THE CANADIAN ENTOMOLOGIST. 231 



20. Third antennal joint quadrangular Townsendi. 



Tliird antennal joint rounded-ovate or ovate 21 



21. Abdomen in both sexes entirely shining 26 



Abdomen of the male largely opaque 22 



22. Posterior femora on basal third, and at apex, yellow ; scutellum 



yellow, except the narrow base pallipes. 



Posterior femora, except the apex, black ; scutellum only piceous at 

 apex ; first posterior cell broader and last section of fourth longi- 

 tudinal vein accordingly longer tristis. 



23. Second abdominal segment partly opaque ; four anterior tibise 



entirely yellow prima. 



Abdomen entirely shining ; four anterior tibite with at least a dark 

 band parva. 



24. Pile of dorsum of thorax black, abundant sorocula. 



Pile of dorsum of thorax sparse, whitish or yellowish 29 



25. Thorax long pilose, third antennal joint moderate ; arista 



pubescent aurotecta. 



Thorax short pilose 27 



26. Anterior femora largely black cyanescens. 



Anterior femora yellow phiviata. 



27. Scutellum with bristlelike hairs Icevis. 



Scutellum destitute of such hairs lucta. 



28. Scutellum with bristles petulca. 



Scutellum without bristles sororia. 



29. Pile of the abdomen long, yellow chalybescens. 



Pile of the abdomen short hoodiensis. 



30. Posterior femora light-coloured at base and apex ; dorsum of thorax 



smooth pallipes. 



Posterior femora light-coloured only at the apex ; dorsum of thorax 

 roughened leitcoparea. 



\ 



CATALOGUE OF THE DESCRIBED NORTH AMERICAN SPECIES OF CHILOSIA. 



Chilosia. 

 Meigen ; Syst. Beschr. III., 296 (1822), Cheilosia. 

 Ibid., id., VII., 128(1838). 



Cartosyrphus, Bigot, Ann. Soc. Ent. Fr., 1883 ; 555. (Will.) 

 Melanogaster, Bigot, Ann. Soc. Ent. Fr., 1883 ; 258. (Pt.) 

 Syrphus and Eristalis ex parte, auctorum. 



