1910] Melander — The Genus Tachydromia 53 



Bay Territory. I do not think this is so. BimaciiJafa is a much 

 smaller species with white palpi, and is rare. The only specimen I 

 have seen is the type from Alaska. I take it however that maculi- 

 pennis is the same as our conmion pusilla Loew. I have examined 

 over fifty specimens of this species from jNIassachusetts, Wiscoiisin, 

 Illinois, Missouri, and South Dakota. Since it is so widely distrib- 

 uted in the States it probably occurs in Canada also. The rest of Mr. 

 Walker's Tachydromias I can not decipher. They may belong to 

 Tachypeza or to the present genus. Osten Sacken listed vicarius as a 

 Phdi/paJpus. The two-line description reads that the legs are slender 

 which raises more doubt as to what the species really is. 



Table of the North American Species of Tachydromia. 



1 . A white glistening pruinose spot between the front coxae and the humeri, 



rarely absent: wings with two dark bands: the distance between the 

 two cross veins more than twice the length of the hind cross vein: 



arista terminal 2. 



No glistening spot on the pleurae: wings with a single brownish subapical 

 cloud or hyaline; cross veins separated scarcely more than the length 

 of the hind cross vein: arista subterminal 6. 



2. Palpi and halteres black: marginal cell obliquely truncate 



enecator Melander. 

 Palpi and halteres paler : marginal cell rounded at the end 3. 



3. Dark cross bands united along the costa varipennis Coquillett. 



Dark cross bands separated 4. 



4. Wings blunt, fringed with comparatively long hairs: propleurae not 



pruinose ciliata sp. nov. 



Wings slender, the marginal hairs short: propleurae pruinose 5. 



o. Legs nearly unifoi'mly dusky schwarzii Coquillett. 



Base of legs pale yellow, outer portions in part black. 



schwarzii var. diversipes. var. nov. 



6. Palpi black: wings with a broad subapical cloud. 



macuhpennis Walker. 

 Palpi yellowish : wings unclouded 7. 



7. Thorax shining, humeri prominent: palpi narrow ,S. 



Thorax and abdomen sub-glaucous, humeri smaller 9. 



8. Third and fourth veins divergent simplicior Wheeler & Melander. 



Third and fourth veins subparallel calva sp. nov. 



9. Palpi long and narrow: scutellum with four bristles: antennae reddish. 



insularis sp. nov. 



Palpi broader: scutellum with two bristles 10. 



10. Acrostichal and dorsocentral bristles present: legs slender piceous, 



antennae black agens sp. nov. 



Middle of dorsum without bristles : base of legs and of antennae yellow, 

 last tarsal joint black universalis sp. nov. 



