80 NOrvTII AMERICAN DIPTERA. 



27. Hind coxie witwout erect hairs on the outer side, third and fourtli veins 



near the tip convergent HYi'OciiARASSus-^firir^irC. 



Hind coxaj wit^^ one or more erect hairs, third and fourth veins paral- 

 lel, wings wide. ......... 28 



28. Scuteihun witli smaller hairs on the disk besides the marginal hristles. 



iASXA.Eiii; R^v- M ik . 

 Seutelluni bare, except for the bristles. . . Augyra Macquart. 



29. Posterior third of thoracic dorsum, before the scutellum, concave or 



at least distinctly flattened. . - 30 



Dorsum rounded as usual. ........ .j2 



;10. Bristles of thorax yellow. ..... Cuuysotimits Loew. 



Bristles black, rarely brownish. ....... ol 



31. Fourth vein parallel with the third beyond the cross-vein, or nearly so. 



Xanthochlorus Loew. 



Fourth vein converging toward the third beyond the cross-vein, either 



gradually or by a doul)le curve.Y^<*J-^^|!V!^^ ■ . . Grft-b5rckrttr4o. 



32. Wings elongate, the posterior cross-vein considerably beyond the mid- 



dle, less than its length from the apex of the fifth vein (Hydropho- 

 rinae). ............ 33 



Wings not elongate, cross-vein scarcel}' beyond the middle, more than 

 its length from the end of tiie fifth vein (if less, the hind metatarsus 

 shorter than the following joint). ...... 35 



33. Fore femora slender. ...... Liancalus Loew. 



Fore femora more or less incrrassated, with spines below. . . 34 



1^ a4l\XA»a)^'''^- !^piiies of fore femora very short, thoracic dorsum without well marked 



x? L /tA»lJi\ poUinose lines Hydropuokus Fallen. 



' Spines of fore femora long, dorsum with pollinose lines. Scei.H'S Loew. 



•VM^, 



35. Outer appendages of the hy])opygium long, filiform. 



Nkmatoprocti'S Loew. 

 Outer appendages not long and filiform. ..... 3(5 



30. Second antennal joint with a tliumb-like i)rojection along the inner 



side of the third (Synarthrus Loew). . . Svntormon. 



Not with such i)roJongation. . 37 



37. Eyes contiguous or nearly so below the anteniup. ... 38 



Eyes contiguous above the antenna\ . . Diaphoris ^leigen. 



Eyes closest together at the level of the antennae, diverging above and 



below ; middle legs of niale distorted. . CAiMPsicNKiMU.s Walker. 



Eyes not ap])ro\iiiiat(d. 39 



