464 COXNECTICUT GEOL. AND NAT. HIST. SUR\^Y [Bllll. 



base of abdomen ; hypop\ gium with inner dististyle shaped more or less 

 like a boomerang, about three times the length of the outer ; gonapophyses 



hairy (Fig. 53, F) fernaldi 



General coloration brown to reddish brown ; antennae short in both sexes ; 

 hypopygium with inner dististyle a slender, sclerotized hook, the outer 

 style so reduced in size a^ to be virtually lacking; gonapophyses glabrous 

 (Figs. 53, H ; 54, F) '. 22 



22. Inner dististyle narrowed to an acute black spinous point ; aedeagus trifid at 



tip (Fig. 54, F) nimbipennis 



Inner dististyle not narrowed into a spine, the obtuse apex bearing a long 

 curved seta; aedeagus simple at tip^ (Fig. 53, H) ingloria 



23. Mesonotal praescutum reddish brown, with a capillary dark brown median 



line ; male hypopygium with both dististyles and each gonapophysis bear- 

 ing a small lateral spine, so as to appear bifid (Fig. 54. H) rubella 



Mesonotal praescutum reddish brown, unmarked with darker ; male hypopyg- 

 ium with both dististyles and the gonapophyses unbranched (Fig. 54, J) 



townesi 



24. Hypopygium with the tergal sheath profoundly divided by a median split : 



longest gonapophyses appearing as exceedingly lengthened, needle-like 



rods that jut from the genital chamber manicata 



Hypopygium with the tergite a simple spatulate plate ; gonapophyses not 

 appearing as needle-like rods 25 



25. Inner dististyle on outer margin before apex with a small, erect, pale lobule ; 



aedeagus elongate (Fig. 53, A) 26 



Inner dististyle not so armed ; aedeagus short 27 



26. Inner dististyle with the lateral lobe very small ; aedeagus blackened, rela- 



tively short and stout, some distance before apex with two subtending 

 black spines; apex of aedeagus microscopically roughened . . . .brevicalcarata 

 Inner dististyle with the lateral lobe elongate ; aedeagus very long and 

 slender, jutting some distance beyond the genital chamber, pale brown 

 in color, not roughened near apex (Fig. 53, A) adirondacensis 



27. Outer dististyle a short, squat, blackened structure, bearing three or four 



acute, black spines ; inner style bidentate at apex, its acute lateral spine 



with microscopic denticulations at base (Fig. 54. G) notmani 



Outer dististyle not as above, either simple or at most bispinous ; inner style 

 simple 28 



28. Coloration of body brown, slightly overcast with gray ; antennae short in 



both sexes ; outer dististyle bispinous ; gonapophyses appearing as slender 



erect rods (Fig. 53, C) bilineata 



Coloration of body light gray ; antennae ( $ ) relatively long, if bent back- 

 ward extending to or shortly beyond root of halteres ; both dististyles 

 appearing as small, ear-like, simple lobes, the outer darkened, glabrous ; 

 gonapophyses appearing as powerful blackened horns, each bearing an 

 acute tooth or spine on the inner or concave face (Fig. 53. E) dentifera 



29. Anal veins strongly divergent ; outer dististyle of hypopygium a curved 



blackened hook (Fig. 54, A) " .' ". megacera 



Anal veins slightly convergent (Fig. Z3, E) ; outer dististyle a small flattened 

 lobe, clothed with transverse rows of blackened setae (Fig. 54. C, D) . . . . 30 



30. Antennae ( $) about equal in length to entire body, the flagellar segments 



elongated, black, attenuated and pale at apices ; gonapophyses heavily 



blackened, bifid (Fig. 54, D) monticola 



Antennae ( $ ) shorter, if bent backward extending about to midlength of 

 the abdomen, the flagellar segments shorter, without pale tips ; gona- 

 pophyses pale, simple, terminating in an acute point that is directed laterad 

 (Fig. 54, C) mesocera 



The groups in the above key that include more than a single species are as 

 follows : 



adirondacensis group. — adirondacensis^ brevicalcarata. 



bilineata group. — bilineata, notmani. 



meigenii group. — carolinensis, frisoni, ithacana. mcigenii, serridens. 



nigripila group. — gaspensis, htteola, nigripila, palpalis. pygmaca. 



