116 BULLETIN 31, UNITED STATES NATIONAL MUSEUM. 



ish ; iu the Western specimen the abdomen is more nearly as Loew de- 

 scribed it. In all the male specimens the hind femora are brownish red, 

 not black. 

 Type specimen in the Loew collection at Cambridge examined. 



BACCHA.* 



Bacchn Fabiicius, Syst. Autl., 199, 1805. 

 Ocyptamua Macquart, Hist. Nat. Dii)t., i, 559, 1834. 

 Bacha Scliiuer, ct auct. 



Medium size, bare species, usually with long, slender abdomen, nar- 

 rowest towards the base, but often shorter and not narrowed at base. 

 Head large and round, broader than the thorax. Autennoe short, third 

 joint rounded or oval ; arista toward the base, slender, bare. Eyes bare, 

 contiguous in the male. Front in female long, narrow, often much nar- 

 rowed above. Face in large part yellowish, nearly straight in profile 

 below the antennae, or only gently excavated above the tubercle ; below 

 the tubercle usually more or less receding; not at all produced below 

 the eyes. Cheeks very narrow, the distance between the eyes below less 

 than the width of the face in the middle. Thorax short, abdomen three 

 or four times as long as the thorax, the second segment very slender, 

 thence gradually widening to tiji of fourth segment, the remaining seg- 

 ments gradually or abruptly narrowed. Legs verv slender, the hind 

 femora elongate, but not thickened, hind metatarsi elongated and thick- 

 ened. Wings as in Syrphus, the small cross-vein sometimes near the 

 middle of discal cell ; often with dark brown or blackish markings. 

 Type of genus, B. elongata Fabr., Europe. 



TABLE OF SPECIES. 



1. — Abdomeu distinctly narrowed toward the base ; elongate, more or less club- 

 shaped or spatulate 2 



Abdomeu shorter than the wings ; either broadest toward the base, or with par- 

 allel sides ; uot cylindrical or clubbed (Ocy^fcmus) 8 



2. — Third joint of the antenna? elongate oval, obtusely pointed; face very prom- 

 inent Babista 



Third joint short oval, obtusely rounded; face not prominent 3 



3. — Wings ciuerous hyaline, without distinct dark markings ; abdomen very slen- 

 der coguata, obscuricomis 



Wings more or less brownish or blackish 4 



4. — Wings with a broad median cross-band, reaching to the fourth posterior cell 5 

 Wings with the front border, at least, for its whole length brownish or black- 

 ish 6 



5.— rScutellum and posterior part of the dorsum shining golden .... aurinota 

 Scutellum translucent, yellowish brown, with a metallic reflection . . lemtir 



6. — Posterior half of the wings nearly hyaline Tcirchetius 



Wings more or less brown or blackish on the posterior part 7 



* Baccha, a mythological name. 



