FAMILY DULICIIOPID.E THE LONG-HEADED FLIES 229 



87. Second antennal segment produced along the inner side of the third 



(67, 73) Coeloglutus Aldrich 



Second antennal segment not produced along the third (63, 86). 



Medeterus Fischer 



88. Sixth (anal) vein absent 89 



Sixth (anal) vein extending almost to the wing margin (52). 



* Neurigona Loew 



89. Arista subapical (62) Achalcus Lcew 



Arista apical 90 



90. Pleura yellowish (4, 36) Xanthina Aldrich 



Pleura metallic green (6, 7) t Collinellula Aldrich 



91. Fourth vein ending well before the tip of the wing, its outer edge 



concave just beyond the bend 92 



Fourth vein ending but little before the tip of the wing, if curved 

 beyond the posterior crossvein there is no concavity on the outer 

 side 93 



92. Dorsocentral bristles strong (19) Plagioneurus Loew 



Dorsocentral bristles hair-like (Edematopus Van Duzee 



93. Posterior crossvein as long or longer than the ultimate section of the 



fifth vein; basal segment of the posterior tarsi longer than the 



second 94 



Posterior crossvein rarely as long as the ultimate section of the fifth 

 vein, if so, the basal segment of the posterior tarsi shorter than the 

 second 97 



94. Pteropleura haired in front of the posterior spiracle 95 



Pteropleura bare in front of the posterior spiracle 96 



95. First antennal segment with stout setulte below (72) .Melanderia Aldrich 

 First antennal segment bare below (Hydrophorus pt) (80). 



Millardia, n. g. 



96. Middle of the propleura haired (26, 43, 56, 78) Hydrophorus Meigen 



Middle of the propleura bare (45, 81) Paraphrosylus Becker 



97. Acrostical setulae present 98 



Acrostical setulse absent (14) Thinophilus Wahlberg 



98. Arista apical or practically so, sometimes arising a little above the 



tip of the pointed third antennal segment 99 



Arista dorsal, rarely arising a little beyond the middle of the third 

 segment 105 



99. Propleura bare or with a single bristle in the middle 101 



Propleura haired in the middle 100 



100. Second antennal segment projecting thumb-like into the third on the 



inner side (9, 84 ) Synarthrus Loew 



Second antennal segment transverse or only gently convex apically 

 (21, 47, 49) t Rhaphium Meigen 



* Van Duzee, 1913, Ann. Ent. Soc. Amer., vi, pp. 22-61. 



t I have not seen specimens of Collinellula but the genus is very riose to Xanthina and 

 no struclui'al differences are mentioned in the description. 



t Curran, 1926-1927, Tr. Roy. Can. Inst., xv, pt. 2, rp. 249-260; xvi, pt. 1, pp. 99-179. 



