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. (d^) 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. (c?') armata *Doane 

 Wings not so marked . . . . , 21 



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



less distinct; eight sternite semicircularly incised; ninth tergite 

 divided by a median suture into two subrectangular processes; ninth 

 sternite large, with downward projecting spatulate processes. Length 



13 mm. (cf). 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. (cT) 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. (cf) aciUipleiira 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,t 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 subfasciata 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. (cf ) incurva Doane 



*see also 60. 



fWould perhaps more properly be placed tmder species: "wings unicolorous, a 

 large white spot before the stigma." 



JThis spot can hardly be called a fascia. 



