412 THE XOETS AMEBIC AX EMPID^—COQUILLETT. vol. xvi 



18. Abdomen wholly black or dark brown I'J 



Abdomen yellowish, at least on hind margins of the segments; hind femora 



thickened; length, 5 nun. ; inhabits New Hampshire rustica. 



19. Knob of haltcres yellowish 20 



Knob of lialteres and antenn:e blackish, hind femora reddish macilenta, 



20. Inhabits California; two basal joints of antennte black, base of hind femora 



yellowish 21 



Inhabits the Atlantic States; two basal joints of antennne yellowish, base 



of hind femora black pnUa. 



21. Antennal style one-half as long as the third joint, wings brownish 



caJifornica (p. 420). 

 Antennal style one-fonrth as long as the thirdjoint, wingshyaline loripedts (p. 419). 



22. Males 23 



Females 37 



23. Eyes contignons or nearly so 24 



Eyes distinctly separated, thorax opaque or only subshining 33 



24. Abdomen, at least on the dorsum, black 28 



Abdomen yellowish 25 



25. Hind femora slender, hind tibi;p and front tarsi, except at apex, yellow 26 



Hind femora thickened, i)ile of thorax black, basal half of hind tibiae and 



front tarsi brown ; proboscis as long as height of head ; length, 



5 mm dimidiata. 



26. Pile and bristles of thorax black, filamentof hypopygium very tlexuous,middle 



laiuelhc not tapering to the apex, the pile black 27 



ile and bristles of thorax yellow, filament not llexuous, middle lamelhi? taper- 

 ing to the apex; length, 3 mm arctiata (p. 421). 



27. Proboscis scarcely longer than height of head, wings hyaline, facets of eyes 



of a uniform size; length, 4 mm dchilis. 



Proboscis three times as long as height of head, wings brownish-gray ; upper 



facets much larger than the lower; length, 5 to 7 mm. ampUpedis (p. 422). 



28. Filament of hypopygium free, except sometimes its extreme apex 30 



Filament hidden except on its lowest one-half or less 29 



29. Thorax and abdomen shining ; length, 6 mm gracilis. 



Thorax and abdomen opaque; middle lamella of hypopygium beyond apex 



of upper lamella i>roduced in a high, conical process; length, 8 to 

 10mm quinqueUneata. 



30. Filament very floxuous toward its apex, not fractured, hind femora slender. 31 

 Filament slightly undulate but not doxuous, middle lamella beyond tip of 



upper one produced in a rounded lobe; length, 9 mm rava (p. 410). 



31 . Upper lamella of hypopygium destitute of a fleshy process, abdomen shining. 32 

 Upper lamella greatly swollen, and below its apex bearing a cylindrical, 



fleshy, bristly jirocess; thorax and abdomen opaque ttrsa (p. 422). 



32. Thorax shining, venter blackish ; length, 3 mm compta (p. 423). 



Thorax opaque, venter yellow, abdomen compressed; length, 4 mm., hiteirentris. 



33. Filament of hyijopygium hidden except its lower part 34 



Filament free, very sinuous toward its apex, wings whitish-hyaline, scutel- 



lum bearing four bristles ; length, 4 mm candicana. 



34. Abdomen opaque, gray pollinose and long yellow pilose 35 



Abdomen shining, depressed, its pile black, palpi yellowish; length, 5 mm, 



inacUcnta, 



35. Wings brownish 36 



Wings grayish, third antennal joint narrow, style very short, hind tibia' 



bearing very long yellow pile; length, 4 mm longipennis. 



36. Length. 6 mm. ; third antennal joint narrow, style robust, hypopygium small, 



its filament very thick, femora robust, setnlose below gilvipes. 



