SYNOPSIS OF NORTH AMERICAN SYRPHID^. XXIX 



Eyes of male not with an area of enlarged facets above; fonrtli abdomiupl f^eg- 



nieut not so marked 31 



31. — Face projeetiiyj below ; slender species (plate iv, fig. l(i) . Sphaerophoria, 104 



Face receding below ; adomen oval, at least not slender Xanthogramma, 91 



32. — Abdomen oval, black, basal ])ortion light-colored; thickly pilose species (i)late 



iii, fig. 6) Leucozona, (Jl 



Thinly pilose species, not so marked 33 



33. — Hind femora thickened 34 



Hind femora slender 37 



34. — Species wholly or chiefly reddish or liitesceut 36 



Black species, sometimes with luteous s])ots on face, hnmeri, basal angles of 



abdomeb, etc 35 



35. — Scntellnm unnsually large, nearly square in outline; males dichuptic 



Chalconiyia, 126 

 Scutelluni not unusually large, considerably broader at the base; eyes of male 



holoptic Myiolepta, 127 



36. — Face carinate; abdomen oval (plate v, figs. 5-7; Brachyopa, 131 



F^ace produced, obtusely tuberculate (plate v, fig. 4) . . Eugeniamyia, 130 



37. — Epistoraa produced into a long porrected snout (plate v, fig. 3) . Rhingia, 129 



Epistoma not at all produced. (See, also, i>acc7irt, 116. ) .... Chilosia, 38 



38. — Third longitudinal vein bent deeply into the first posterior cell .... 40 



Third vein not deeply bent into the first posterior cell ; autenn:e elongate . 39 



39. — Arista feathery plumose (plate vi) Volucella, 134 



Arista very densely plumose, appearing like a solid mass . Copestyluni, l."»l 

 40. — Hind femora with sharp tooth-like projection below near the outer end ; large 



species (plate xii, fig, 2) Milesia, 254 



Hind femora without tooth-like projection below 41 



41. — Fioutal triangle of male strongly protuberant (plate viii, fig. 8) 



Doliosyrphus, 178 



Frontal triangle not protuberant 42 



42. — Thorax with distinct yellow markings ; femora thickened; hy]»opygium large 



(plate vii, fig. 1) Pteroptila, 179 



Thorax without distinct yellow markings; hind femora occasionally thickened ; 



liypopygium not prominent Eristalis. l.")-< 



43. — Arista plumose (plate vii, figs. 2-5) 44 



Arista bare or pubescent 45 



44- — Thinly pilose, abdomen with yellow bands Sericomyia, 153 



Thickly pilose, abdomen without yellow Arctophila, 157 



45. — Third longitudinal vein bent deeply into the first posterior cell ; hind femora 



thickened 46 



Third vein only gently curved 51 



46. — Face with a sharp longitudinal ridge in the middle ; hind femora with an angu- 

 lar ])rotuberance below near outer end Tropidia, 20() 



Face tuberculate or arched, not carinate 47 



47. —Thorax and scutellum very densely pollino.se above (plate viii, fig. 9). 



Pterallastes. 19-^ 



Scutellum not densely pollinose above 43 



48. — Third joinj^ of antennse broad, thorax not vittate 49 



Third joint oval ; thorax usually vittate above Helopbikts, lc3 



49.— Thickly j.ilose Mallota, 201 



Thinly pilose 50 



50.— Hind tibi;c of male with an internal median .spur (plave ^iii, fig. 12) 



Teuchocneniis, 199 

 Hind tibiiB of male not with an internal median spur (plate ix, fig. 1) 



Triodonta. 205 



