NORTH AMERICAN DIPTKKA. 139 



78 Facial riducs (not sides of face) witli a row of bristles extending to, or nearly 



to base of antemifB Degeeria Mg. 



Facial ridges without such bristles 79. 



79. Abdomen elongate, cylindrical; frontal bristles not descending below an- 



tenuip Polygaiiter v. d. \V. 



Abdomen not unusually elongate and cylindrical 80. 



80. Wings very long; sides of face minutely short hairy. 



Kinpliaiiopleryx Twn.s. 

 Wings usually about length of abdomen 81. 



81. Vibrissa either absent, or hardly longer than the short bristles next theni..82. 

 Vibrissic present, distinct 84. 



82. Wings without costal spine 83. 



Wings with costal spine; abdomen transparent, with black spots. 



Onosoma v. d. W. 



83. Sides of face bare; second vein close to costa and far removed from third, 



costa much dilated in % Pliasioptery.v B. it 15. 



Sides of face with a row of hairs; vibrissse a little stronger than the bristles 

 below them : costa not dilated in % , bead wide below. 



Phasiocli.sta Twns. 



84. Abdomen elliptical, conical, or ovate Aiii^ia v. d. W. 



Abdomen broad, rounded Sphfl^riiia v. d. W. 



85. Third antennal joint many times, and always at least more than three times 



as long as second 86. 



Third joint at most three times as long as second, but usually shorter 87. 



86. Proboscis short and fleshy, with large labella HypoNfeiia Mg. 



Proboscis long and slender, labella very small Sipli<»<'lytia Twns. 



87. Front tarsi twice as long as tibife. legs strongly elongate .^lyobia R. D. 



Front tarsi little longer than tibife 88. 



88. Wings as long, or scarley longer than the elongate-round abdomen ; front 



slightly produced Cl.vtia R. D. 



Wings considerably longer than the conical, ovate or elongate-niund abdo- 

 men ; front not produced Telotliyria v. d. W. 



89. Whole body thickly beset with bristles and hairs, or at least the scutellum 



and abdomen unusually beset with macrochsetse 90. 



Not such species 91. 



90. Sides of face bare; apical cross- vein strongly bowed in...£iasioiia v. d. W. 

 Sides of face bristly ; apical cross-vein nearly straight ..EiilaNioiia Twns. 



91. Third antennal joint as long as, or scarcely longer than second ; arista pu- 



bescent, 2-jointed 92. 



Third joint at least twice as long as second 93. 



92. Vibrissse inserted on oral margin ; sides of face hairy-Wacqiiarlia R. D. 

 Vibrissa inserted far above oral margin; sides of face with several rows of 



bristly hairs Knnyoniiiia Twns. 



93. Arista not visibly jointed : third antennal joint at least four times as long as 



second, facial ridges ciliate Diflyiiia v. d. W. 



Arista distinctly 3-jointed ; third antennal joint not more than three times 

 as long as second 94. 



94. Second aristal joint elongate, arista wholly naked Polidea Mcq. 



Second aristal joint short Myiopliariis R. A B. 



95. Eyes naked 99. 



Eyes hairy (rather indistinctly so in Atrophopoda) 96. 



TR.\NS. AM. ENT. SOC. XIX. JUNE, 1892. 



