1895. PROCEEDINGS OF THE NATIONAL MUSEUM. 413 



Length, 4 mm.; third auteunal joint broad, style minute, hind tibiaj and 



metatarsi hearing many long pile, hypopyginm large, ascending. Zi^wraYa, 



37. Abdomen, at least dorsally, black or dark broTrn 39 



Abdomen yellowish, wings brownish 38 



38. Proboscis at least three times as long as height of head, under side of 



middle and hind femora ciliato Avith scale-like seta> ; length, 5 to 



7 mm ampUpedis (p. 422). 



Proboscis scarcely exceeding height of head ; length, 4 mm deMlis. 



39. Hind legs bearing nearly erect scales, discal and iiosterior cells normal; 



length, 4 mm 40 



Hind and other legs destitute of such scales 41 



40. Middle and hind femora ciliate with scales on the under side, hind tibiae not 



ciliate efera (p. 427). 



Middle and hind femora destitute of scales, both sides of hind tibire ciliate, 



basal third of wings hyaline, the remainder brown basalis (p. 410)- 



41. Discal and posterior cells normal, abdomen not silvery pollinose 43 



Discal cell unusually long, sending only two veins to the wing margin; 



length, 4 mm 42 



42. Abdomen silvery white pollinose Vtiurata. 



Abdomen not silvery pollinose longipennis. 



43. Wings marked with a black spot in the submarginal and first posterior cells 



only ; thorax shining ; length, 6 mm gracilis. 



Wings with at least the posterior cells blackish brown ; thorax opaque 44 



Wings destitute of such spots, uniform in coloring; length, 4 to 6 mm 45 



44. Brown near apex of wings in the form of a cloud which does not invade the 



submarginal cell quiuquelineata. 



Brown covers apex of wing, invading the submarginal cell, b'asal half of 



Aviugs yellowish gray rava (p. 410). 



Brown covers apical half of wings, the basal half whitish hyaline; venter 



yellow; length, 5 mm nasoni (p. 423). 



45. Venter black 46 



Venter pnrtly yellow, pile in front of halteres black, middle and hind tibia' 



dark brown htieiventris. 



46. Thorax opaque 47 



Thorax shining, halteres yellow, pile in front of them black, third antennal 



joint broad at base, hind femora slender: Californian species 



calif ornica (p. 420). 



47. Knob of halteres yellowish 48 



Knol) of halteres dark brown, pile in front of halteres blatjk, third antennal 



joint linear ; hind femora thickened, blaak setulose below macilenta. 



48. Wings grayish hyaline, hind femora slender, pile in front of halteres white, 



third antennal joint broad at the base americana. 



Wings grayish, veins brown, hind femora thickened, black setulose below, 



third antennal joint narrow ; length, 6 mm gilvijyes. 



Wings whitish, A^eins except the costa and first vein whitish ; length, 4 mm. 



candicans. 



49. Wings brown, the base hyaline or yellowish ; length, 3 to 5 mm 50 



Wings uniformly hyaline or grayish 54 



Wings uniformly brown or blackish 107 



50. Discal and posterior cells normal 51 



Discal cell unusually long, sending onlj- two veins to the wing margin, abdo- 

 men silvery pollinose at base ; length, 4 mm. ; Californian species 



am2)HccUa (p. 431). 



51. Knob of halteres yellowish 52 



Knob of halteres blackish 53 



