XXVIII BI'LLKTIX 31, T^XITED STATES NATIONAL MUSKI'M. 



14. — Scnti'llniii iiiiiisiiiilly larj^o. nearly s(|nan'; nialcs (lic-liojjtic (plate iv. fi^. 14) 



Chalcomyia, 126 



Scutt'lliini uot uiiusually large, coiiisiclerably broader at the base; uiaks liolop- 



tic and wiili a facial tubercle (plate v.ligs. 1-2) . . . Myiolepta, 1'27 



15. — Epistoma projecting ; small black species 16 



Face tubercnlate, the oral margin not iirojectiug 17 



Face rounded, pilose, uot tnberculate, the oral margin not projecting (plate ii, 



tigs. 2-5) Pipiza, '22 



16.— Frout in female, and the face iu both sexes usually, with transverse wriukles 



(plate ii, fig. 10) Chrysogaster, 'M 



Face and front uot wrinkled ; face pilose, without tubercle . . Psilota, :>0 

 17.— Metallic green, metallic green and black, or black species; abdomen oval, never 

 with entire shiuing cro.ss-bands (plate iii, figs. 1-5) . . . Chilosia, :{8 

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

 inal niarkiugs, or if uot, at least with entire shining cross-bauds : abdomen 



usually elongate 18 



18.— Wings uot longer than the abdomen; ocellar tubercle large; abdomen de- 

 pressed, long elliptical, somewhat narrowed toward the base, the lighter 

 markings ferruginous or orange-yellow (plate iii, fig. i:>) Pyropheena, 54 

 Wiugs louger than the abdomen, usually more slender .species, abdominal cro.ss- 

 bands yellow or greenish yellow, or sometimes shiuiug metallic . . 19 

 19.— Front tibia, distdlly, and tarsi of the male dilated, those of the female a little 



widened (plate iii, figs. 10-12) Platychirus, 56 



Frout tibite aud tarsi slender iu both sexes ...... Melauostoma, 46 



20. — Dorsum of thorax with yellow lateral stripes 29 



Dorsum of thorax not with yellow lateral stripes 21 



21. — Abdomen narrowed toward the base, in outline club-shaped or spatulate . 22 



Abdomen oval or slender, not si)atulate or club-shaped 24 



22.— Hiud femora slender; abdomen elongate, slender toward the base; front of fe- 



uuile long, narrow above (plate iv. ligs. 7-9) Baccha, 116 



Hind femora thickened 23 



23. — Epistoma ])roduced anteriorly, iu jirohle deeply concave from antenme to oral 



margin; third joint of antenntc rounded (plate iv, figs. 11,12 Sphegiiia, 113 



Epistoma ]»roduced more downward, iu profile gently coucave ; third joint of 



antenme uot rounded (plate iv, fig. 10) Neoascia, 111 



24. — Abdomen with definite yellow cross-bands, interrupted or entire .... 25 



Abdomen not with definite yellow cross-bands 32 



25. — Hind femora extraordinarily thickened Syritta, 2'M) 



Hind femora slender 26 



26. — Sixth abdominal segment iu the male as long as the two preceding together, 

 cylindrical (plate iii, fig. 14); fifth segment in the female one-half as long 



as the i)receding Enpeodes, 64 



Sixth segment not peculiar: the fiith seguient iu the female one-third or one- 

 fourth as long as the preceding 27 



27. — Front very convex ; eyes of male with an area of enlarged f^xcets above ())late 



iv, lig. 1) Catabomba, 62 



F)-ont not remarkably convex 28 



28. — Third longitudinal veiu.with a distinct curvature into the fir.st posterior cell ; 

 third joint of antenna elongate oval (plate iv, fig. 4) .... Didea, 89 



Third longitudidal vein straight or gently curved Syrphus, 66 



29. — i)or.sum of thorax with a median cinereous line Mesograpta, t'8 



Dorsum without such line 30 



30. — Eyes of male with an area of enlarged facets above ; fourth segment of abdo- 

 men with two median yellow stripes and an oblique side spot 



AUograpta, 96 



