Diptera. 7 1 



71. Costa microscopically broken twice, just beyond the humeral crossvein and 



at the end of the auxiliary vein (best seen by transmitted light) ; postvertical 



bristles convergent; no bristle above the front coxse 72 



Costa not broken near the humeral crossvein; mouth-opening not wide; 

 arista not feathery 74 



72. Anal cell wanting and basal cell fused with the discal cell (except Canace); no 



vibrissas; clypeus very large; mouth-opening very large, the center of the 

 face raised; foremost fron to-orbital bristles diverging; arista bare, hairy 

 or feathered; dark-colored, shore-living species. (Notiphila, Hydrellia, 



Parydra, Ephydra.) EPHYDRIDiE 



Anal cell almost always present; second basal cell usually complete; vibrissas 

 present; mouth-opening not large; center of the face concave 73 



73. Foremost pair of fronto-orbital bristles converging; bristles of the middle of 



front less evident; arista loosely pubescent; clypeus small; occiput reaching 

 forward under the eyes. (Milichiella, Desmometdpa, Meone^a) (PI. 



12, fig. 282) MILICmiD^ 



Foremost fronto-orbital bristles proclinate; interfrontal bristles rare; arista 

 almost invariably feathered; clypeus large; occiput not forming part of the 

 cheeks. (Phortica, Cyrtonotum, Drosophila [Pomace-fly]) (including 

 ASTEID^) DROSOPHILID-S 



74. Anal and second basal cells absent; interfrontalia large; postvertical bristles 



converging; usually no vibrissse, fronto-orbital or interfrontal bristles. 

 (Meromyza [M. americana. Wheat-stem maggot], Chlorops, Hippelates, 

 Oscinis {= Botanobia) [Frit-fly]) (PI. 9, fig. 256) (OSCINID.E). 



CHLOROPID-E 

 Anal and basal cells complete 75 



75. Oral vibrissse present (exceptionally absent in Geomyzidae); costa almost 



always broken near the end of the first vein 76 



Oral vibrissse absent; auxiliary vein ending in the costa; clypeus small. . . .78 



76. Postvertical bristles convergent when present; auxiliary vein independently 



ending in the costa; clypeus large; foremost fronto-orbital bristles directed 

 backward; mesopleural bristles present; cilia of the calypteres loose. (Tm- 

 oscelis, Diastata, Anthomyza) (PI. 12, fig. 279). 



{OPOMYZIDM) GEOMYZIDiE 



Postvertical bristles divergent when present; fringe of the calypteres dense; 



clypeus small 77 



77. Only the uppermost fronto-orbital bristles present; auxiliary vein ending in 



the costa; no mesopleural or prothoracic bristles; arista bare. (Prochyliza, 



Piophila [P. casei, cheese-skipper] Mycetaulus.) PIOPHLLID.^ 



Lower fronto-orbitals convergent; auxiliary vein usually ending in the first 

 vein; mesopleural and one prothoracic bristles present; arista closely pubes- 

 cent. (Cerodonta, Agromyza, Phytomyza, Odinia.) 



(including PHYTOMYZID^) AGROMYZIDiE 



78. Costa usually entire, at most slightly weakened just before the end of the 



auxiliary vein; basal cells small; postvertical bristles convergent; arista bare; 



