NORTH AMERICAN DIPTERA. 309 



Southern character is well indicated in our fauna. Helophihis, which 

 with us is distinctly a Northern type, is poorly represented. Species 

 and genera with club-shaped abdomen are unusually numerous, and 

 are undoubtedly mostly very active in their habits. Forms con- 

 spicuous for their absence are the larger, bright-colored, less active 

 species. I find no certain indication of a single species of Milesia, 

 Spilomyia, or Temnostoma, having been hitherto described. The typical 

 American genus Mesograpta is very rich in species, apparently, while 

 Syrphus, in the narrow sense, I do not believe will be found as well 

 represented as in North America. Nor do there seem to be any 

 species of Chilosia now known. Owing to the greater diversity of 

 ])hysical conditions, it is very probable that a far richer and more 

 varied fauna will be eventually disclosed, and one more divergent 

 from the European, than is our own. The genera Pia, Bhoga, Sal- 

 jjingogaMer, Meromacrus, Ortholophus, StUbosoma, 3Iacrometopia, Ster- 

 phus, and the less differentiated Phalacromyia and Glaurotricha, are, 

 so far, peculiar to the region South of the United States. 



Walker's species will be found in a list by themselves at the close. 

 Generic names with him afford evidence so unreliable of the real 

 affinities of the insects, that it is safest to consider the generic limits 

 as commensurate with those of the family. 



I desire to express my hearty thanks to Mr. George B. Cresson, 

 Custodian of the American Entomological Society, for very kind 

 assistance in the preparation of this paper. 



IVIIXOGASTER. 



Macquart, Dipt. Exot. ii, 2, 14, 1842. 

 conopsoides Macquart, Dipt. Exot. ii, 2, 14, pi. iii, fig. 1. — Brazil. 



miCRODON. 



Meigen, lUiger's Magazine, ii, 275, 1803. 



angustiventris Macquart, Dipt. Exot. 5e Suppl. 85, 14, pi. v, fig. 1. — S. America, 

 angustus Macquart, Dipt. Exot. ler Suppl. 122 (Aphritis) ; ibid. 3e Suppl. 38, 10 



{id.). — Cayenne, [gen. nov. ? Macq.] 

 aurifex Wiedemann, Auss. Zweifl. Ins. ii, 85, 7; Macquart, Dipt. Exot. ii, 2, 11, 



2, pi. ii, fig. 2 (Aphritis) ; ? Williston, Synopsis, etc., 9. — Brazil. 

 ? Mierodon Trochilus Walker, Dipt. Saunders, 216. — Mexico, 

 bidens Fabricius, Syst. Antl. 185, 6 (Mulio) ; Wiedemann. Auss. Zweifl. Ins. ii, 



84, 6. — S. America. 



I 



