Williston,] ^1" LMa*'W, 



thorax. The wings show scarcely any variation ; the third longitudinal is 

 deeply bent into the first posterior cell, and the marginal cell is closed, 

 the latter character separating it from all other North American genera 

 except the ones previously mentioned. 



Eristalis. 



1. — Arista naked or indistinctly pubescent 2. 



— Arista pilose or distinctly pubescent (near the base^ 3. 



2. — Scutellum of the same color as thorax, abdomen without light mark- 

 ings, shining, eyes nearly bare, spotted in life, dorsum of thorax in 



female distinctly vittate (eneus. 



— Scutellum yellowish translucent, lighter than the thorax ; abdomen 

 unicolorous, shining blackish, with indistinct or subobsolete side 

 spots on second segment, pile of eye mostly confined to an elongated 



vertical elliptical line. Size and appearance of a honey-bee tenax. 



3. — Thorax with thick or long pile, posterior border of third segment not 



velvety black, wings mostly with a brown spot 4. 



— Thorax and abdomen nearly bare, or with short, not wooly pile, the 

 abdominal segments usually with lighter hind bordei-s. Less 



i>o»i6?<s-like 8. 



4. — Tarsi red, large species ; humble bee-like 5. 



— Tarsi dark, smaller species 6. 



5. — Thorax wholly yellow pilose above flavipes. 



— Thorax with black pile in the middle when seen from the side 



flavipes var. mehoiostomus. 



6. — Abdomen with yellow or reddish on the sides of the second segment 



only, thickly mostly black pilose elsewhere, ix>sterior half of third, 



and the fourth segment shining ; legs black Bastardi. 



— Third segment with yellow or red, the pile of the abdomen almost 



wholly yellowish, and long 7. 



7. — Abdomen mostly reddish-yellow with a nearly equal median black 



stripe ; eyes barely meeting in the male ; legs black. wwiirtnMS, sp. nov. 



— Third segment with a smaller reddish-yellow spot in the side, second 



segment velvety black, third with a triangular velvety expansion in 



front occiclentalU, sp. nov. 



8. — Third abdominal segment with a posterior velvety black cross-band 



not interrupted in the middle 9. 



— Third abdominal segment with a distinctly interrupted band, or else 



wholly shining. Not with a complete band 13. 



9. — Thorax with transverse olivaceous fiiscite, front narrow above ( 9 ).10. 



— Thorax without such fasciae 11 



10. — Hind femora not swollen, second segment of abdomen with large 

 spots, third segment in the male, with anterior rectangular spots 

 wanting in the female, and hind borders of second, third and fourth 

 segments yellow. Legs varying from almost wholly yellow with 

 black on tips of hind femora and tibice, to black with yellow knees. . . 



transversus- 



