270 Journal New York Entomological Society, [^'o'- xxi. 



section, the third vein ending a little in front of the tip of the wing; 

 abdomen subopaque. (Eur.;* Greenl., Cal., Id.,* Wash.*) 



ohscurella Fallen, sens. str. 

 Legs black ; the second section of the costa about three times longer than 

 the third section, the third vein ending much before the tip of the 

 wing; abdomen more shining. (Eur.;* Greenl., Id.,* Wash.*) 



ohscurella var. nigritella Zetterstedt. 



10. Thorax opaque, cinereous dusted, with a faint yellowish humeral spot. 



(D. C, Mass., Cal., Ore., Wash.,* Alaska.) 



ohscurella var. ilicicola Loew. 



Thorax subshining, slightly dusted, no humeral spot. (Eur. ;* Id.,* Wash.,* 



Alaska.*) ohscurella var. nigra Meigen. 



11. Antennae yellow, the third joint sometimes infuscated 12. 



Antennae black, or at least the third joint entirely black 14. 



12. Cheeks broader than the eye-height; the third antennal joint elongate- 



oval ; pleurae and legs yellow. (111.*) genalis n. sp. 



Cheeks narrower than the eye-height; the third antennal joint short- 

 rounded 13. 



13. Third antennal joint bluntly rounded, pubescent and dusky; pleurae, abdo- 



men and legs yellow. (Eur. ; Ind.*) analis Zetterstedt. 



Third antennal joint minute and bare; pleurae, abdomen and legs black, 

 but variegated with yellow. (Eur. ;* Ohio, 111., Alaska.) 



flavicornis Zetterstedt. 



14. Femora in part at least yellowish; base of antennae yellow; lateral margins 



of thorax at least broadly yellow 15. 



Femora black, except the knees ; antennae entirely black or dark brown ; 

 blackish species 19. 



15. Wings dark, veins blackish; scutellum cinereous black; opaque black spe- 



cies. (D. C.) nervosa Loew. 



Wings hyaline ; scutellum yellow, or at least usually yellow in the middle ; 

 species often yellow 16. 



16. Body subshining; mesonotum marked with four brown vittae, the middle 



pair scarcely extending beyond its middle. (Tex.) 



clemativora Coquillett. 



Body opaque dusted ; mesonotum marked with cinereous black, (flava 



Fallen.) 17. 



17. Pleurae, abdomen and legs largely yellow 18. 



Pleurae, abdomen and legs largely black. (Eur.;* Greenl.) 



flava var. settersiedti Schiner. 



18. Pleurae, except part of the sternopleura, yellow; abdomen yellow; meso- 



notum with two narrow yellow vittas dividing the dark color into 



three parts. (Eur. ;* Wash.*) flava Fallen sens. str. 



Pleurae with the dark color more extended; abdomen sometimes dusky in 

 part; yellow stripes of the mesonotum not evident. (Eur.;* Id.,* 

 Ore.*) flava var. flavosciitellafa Fallen. 



