162 



NORTH AMERICAN* DIPTERA 



KEY TO GENERA 



1. Antennas longer than the width of the head (Brazil) . .Cerocatus Rondani 

 Antennae at most half as long as the width of the head 2 



2. Apical cell closed and petiolate 3 



Apical cell open (1, 2) Scenopinus Latreille 



3. Body with metallic scales (3, 4) Metatrichia Coquillett 



Body without metallic scales (5) Pseudatrichia Osten Sacken 



Scenopinidae. — 1, 2, Scenopinus fencstralis; 3, 4, Metatrichia: 5, Pseudatrichia. 



