36 BULLETIN 116, UNITED STATES NATIONAL MUSEUM. 



157. Middle basitarsi wholly black 158. 



Middle basitarsi yellow with a black tip 159. 



158. Second and third antennal joints wholly black.. .No. 129, dasypodus Coquillett. 

 First, second and part of third antennal joints yellow. 



No. 130, nocorcula, new species. 



159. Last section of fourth vein bent near its middle. 



No. 148, walkeri, new species. 

 Last section of fourth vein bent a considerable distance before its middle. 



No. 150, procerus, new species. 



160. Front blue or violet 161. 



Front green or bronze 164. 



161. Second antennal joint whoUy black No. 153, sufflarus, new species. 



Second anternnal joint partly or wholly yellow 162. 



162. Second joint of middle tarsi a little longer than the first No. 127 pugil Loew. 



Second joint of middle tarsi about half as long as the first 163. 



163. Middle basitarsi without a bristle above No. 113 vmrginatus Aldrich. 



Middle basitarsi with a large bristle above, a little beyond its middle; small 



species No. 137, wheehrii Melander and Brue?. 



164. Third antennal joint wholly black 165. 



Third anternnal joint partly or wholly yellow 173. 



165. Second antennal joint wholly black 166. 



Second antennal joint yellow, at least on inner side 171 . 



166. Hairs on fore coxae mostly yellow and rather long 167. 



Black hairs on fore coxae conspicuous and covering most of the anterior sur- 

 face ^ 168. 



167. Hairs on inner edge of fore coxae and those near the tip black, also a cluster of 



longer black hairs at base on inner edge No. 155, lobatus Loew. 



Hairs on fore coxae almost wholly yellow No. 156, omnivagus, new species. 



168. First joint of fore tarsi not or but slightly longer than the two following joints 



taken together No. 151, completus, new species. 



First joint of fore tarsi nearly or quite as long as the three following taken to- 

 gether 169. 



169. Tip of third vein considerably bent backward ; fifth joint of fore tarsi distinctly 



longer than fourth 170. 



Tip of third vein bent back-ward a little; fifth joint of fore tarsi scarcely longer 

 than fourth No. 150, procerus, new species. 



170. Middle basitarsi with the large bristle on upper edge at apical third, and with 



another rather large bristle near it on upper anterior edge. 



No. 152, oeratus, new species. 



Large bristle on middle basitarsi placed before apical third, without another 



bristle near it No. 153, sufflavus, new species. 



171. Middle basitarsi without a bristle above No. 198, plumosus Aldrich. 



Middle basitarsi with a large bristle above ^ 172. 



172. Fore coxae with their hairs mostly yellow; hind margin of wing with a very 



small, but distinct lobe or expansion at tip of sixth vein . No. 155, lobatus Loew. 



Fore coxae with black hairs, and with scarcely a trace of an expansion at tip 



of sixth vein No. 154, coloradensis Aldrich. 



173. Front and dorsum of thorax opaque with pollen; last section of fourth vein with 



a stump at the bend No. 126, bifractus Loew. 



Front and thorax shining, metallic; last section of fourth vein without a stump 

 at its bend 174. 



174. Face wide, yellowish, or grayish white No. 131, fulvipes Ix)ew. 



Face silvery white, not very wide for a female No. 134, gracilis Aldrich. 



