18iir.. VROCEEDlXas OF Til IC XATKtXAL MISFA M. 417 



97. Thorax wholly opaiiut! gray polliuose 98 



Thorax shilling, two vitta' and the sides gray pollinose, a long seta (uot the 



central filament) issiU'S from apex of lower lamella of hypopygium; 



California species duplicis (p. 424). 



Thorax and abdomen ^'elvet black, filament hidden expuha. 



98. rile of abdomen short, black 99 



rile of abdomen rather loiig, yellowish; filament of hyi)<)pyginm bristle- 

 like (d-ida (p. 425). 



99. I'ilament of hypopygium suddenly thickened at base; upi>er lamella' as 



broad as long seiosa ( p. 426). 



I'ilament slender, upper lamella- also slender clarii/cra. 



100. Abdomen opaque 1 101 



. Abdomen shining, filament of hypopygium very thick at base, third anten- 



nal joint slender ; length, 5 mm Joiinicornis. 



101. Hy]iopygium large, erect, black pilose, upper lamelhe oblong, the median 



ones broad, third antennal joint broad ; length, 4 mm limbata. 



Hypopygium subglobose, long yellow pilose; length 3 nmi .' hirtipes. 



102. Middle and bind femora on each sid(^ bearing nearly ere* t scales 103 



Middle and other legs destitute of scales 104 



103. Hind tibiiB on both sides bearing nearly erect scales; inhabits Colorado; 



length, 3 mm otiosa (p. 425). 



Hind tibiie destitute of scales; thorax wholly opaque; inhabits the Atlan- 

 tic States ; b^ngth, 4 mm ? liirtipea. 



104. Front metatarsi as long as, and thicker than, the front tibia- ; length, 3| mm. 



rtifirostris.' 

 Front metatarsi two-thirds as long as. and more slender than, the front tibiae. 105 



105. Antennal style not over one-sixth as long as the third joint, hind tarsi less 



than twice as thick as the middle ones 106 



Antennal style one-fourth as long as the third joint, hind metatarsi nearly 



three times as thick as t lie middle ones; California species, bifilata (p. 424). 



106. Femora wholly blackish, abdomen subopaqne black ; length, 3 to 4 mm 111 



Femora yellow at base, al)domen shining dark l>rown. not white pollinose; 



length, 5 mm lonf/icorms. 



107. Thorax wholly shining, not pollinose, discal and posterior ci-lJs normal 108 



Thorax more or less opai^ue and jxdlinose 112 



108. Knob of halteres yellowish 109 



Knob of halteres blackish, eyes of male contiguous, filami-nt of hypo- 

 pygium free at base Jnctifera. 



109. Females ; some of the legs bearing nearly erect scales 110 



Males; legs never bearing scales, eyes contiguous, extreme base of wings 



whitish, filament of hypopygium slender; length, 3 mm polita. 



110. Front and other femora and tibia- bearing nearly erect scales on both sides; 



length, 4 mm hvi-Ujain. 



Front legs destitute of scales ; length, 2). mm nava. 



111. Abdomen densely grayish white pollinose niijricaiia. 



Abdomen destitute of light colored pollen expitJua. 



112. Kjiob of halteres yellowish 113 



Knob of halteres blackish, discal and posterior cells normal 118 



113. Males ; eyes contiguous, discal cell normal, filament of hypopygium hidden 



toward its apex ; length, 8 mm 114 



Females 115 



114. Antennal style one-half as long as the third joint, proboscis scarcely twice 



as long as height of head; California species sudigeronis (p. 431). 



Antennal style one-sixth as long as the third joint, proboscis over three 



times as long as height of head ; Eastern species umhrosa. 



Proc. N. M. 95- 



-27 



