' Ocyduomia Meigen. 



4. Origin of the second longitudinal vein nearer the humeral tiian the an- 



terior cross-vein; wings usually spotted. . Syneches Walker. 

 Origin not nearer the humeral cross-vein ; wings not spotted. . 5 



5. Vein between the first and second basal cells indistinct. Syndy'as Loew. 

 Vein between the first and second basal cells distinct. Hybos Meigen. 



EMPIDIN^??. 



1. Third longitudinal vein furcate 2 



Third vein simple Riiamphomyia Meigen. 



2. No discal cell. Cyrtoma Meigen. 



A discal cell present o 



o. Proboscis distinctly longer than the head 4 



Proboscis not longer than the head. ...... 6 



4. All the legs of nearly equal length; hind femora much thickened. 



Pachymeria Stephens. 



Hind legs longer than the others, their femora but little or not at all 



thickened. ........... 5 



5. Proboscis slender, directed backward or downward. . Em pis Linne. 

 Proboscis moderately thickened, directed forward. 



Iteapiiii.a Zetterstedt. 



