DESCRIPTION OF THE SPECIES. 295 



Observation 2. — Should we distribute the present and all the 

 next following species among the subgenera which I have estab- 

 lished for the European Trypetidae, they would have to be 

 referred to the genera Oxyphora, Oxyna, Tephritis, and Urellia, 

 The genus Urellia is easily distinguished from the others by the 

 picture of the wings : it consists in a conspicuous star-shaped 

 black design near the apex, while the rest of the wing is alto- 

 gether immaculate, or is marked with only a few isolated spots, 

 at the utmost with a very pale reticulate picture. A part of the 

 species described in the sequel, can undoubtedly be referred to 

 Urellia. Among the remaining species, those would have to be 

 located in the genus Oxyphora, which have the third longitudinal 

 vein of the wings beset with bristles. This character is of a very 

 easy application w r hen a number of well-preserved specimens is at 

 hand, but it becomes of much less value when applied only to 

 single and indifferently preserved specimens. For this reason I 

 am not quite sure whether in all the species in which I have not 

 been able to discern the presence of bristles on the third vein, 

 they are really wanting ; and hence, with the materials I now 

 possess, I am not able to refer with certainty to Oxyphora 

 the North American species which may belong to it. Among the 

 North American species with a distinctly bristly third longitudinal 

 vein, T. geminata alone comes near the European species of 

 Oxyphora, while T. timida is more related not to the former, but 

 to the European T. guttata Fall., and to the American T. tenuis, 

 melanogastra, and mexicana, in which I am unable to discern 

 the bristles upon the third vein. Thus, the maintenance of the 

 genus Oxyphora for those species only which have bristles upon 

 the third vein, w r ould separate from each other species most 

 closely allied. In order, therefore, to make this genus applicable 

 to the North American species, we should exclude from it all the 

 species the picture of the wings of which ends in distinctly 

 developed rays, in which case only T. geminata would remain in 

 it. Theoretically there is no objection to such an arrangement ; 

 practically, however, there remains the difficulty of ascertaining 

 positively the presence of bristles upon the third vein in all the 

 specimens which I have at hand, and this difficulty compels me 

 to drop entirely the genus Oxyphora for the present. Should we 

 follow the suggestion already made above, of removing from the 

 genus Oxyna those species which have remarkably prolonged 



