OSTEN SACKEN ON WESTERN DIPTERA. 307 



dark brown; white cross bands on abdominal segments entire, somewhat 

 interrupted on the fifth segment only, rarely (in the male) on the fourth. 

 Length, $ 7-8 mm . ; 9 10-ll mm . Two males and four females. (In the 

 male, the brownish tinge of the distal half of the wing is more marked 

 here than in any of the four following species.) 



12. Cyrtopogon rejectus n. sp., 9.— First abdominal segment 

 whitish-pollinose on the sides only; the white cross-bands on segments 

 2-4 interrupted; on segment 5, the extreme sides only of the hind 

 margin are white. Median germiuate thoracic stripe less well marked 

 and abbreviated earlier posteriorly ; the portion of the lateral stripe 

 anterior to the thoracic suture is well marked, brown. Length 9-10 mm . 

 Four females. 



13. Cyrtopogon nugator n. sp., {$%) 9. — First abdominal segment 

 whitish-pollinose on the sides only; the white cross-bands on segments 

 2-5 very markedly interrupted; length of the interruption nearly equal 

 on segments 2-4. The abdomen ( ? )is narrower, more cylindrical and con- 

 vex, of more equal breadth from the base than in the 9 of widens and 

 rejectus. Wings almost uniformly hyaline. Thoracic stripes very dis- 

 tinct, more blackish; the portion of the lateral ones preceding the suture 



j is not conspicuously darker, and has not the rich dark brown color which 

 • distinguishes it in evidens and rejectus. Ungues whitish-yellow, the tips 

 black. In size, this species is smaller, the 9 being only 7-8 mm . long. I 

 i have a male specimen which seems to belong here on account of its size 

 I and hyaline wings; but the stripe on the second abdominal segment is not 

 I interrupted (the thorax of the specimen is greasy) ; the ungues are whit- 

 ish-yellow, with black tips, a very characteristic mark of the species. 



II. The fan-like fringe of hairs in front of the halteres is black : 



14. Cyrtopogon positivus n. sp., $ . — Peculiar coloring of the tho- 

 racic dorsum : the extreme anterior margin and the posterior beyond the 



! thoracic suture are grayish ; the intervening space is of a rich dark 

 | brown, the usual stripes coalescing completely ; they reach for a very 

 | short distance beyond the thoracic suture ; the longitudinal dividing 

 \ line of the median stripe is very feebly marked with paler pollen (some- 

 times indistinct) ; front and face rather narrow, clothed with brownish 

 I pollen and dense deep black pile; first segment black, with very little 

 white on the sides ; posterior margin of abdominal segments 2-5 marked 

 with white on the sides only, the interruption growing wider on each 

 subsequent segment. Length, $ 7-8 mm . Three males. 



15. Cyrtopogon sudator n. sp., $ 9. — Front and face distinctly 

 broader than in the four preceding species, clothed with a whitish hoary 

 bloom ; pollen on the thorax also whitish-gray in most specimens ; the 

 brownish stripes are variable, but often feebly marked, although dis- 

 tinct. First abdominal segment marked with white on the sides only ; 

 in the female, the usual white cross-bands on segments 2-4 are entire, 

 on the fifth interrupted, occasionally subinterrupted on the fourth ; in 



