132 NORTH AMERICAN DIPTERA. 



2. One sternopleural bristle ; wings without spots 3 



No sternopleural bristle; wings with round, brown spots. 



ERNONEURA Becker. 



3. Front tibiae with a terminal, short rectangularly spine (in addition to 



the ordinary bristles). . . . . ACANTHECNEMA Becker. 

 Front tibiae without such spine 4 



4. Hypopygium with long tufts of hairs 5 



Hypopygiuni without long tufts of hairs 8 



5. Third antennal joint somewhat elongate, angulated at the tip ; oral 



border with numerous, closely placed bristles. ... 6 



Third antennal joint short, rounded at tip; oral border with two remote 



bristles. . . . . . . BOSTRICHOPYGA Becker. 



6. Wings with two supernumerary cross-veins. POGONOTA Zetterstedt. 

 Wings not with supernumerary cross-veins. . OKENIA Zetterstedt. 



7. First posterior cell closed LASIESCELUS Becker. 



First posterior cell open or but little narrowed 8 



8. Much elongated species. 9 



Short or but little elongated species 10 



9. Middle and hind femora of the male strongly thickened. 



ST^GERIA Rondani. 

 All the femora slender COSMETOPUS Becker. 



10. Third antennal joint rounded distally. . MICROPRESKPA Becker. 

 Third antennal joint angulated distally. . . . . .11 



11. Mesonotum and legs thickly hairy. . . SPATHIOPHORA Rondani. 

 Mesonotum and legs thinly and not long hairy 12 



12. Antennae small, abgulated at tip; arista thickened at base ; small, short, 



gray species. ...... TRICOPALPUS Rondani. 



Antennas large, broad, rounded at tip ; arista thickened to near the tip. 



ACEROCNEMA Becker. 

 CLEIGASTRIN.E. 



1. Five dorsocentral, two scutellar, one posthumeral bristles ; black 

 species. . r . . . . . CLEIGASTRA Macquart. 



Two or three dorsocentral, front scutellar and two post-humeral bris- 

 tles; honey-yellow species. . . . GIMNOMERA Rondani. 



NORELLINJE. 



1. Front femora with two rows of strong bristles, the outer ones long and 

 strong, the inner ones short. . . . NORELLIA R. Desvoidy. 

 Front femora witli four spines, bristles on the outer side only. 



ACHANTHOLENA K'HIlluili. 



