303 



rWilliston, 



D. — False vein of wing usually indistinct or absent ; front in 9 . oi' face 

 also (c? 9) vpith transverse wrinkles ; hind border of scutelluin sharp ; 

 small, oval, metallic, nearly bare species Chrysogaster. 



a._Outer posterior angle of first posterior cell ohtnsG . Chrysogaster. 



aa. — Outer posterior angle of first posterior cell rectangular or 



acute Ortlioneura. 



The character given is that usually taken as the distinction between the 

 two genera, but is very unreliable and misleading, and, moreoverj sepa- 

 rates closely related species ; the length of the antennaj is equally unre- 

 liable ; I place all the species In Meigen's genus. There are sufficient 

 plastic characters to render the tabulation and identification of our species 

 a comparatively easy matter. At all events, it is evident that Orthoneura 

 cannot be used in Loew's or Schiner's sense even as a sub-genus for the 

 North American species. 



Our species may be tabulated as follows : 



a. — Third joint of antennae ovate or orbicular &. 



— Third joint of antennae elongate «. 



b. — Third joint of antennae ovate c. 



— Third joint of antennae orbicular d. 



c— Dorsum of thorax opaque black {(^) *)ugripe9, 



— Dorsum of thorax not black opaque, with dark stripes ; finely punc- 



tulate ; tip of fourth vein bent inwards nigrovittatus. 



d. — Outer posterior angle of first posterior cell not obtuse ; latus. 



— Outer posterior angle of first posterior cell obtuse ustulatus. 



e. —The ultimate section of fourth longitudinal vein joins the third be- 

 yond the lip of second vein, the dark clouds not continuous nor in 

 the same line ; second joint of antennae nearly as long as third ; eyes 

 Avith distinct linear markings ; posterior borders of second and third 



abdominal segments brown nitidus. 



—Ultimate segment of fourth vein joins the third opposite or before 



tip'of second, abdomen not ftisciate ./. 



/. — Cloud from tip of second vein continuous or in same line with ulti- 

 mate section of fourth vein ; eyes with markings ; second joint of 



antennae nearly as long as third , bellulus, sp. nov. 



—Second joint of antennae considerably shorter than third, abdomen 

 shining brassy on the sides, the disc more or less opaque ; eyes 



nearly unicolorous ; stigma brown g 



g. — Second joint of antennae half as long as third ; the third joint some 



what narrowed beyond the middle pictipennis. 



— Antennae not longer than the face, second joint short stigmatus, 



sp. nov 

 Chrysogaster STIGMATUS, sp. nov. 



(1^ 9 • Antennas black, not longer than the face, first joint short, second 

 joint twice as long, about one-fourth as long as third. Face deep green, 

 shining, nearly smooth, with sparse pile, and a silvery white triangular 



