1895. PROCEEDINGS OF THE NATIONAL MUSEUM. 399 



28. .Scntellum bearing at least sis bristles, under side of apical half of bind femora 



of female ciliate with scales ravida (p. 403). 



Scutelhim bearing only two bristles, both sides of middle and hind femora 



and tibi;t3 of female ciliate with scales captus (p. 405), 



.Scutellnm bearing four bristles, legs of female not ciliate. 29 



29. Wings grayish, stigma distinct avida (p. 405). 



Wings whitish, stigma wanting levicula (p. 406). 



30. Males 31 



Females 36 



31. Filament of liypopygium free, at least on lower half 32 



Filament hidden, eyes widely separated; hind femora on under side near the 



tip, and hind tibia' near the base, bearing teeth-like processes. .. poiilitea. 



32. Hind femora near the tip and hind tibi;c near the base destitute of teeth- 



like processes 33 



Hind femora and tibia' bearing stich processes, eyes separated marica (p. 406). 



33. Abdomen shining 34 



Abdomen opaque, eyes widely separated, hind trochanters produced at apex 



and ciliate with black spines; filament of hypopygium unusually 

 thick at base 35 



34. Front coxfe black, eyes widely separated, scntellum bearing four bristles, wing 



veins brown ; length, 5 ram. ; antennal style one-third as long as the 

 third joint otiosa (p. 407). 



Front coxa' black, veins brown, antennal style over one-half as long as third 



joint Immile (p. i03). 



Front coxiT> yellow, wing veins white ; length, 3 mm varipes. 



Front coxfe brown, scutellum bearing only two bristles, all femora not fur- 

 nished with black spines on the under side, wing veins blackish ; length, 

 4 mm distans. 



35. Hypopygium with a backwardly curving, lunate jirocess on its under side, 



wings pure hyaline, pollen of abdomen light gray reciproca, 



Hypopygium destitute of such a process, wings grayish, pollen of abdomen 



brownish nuda. 



36. Abdomen opaque 3g 



Abdomen shiuiug 37 



37. Front coxte yellow ; length, 3^ mm varipes. 



Front coxic black ; length, 6 mm otiosa (p. 407). 



38. Costa destitute of a long bristle near its base 39 



Costa bearing such a bristle, which equals the second joint of the front tarsi 



in length ; front and hind metatarsi subequal in length manca (p. 406). 



39. Metatarsi yellowish 40 



Metatarsi black, pollen of abdomen brownish nuda. 



40. Third antennal joint slender, elongate 41 



Third joint broad, short, scarcely twice as long as the style; second segment 



of abdomen bearing a fringe of long black bristles toward the sides 

 near the hind margin gulosa (p. 408). 



41. Eastern species (New Hampshire) reciproca. 



Y/estern species (Colorado to Alaska) poplitea. 



42. Knob of halteres blackish 55 



Knob of halteres yellowish 43 



43. Males 44 



Females 5q 



44. Eyes contiguous, or nearly so 46 



Eyes distinctly separated 45 



45. Legs very slender, filament of hypopygium hidden, abdomen opaque; length, 



4 mm stenoptera. 



Legs very robust, filament free, abdomen shining, the last segment destitute 



of white pollen otiosa (p. 407). 



