AMERICAN DIl'TERA. 251 



obtusely oval ; tliird joiut of style three times as long as the lirst 

 two together; proboscis reaching about to hind coxse ; laiuelUe of 

 ovipositor slender, black, about as long as middle femora. 



C. — Proboscis short ; subf. Hirmonfitrinx (Miocene and Living). 



HIR.nOIWEURA Meigen, 1820 (Type H. obscnra (W.) Meig.). 



The following table separates the North American species: 



Terminal luanclies of both media and cubitus uniting before reaching the mar- 

 gin of the wing, forming closed cells (subg. Partisymmictus Bigot). 



H. clan$$a O. S. 



Branches of media meeting, enclosing a cell, but those of cubitus parallel, not 

 even approaching; eyes pubescent H. breviroistri* Macq. 



Branches of media and cubitus not meeting apicaily 1. 



1. Miocene species 2. 



Living species 3. 



2. Stem of cubitus nearly in a straight line with its lower branch. 



II. vulcanica Ckll. 

 Stem of cubitus not nearly in a straight line with either branch. 



H. inelaiifleri Ckll. 



3. Eyes hairy, with quite long black pile • • • 11. texaua t'kll. 



Eyes bare, or at most with very few minute hairs 4. 



4. Brown, with pale rufous legs ; paljji rufous H. psilotes O. 8. 



Black, with yellowish legs; palpi yellow II. flavipes Williston. 



The genus appears to contain discordant elements, which might 

 form the basis of two or three genera or subgenera, but upon closer 

 aiialvsis such divisions seem of doubtful value. The venational 

 character of the closed cells in the branches of the media and cubi- 

 tus is important, but not so stable in tliis family as in others. In a 

 specimen of Ehynchoeephalus sackeni the branches of the media 

 fuse on one side, and remain open on the other. 



The hairiness of the eyes seems equally important ; but it is not 

 an absolute character, as Williston notes that the female U. flavipti< 

 shows a few scattering hairs, visible with a lens, and suggests that 

 the male may prove to have the eyes distinctly pubescent. It is 

 noteworthy that H. brevirostris and II. texaiut, known only in the 

 male, have hairy eyes; while H. cluusa, H. psilotes and H. flavipes, 

 known only in the female, have them bare. H. obscura, the type 

 of the genus, has them bare. 



Ilirinonenra claiiMa Osten Sackeu, Western Diptera (1877), p. 225. 

 Dallas, Texas {Boll). Figured in Comstock's Manual, p. 460, as 

 /' hyn c/iocep ha lus. 



TRANS. AM. ENT. 90C. XXXIV AUGUST, 1908. 



