FAMILY TACHIXID.i: THE TACHIXIDS 429 



69. Not metallic green or blue 70 



Metallic green or blue Chrysotachina Brauer & Bergenstamm 



70. Parafrontals polliiiose, at most bare at the vertex 71 



Paraf rentals shining black Polidaria n. g. 



71. Oral margin not strongly obliciue in front nor carried strongly up- 



ward toward the base of the antennae; antennse situated at or above 



the middle of the eyes; oral margin produced or not 72 



Oral margin and antennal base unusually approximated, the oral mar- 

 gin strongly oblique in front; antennfe situated below the middle 

 of the eyes; paraf acials always with many hairs below the frontals. 



Lydina Desvoidy 



72. Ocellar bristles strong 75 



Ocellars absent or very weak 73 



73. Antennae inserted at upper fourth of eyes; bend of fourth vein with 



stump (141, 167) Xanthophyto Townsend 



Antennae inserted at middle of eyes; bend of fourth vein wathout 

 stump 74 



74. Arista plumose (188, 195) Zonalia, n. g. 



Arista short pubescent or bare (146, 161, 166, 187) Corozalia, n. g. 



75. Head almost as long below as at the antennae, the oral margin pro- 



duced; vibrissfe usually situated above oral margin 77 



Face retreating below; vibrissae level with oral margin 76 



76. Fifth vein bristled Minthoplagia Townsend 



Fifth vein bare 78 



77. Palpi of normal length, more or less swollen apically 78 



Palpi not more than half the usual length, never widened apically; 



fourth vein with long appendage at bend (77) . . . .Linnaemya Desvoidy 



78. Pteropleural bristle extending to the apex of the squamae 81 



Pteropleural bristle normal 79 



79. Face about as long below as at the antennse 80 



Face strongly receding Thelairodoria Townsend 



80. Abdomen long and slender Oxydexia Bigot 



Abdomen short, robust Mericia Desvoidy 



81. Posterior pair of presutural acrosticals situated very close to the 



suture 82 



Posterior pair of presutural acrosticals situated far before the suture; 

 female ocellars reclinate; male with outer verticals. 



Trafoia Brauer & Bergenstamm 



82. Pleura with fine, pale pile below; third antennal segment rounded 



apically Neoerigone Townsend 



Pleura wholly black haired 83 



83. Front tarsi of female broadened; third antennal segment rectangular 



at upper apex (142) (Exoristoides Coquillett, Exoristopsis Town- 

 send ) *Eversmannia Desvoidy 



Third antennal segment rounded at upper apex Mericina Curran 



* The tienera Neoerigone, Eversmannia and Mericina are so poorly distinguished that I 

 think they should be united. For key to species see Aldrich, Proc. U. S. N. M., Ixxxi, Art. 9, 

 p. 24 (Exoristoides). 



