NOKTII AMERICAN DIPTKKA. 275 



22. Antennae, itiserted on a line iliavvn tliiough middle of eyes 23. 



Antenupe inserted on or below such line 24. 



23. Arista short-haired ; hind cross-vein half way between small cross-vein and 



bend of fourth vein Acroiiacantlia v. d. W. 



Arista distinctly plumose ; hind cross-vein nearer to bend of fourth vein than 

 to small cross-vein OexioNOiiia Rdi. 



24. Eyes small, less in diameter than width of cheeks 25. 



Eyes of usual size, of greater diameter than width of cheeks 26. 



25. Fourth vein with a stump at bend illicroplitlialiiia Mcq. 



Fourth vein without stump of vein at bend ...Macroinetopa H. & B. 



26. Costa of witigs bristly, or at least with a costal spine 27. 



Costa of wings without bristles, or costal spine; hind cross-vein nearer to 



bend of fourth than to small cross-vein 29. 



27. Abdomen elongate, nearly cylindrical, twice as long as thorax ; segments of 



equal length Kteiiodexia v. d. W. 



Abdomen short, stout, first segment somewhat shortened 28. 



28. Sides of face hairy; claws of % elongate Ptilofle.via B. <t B. 



Sides of face naked ; claws of both sexes alike, usually short. 



Sar<liocera B. & B. 



29. Abdomen conical or elongate-oval 30. 



Abdomen cylindrical or elongate-conical, much longer than the thorax.. ..31. 



30. Middle legs of % disproportionately long C'lioloinyia Big. 



Middle legs hut little, if at all, longer than the others..IfIelaIeiica v. d. W. 



31. Apical cell widely open; wings unicolorous Eiiaiitlia v. d. W. 



Apical cell narrowly open; wings unicolorous. nearly hyaline 32. 



32. Eyes bare; anal segment shorter than preceding one Lieptoda v. d. W. 



Eyes pilose; anal segment very elongate in % Uraiiiyia R. D. 



33. Abdomen cylindrical, very elongate and strikingly attenuated at the base. 



<;ord.vIi$;aster Mcq. 

 Abdomen oval, conical, or subcylindrical, never petiolate 34. 



34. Frontal bristles descending below ba.se of antennae 35. 



Frontal bristles never descending lower than base of antennsie .36. 



35. Antennae inserted above a line drawn through middle of the e.ves. 



C'lisrtoiia V. d. W. 

 Antennae inserted on or below a line drawn through the middle of the eves. 



Sar€4Mle.icia Towns 



36. Third vein with a row of bristles 37. 



Third vein without bristles, except at base 38. 



37. Third antennal joint at least four times as long as second. 



TlieIairo<l<>N v. d. W. 

 Third .joint about twice as long as second Tlicljiira R. D. 



38. Abdomen yellow, with or without black markings 39. 



Abdomen black, sometimes partly whitish or cinereous 40. 



39. Apical cell broadly open Xaiif lio<le.\ia v. d. W. 



Apical cell narrowly open Calodt'xia v. d. W. 



40. Curvature of fourth vein arcuate Klionibotli.Tria v. d. W. 



Curvature of fourth vein angular 41. 



41. Arista short-hairy...., l*M<'ii<l4»iiioriiiia v. d. W. 



Arista distinctl.v plumose 40 



42. Eyes bare Moriiiia Meig. 



Eyes i)ilose <'uiii.y4»|»<i» v. d. W. 



TRANS. AM. KNT. SOC. XIX. DECEMBER, 1892. 



