No. 64] DIPTERA OF CONNECTICUT : TAXONOMY 269 



relatively few setae. An elongate yellow lobe arises from ninth ster- 

 nite. Eighth sternite large, deeply emarginate, the lobes clothed with 

 long yellow setae. $ . L. about 10 mm. ; w. 12.3 mm. 



(Sept.) Lab. (Hudsonian). - 



The trivittata group. 

 Key to Species 



1. Tip of Ri+i atrophied 2 



i?i+3 entire 4 



2. Wings with basal fourth nearly clear, without well-defined clouds ; Rs and 



Ri subequal in length ; male hypopygium with basistyle produced into an 



acute spine penobscot 



Wings with clouds in cells R and M basad of origin of Rs and in bases 

 of Anal cells ; Rs relatively long, exceeding Rs ; male hypopygium with 

 the basistyle simple (not known to me for siihfasciata) 3 



3. Flagellum uniformly darkened; cell 1st Mi long, subequal in length to cell 



Mi; praescutum with three brown stripes subfasciata 



Flagellum weakly bicolorous, dark brown, the basal enlargements of the 

 segments brownish black ; cell 1st M2 shorter than cell Mx ; praescutum 

 with four brown stripes, the intermediate pair divided by a pale vitta.. .decora 



4. Nasus lacking 5 



Nasus present 6 



5. Abdominal tergites with a dark median stripe ; male hypopygium with a 



small median depressed bispinous plate on caudal margin of eighth sternite 



(Fig. 30, K) serta 



Abdominal tergites with the median stripe lacking or subobsolete ; male hypo- 

 pygium with a short finger-like lobe on either side of a median sub- 

 quadrate fleshy plate (Fig. 30, L) neptun 



6. Bases of cells R and M beyond arculus clear ; white band beyond cord short, 



extending only into base of cell Ma ; ovipositor with cerci relatively short 



and pale, feebly sclerotized 7 



Bases of cells R and M with a dark spot beyond arculus; white band be- 

 yond cord completely traversing wing or nearly so, attaining the posterior 

 margin in cell Ma (exceptions in stylifcra and ternaria) ; ovipositor with 

 cerci long and slender, heavily sclerotized and blackened 8 



7. Abdominal tergites pale brown, without dark stripes ; male hypopygium with 



median plate of eighth sternite with two lateral spines on either side (Fig. 



30, F) ; ovipositor with cerci broad senega 



Abdominal tergites obscure orange, trivittate with dark brown, the median 

 vitta broad; male hypopygium with median plate of eighth sternite with a 

 single lateral spine on either side (Fig. 30, D) ; ovipositor with cerci nar- 

 rowed and subacute on apical half illinoiensis 



8. Antennae entirely darkened; pale area beyond cord of wing confined to 



radial field; abdominal tergites beyond the second conspicuously ringed 



caudally with yellow ternaria 



Antennae with at least the basal two or three segments pale; crossband 

 beyond cord traversing the wing or virtually so; outer abdominal tergites 

 not ringed caudally with yellow 9 



9. Antennal flagellum uniformly brownish black or black 10 



Antennal flagellum distinctly bicolorous 12 



10. All femora with a subterminal yellow ring, preceded and followed by a broad 

 black annulus ; abdominal tergites with a conspicuous median black stripe ; 

 praescutal interspaces without brown dots ; male hypopygium with eighth 



sternite provided with two long hair tufts margarita 



All femora yellowish or brownish yellow; abdominal tergites not conspic- 

 uously trivittate with black; praescutal interspaces with abundant brown 

 setigerous punctures; male hypopygium with eighth sternite unarmed 11 



