464 Annals Entomological Society of America [Vol. VI, 



18. Origin of praefurca fuscous; mesonotum with six brown stripes, median 



pair broad, conspicuous. Brown; lateral and posterior margin of 

 abdominal segments paler; eight sternite with median, short, two 

 lobed appendage; hypopygium small, elongate, ninth tergite with deep 

 V-shaped incision; ninth sternite narrowly divided in almost its entire 



length. Length 11 mm. (d* ) tristis Doane 



Origin of praefurca not fuscous; mesonotum with three dark stripes, 

 each of which is divided by a light brown line. Brown; lateral mar- 

 gin of abdominal segments broadly, posterior narrowly paler; ninth 

 tergite with deep, narrow. V-shaped incision; no pleural suture. Length 

 13 mm. (o 71 ) marina Doane 



19. A fuscaus spot at beginning of praefurca 20 



Without such a spot 22 



20. Wings brownish, darker towards the apex, a faint spot in first basal cell, 



a whitish spot in posterior margin of axillary cell. Yellow; mesono- 

 tum with four stripes; abdomen trivittate, lateral stripes faint; eight 

 sternite produced and narrowed posteriorly; hypopygium large, ninth 

 tergite produced into two long, somewhat flattened triangular pro- 

 cesses; ninth sternite with lateral appendages and posterior margin 

 with two small median ones. Length 17 mm. (d 1 ) armata *Doane 

 Wings not so marked 21 



21. Yellow, a whitish spot beyond the stigma. Mesonotal vittae more or 



less distinct; eight sternite semi circularly incised; ninth tergite 

 divided by a median suture into two subrectangular processes; ninth 

 sternite large, with downward projecting spatulate processes. Length 



13 mm. (c 71 ). 12 mm. (9) derbyi fDoane 



Brownish yellow, no white spot beyond the stigma. Thorax with three 

 brown stripes; abdomen with three distinct brown stripes, posterior 

 margin of segments whitish; eight sternite with rounded incision of 

 the posterior margin, lateral angles with triangular, hooked append- 

 ages; ninth tergite with broad, deep V-shaped incision; posterior mar- 

 gin of ninth sternite with broad U-shaped incision, containing a pair 

 of tumid appendages. Length 15 mm. (c 71 ) occidentalis Doane 



22. All posterior cells more or less white. Light brown; mesonotum with 



four rather broad vittae; abdomen with broad dorsal vitta; eight 

 sternite narrowed posteriorly, emarginate at apex; ninth tergite small 

 with deep V-shaped incision and narrow median depression; ninth 

 sternite almost divided by a deep, U-shaped incision, containing a 



pair of tumid appendages. Length 11 mm. (c 71 ) acutipleura Doane 



Some or all posterior cells not tinged with white 23 



23. Gray, fourth posterior cell except its apex, occupied by a fascia-like 



spot, J first posterior cell with a spot in the middle and extreme apex 

 white. Thorax whitish, vittae slightly darker, not margined; abdo- 

 men trivittate. Length 14 mm snbfasciata Loew 



Brown, posterior cells not white; the white fascia extends from before 

 the stigma through outer parts of basal cells to the posterior margin . 

 Mesonotum quadrivittate; anterior margin of abdominal segments 

 darker brown; ninth tergite short, broad, with inconspicuous median 

 ridge, posterior margin slightly emarginate, lateral angles ending in 

 short, downward projecting processes; ninth sternite with broad, 

 rounded incision, lateral angles with two lobed appendages. Length 

 10 mm. (o 71 ) incurva Doane 



*see also 60. 



t Would perhaps more properly be placed under species: "wings unicolorous, a 

 large white spot before the stigma." 



JThis spot can hardly be called a fascia. 



