176 D. W. COQUILLETT. 



67. — TomtMitum of occiput white; outline of brown of wings distinct 68. 



Tomentum of occiput yellowish 71. 



fi8. — Thorax opaque, velvet-black, destitute of brassy or violaceous tomentum. .69. 



Tiioras polished black, its toraeutum somewhat brassy or violaceous 70. 



69. — Venter with golden-yellow, but no snow-white, tomentum 28. relor. 



Venter with snow-white, but no golden-yellow tomentum 25. «*urta, 



70. — Brown in marginal cell reaches far beyond that in first submarginal cell ; 



basal two-thirds of axillary cell brown 26. Mcitiila. 



Brown in marginal cell reaches only as far as that in first submarginal cell ; 



whole of axillary cell hyaline 53. itrizoneusi$<». 



71. — Ground color of thorax polished black ; dark color of wings pale brown. .72. 

 Ground color of thorax opaque, velvet-black ; anal and axillary cells wholly 

 brown ; dark color of wings opaque, dark reddish brown. 



31. fiilvoliirta. 

 72. — Outline of brown on wings distinct; second abdominal segment destitute 



of white tomentum 73. 



Outline of brown on wings indistinct; abdomen destitute of white tomen- 

 tum 75. arenosa. 



Outline of brown on wings indistinct ; second and third abdominal segments 



furnished with white tomentum 27. Tana. 



73. — Axillary cell, third and fourth posterior cells and over half of the anal cell 



hyaline 70. lepidota. 



Axillary and anal cells having the basal half brown; bases of third and 



fourth posterior cells also brown 30. bigra<Iata. 



74. — Ai)ex of wings beyond base of second submarginal cell distinctly hyaline 



and brown 75. 



Apex of wings beyond base of second, sulnnarginal cell either wholly hya- 

 line, wholly gray, or wholly brown 80. 



75. — Third posterior cell never divided into two cells 76. 



Third posterior cell divided by a cross-vein into two cells; a stump of a 

 vein projects into the second posterior cell from the great cross-vein. 



•50. alcyoii. 

 76. — Marginal, first submarginal, second and third posterior cells each usually 



containing a hyaline spot 77. 



Marginal, first submarginal, second and third posterior cells wholly lirown. 



52. effreua. 



77. — Basal fourth of axillary cell brown — 78. 



Basal fourth of axillary cell hyaline, this usually extending into the anal 

 cell; a portion of the vein between the first and second submarginal 

 cells, and of that between the discal and third posterior cells, not bor- 

 dered with brown 71. poecilogaster. 



78. — Posterior edge of axillary cell wholly brown 79. 



Posterior edge of axillary cell largely hyaline; the base, front edge, and 



apes of this cell being brown 49. WillLstoiiii. 



79. — Dark color of wings brownish black; eastern species 51. ceyx. 



Dark color of wings yellowish brown; western species 48. alpha. 



80. — Proboscis not projecting more than the length of its labellse beyond the 



oral margin 81. 



Proboscis projecting half its length beyond the oral margin; base of the 

 third antennal joint subglobular, the styliform portion slender and 

 linear 42. parvicoriiis. 



