R R a Pair of Horns resembling those of an Ox inverted, with Bristles at their Tops,
and seeming to be hollow. These are moveable every Way, and may probably be of
considerable Service to the Insect.
Its Mouth is pretty large, in the Fashion of a Crab's or Lobster's, and it may fre-
quently be seen feeding on some minute Substances in the Water.
This Creature moves in the Water with its Tail forwards, jerking itself along by
the Frisking to and fro of the Tust growing out from the Stump thereof. It has
also another Motion, more resembling that of other Animals, and with its Head fore-
most ; for by the opening and shutting of its Jaws, it sinks gently towards the Bottom
of the Water, and presently afterwards seems as it were to eat its Way up again.
When the Body ceases to move, the Tail being higher than the Water wherein it
swims, or than any other Part of the Insect, presently buoys it up to the Surface of
the Water, where it hangs suspended with its Head always downwards ; for the Brush
at the Tail being smeared over with an oily Fluid, serves like a Cork to keep it above
Water ; and if that Oil begins to dry, the Creature by drawing the Tail through its Mouth
sheds thereon a new Supply, and enables it to hang to the Top of the Water, or steer
where it pleases, without being wetted or damaged by it.
PLATE XXIV. FIG. 2.
The Nympha or Aurelia of the Gnat
THE Animal just now described, after about three Weeks, assumes a Form
very different from what it had before, and agreeable to what we see before
us. The Head and Body become larger and deeper, but not broader ; the Belly and
hinder Parts appear more slender, and seem coiled about the Body in the Fashion re-
presented by the pricked Lines in the Picture.
In this new State, the Head and Horns, which before hung downwards in the
Water, rise uppermost to the Surface ; and what is very remarkable, the Insect becomes
now suspended from the Top of the Water by its Horns
, as it was lately by its Tail.
The whole Bulk of the Body is also evidently higher ; for when by being frighted it
frisks out its Tail, as B C represents, and thereby sinks below the Surface and towards
the Bottom, it re-ascends much more swiftly than in its former State.
|Vid. Swammerd. Hist. Gen. des Insects. 410. p. 105.|
If its Progress be now observed from Time to Time, its Body will be found gra-
dually to inlarge ; Nature fitting it by Degrees for that Element of which it must
quickly be an Inhabitant. The Microscope also shews, that its Eyes are now pearled
like the Eyes of Gnats (vid. A) not smooth as they were before: And that this Club Head
really contains the Thorax and Wings of the future Gnat. A little longer Observation
will shew it swimming partly above and partly below the Surface of the Water ; and
though it may then be made to plunge down by touching it with any Thing, it in-
stantly comes up again, and appears in its former Posture.
And now, if we have Patience to watch it narrowly, we shall be rewarded with the
Satisfaction of beholding the Head and Body of a Gnat beginning to shew themselves above
the Surface of the Water : We shall see its Legs gradually drawn out, first the two fore-
most, then the others ; and soon after, its whole Body will appear rising out of the
Husk or Case perfect and intire : We shall see it disengage itself from this Case, and stand
on its Legs upon the Top of the Water ; there by Degrees try the Activity of its Wings,
and in a few Minutes fly away a compleat Gnat.
PLATE XXIV. FIG. 3. and 4.
THESE two Figures are given from P?so's Natural History of Brasil, in the
second Chapter of his fourth Book ; where speaking of Sea Productions that bear
a near Resemblance to Productions upon Land, he tells the Story of a Fisherman,
whose Hook being entangled contrary to his Expectation, on a rocky Shallow not far
from Paranambuque, brought up with it, on his pulling it out of the Water, Spunges,
Corals, and Sea-weeds, instead of Fish.