398 THE XOBTR AMERICAN EMPIDJE—COQUILLETT. vol.xviii. 



12. Abdomen, except sometimes the sides, wholly hlackish; autenuie black 14 



Abdomen yellowish; apex of each segment, and sometimes a median vitta, 



blackish ; doisnm of thorax grayish black 13 



Abdomen and thoiax yellow, unmarked; eyes of male snbcoutiguous; fila- 

 ment of hypopyginm free, slender, arcuate riifescens. 



13. Abdomen with a medio dorsal black vitta, first two joints of antenna' black, 



pleura unmarked -• lougipes. 



Abdomen destitnte of a medio-dorsal vitta, first two joints of anteunai 

 yellow, pleura marked with black, scutellum bearing four bris- 

 tles 7ii(m;7e(p.403). 



14. Sides of thorax and of veuter not thickly pilose 15 



Sides of thorax and of veuter covered with long, abundant yellow pile, hmirentris. 



15. Tibiio wholly yellow, hind legs simple amijiis. 



Tibia black on apical part, hind ieniora near the apex and hind tibiie near 



the base furuished with teeth-like processes in the male; eyes widely 

 separated, scntellum bearing two bristles loripedis (p. 400). 



16. Femora black or very dark brown 42 



Femora largely or wholly yellowish 17 



17. Knob of halteres yellowish 22 



Knob of halteres blackish 18 



18. Front and middle cox;tp black 19 



Front and middle cox;b yellow, anterior branch of third vein usually ending 



in the second, eyes of male contiguous, filament of hypopygium slen- 

 der, hidden except on basal part; both sides of each femur and tibia, 

 and upper side of front and hind metatarsi in the female ciliate with 

 scales clauaa (p. 401). 



19. Pile of abdomen black, sparse; that of thorax sparse 20 



Pile on sides of abdomen white, abundant, thorax thickly pilose, scutellum 



pilose and bearing twelve marginal bristles, hind femora twice as thick 



as their tibiie, anteunal style as long as the third joint., comanfis (p. 402). 



20. Palpi yellow ; length, 7 to 9 mm 21 



Paljii black, apices of tibia- blackish, wings brownish, eyes of male contig- 

 uous, filament of hypopygium hidden ; length, 4 mm spiloptera.' 



21. Sciatellum bearing ten marginal bristles, abdomen on first four segmeuts 



opaque gray pollinose, wiugs hyaline vnlentis (p. 402). 



Scntellum bearing only four bristles, abdomen shining, wings brownish gray, 



eyes of male separated, filament of hypopygium filiform., liumile (p. 403). 



22. Wings hyaline or grayish 24 



Wings brown 23 



23. Anteunal style almost one-half as long as the broad third joint, eyes of male 



widely separated itnehrosa (p. 404). 



Anteunal style less than one-fourth as long as the elongated third joint, eyes 



of male contiguous S2)ectahiUs. 



24. Abdomeu black or dark brownish 27 



Abdomen yellowish, sometimes marked witli black 25 



25. Dorsum of abdomeu not marked with black in the middle 26 



Dorsum of abdomen more or less black in the middle, eyes of male wideh' 



separated, filament of hypojiygium very thick at base, then suddenly 

 attenuated ; length, 6^ mm loripedis (p. 400). 



26. With a long bristle on costa near its base, pile of abdomen black, stigma dis- 



tinct; length, 6 mm tersa (p. 404). 



Without such a bristle, pile of abdomen whitish, stigma wanting; length, 



31 mm compta (p. 405). 



27. Pile in front of halteres black 30 



Pile in front of halteres whitish ; length, 6 to 7 mm 28 



