Sept., I9I3-] Melander: Synopsis of Diptera. 235 



7. Front narrow, nearly three times as long as the width above, with about 



eleven pairs of uniform fronto-orbitals ; first vein ends near the 

 middle of the wing ; third and fourth veins converging so as almost 

 to close the first posterior cell ; three humeral bristles, one presutural, 

 two small dorsocentrals placed well back ; costa almost bare ; calypteres 

 rather large, the upper one delicately ciliate ; head large, hemispherical, 

 cheeks very narrow, no vibrissal angle ; proboscis very long, slender 

 and geniculate; eyes bare. (North America..) . .Eiisiphona Coquillett. 

 Front relatively broader, never with many large fronto-orbitals ; first vein 

 ends nearer base of the wing; first posterior cell never markedly 

 narrowed ; calypteres rudimentary 8. 



8. Hairy, almost bristleless, no vibrissse, fronto-orbitals or scutellars ; front, 



eyes, mesonotum and pleurae hairy ; front below ocelli over twice as 

 long as wide ; cheeks one sixth the eye-height ; proboscis short and 



robust. (North America.) Arctobiella Coquillett. 



Not densely hairy species, macrochsetse differentiated ; front transverse or 

 quadrate (rarely, e. g., Platophryniyia, Leptometopa), longer than 

 wide 9. 



9. Proboscis long, chitinized and geniculate, the outer portion folding back ; 



vibrissal angle of cheeks usually distinct 10. 



Proboscis very short, fleshy, the labella not strongly geniculate, nor con- 

 structed for piercing; oral margin not or scarcely projecting, usually 

 several vibrissas in an oblique row in front 22. 



10. Arista thickened; third antennal joint small; front square; palpi linear, 



long and porrect ; bristles strong, a presutural and a dorsocentral 

 present in front of the suture ; costa not bristly, stopping at the third 



vein. (North America.) Aldrichiella Hendel. 



Arista slender ; front usually transverse ; palpi more or less clavate ; meso- 

 notum rarely bristly in front of the suture 11. 



11. Posterior crossvein and anal cell entirely wanting, the anterior crossvein 



located much before the end of the first vein, the costa stopping at 



the third vein ; cheeks narrow ; palpi slender ; tibia slender 12. 



Posterior crossvein present, the anterior crossvein opposite or beyond the 

 end of the first vein; anal cell usually present I3- 



12. Face with a prominent central nasiform projection ; antennae rather long, 



arista bare; one presutural, mesopleural bristles present. (Africa.) 



Risa Becker. 

 Face deeply concave; antennae short, the third antennal joint large, orbicu- 

 lar, the arista pubescent ; no mesopleural bristles. (North America.) 



Paramyia Williston. 



13. Tibias, especially the hind pair, compressed, explanate, and more or less 



clavate, particularly in the male; costa extends to the fourth vein. .14. 

 Tibiae not compressed and clavate in either sex; palpi large, porrect. .. 17. 



14. Head horizontally longer than high, the entire under side horizontally 



straight ; front longer than wide ; pteropleurae with bristles ; third and 



