SYNOPSIS OF NORTPI AMERICAK SYRPIIID^E. XXVII 



part of the body; the body generally thinly pilose or nearly bare, but 

 sometimes clothed with thick pile. Wings comparatively large, when 

 at rest folded together over the abdomen, or half oi)eu ; third longi 

 tudinal vein never forked, frequently with a more or less deei) curva- 

 ture on the outer part; marginal cell opened or closed, the fourth vein 

 terminates in the third vein at or before the tip; neither of the inter- 

 calary veins present ; anal cell always closed before the border of the 

 wing ; anterior cross-vein before or beyond the middle of the discal cell ; 

 heticeen the third and fourth Jougitudhial veins and nearly parallel with 

 them there is a false or spuri'ius rein, uear\\, always present, and cbar- 

 acteristic of the family. 



TABLE FOR THE DETERMINATION OF GENERA. 



1. — Antenute with a teriniaal style 2 



AnteniKB with a dorsal bristle 3 



2.— AutenniB cylindrical, iirst two joints elongate Ceria, '259 



First two joints short, third comj)ressed (plate iv, tig. 14) . Pelecocera, llt> 



3.— Marginal cell of the wing closed and petiolate 38 



Marginal cell open * 



4. — Anterior cross-vein of the wing distinctly before the middle of the discal cell, 



nsu.nlly rectangular ^ 



Anterior cross- vein ending near or beyond the middle of the discal cell usually 



oblique ^3 



5. — AntenniB elongate • • • ^ 



AntenniB short ' < -^^ 



6.— Dorsum of thorax without yellow lateral stripes 7 



Dorsum of thorax with yellow lateral stripes; large species (plate i, lig. ;">) 



Chrysotoxum, lo 



7.— Face rounded, pilose, not tuberculate, oral margin not projecting .... 8 



Face not evenly arclied ; tuberculate, or the oral margin projecting ... 9^ 



8.— Large species; scutellum flattened, usually with spines or tubercles; a stump 



of vein in the first posterior cell from the third longitudinal vein (plate i, 



f <r8. i_3^ Microdon, S 



Small species; scutellum without points; no such projecting stump (plate ii, 



fig. 1) Pipiza, 22 



9._Body clothed with sparse tomentum; all the femora thickened and with a row 



of short spines below (see, also, Mjiinlepfa strigilata) . . Lepromyia, 31 



Body not tomeotose ; all the femora not thickened and uot with spines below 



la 



10.— Face tuberculate below, partly or wholly yellow ; cpistoma receding ; face and 



front not wrinkled (plate i, figs. 7-U) Paragus, 17 



Epistoma projecting ; front and face with transverse wrinkles (plate ii, -figs. 



6_9) Chrysogaster, 31 



11. — Face black in ground color 12 



Face more or less yellow in ground color 20 



12.— Abdomen with only four visible segments; first two joints of the antenufe very 

 short, third large, subquadrate, with a short, subterminal arista (plate i. 



tig. 10) Nausigaster, 21 



Abdomen with more than four visible segments 13 



13. — Hind femora distinctly thickened 14^ 



Hind femora but little or not at all thickened 15 



