SYRPHIM. 257 



56. Antennae elongate, the third joint more than twice as long as wide 



{Phalacromyia, Glaurotrtcha). . . . Volucella. 



Antennae short, the third joint not more than twice as long as 



wide; third vein nearly straight, or gently or considerably 



curved into first posterior cell. . . 57 



57. Thinly pilose; abdomen with yellow bands. ... 58 

 Thickly pilose; abdomen not with yellow bands. ... 59 



58. Third vein straight or moderately curved. . . Sericomyia. 

 Third vein considerably curved.* . . . Condidea Coq. 



59. Eyes pubescent! Pyritis. 



Eyes bare (15) Arctophila. 



60. Third longitudinal vein deeply curved into the first posterior 



cell 61 



Third vein only gently curved. ...... 70 



61. Hind femora thickened. ....... 63 



Hind femora slender. ........ 62 



62. Abdomen elongate, narrowed at base, spatulate in outline (11). 



Salping-ogaster. 



Abdomen oval, with yellow, interrupted bands; mesonotum with 



yellow margins; antennae elongate (22, 41). Chrysotoxum. 



63. Face carinate or subcarinate; hind femora with an angular pro- 



tuberance or spur below at outer end: 

 Face protuberant in profile (19, 36) . . Tropidia. 



Face concave in profile, subcarinate; spur of femora bifid. 



Senogaster. 

 Face tuberculate or arched, not keeled. .... 64 



64. Abdomen much narrowed at base, club-shaped. Ceriogaster. 

 Abdomen not at all pedunculate or basally narrowed. . 65 



65. Antennae elongate; eyes pubescent; wings colored anteriorly. 



"Platynochsetus" niger.^% 

 Antennae not elongate. ........ 66 



* This character is found in some of the species of Arctophila, Tro- 

 pidia, etc., but is not considered generic. 



t Ocular pubescence alone is not of generic value; I do not know 

 the genus. 



% This is perhaps not a true Platynochcztus. The terminal expan- 

 sion of the arista is a male character. I do not know it. 



