12 NORTH AMERICAN DIPTERA. 



3. Antennae bead-like, the joints verticillate 4 



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

 vided with short, close hair 11 



4. The third longitudinal vein terminates in the costa before the tip of the 



wing. . . . (Dasyneura) CECIDOMYIA Loew (non Meigen). 

 The third vein terminates at or beyond the tip of the wing. . 6 



5. Thorax highly arched, hood-like, over the head. HORMOMYIA Loew. 

 Thorax only moderately arched ; wings irridescent. ... 6 



6. Wings with but three longitudinal veins, the first, third and fifth. 7 

 Wings apparently with four longitudinal veins, the first, third and two 



in place of the fifth, the furcation taking place so near the root of 

 the wing as to give the appearance of two longitudinal veins. 10 



7. The anterior cross-vein, that is the vein arising at the root of the wing 



and connecting with the third nearly where it arises from the first, Ss 



curved y : shaped. 8 



The anterior cross-vein is nearly straight, appearing as the beginning 

 of the third vein. 9 



8. Wings very long and narrow. . . . COLPODIA Winnertz. 

 Wings not more than three times as long as wide. EPIDOSIS Loew. 



9. Joints of the antennae petiolate, in the male usually with two bead-like 



swellings on each joint. 



(Ce.cidomyia Meigen non Loew) DIPLOSIS Loew. 



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

 swelling on each joint. . . .'*'. DIRHIZA Loew. 



10. Palpi large, with the last joint elongate ; anterior cross-vein /"-shaped. 



ASYNAPTA Loew. 



Palpi small, the last joint but little or not at all longer than the penul- 

 timate; anterior cross- vein but little curved. WINNERTZIA Rondani. 



11. The third longitudinal vein terminates before the tip of the wing; fifth 



vein not furcate. SPANIOCKRA Winnertz. 



The third vein terminates at or beyond the tip of the wing ; fifth vein 

 furcate , . . ASPHONIJYLIA Loew. 



12. Proboscis much elongated, directed downward. CLINOIUIYNCHA Loew. 

 Proboscis short '"'. 13 



13. Metatarsi shorter than the following joint. . LASIOPTKRA Meigen. 

 Metatarsi longer than the following joint. . DIOMYZA Stephens. 



14. Wings with but two longitudinal veins, the first and fifth, the latter not 



furcate, and neither reaching beyond the middle of the wing. 



HETEROPEZA Winnertz. 



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

 reaching to the tip of the wing, the fifth not furcate. 



MIASTOR Meinert 



