%, 
364 INSECTA, 
Trixa, Meigq., 
Where its length but little exceeds that of the second *, 
There the abdomen is sometimes strongly inflated, and, as if vesi- 
cular, with the divisions of the annuli but slightly marked; sometimes 
it is much flattened. The wings in the last case are very distant, and 
frequently somewhat arcuated exteriorly. 
Gymnosomia Meig.—Tacuina, Fab., 
Where the abdomen is inflated, as if vesicular or ovoid, with the sepa- 
ration of the annuli rather indistinct; the antenne are as long as the 
face of the head, the second and third joints of almost equal length, 
and the latter linear +. 
CistoGastER, Lat., 
Where the form of the abdomen is the same; but the antenne are 
much shorter, with the third joint longer than the preceding one, 
almost square, somewhat larger, and rounded at the end f. 
Puasia, Meig.—Turreva, Fab., 
Where the abdomen is strongly flattened, and almost semicircular ; 
the tibize are simply furnished with little hairs §. 
Tricuiopopa, Lat.—Tacuina, Fab., 
Where the abdomen is also flattened, but oblong, and the two pos- 
tericr tibiz are provided exteriorly with a fringe of lamelliform 
cilia |]. 
ee the antericr face of the head presents two ranges of 
long hairs, forming a sort of mustachios, 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. 
Loposia, Meiq., 
Where the last joint of the antenne forms a very large triangular 
palette 4. 
Ocyrrera, Meig., Fab., 
Where the same joint of those organs, hardly wider than the penulti- 
mate, resembles a linear palette, or one forming a long square. 
* Meigen. 
+ Idem. 
t Confounded with the preceding subgenus. 
§ Lat., Gen. Crust. et Insect., IV, 344; see also Fab. and Meigen. 
\| The Thereva plumipes, lanipes, Fab., and various undescribed species, all from 
America. 
© See Meigen. 
