DIPTERA. 271 
the stilet or seta, presents at most five or six rings. This 
stilet, or that seta, exists in almost all of them, and in those 
where they are wanting, the third joint is elongated and fusi- 
form, and always divided into five or six rings. The wings 
are always incumbent one on the other. In several of those 
species where the antenne terminate in a somewhat oval and 
globular club, and always furnished with a stilet or a seta, the 
scutellum is not spinous. 
This section comprises the genus 
StTratiomys, Geoff. 
In some, the third joint of the antennz is elongated, fusiform or 
conical, without a seta at the end, and almost always terminated by 
a bi-articulated stilet. The scutellum, in most of them, is armed 
with two spines or teeth. 
Here the proboscis is very short. The anterior portion of the head 
does not project in the manner of a rostrum, receiving that organ 
inferiorly, and bearing the antennz above. ‘The latter are inserted 
in the front, as usual. 
‘ Srratiomys, Fab. 
Or Stratiomys, properly so called, where the antenne are much 
longer than the head, the first and last joint being greatly elongated; 
the latter is fusiform, or resembles a narrow and elongated club, nar- 
rowed at both ends, consisting of at least five distinct rings(1), with- 
out an abrupt stilet at the extremity. The two rings that compose 
it are not distinguished from the others by any sudden ‘contraction. 
The body of the larvz is long, flattened, invested by a coriaceous 
or firm skin and divided into annuli, of which the three last form a 
tail terminated by numerous plumous hairs which radiate from the 
extremity. The head is squamous, small, oblong, and furnished 
with a great number of little hooks and appendages with which 
they agitate the water that constitutes their domicil. ‘They respire 
by keeping their tail on the surface of the water, an orifice situated 
between the hairs at its extremity affording a passage to the air. 
(1) There are six of these rings, as in the following Insects, but the fifth is very 
short and indistinct. The two last are converted into a stilet or a seta. 
