NORTH AMERICAN DIPTEKA. i:]7 



48. Apical cell dosed in mavKin ; second and third anfennal joints about f.,„al 



in length, vibrissa' inserted considerably above oral margin. 



.MnM<M»i>tery.v Twns. 



Apical cell pctiolate; third anteunal joint many times longer than s.'cond, 



vibrissas inserted on oral margin I^aM-luioiuma Twns 



49. Third antennal joint as long, or at most twice as long as second .5o! 



Third joint always more than twice as long as second* fj^ 



50. Shining gold-green or blue species Gyiinioclia'tai r' I)' 



Other colored species .-i 



51. Fourth vein with distinct stump of vein at bend ; palj.i small, rudimentary! 



.Microi>alpii<i« Mcq. 

 Fourth vein with at most a wrinkle appearing like a stump r>2. 



52. First abdominal segment .somewhat shortened : tail unarmed. 



x\eniori(>a It. D. 

 First segment not shortened; tail of 9 with forceiKS-like appendage. 



Iial»i€li$;aster Mcq. 



53. Fourth vein with stump of vein at bend ><<'laiiO|>lir.y<s Will. 



Fourth vein without stump at bend, at most with a wrinkle '. .",4. 



54. Hind tibiasciliate; last tarsal joint of ? enlarged, ovaL.Masipoda H. A H. 

 Hind tibiae and tarsi normal in both sexes 55 



55. Vibrissa inserted at some distance above oral margin, epistoma nor promi- 



"^"t nj>itac-«'Ha V. d. W. 



\ibrissie inserted on, or very near oral margin 5(5 



56. Frontal bristles reaching only to base of antennai, cheeks usually hairy. 



.4poria .Mcc]. 

 Frontal bristles extending below base of antennse ,-,7 



57. Eyes only thinly hairy, more distinctly so in % . 



llyi>liaiitroi>liaja;a Twus. 

 Eyes very thickly and distinctly hairy in both sexes K.vori.ttta Mg. 



58. Eyes naked (very thinly hairy in Plngiprosphenjsa) ijl. 



Eyes hairy, at least in % gy 



59. Head more or less swollen (like CnephnUa), frontal bristles in double row; 



arista thickened its whole length I>i.<«tiolioiia v. d. \V 



Head not swollen, frontal bristles in single row; arista thickened not more 

 than half its length ^•Q 



60. Vibrissa; inserted well above oral margin ■'^■■plioroocra Twns. 



Vibrissa; inserted nearly on oral margin I'liorocera R. D 



61. Apical cell closed in margin, petiolate, or exceptionally very narrowly opeu..63 

 Apical cell always open qo 



62. Hind cross-vein oblique, venation P/flgia-like..l»Iagi|»roN|»liei\ysa Twns. 



Hind cross-vein normal. 



.66. 



63. Sides of face and cheeks narrow : eyes large, extending downward nearly as 



far as tips of antenna' g4 



Sides of face and cheeks extraordinarily wide ; eyes very small in proportion, 

 hardly extending below middle of head Baiiniliaii<>ria Mg. 



64. Arista geniculate, second joint elongate (j.. 



Arista not geniculate I'rosopn'a Rdi. 



■•" In some species of Mystacella the tliird joint is just twice as long. 



TR.iN^S. .\M. ENT. SOC. XIX. (18) JUNE, 1892. 



