1. — Hind tibiae with spurs at their tips (sometimes small:. ( Pangonince. ) 2 



Hind tibiae without spurs; ocelli absent. ( Tabanince.) 5 



2. Third joint of the antennae composed of eight annuli, the lirst of which is only a 



little longer than the following ones , 3 



Third joint composed of five or fewer segments, the first of which is much longer 



than the following; ocelli present 4 



3. — Front of female narrow, without denuded callus; ocelli rarely absent.. Pangonia. 



Front of female broad, with a large, broad, denuded callus; ocelli present 



Apatolestes, ^. 11. 



4. Second joint of the antennae about half as long as the first; wings hyaline or with 



small spots; eyes in life with numerous small dots Silvius. 



Second joint as long, or but little shorter than the first; wings with a dark pic ure; 

 eyes in life with fewer, larger spots Chrysops. 



5. - -Front of the female as broad as long; callus transverse; front tibia; a little 



dilated; base of third antennal joint not dilated Haematopota. 



Front of female narrow 6 



6. — Front tibia; very much dilated; third antennal joint not strongly angulated above 



Lepidosiimjii. 



Front tibiae moderately dilated ; face short Diachlorus. 



Front tibioe not dilated 7 



7. — A small ocelligerous tubercle present in the female; eyes pubescent, more dist- 

 inctly in the male Therioplectes. 



( >celligerous tubercle absent; eyes pubescent Atylotus. 



Ocelligerous tubercle absent; eyes bare Tabanus. 



LEPTID^. 



Third joint of antennce simple ; with a simple, or thickened siyliform, 

 bristle; tegulce rudi??ientaty. 



Rather small to rather large species; thinly pilose, with short thorax, 

 elongate abdomen and large wings. Head short, eyes of male contiguous 

 or approximate; ocelli present. Antennae mostly short, never elongate, 

 the third joint with a terminal or dorsal bristle, or terminal slender style. 

 Face small, excavated. Proboscis short; palpi slender, porrect, often 

 bushy pilose. Abdomen elongate, broadest toward the base, composed 

 of seven segments; the female ovipositor pointed. Legs slender, the hind 

 pair somewhat elongate; some or all the tibiae spurred. Posterior cells of 

 wings all open. 



Larvae carnivorous, living in earth, decaying wood, dry sand, 

 in moss or in water. The flies are usually found about meadow 

 and low woodlands, on bushes, etc., and prey upon other insects. Some 

 western species of Symphoromyia, according to Osten-Sacken, suck blood, 

 as do the horse-flies. 



