402 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 5«. 



Ninth tergite with the lateral lobes short and blunt; eighth tergite with a 

 brush of long yellow hairs. (Regional.) T. hirsuta Doane. 



35. Wing apex a little grayer than the basal cells of the wings ; a brown spot 



at the origin of the sector ; male hypopygium with the ninth tergite large, 

 deeply split by a broad V-shaped notch, the lateral lobes acutely pointed— 



T. suhmaculata (p. 406). 

 Wing apex concolorous with the rest of the wing; ninth tergite other- 

 wise 36, 



36. Ninth tergite with the median area produced caudad into two parallel or 



divergent horns or lobes; coloration grayish, the pleura light blue-gray; 



size small, wing of the male about 12 mm 37. 



The combination of characters otherwise; size larger, wing of the male 

 over 15 mm 37, 



37. Male hypopygium with the ninth tergite produced medially into two flat- 



tened divergent horns; outer pleural appendage elongate, conspicuous; 



inner pleural appendage short, broad T. dejecta (p. 404). 



Male hypopygium with the ninth tergite produced medially into two parallel 

 lobes, the lateral angles of the sclerite produced caudad into blunt, 

 minutely roughened lobes; outer pleural appendage inconspicuous, inner 

 pleural appendage long, narrow T. aprilina (p. 403). 



38. Coloration of the thoracic pleura light gray; thoracic dorsum gray or 



grayish, with brown stripes 39. 



Coloration of the thoracic pleura yellow, in some cases whitish pollinose; 

 dorsum yellow or brown 40, 



39. Antennae short, the flagellar segments deeply constricted beyond the basal 



enlargement ; six brown stripes on the mesonotal praescutum ; male 

 hypopygium with the eighth sternite with four conspicuous lobes, an 



outer broad and flattened pair, the inner pair median in position 



T. aus traits (p. 403). 



Antennae longer, the flagellar segments not constricted beyond the basal 



enlargement; three brown stripes on the mesonotal praescutum; male 



hypopygium without lobes on the eighth sternite T. dietziana (p. 404). 



40. Nasus short; cell 1st M2 of the wings very small and pentagonal; male 



hypopygium with the ninth tergite tumid, unarmed or provided with 



horns ( bicornis group) 41, 



Nasus usually longer; cell 1st M2 of the wings not small and pentagonal; 

 male hypopygium with the ninth tergite not tumid (translucida group) _43. 



41. No horns on the ninth tergite T. johnsoniana (p. 405). 



Ninth tergite armed with horns 41, 



42. Horns on the ninth tergite directed upward, or dorsjid__T. Mcornis (p. 404). 

 Horns on the ninth tergite directed laterad or slightly ventrad 



T. morrisoni (p. 406). 



43. Caudal margin of the ninth tergite with three prominent lobes, the median 



lobe acute; antennae bicolorous ; body coloration light yellow, the thoracic 

 stripes reddish brown ; abdomen with a series of about four conspicuous, 



rounded brown spots along the sides T. triton (p. 407). 



Caudal margin of the ninth tergite not conspicuously trifid 44. 



44. Caudal margin of the ninth tergite deeply notched, the lateral lobes pro- 



duced into long, slightly curved horns ; antennae bicolorous ; body colora- 

 tion yellowish, the thoracic stripes very indistinct ; wings yellowish 



T. tuscarora <p. 407). 

 Male hypopygium otherwise 45. 



