to which some of the feet are affixed. The upper part is the thorax,
behind which is the scutellum, or, escutcheon, mostly of a triangular
form, and occupying a part on the margin of each elytron, or
upper wing. The under part is the sternum, or breast.
The thorax is the upper part of the breast between the head and
wing-cases, and in form various. If the sides are armed with'points,
it is called dentatus; when they are placed on the back, spinosus;
and if the margin is laterally dilated, marginatus.
The abdomen is mostly distinct from the thorax, and forms the
posterior part of the insect: it contains, the stomach, intestines,
and viscera, and is composed of five annular rings, or segments; on
the sides of which, are the ,spiracula, or pores, which serve for respiration
; the upper side of the abdomen is called the tergum, or
back; and the under part, the venter, or belly, at the extremity
of which is the anus*
At the end of the abdomen is the tail, which in many objects has
two appendices, in some three, and in others none; this part
is either simple, or armed with a forceps, sharp point, or sting,
which again, is either smooth or serrated.
Pedes, or legs, are composed of the following divisions, viz.
femora, or thighs, joints next the body: tibiae, or shanks, the second
joints; the tarsi, or feet, form the third, set, and are composed
of an indefinite number of articulations, at the extremity of which
are the ungues, called claws, or nails; the hind feet are calculated
for different motions, as swimming, leaping, or running.
Alae, wings, are membraneous, and undivided; some insects
have two, others four, which are either,
Plain, or extended their whole length without folds.
Plicatiles, folded, as in the vespa, wasp, when at rest.
Erectae, erect, when the extreme parts of their wings are in
contact, or nearly meet over the body of the insect, while
standing.
Patentes, or open, completely expanded in an horizontal position
when resting, as in the libellulse, and in the phalenae geo-
metrae.
Incumbentes, covering horizontally the upper part of the abdomen,
whilst the insect is resting.
Deflexae, reflected, or declining downwards like the ridge of a
house, but placed so that the inner margins are seen above the horizon.
Reuersae, reversed, in which the upper wings are in the same
position as the last mentioned; but the under wings are placed horizontally,
so that the edges project from under the margin of the
upper ones.
Dentatae, with indented, or scolloped edges.
Caudatae, with one or more fibres of the wings extended from
the margin, appearing like a tail.
Reticulated, with the membranes crossing each other like the
meshes of a net. They are marked with different figures, as spots;
bands, streaks, and eyes, the latter of which are extremely beautiful
and curious.
They have two elytra, or wing-cases, which are of a crustaceOus,
hard substance; their upper part is mostly convex, their under
part concave. These, in the act of flying, are expanded, but it is