32 BU]LLETIN 116, UNITED STATES NATIONAL MUSEUM. 



83. Antennae black, the first and second joints may be yellow below 84. 



^ntennae yellow, at least the first joint wholly yellow 102. 



84. Anterior coxae blackened at base for half their length or more, sometimes the 



yellow extends to the base on inner edge 85. 



Anterior coxae yellow, at least on the front side 89. 



85. Hind femora and tibiae each with a black tip .No. 6d,fucatus, new species 



Hind femora wholly yellow 88. 



[86, 87, omitted.] 



88. Hind tibiae black at tip for one-fourth their length. .No. 116, pilatus, new species. 

 Hind tibiae wholly yellow, their tarsi wholly black.. No. 138, longimanus Loew, 



89. Hind tibiae distinctly blackened at tip 90. 



Hind tibiae wholly yellow, or very nearly so 93. 



90. Middle tibiae with three bristles below, two near apical third and one near basal 



third No. 115, albicoxa Aldrich. 



Middle tibiae with only one bristle below, placed near apical third (the cilia of the 

 calypters are often more or less black in the three forms coming under this) . . 91 - 



91. Fore coxae wholly yellow; last three joints of fore tarsi of equal length. 



No. 92, indigena, new species. 



Fore coxae with a small blackish spot at base on outer surface; third joint of fore 



tarsi longer than fourth, fifth equal to fourth 92. 



92. Fifth joint of fore tarsi yellow or yellowish, paler than those preceding it. 



No. 89, socius Loew. 

 Fifth joint of fore tarsi black No. 90, socius, var. gladius, new variety. 



93. Anterior coxae -with a green or blackish streak on posterior edge of outer sm-face. 



No. 159, crenatus Osten Sacken. 



Anterior coxae wholly yellow or with a small blackish spot at base on outer 



surface 94. 



94. Hind tarsi wholly black, or very nearly so 95. 



Posterior basitarsi largely yellow 98. 



95. First antennal joint yellow below No. 115, albicoxa Aldrich. 



Antennae wholly black, or very nearly so 96. 



96. Cross- vein long, nearly equaling in length the distance to the bend in last section 



of fourth vein, which is near its basal third No. 188, palaestricus Loew. 



Cross-vein distinctly shorter than the distance to the bend in last section of fourth 

 vein 97. 



97. Bend in last section of fourth vein just before its middle. 



No. 141, splendidus Loew. 

 Bend in last section of fourth vein at second fifth of its length. 



No. 142, splendidulus Loew. 

 (The characters given as separating these three last species are unsatisfactory and 

 probably uncertain.) 



98. Middle basitarsi without a bristle above No. 183, bolsteri, new species. 



Middle basitarsi with a large bristle above near apical third 99. 



99. Middle basitarsi with two bristles near basal third, the one on upper anterior edge 



may be a little the smallest 100. 



Middle basitarsi with only one large bristle above 101. 



100. Antennae wholly black when viewed from above No. 189, batillifer Loew. 



First antennal joint yellow on the lower edge No. 184, tonsus Loew. 



101. Face white No. 186, versutus, new species. 



Face slightly yellowish. No. 187, dakotensis Aldrich. 



Face distinctly tinged with yellow No. 185, eudactylus Loew. 



(Characters given as separating these three species very unsatisfactory.) 



102. Middle tarsi wholly deep black (Alaska) No. 219, new species. 



Middle basitarsi yellow, black at tip 103. 



