181 



strong thorns, or if these are absent the antennae are very short 

 and project downward and outward and do not curve over the 

 upper margin of the eye or reach nearly to base of wing ; thoracic 

 respiratory organs sessile, rarely stalk-like; legs of variable 

 length ; abdomen usually armed with strong spines or bristles, or 

 if unarmed there are only 4 or 5 distinct pairs of abdominal spira- 

 cles BRACHYCERA (p. 307). 



IMAGINES 



1. Antenna consisting of at least 7 joints, frequently filiform, rarely 

 conspicuously thickened, but if so the joints are distinct and the 

 flagellum does not appear as a single joint with poorly defined 

 subdivisions, and the palpi are pendulous, consisting of 4 or 5 

 joints; antennae with or without whorls of hair on the joints, 

 never with a terminal arista or style ; palpi always pendulous, 



normally consisting of 4 or 5 joints, very rarely of only 2 



NEMATOCERA (p. 182) . 



— Antennae consisting of 3 joints, the third occasionally having more 

 or less distinctly annulated subdivisions, but in such cases the 

 palpi are porrect and consist of 1 or 2 joints; antennae with short 

 pubescence or with thick branches, in some families with either a 

 terminal or subterminal style or arista; palpi projecting forward, 

 consisting of 1 or 2 joints BRACHYCERA (p. 307). 



