56 NORTH AMERICAN DIPTERA. 



17. All the tibia? and the hind femora with short, strong setae. 



ECTHODOPA Loew. 

 Hind femora without such setae. . . . DIOCTRIA Meigen. 



18. Face distinctly swollen in profile, gibbose. . . . .19 

 Face flattened or gently convex 20 



19. Thickly pilose species; the gibbosity of the face reaches to the base of 



the antennae; anal cell usually open. '."" CYRTOPOGON Loew. 

 Thinly pilose, more pollinose species, the convexity of the face con- 

 fined to the lower part; anal cell usually closed. LASIOPOGON Loew. 



20. Abdomen elongate; front broad anteriorly, narrow behind. 



PLESIOMMA Macquart. 

 Front not narrowed behind 21 



21. Hind tibiae toward the tip and the hind metatarsi much thickened. 22 

 Hind tibiae not, or but slightly, thickened toward the tip ; metatarsi not 



thickened 23 



22. Head much broader than high, transverse, "goggle-like "; abdomen 



short, wings large HOLCOCEPHALA Jaennicke. 



Head only moderately broader than high, not at all spectacle-like in 

 appearance. ....... HOLOPOGON Loew. 



23. Abdomen with thick, recumbent pile above; thickly pilose species; 



antennae slender PYCNOPOGON Loew. 



Abdomen without such pile above 24 



24. Slender, nearly bare species ; face perpendicular, straight or gently 



concave, narrowed above and bare, except on oral margin. . 25 



Face gently rounded, not prominent below, in large part hairy and not 



or but slightly narrowed above. 26 



25. Thickly whitish pollinose ; abdomen flattened, usually reflected up- 



ward ; third joint of antennae and the style both slender. 



STICHOPOGON Loew. 



Less thickly pollinose ; abdomen cylindrical, a little broader at the 

 base ; third joint of antennae short and broad, the style minute. 



See HABKOPOGON BILINEATUS Will. 



26. Large, elongate species, the style of antennae short. CALLINICUS Loew. 

 Moderately large, and not much elongate species. . . . 27 



27. Abdomen broader at the base, depressed; thorax much convex above; 



antennae slender, the style long and slender (compare also species of 



Cyrtopogon) HETEROPOGON Loew. 



Abdomen short, cylindrical; black, with bright golden opaque pollin- 

 ose markings on thorax and abdomen. 



See LAPARUS PICTITARSUS Bigot. 



