I2 6 NORTH AMERICAN DIPTERA. 



5. Proboscis much elongated, directed downward. Clinorhyncha. 

 Proboscis short (1) Lasioptera. 



6. Antennae bead-like, the joints verticillate. ... 7 

 Antennae cylindrical, the joints approximated, not petiolate, pro- 

 vided with short, close hairs; the third vein terminates at or 

 beyond the tip of the wing. . . . Asphondylia. 



7. The third longitudinal vein terminates in the costa before the tip 



of the wing (3) , Cecidomyia. 



The third vein terminates in the costa at or beyond the tip of the 

 wing. ..... ... 8 



8. Thorax highly arched, hood-like over the head (4). Hormomyia 

 Thorax only moderately arched. ...... 9 



9. Wings with but three longitudinal veins, the first, third and fifth. 10 

 Wings with apparently four longitudinal veins, that is the first, 



third and, two in place of the fifth, the furcation taking place 

 so near the root of the wings as to give the appearance of an 

 additional longitudinal vein. ...... 13 



10. The anterior cross-vein, that is the vein arising from the root of 

 the wing and connecting with the third vein nearly where it 

 arises from the first, is curved S-shaped. . . . . u 

 The anterior cross-vein is nearly straight, apparently the begin- 

 ning of the third vein. ....... 12 



u. Wings very long and narrow (1O). . . . Colpodia. 



Wings not more than three times as long as wide (2). Epidosis 



12. Joints of the antennal flagellum petiolate, in the male with two 



bead-like swellings on each joint (14) . . . Diplosis. 



Joints not petiolate, or at most the males with a single bead-like 



swelling on each joint. ...... Dirhiza. 



13. Palpi large, with the last joint elongated, anterior cross-vein 



S-shaped Asynapta. 



Palpi small, the last joint not or but little longer than the penulti- 

 mate; anterior cross-vein but little curved (13) . Winnertzia. 



14. Wings with but two longitudinal veins, the first and fifth, the lat- 



ter not reaching beyond the middle of the wing (11) . 



Heteropeza. 

 Wings with three longitudinal veins, the first, third and fifth. 15 



15. Fifth vein furcate. ...... .16 



Fifth vein simple, not furcate (7) Miastor. 



