SYRrilTDTR. 85 



13. Hind metatarsi mucli dilated. .... Ubristes AYalker. 

 Hind metatarsi not conspicuously dilated. . Microdon Meigcn. 



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



with spinous bristles below (Central and South America and West 

 Indies). ........ Lepidostoi.a Mik. 



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



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



face and front not wrinkled Paragus Latreille. 



Epistoma projecting ; front and face black. .... 21 



16. Face black in groimd-color. ....... 17 



Face more or less yellow in ground-color. ..... 20 



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



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

 arista. ....... Xausigaster 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. 



I'iPizA Fallen. 

 Face tuberculate or the oral margin j)rojecting. .... 21 



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

 Face tuberculate, the oral margin not ])rojecling. . . . 2o 



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



wrinkles ; vena spuria obsolete. . . Chrysogaster Meigcn. 

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



Fsu.ota Meigcn. 



2:*. Metallic green, metallic green and black, or black species ; facial orbits 



se])arated by a slender parallel groove. . . Chilosia Meigen. 



Black with more or less metallic green or blue, with 3'ellow or yellowish 



cross-bands on the abdomen ; face without i)ar;illcl grooves. . 24 



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



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



markings ferruginous or orange yellow. . PYR(>i'ir^:NA SchiiuT. 



Wings longer than the abdomen; abdomen with yellow or greenish 



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



