16 BULLETIN 116, UNITED STATES NATIONAL MUSEUM. 



21. Antennae wholly black; cilia of hind femora rather scattering, extending nearly 



their whole length (Hudson Bay Territory) No. 139. suhcilintus Loew. 



First antennal joint reddish or yellowish below; cilia of hind femora dense and 

 confined to a short space on lower inner edge (Colorado). 



No. 140, (nnplipennis, new species. 



22. Costa with a small knot-like enlargement at tip of first vein (eastern). 



No. 142, splendidulus Loew. 

 Costa with an elongated enlargement at tip of first vein (Eastern States). 



No. 141, splendidus Loew. 



23. Fore tarsi with the fifth joint compressed 24. 



Fore tarsi plain 29. 



24. Fore tarsi dark yellow with fifth joint only a little compressed (Newfound- 



land) No. 183', bolsteri, new species. 



Fourth and fifth joints of fore tarsi much compressed, fourth white, fifth 

 black 25 . 



25. Fourth joint of fore tarsi distinctly less than half as long as fifth; hind tibiae 



considerably thickened in the middle (Eastern States). No. 189, batilHfer'LQew. 



Fourth joint of fore tarsi three fourths or more than three fourths as long as 



fifth 26. 



26. Third joint of fore tarsi a little compressed, white; hind tibiae but little 



thickened (eastern) No. 187, dakotensis Aldrich. 



Third joint of fore tarsi normal or very nearly so, yellow 27. 



27. Hind femora not ciliated (eastern) No. 184, tonsus Loew. 



Hind femora ciliated on lower inner edge 28. 



28. Third and fourth joints of fore tarsi of equal length, fifth a little shorter, sometimes 



the last three joints are of nearly equal length (Eastern States). 



No. 185, eudactylus Loew. 

 Third and fifth joints of equal length, fourth a little shorter (Indiana; Ontario). 



No. 186, versutus, new species. 



29. Second abdominal segment with a tuft of long yellow hairs on each side and a 



smaller and shorter one on each side of third segment (California; Utah: New 



Mexico) No. 158, afflictus Osten Sacken 



Abdomen \vithout such hair 30. 



30. First antennal joint long and thick, densely hairy on the outer side (Western 



States) No. 159, crenatus Osten Sacken . 



First antennal joint normal; enlargement of the costa at tip of first vein as long 

 as the cross-vein (Idaho; California; Oregon).No. 163, irfaftoensis, new species). 



31. Last joint of fore tarsi compressed (Illinois; New York; Wisconsin). 



No. 190, tener Loew. 

 Fore tarsi plain 32 . 



32. Hind femora without cilia below (Colorado) No. 178, celeripes, new species. 



Hind femora ciliated on lower inner edge 33. 



33. The longest hairs that form the cilia on the hind femora not more then three-fourths 



as long as the width of the femora: hind basitarsi mostly yellow (VirgiTiia). 



No. 136, greenei, new species. 



The longest cilia on hind femora fully as long or longer than the width of the 



femora ; hind basitarsi usually wholly black 34. 



34. Fore tarsi with, only the fifth joint black (widespread). No. 135, luteipennis Loew. 

 Fore tarsi blackened from the tip of the first joint (widespread). 



No. 133, variabilis Loew. 



Group G. 



1. First antennal joint black, at least on upper edge -■ 



First antennal joint wholly yellow 43. 



