14 Everett E. Wehr 



works have aided materially in making identifications and in 

 preparing the synoptic tables. 



To Professors Myron H. Swenk and R. W. Dawson the 

 writer wishes to express his gratitude for the many valuable 

 criticisms and suggestions offered during the preparation of 

 this paper, and also for a critical reading of the manuscript. 



CHARACTERS OF THE FAMILY SYRPHIDAE 



Antennae three-jointed ; usually with a dorsal arista, rarely 

 with a terminal style ; third vein of the wings without an an- 

 terior branch ; anal cell acute and prolonged nearly to the wing 

 margin ; either a spurious vein present between the third and 

 fourth veins, or a subsquamal plumose filament (the plumula) 

 present, usually both present ; empodium bristle-like ; hypopy- 

 gium asymmetrical, an elongated mesocoxal projection present 

 on middle coxae. 



TABLE OF SUBFAMILIES OF SYEPHIDAE 



1. Chitinous parts of body thickly punctate; prostigma placed on 

 cephalic aspect of thorax, thorax being foreshortened ; abdomen 

 of both sexes consisting of four visible segments; arista as short 

 as the width of third antennal joint; spurious vein of anal cell 

 (elsewhere called the anal furrow) very short, not extending as 

 far as anal lobe incision; eyes faintly pubescent. Medium sized 



^^^ Nausigasterinae 



Body not punctate and otherwise not as above 2 



2. Antennae very elongate and with a terminal style; anterior 

 cross-vein joining discal cell at or beyond the middle; usually 

 an adventitious branch extending into first posterior cell (discal 

 cell, Shannon) from third vein; face produced downwards, bare;' 



■ plumula absent; males holoptic, with only four visible abdo- 

 minal segments; females with five abdominal segments....Ce?-ioJdmae 



Antennae without a terminal style, excepting in CalUcera and 

 Pelecocera, but these genera have the anterior cross- vein joining 

 the discal cell well before the middle 3 



3. Antennae very elongate, with a bare dorsal arista; face evenly 



120 



