512 PROCEEDINGS OF THE ACADEMY OF [Oct., 



10. Pleura unstriped; Sc rather short, extending to about one-fourth 



the length of the sector; no dark blotch at the tip of Sci; 

 apices of cells R s and R 5 largely darkened. (Eastern United 



States.) blanda Osten Sacken. 



Pleura striped with brown; Sc long, ending at about half the 

 length of the sector; a dark blotch at the tip of Sd; apices of 

 cells Rz and R only slightly darkened. (Western United 

 States.) - calif ornica Alexander. 



11. Antennae orange at the base, the flagellum dark 12 



Antennae black throughout 15 



12. Cell 1st M 2 closed; femora with a dark brown subterminal 



annulus. (Eastern United States.) sulphurella Osten Sacken. 



Cell 1st Mo open; femora without a darker subterminal annulus... 13 



13. Sc short ending before the origin of Rs, this distance being about 



equal to the vein R 2 . (Western United States.) 



flavibasis Alexander. 

 Sc longer, ending opposite, or just before, the origin of Rs 14 



14. Male hypopygium with the dorsal angle of the pleurite stout, 



with numerous (about fifteen) slender hairs; ventral append- 

 age simple, stout, tipped by a blunt black spine; second 

 appendage a powerful, curved, subchitinized arm directed 



proximad. (Northeastern United States.) fiorens Alexander. 



Male hypopygium with the dorsal angle of the pleurite slender, 

 with a few (about ten) stout hairs; ventral appendage bifid, 

 the arm with a long slender black spine; second appendage a 

 slender pale arm that is almost straight, with two hairs at 

 the tip. (Eastern United States.) cognatella Osten Sacken. 



15. Wings with slender veins, clouded with a milky suffusion; Rs 



very long and straight. (Northwestern North America.), 



galactoptera Bergroth. 



Wings with stouter veins, pale gray to hyaline; Rs shorter, more 



arcuated basally 16 



16. Subcosta short, ending before the origin of Rs, the distance about 



equal to the r-m cross-vein; vein R- 2 oblique, a little longer 

 than the cross-vein r-m; male hypopygium with the gona- 

 pophyses and penis-guard fused into a large, prominent, 



cylindrical tube. (Northeastern United States.) 



noveboracensis Alexander. 



Subcosta longer, ending about opposite the origin of Rs ; vein R 2 



longer, the cell R 2 being larger; male hypopygium with the 



gonapophyses and penis-guard not fused into a cvlindrical 



tube 17 



17. Wings long and slender with a strong grayish brown suffusion; 



halteres elongated; male hypopygium with the ventral pleural 

 appendage very elongate, slender, slightly expanded toward the 



tip. (Eastern Rocky Mountain region.) filicauda Alexander. 



Wings broader, not strongly tinged with grayish ; halteres shorter 

 male hypopygium with the ventral pleural appendage not 

 strikingly elongated 18 



