300 NORTH AMERICAN DIPTERA 



thickened; posterior tibiae often dilated. Apical cell narrowed apically; 

 auxiliary vein absent or present; second basal and anal cells present. 

 Only about a dozen species are known, all occurring in Central 

 or South America. Evidently they are not uncommon at certain seasons 

 of the year as ]\Ir. Banks secured a number of specimens in Panama 

 during July and August although I saw only two from December to 

 IMarch. They are evidently seashore inhabitants which extend their 

 range up the rivers. The adults are fast in flight and are excellent 

 hoverers. There is a recent revision of the family by Lindner.* 



KEY TO GENERA 



1. Auxiliary vein present 2 



Auxiliary vein absent Rhinotora Schiner 



2. Scutellum oval 3 



Scutellum pyramidal, directed obliquely upward; arista plumose or bare 



(2, 3) Ropalomera Wiedemann 



3. Arista plumose 4 



Arista bare Kroberia Lindner 



4. Face tuberculate; frontal bristles absent (5) . . . . Apophorhynchus Williston 

 Face carinate; frontals present (1, 4) Willistoniella Mik 



1930. Deutsch. Ent. Zeitschr.. 1930-31. pp. 122-137. 



