SYRPHIDvE. 87 



38. Males holoptic. SYRPHUS Fabrieius. 



Males broadly dichoptic. .... CH^EMOSYRPHCS Mik. 



39. Dorsum of thorax with a median cinereous line; ocelli usually remote 



from the vertex. . . . . . MESOGRAMMA Loew. 



Dorsum of thorax without such line. . . ... . . 40 



40. Eyes of $ with an area of enlarged facets above ; fourth segment of 



the abdomen with two median yellow stripes and oblique side-spots. 



ALLOGRAPTA Osten Sacken. 



Eyes of $ not with an area of enlarged facets above ; fourth abdom- 

 inal segment not so marked. . . . . . . 41 



41. Face projecting below ; slender species. SPIMCROPHORIA Macquart. 

 Face receding ; abdomen oval. . . XANTHOGBAMMA Schiner. 



42. Thickly pilose species; abdomen black, the basal portion light-col- 



ored. . . .. r .'..... . LKUCOZONA Schiner. 



Thinly pilose species, not so marked. . . . -. . . . 43 



43. Hind femora thickened. . . . . . . . . 44 



Hind femora slender. 47 



44. Species wholly or chiefly reddish or lutescent 46 



Black species, sometimes with luteous spots on face, humeri, and basal 



angles of the abdomen. ........ 45 



45. Scutellum unusually large, nearly square in outline ; males dichoptic. 



CHALCOMYIA Williston. 



Scutellum oval ; males holoptic. . . . MYIOLEPTA Newman. 

 4(5. Face carinate ; abdomen oval. . . . BRACHYOPA Meigen. 



Face tuberculate. . . . . HAMMERSCHMIUTIA Schummel. 

 47. Epistoma produced into a long porrected snout. RHINGIA Soopoli. 



Epistoma not produced. . . ,. . . CHILOSIA Meigen. 



48. Third longitudinal vein bent deeply into the first posterior cell. 51 

 Third longitudinal vein not bent deeply into the first posterior cell ; 



antennae elongate. . 48 



49. Arista very densely plumose, appearing as a solid mass. 



OOPESTYLDM Macquart. 

 Arista feathery plumose. . . . . . . . 50 



50. Males dichoptic MEGAMETAPON Giglio-Tos. 



Males holoptic. . .- . . . . VOLUC ELLA Geoff roy. 



51. Hind femora with a sharp tooth-like projection below near the distal 



end. . . .. . 4 ... . MILESIA Latreille. 



Hind femora without such tooth. . 52 



