280 Mr. C. H. T. Townsend on Diptera 



varies from reddish yellow to black. It is black in nearly 

 all of the females, while in most of the males it is lighter. 

 The females are all quite constant in being without the 

 postsutural golden markings of mesoscutum, or with only a 

 trace of them. These markings consist in these forms of 

 three golden lines joined posteriorly by a transverse line. 

 They are constant and well defined in all of the males. The 

 males vary in wing-colouring from specimens having a large 

 yellow patch extending along costal margin from base of 

 wing two-thirds way to tip, to others in which the yellow is 

 subobsolete or entirely wanting; while the females, though 

 usually without any yellow, in several cases show a trace of 

 it on the wings. The femora in all the specimens are more 

 or less broadly yellowish at base. Palpi reddish yellow. 

 The orbital margins in all the females are silvery pollinose, 

 in the males golden pollinose. The claws of both sexes, 

 especially the female, vary in length, but they are usually 

 comparatively longer in the male. The female abdomen is 

 usually narrowed at tip. The abdomen of all the males is 

 distinctly truncate apically, usually more or less flattened, 

 and rarely subcylindrical. But in this connexion the male 

 taken June 18 deserves special mention. It has the elongate 

 tapering subcylindric abdomen of the female, is entirely 

 without yellow on the wings, and has the postsutural golden 

 markings less distinct; but it has the claws characteristic of 

 the male, and possesses the male hypopygium. This differ- 

 ence in shape of the abdomen may be abnormal in this 

 specimen. Another male, with well-marked yellow on the 

 wings, approaches it somewhat in this respect. 



Typical var. 2:>ennipes, Fabr. — The specimens of the above 

 which I refer here are as follows : Thirteen males, one each, 

 March 9, June 30, July 1, 2, 3, and 17 ; two each, July 4 

 and 5 ; and three, July 6. Two females, July 4 and 18. 

 Length 6|- to 10 millini. 



Characterized by having a more or less distinct patch of 

 yellow on wings in both sexes, less distinct in the female. 

 Scutellum generally lighter in coloration. Wings appearing 

 less pronouncedly black. Abdomen rust-yellowish. 



Var. pilipes, Fabr. — The specimens which I would refer 

 here are : Three males, June 18 (the ones specially mentioned 

 above), July 4 and 10; six females, all July 3, except one 

 July 2. 



Length 7 to 11 millim. 



Characterized by having no yellow on wings in either sex, 

 or hardly a trace in the male. Scutellum generally shining 



