342 A. L. MELANDER, 



Platypalpus flaTJrostris Loew. 

 Loevv's type specimen has four narrow dusky vittse on the casta- 

 neous thoracic notura. Another female from the Osten Sacken col 

 lection is somewhat smaller and has no dark vittse. The ground 

 color of the head is black. 



Page 222. Platypalyus discifer Loew. 



The middle tarsi of the male are greatly enlargened and flattened, 

 and feathered along the edge with close black scale-like hairs. 



The species trivialis, (equalis and crassifemoris of Platypalpus are 

 all quite similar, and probably represent one extremely variable 

 species. The characters chosen in the table will render the divi- 

 sions somewhat homogeneous, but too much stress must not be laid 

 on the infafibity of the separation. The species as defined in this 

 way do not conform exactly with those Dr. Loew had in mind. 



Page 225. TACH YDROM I A. 



Modify table as follows ; 



10. Wings with a black spot at outer third of costal margin. 



maeuiipennis Walker. 



Wings infumated, except the whitish base 10a. 



10a. Anal cross- vein wanting 11. 



Anal cross-vein present • • lla. 



11. Legs black ; second basal cell shorter than first iiubifera Coquillett. 



Legs more or less yellowish ; second basal longer than first- -piisilla Loew. 



lla. Front tibife strongly incrassate ; first basal cross-vein oblique, second per- 

 pendicular clavipes Loew. 



Front tibiae not greatly thickened 12. 



12. Second basal cell but little exceeding the first, its cross-vein perpendicular; 



proboscis reddish at base 13. 



Second basal cell longer than the first by at least the length of its oblique 

 cross- vein ; proboscis black ; pleurje shining rapax Loew. 



13. Pleuree shining; front tibiae with no teeth below; middle femora more slen- 



der than front ones ; eastern species 13a. 



Pleurae opaque ; front tibiae closely mucrouate with black setulae below ; mid- 

 dle femora as thick as the front ones ; we^eru species. 



corticalis sp. nov. 

 13a. Front femora bare beneath ; hypopygium without bristles. 



rostrata Loew. 

 Front femora ciliate beneath ; hypopygium with long black bristles above. 



bracbialis sp. nov. 



Tachydromia nubifera Coquillett. 

 Fur Seals and Fur Seal Islands of N. Pacif. Ocean, 1898, iv, p. 343. 

 Male and Female. — Black, the bases of the halteres yellow ; hairs and bristles 



