9. Third joint of antennae with a distinct basal angle or process 

 above. .......... n 



Third joint of antennas not with a process or distinct angle 

 above. .......... 10 



10. Front of female narrow; front tibiae rather broad (7) . 



Diachlorus. 



Front of female of normal width; front and middle tibiae greatly 

 dilated (9) Lepidoselaga. 



11. Hind tibiae ciliate with long hairs. ..... 12 



Hind tibiae not ciliated. ....... 13 



12. Third antennal joint with a very long basal process, the annulate 



portion short; front tibiae dilated (1O). . . Stibasoma. 



Third antennal joint with a basal prominence; antennae situated 



on a projecting prominence (5). . . . Snowiellus. 



13. Basal process of third antennal joint unusually long, at least reach- 



ing the third ring of the joint; body long (4) Dichelacera. 



Basal process of third joint often short or obsolete, at most not 



reaching the end of the first segment (2, 3). . Tabanus. 



A. Eyes pubescent; an ocelligerous tubercle present in the male. 



Therioplectes. 



B. Eyes bare; no ocelligerous tubercle. . . Tabanus. 



C. Eyes pubescent; no ocelligeroiis tubercle. . Atylotus. 



