THEREVID.E. 



207 



Metaphragma is, I believe, purel} T a specific character, 

 and will not be found in allied species. 



Fig. 80. Therevidse. I, Tabuda, head; 2, Psiloccphala, wing: 3, 

 Psilocephala.) antenna. 



TABLE OF GENERA. 



1. First antennal joint much thickened and elongate. . . 2 

 First antennal joint not noticeably thickened. ... 5 



2. Head not as broad as long; vertical diameter of the eyes equaling 



the horizontal diameter; eyes of male dichoptic. Nebritus. 

 Head distinctly broader than long. ...... 3 



3. Third antennal joint about one-third the length of the first; fourth 



posterior cell open. ........ 4 



Third antennal joint more or less elongated. . Thereva, pt. 



4. First posterior cell divided by a cross-vein. . Metaphragma. 

 First posterior cell not divided by a cross-vein ( ? Pachyrhiza, 



? Baryphora] (1). . .... Tabuda. 



5. Third joint of the antennae about four times the length of the first; 



without style; fourth posterior cell closed; front of male broadly 



dichoptic Henicomyia. 



Third joint of antennae not four times the length of the first; fourth 

 posterior cell open or closed. ...... 6 



6. Face bare; usually more bare and shining species (2, 3) (Ozodi- 



ceromyia] . ....... Psilocephala. 



Face distinctly pubescent or hairy; usually more pilose and polli- 

 nose species. (Fig. 80; also fig. 15, p. 42, not Rhyphus.} 



Thereva. 



