SYRPHIDJE. 85 



13. Hind metatarsi much dilated UBRISTES Walker. 



Hind metatarsi not conspicuously dilated. . MICRODON Meigen. 



14. Body clothed with sparse tomentum ; all the femora thickened and 



with spinous bristles below (Central and South America and West 



Indies) LEPIDOSTOLA Mik. 



Body not with flattened tomentum. . . . . . . 15 



15. Face tuberculate below, partly or wholly yellow; epistoma receding; 



face and front not wrinkled PA RAG us Latreille. 



Epistoma projecting ; front and face black. 21 



16. Face black in ground-color. 17 



Face more or less yellow in ground-color 26 



17. Abdomen with only four visible segments ; first two joints of the an- 



tennae very short, third large, subquadrate, with a short, subterminal 



arista ... . . NAUSIGASTER Williston. 



Abdomen with more than four visible segments. ... 18 



18. Hind femora distinctly thickened. ...... 19 



Hind femora but little or not at all thickened 20 



19. Scutellum unusually large, nearly square ; males dichoptic. 



CHALCOMYIA Williston. 



Scutellum not unusually large, considerably broader at the base ; males 

 holoptic and with a facial tubercle. . .. MYIOLEPTA Newman. 



20. Face rounded, not tuberculate, the oral margin not projecting. 



PIPIZA Fallen. 

 Face tuberculate or the oral margin projecting 21 



21. Epistoma projecting; small, black species. .... 22 

 Face tuberculate, the oral margin not projecting. ... 23 



22. Front in the female and usually the face in both sexes with transverse 



wrinkles ; vena spuria obsolete. . . CHRYSOGASTER Meigen. 

 Front and face not wrinkled ; face pilose and not tuberculate. 



PSILOTA Meigen. 



23. Metallic green, metallic green and black, or black species ; facial orbits 



separated by a slender parallel groove. . . CHILOSIA Meigen. 



Black with more or less metallic green or blue, with yellow or yellowish 



cross-bands on the abdomen; face without parallel grooves. . 24 



24. Wings not longer than the abdomen; ocellar tubercle large; abdomen 



depressed, long-elliptical, somewhat narrowed toward the base, the 



markings ferruginous or orange yellow. . PYROPH^NA Schiner. 



Wings longer than the abdomen; abdomen with yellow or greenish 



yellow or shining metallic cross-bands; usually elongate species. 25 



