The head of thelarvaof this infeft is exceedingly Angular, being
covered with a mafk which goes over the whole fore part o f the
head, having proper cavities within to fuit the different prominencies
of' the face, and fits it more ex aft] y than the common
mafic does the human face ; it is o f a triangular form, growing
finaller towards the bottom : at the bottom there is a knuckle
which fits a cavity near the neck ; on this part it turns as on a
pivot. The upper part o f this mafk is divided into two pieces/
or fhutters, which the infeft can open or clofe at pl'eafure; it: tan
alfo let down die whole mafk whenever it pleafes. The edges
o f the fhutters are toothed like a faw. It makes ufe o f the mafk
to feize and hold it’s prey.
There is a confiderable difference in the fhape o f thefe inafks in
different fpecies of the libellula, fome having two claws near the
top o f it, which they can throw in or out at pleafure, and which
make it a very formidable inflrument to the infefts: on which it
feeds.
Thefe animals generally live and feed at the: bottom o f the
water, fwimming only occafionally; their manner of fwimming,
or rather moving in the water, is curious, being by hidden jerks
given at intervals; but this motion is not occafioned by their
legs, which at this time are kept immoveable and clofe to the
body : it is by forcing out a ftream of water from the tail, that
the body is carried forwards; this may be eafily perceived by
placing them in a flat veffel, in which there is only juft water
enough to cover the bottom. Here the aftion o f the water fquirted
from their tail will be very vifible; it will occafion a fmall current,
and give a fenfible motion to any light bodies that are lying on
the
the furface thereof. This aftion can only be effefted at intervals,
becaufe after each ejaculation the infeft is obliged to take a frefh
fupply of water. The larva will fometimes turn it’s tail above the
furface o f the water, and force out a fmall ftream from it, as from
a little fountain, and with confiderable force.
The pupa differs but very little from the larva; the bunches,
containing the wings, grow large, and begin to appear like four
fhort thick wings. It is full as lively as the larva, feeking and
enjoying it’s food in the fame manner: when it is arrived at it’s
full growth, and is nearly ready to go through it’s laft change,
it approaches the edge of the water, or comes entirely out o f it,
fixing itfelf firmly to fome piece o f wood or other fubftance by
it’s acute claws. It remains for fome time immoveable ; the fkin
then opens down the back, and on the head ; through this opening
they exhibit the real head and eyes, and at length the legs ;
it then creeps forward by degrees, drawing it’s wings, and then
the body, out of the fkin. The wings, which are moift and folded,
now expand themfelves to their real fize ; the body is alfo extended
till it has gained it’s proper dimenfions, which extenfion
is accomplifhed by the propelling force o f the circulating fluids.
When the wings and limbs are dry, it enters on a more noble
ftate of life, it now wings the air and feeks it’s mate.
--------------- What terms expreffive may relate
The change, the fplendor of their new-form’d ftate ! -
In ey’ry eye ten thoufand brilliants blaze,
And living pearls the vaft horizon gaze ;
F f Gcmm’d