948 Charles Paul Alexander 



42. Coloration bluish gray, including the abdomen; ninth tergite (Plate L, 284) with the 



caudal margin bluntly toothed. [Ross's Voyage to the Arctic Regions, p. 77, pi. a, 



fig. 15. 1831.] T. arctica Curt. 



Coloration brown, the abdomen dull browni.sh yellow with an interrupted dorsal stripe; 

 ninth tergite (Plate L, 283) short and broad, the caudal margin heavily chitinized, 

 deeply concave, and slightly roughened in places, the lateral angles produced into 

 conspicuous chitinized points. [Berl. Ent. Ztschr., vol. 7, p. 278. 1863.] (Plate LIV, 

 338, lateral aspect of male hypopygium.) T. seplentrionalis Loew 



43. Ninth tergite (Plate L, 280) small, heavily chitinized, shiny black, the caudal margin 



with a deep U-shaped notch, a second tooth on either side, subbasal in position; wing 

 of male 17.5 mm.; head light gray, with a narrow, impressed median line; antennae 

 with the first three flagellar segments indistinctly bicolorous, the remainder uniformly 

 dark brown; abdomen orange, with an interrupted dorso-median stripe. [Berl. Ent. 

 Ztschr., vol. 8, p. 60. 1864.] (Plate LIV, 339, lateral aspect of male hypopygium.) 



T. centralis Loew 

 Ninth tergite larger, not as above 44 



44. Ninth tergite (Plate L, 279) heavily chitinized, black, hollowed out in a shallow saucer, 



the dorsal surface near the caudal margin with a prominent median tooth that is 

 directed backward; margin of the saucer denticulate, more strongly behind; wing 

 16.8 mm.; head light gray; thorax dull gray, the prescutal stripes margined with 

 brown. [Berl. Ent. Ztschr., vol. 7, p. 284. 1863.] (Plate XLVI, 227, wing; Plate 



LIV, 337, lateral aspect of male hypopygium.) T. balioptera Loew 



Ninth tergite not as above 45 



45. Ninth tergite (Plate L, 282) very large and extensive, narrowed slightly toward the 



apex, which consists of a flattened yellowish margin bearing a deep tho small median 

 notch, the broad adjacent lobes with about three tiny teeth, the outermost one the 

 largest; the part of the tergite behind the yellow caudal margin elevated, black, and 

 including the basal two-thirds of the segment; wing 15 mm.; antennae blackish; 

 prescutum light grayish brown, with about five dark brown stripes; abdominal seg- 

 ments dark brownish black, the caudal margin of each segment bright yellow, the 

 lateral margins broadly gray; wings with a heavy pattern; a conspicuous dark spot 

 at the base of the wing. [Berl. Ent. Ztschr., vol. 8, p. 57. 1864.]. . . .T. ternaria Loew 

 Ninth tergite not as above 46 



46. Ninth tergite (Plate L, 281) telescoped beneath segments 7 and 8; the sclerite not 



chitinized, very broad and short, the caudal margin broadly concave and provided 

 with a uniform fringe of long yellow hairs; wing 15.7 mm.; antennae somewhat 

 bicolorous, the basal enlargement of the flagellar segments dark brown, the remainder 

 of each segment a little paler; prescutum whitish gray, with broad dull gray stripes 

 narrowly and indistinctly margined with brown; abdomen dull yellow, with an indistinct 

 dorso-median stripe which broadens out on segments 6 to 8; less distinct submarginal 

 stripes on the sides of the abdomen. [Berl. Ent. Ztschr., vol. 8, p. 59. 1864.] (Plate 



LIV, 341, lateral aspect of male hypopygium.) T. canadensis Loew 



Ninth tergite not as above 47 



47. Ninth tergite (Plate L, 276) large, pale, not chitinized, with two rounded lobes separated 



by a narrow, deep notch; antennae elongate, the segments of the fiagellum not incised 

 beneath; ventro-caudal angle of each pleurite bearing a prominent, pale, fleshy lobe. 

 [Berl. Ent. Ztschr., vol. 7, p. 286. 1863.] (Plate XLV, 212, wing.) 



T. angusiipennis Loew 



Ninth tergite not as above, more or less chitinized caudally; antennae shorter, the flagellar 



segments deeply incised beneath , 48 



48. Ninth tergite (Plate L, 277) with a broad median chitinized tooth on the caudal margin; 



adjacent lateral lobes terminating in small, acute, chitinized points; antennae moderate 

 in length, extending slightly beyond the wing root; prescutum fawn-colored, with 

 four broad grayish brown stripes narrowly margined with brown; abdomen dull yellow 

 with a rather indistinct brownish median stripe which is clearer behind. [Berl. Ent. 

 Ztschr., vol. 7, p. 283. 1863.] T. serta Loew 



