376 CHARLES T. BRUES. 



Front in the male rather narrow, only about one fifth the width 

 of the head, in the female one-third or one-fourth. Frontal bristles 

 twelve in number, all reclinate, the lower, ones in the middle smaller 

 than the others ; arranged in four transverse rows, on the vertex 

 four, then follow three rows each of two lateral bristles; below the 

 ocelli are two more bristles which are somewhat nearer to the mid- 

 dle. Cheeks without bristles. Fore tibiae unarmed, middle tihise 

 on the posterior part of the upper surface with a row of very long 

 setae in the male, four to six in number, in the female only two, 

 rarely three. In both sexes there are setae also on the fore and hind 

 tibiae. Dorsum of the thorax with no longer hairs and bristles than 

 in other genera ; velvety ; with one pair of dorsocentral macrochaetae 

 and two marginal scutellar bristles. Third vein of wing not forked, 

 first running parallel with the costa rather far from it, then making 

 a somewhat abrupt turn toward it, ending about half way between 

 the humeral and costal. Auxiliary vein distinct, ending in the 

 first longitudinal just before the latter turns forward. Antennae 

 rounded, with dorsal arista, palpi small, bristly only at the tips. 

 Eyes bare. 



The venation and abundance of short velvety hair upon the dor- 

 sum of the thorax, afford the essential generic difference. 



Table of Species. 



1. Front tarsi not enlarged or widenend in either sex, costal vein not quite attain- 



ing the middle of the wing, third vein far from costa at base. 



aterrima Meig. 



Front tarsi enlarged and flattened in both sexes, more distinctly so in the 



female, third vein nearer to costa at hRse. costa reaching to or beyond 



the middle of the wing • •-. 



2. Front tarsi very strongly flattened and enlarged, fourth vein curved at base, 



straight at apex, ending before the wing tip. • • molilalia sp. nov. 



Front tarsi distinctly flattened, but not remarkably enlarged, fourth vein 



evenly curved, endingjust beyond the wing tip- . -.volutina Meig. 



Under the first species I have traced somewhat the history of the 

 genus. When Meigen became acquainted with Latreille's descrip- 

 tion of the genus Phora, he considered that it covered the same 

 ground and withdrew his own genus Trineura* 



The genus is represented in North America by three species, one 

 (aterrima) originally described from Europe and first recorded from 

 this side of the Atlantic by Walker in his "List" (1849), and 



* See Appendix, Note 1. 



