FAMILY DOLICHOPID.E THE LOXG-HEADED FLIES 227 



74. Third and fourth veins conspicuously converging apically or the fourth 



strongly curved 75 



Third and fourth veins parallel beyond the posterior crossvein, or 

 nearly so ( 1 ) Anepsiomyia Bezzi 



75. Fourth vein approaching the third in a broad curve and running paral- 



lel with it at the apex Paracleius Bigot 



Fourth vein not so strongly approaching the third or not parallel with 

 it apically (3) ' 76 



76. A second pair of weak scutellar bristles or hairs; metapleura bare; 



fourth vein sometimes angularly curved 77 



A single pair of scutellar bristles; metasternum with two or three 

 minute hairs in front of the posterior spiracle, visible only in some 

 lights; fourth vein with single curve (3, 37) Stolidosoma Becker 



77. Fourth vein straight beyond the posterior crossvein, though approach- 



ing the third (61, 76) Hercostomus Lcew 



Fourth vein curved beyond the crossvein 78 



78. Sixth (anal) vein extending close to the margin of the wing (68) .... 79 

 Sixth (anal) vein extending little more than half way to the margin 



of the wing beyond the anal cell (15, 38) Polymedon Osten Sacken 



79. Fourth vein bent twice in middle of apical section (68, 82). 



Syntomoneurum Becker 

 Fourth vein not bent at nearly right angles (29, 44). .Tachytrechus Lcew 



80. A longitudinal flat or slightly concave area on the posterior third of 



the mesonotum 81 



No such area although there is usually a more or less distinct trans- 

 verse depression immediately before the scutellum 91 



81. Third and fourth veins parallel or almost so beyond the posterior 



crossvein 82 



Fourth vein converging toward the third 86 



82. Hair and bristles wholly yellow 85 



Hair and bristles pai'tly or wholly black or brown 83 



83. Acrostical setulse in two row^s 88 



Acrostical setul* distinct only on the anterior border of the mesono- 

 tum, or absent 84 



84. Yellowish species (60) Xanthochlorus Lcew 



Black or green species Micromorphus Mik 



85. Sixth (anal) vein absent (31, 59) Thrypticus Gerstsecker 



Sixth vein present (11) Chrysotimus Loew 



86. Fourth vein conspicuously doubly curved forward beyond the cross- 



vein; sixth (anal) vein reaching the wing margin or practically so, 

 strong and curved backward at the tip; usually large species (52). 



" Neurigona Rondani 

 Fourth vein straight beyond the posterior crossvein; sixth vein weak, 

 sometimes represented by a fold and usually curving toward the 

 apex of the wing before its end 87 



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



