274 



MEDICAL ENTOMOLOGY 



4. Third joint of antenna with each segment branched . ' < 

 Third joint of antenna not branched 



5. Upper corner of eyes terminating in an acute angle . 

 Upper corner of eyes not terminating in an acute angle . 



6. Antenna deep-seated, inclined downwards ; palp very large 



and thick .......... 



Antenna not deep seated not inclined downwards ; palp not 

 very large and thick . 



7. Antenna subulated ; proboscis with terminal lips in form of a 



hatchet ; anal cell open and anal vein curved 

 Antenna not subulated; proboscis simple; anal cell closed, 

 anal vein not curved . . . 



8. Proboscis scarcely extending beyond palpi .... 

 Proboscis extending beyond palpi . . . 



9. Wing with fourth posterior cell closed ..... 

 Wing with fourth posterior cell open . . . 



10. Eyes not bare .......... 



Eyes bare .......... 



11. Wing with first posterior cell closed ; eyes bare or hairy . 



(including subgenera) 



Wing with first posterior cell open ; eyes hairy or bare . 



(including subgenus) 



SILVIUS AND ALLIED GENERA 



12. First and second joints of antenna short 



First and second joints of antenna long 



13. First joint of palp thickened ....... 



First joint of palp not thickened ...... 



14. Second segment of abdomen unusually large ; spurs on tibiae 



small ........... 



Second segment of abdomen not unusually large ; spurs on 

 tibiae not unusually small , . . . , 



15. Face concave in the middle 



Face not concave in the middle ...... 



16. Wings with first posterior cell open ..... 



(including subgenus 



Wings with first posterior 1 cell closed ; frontal callus absent 

 Wings with first posterior cell closed ; frontal callus present. 



17. Third joint of antenna with an acute spine on the first annulation 

 Third joint of antenna with no spine on the first annulation. 



18. Second joint of antenna as long, or nearly as long, as the first 



joint ; wings usually with black or brown designs 



B 

 SUBFAMILY TABANINAE 



1. Third joint of antenna consisting of four divisions, without a 



tooth or angulation ; . . 

 Third joint of antenna with five divisions 



Pityocera. 

 Goniops. 



Cadicera. 



Pelecorhynchus. 



Apatolestes. 



9 

 10 

 11 



Scione. 

 Dorcalaemus. 

 Pangonia. 

 Erephrosis and 

 Subpangonia.) 

 Diatomineura. 

 Corizoneura. 



13 

 18 



Scepsis. 

 Adersia. 



Pronopes. 



Rhinomyza. 



15 

 16 



Silvius. 



Esenbeckia.) 



Aegophagamyia. 



Bouvierella. 



Gastrixodes. 



18 



Chrysops. 



