j-2 NORTH AMERICAN DIPTERA. 



41. Third joint antennae oblong, with its apex attenuated, the arista 



bare; scntelhim bispinose (Spyridopa, S. A.). 

 Third joint snbglobose; scntelhim bispinose (Panacris, S. A.) 



42. Upper branch of antennae with a terminal arista and a lateral pro- 



cess. ........ Neochauna. 



Upper branch with a short, slender style and no lateral process 

 (Blastocera, S. A.). 



43. The scntelhim terminates in a stout median spine or process (4, 5) 



Cynipimorpha. 

 Scntelhim without median spine or process, simple. . . 44 



44. Third vein with an anterior branch. ..... 45 



Third vein without branch. , Zabrachia. 



45. Third antennal joint oval, with its terminal arista briefly but 



densely plumose. ...... Lophoteles. 



Third joint rounded or oval, its terminal arista bare (27). 



Pachygaster. 



The relationships of the genera allied to Sargus(Geosargus} IWero- 

 sargus, Macrosargus (Pedicella Bigot), Chrysochroina, JMicrochrysa 

 and Myiochrysa, are all more or less doubtful. Even Ptecticus can 

 not be sharply limited by the structure of the second antennal joint. 

 I suspect that Pedicella will have to take precedence over Sargiis', 

 Macrosargus and Geosargus,.Sind that Chrysochroma will have to be 

 merged into Merosargus. The whole group sadly needs revision. 

 The: genus Notliomyia, which I do not know, may perhaps find its 

 proper place under 28. 



