FAMILY SYRPHID.E — THE FLOWER FLIES 257 



40. Abdomen broad and flat; face narrowed below; tip of scutellum usu- 



ally yellow Xanthandrus Verrall 



Abdomen with parallel sides, less flattened; face at most parallel 

 sided, usually widened below; scutellum wholly black 41 



41. Male with the anterior tibiae or tarsi, or both, dilated (31, 100, 101). 



*Platycheirus St. Fargeau and Serville 

 Legs simple (44, 48) fMelanostoma Schiner 



42. Anterior crossvein situated well before the middle of the discal cell, 



or the mesonotum with bristles (91 ) 43 



Anterior crossvein situated at or beyond the middle of the discal cell, 

 thorax rarely with short spines (115) 65 



43. Eyes bare 44 



Eyes pilose 45 



44. Facial grooves extending almost to the antennae; fourth vein joining 



the third well before the wing-tip; thorax often with bristles; an- 

 terior crossvein near the basal third of the discal cell; arista often 



plumose (45, 91, 104) JCartosyrphus Bigot 



Facial grooves less distinct or the anterior crossvein near the middle 

 of the discal cell 50 



45. Facial grooves distinct and extending almost to the antennse (8, 49). 



§Cheilosia Meigen 

 Facial grooves usually forming pits below^ and never extending dis- 

 tinctly to near the antennse 46 



46. Face evenly receding, the anterior oral margin pi'ojecting.Psilota Meigen 

 Face tuberculate, or the oral margin not conspicuously projecting. . . 47 



47. Face widening below TJPipiza Fallen 



Face not wider below than at the antennae 48 



48. Middle tibiae slender, not convex anteriorly from dorsal view 49 



Middle tibiae in male conspicuously broadened, in the female slightly 



broadened and gently convex anteriorly from dorsal view; middle 

 coxae of male with small slender process near their inner end. 



j Cnemodon Egger 



49. Fifth sternite only half as long as the fifth tergite in the male; 



antennas of female elongate oval "Heryngia Rondani 



Fifth sternite three-fourths as long as the tergite; antennae of female 

 more than twice as long as wide; eyes usually with an indistinct, 

 transverse, less thickly pilose stripe (6, 30) "Pipizella Rondani 



50. Mesonotum with strong bristles, the legs never bristled; abdominal 



pile erect; face tuberculate (25, 99) Ferdinandea Scopoli 



Mesonotum without bristles or the legs also with bristles 51 



* Cuiran, 1927. Amer. Mus. Novit. No. 247, p. 1. 



t Curran, 1930. Bull. Amer. Mus. Nat. Hist., Ixi, p. 64. 



} Shannon, 1922, Ins. Ins. Mens., x. p. 131. 



§ Shannon, 1922, Ins. Ins. Mens., x. p. 127. 



"1 Curran. 1921, Pr. Calif. Acad. Sci., xi, p. 374. 



II Curran, 1921, Pr. Calif. Acad. Sci., xi, p. 358. 



o Curran, 1921, Pr. Calif. Acad. Sci., xi. :„ 354. 



Curran, 1924, Tr. Amer. Ent. Soc, xlix, p. 340. 



