242 



NORTH AMERICAN DIPTHRA. 



basal cells small, the anal always longer than the second 

 basal ; posterior cross- vein sometimes wanting. 



The flies of this small family have been seen dancing 

 in the air in small swarms, or running about on the 

 leaves of underbrush. The most remarkable thing about 

 them is the oftentimes extraordinary ornamentation of 

 the hind tarsi of the males, which are always different in 

 structure from those of the females. The flies are not 

 tften met with, and maybe entirely wanting even in con- 

 siderable collections of diptera. Some, perhaps all pla- 

 typezid larvae live in fungi (Agariciis, Lepiota, etc.). 

 They are flat, oval, with jointed, thread-like processes 

 on the sides of the segments. The puparia are not very 

 different from the larvae. 



Fig. 94. Platypezidae. i, Platycnema^ wing; 2, Callimyia, wing; 

 3, Callimyia, hind tarsus of male; 4, Platypeza, wing; 5, Platypeza, 

 hind tarsus of male; 6, Calotarsa, wing; 7, Calotarsa, hind leg of 

 male; 8, Agathomyia, antenna (Verrall). 



