DIPTERA. 295 
much shorter, with the third joint longer than the preceding one, 
almost square, somewhat larger, and rounded at the end(1). 
Puasia, Meig.—TZhereva, Fab. 
Where the abdomen is strongly flattened, and almost semicircu- 
lar; the tibiz are simply furnished with little hairs(2). 
Tricniopopa, Lat.—Zachina, Fab. 
Where the abdomen is also flattened, but oblong, and the two pos- 
terior tibie are provided exteriorly with a fringe of lamelliform 
cilia(3). 
Sometimes the anterior face of the head presents two ranges of 
long hairs, forming a sort of moustachios, two of which are usually 
the longest, and situated at the superior extremity of the buccal ca- 
vity, one on each side. 
In some, the wings are vibratile, and the abdomen is narrow, elon- 
gated, almost cylindrical, or forming an elongated cone. They form 
three subgenera. 
In the wings of the two first, as in those of the preceding ones and 
most of the others, the two external and closed cells of the poste- 
rior extremity are almost equally prolonged backwards; the outer 
one extends somewhat beyond the other, and its posterior angles are 
acute. The antenne are as long as the face of the head, or hardly 
shorter. 
Lornosia, Meig. 
Where the last joint of the antennez forms a very large triangular 
palette(4). 
Ocyrrrra, Meig. Fab. 
Where the same joint of those organs, hardly wider than the pe- 
nultimate, resembles a linear palette, or one forming a long square. 
In a“ Mémoire pourservir a l’Histoire du genre Ocyptera,’—Ann. 
(1) Confounded with the preceding subgenus. 
(2) Lat., Gener. Crust. et Insect., IV, 344; see also Fab. and Meigen. 
(3) The Thereva plumipes, lanipes, Fab., and various undescribed species, all 
from America. 
(4) See Meigen. 
