10 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 79 



17. All legs in pai't black or brown, never immaculate yellow, length 



of body 3.3 to 4.6 mm isis (p. 30 1. 



Legs mostly yellow, only hind femora and tibiae sometimes 

 brownish to blackish 18. 



18. Subniarginal baud 'always at least twice as long as wide, with 



an angular emargination on proximal margin and heellike 

 prominence on distal margin, legs immaculate yellow, length 



of body 3.4 to 4 mm., vestiture of wings normal -flavipes (p. 52 1. 



Band not angulate, not more than twice as long as wide, some- 

 times only one-fourth longer, length of body 3.7 mm., surface 

 and marginal vestiture of wings (not including setae on sub- 

 marginal vein) very short and inconspicuous, the usual pat- 

 tern of larger hairs on basal third lacking flamminneiventris (p. f>r) \. 



19. Head twice as wide as long, face flat, or feebly convex, length 



of body 3.2 to 4 mm., 13 to 19 setae on submarginal vein 20. 



Head more than half as long as wide, or sometimes twice as 

 long (occasionally hrevilohae) , length 2.2 to 3 mm., 11 to 

 15 setae on submarginal vein 22. 



20. Color of head and thorax almost or entirely reddish yellow. 



dubia var. rufosa (p. 41 1. 

 Color of head and thorax, as well as abdomen, mostly not red- 

 dish yellow 21. 



21. Length range 3.2 to 4.3 mm., face extremely flat and scarcely 



protruding in front of eyes, 15 to 19 setae on submarginal 



vein, in general not so dark as variety doanei dubia (p. 38). 



Length range 3.2 to 4 mm., face fairly flat, but protruding more 

 distinctly in front of eyes, 13 to 16 setae on submarginal vein, 

 in general darker than dubia dubia var. doanei (p. 43 1. 



22. Head five-eighths as long as broad, rather blocky in form, bofly 



as a whole robust, large for the genus, 2.6 to 4.3 mm. long, 

 more often 3.5 mm., submarginal band tapering and bending 



sharply at apex novascotiae (p. 50). 



Head not so robust or subquadrangular, body less robust, 

 usually smaller than 3.5 mm., submarginal band not as de- 

 scribed above 23. 



23. Head mostly light brownish yellow, only throat, vertex narrowly 



around ocelli, and occiput around foramen, black, face pro- 

 truding broadly and roundly in front of eyes, about 12 setae 

 on submarginal vein, cheeks polished or inconspicuously 



sculptured lobatae (p. 45 >. 



Head and thorax in general darker, body mostly black, face 

 not well rounded and prominent, cheeks reticulate-punctate, 

 11 to 15 setae on submarginal vein 24 



24. Abdomen entirely black, or anterior-ventral fourth light brown, 



antennae dusky, legs, especially hind coxae and femora of 



middle and hind legs, dark globuli (p. 47). 



Abdomen less black on anterior-ventral aspect, legs mostly 



yellow brevilobae (p. 56). 



