June, 1919 Bulletin of the Brooklyn Entomological Society 105 
there is a transverse flattened plate whose lateral angles are produced 
into stout, curved chitinized hooks that are directed proximad; the pos- 
terior median portion of this plate is still further produced into a small, 
flattened bifid blade. 
The female is similar to the male but the abdominal tergites are darker ; 
the ovipositor is very long, especially the tergal valves which are slightly 
upcurved at their tips. 
Habitat—Colorado. 
Holotype, 3, Platte Cafion, altitude 10,000 feet, August 29, 1915 Cire 
Oslar). 
Allotopotype, 2. 
Paratopotype, 3, August 21, 1915; paratypes, 2 d3’s, Colorado Springs, 
June 8, 1915 (M. C. Van Duzee). 
A paratype is in the collection of Mr. Van Duzee. 
Erioptera margarita is close to E. microcellula Alex. (Proc. 
Acad. Nat. Sci. Phila., for 1914, p. 585), but the structure of 
the male hypopygium is different. In microcellula the outer arm 
of the appendage is blunt and sparsely hairy at the apex, the 
inner flattened blade with a group of small teeth in its angle in- 
stead of a single powerful conical tooth. The gonapophyses of 
E. microcellula have numerous appressed teeth along their mar- 
gins. E. lucia Alex., a third member of this group, is a very dif- 
ferent fly and needs no comparison with this new species. It is 
probable that these three species belong to the group of Erioptera 
trivialis Meigen, of Europe, deviating from the general charac- 
ters of the subgenus Erioptera in the often closed cell rst M,, 
the straight second anal vein and a more or less tumid second 
antennal segment. 
THE CHLOROPHYLLA GROUP. 
As stated in the introduction to this article, several species 
were found to be confused under the name of Erioptera chloro- 
phylla O. S. It will be necessary to review the specimens in the 
different museums to get a clear idea of the distribution of the 
species. 
The species known to the writer may be separated in accord- 
ance with the following key: 
