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in its first or vermicular state considerably magnified. It retains this shape, according to Reaumur, from its first appearance in life for the space of about twentyone months, and in this shape it acquires its full increment of growth. B. represents the same insect in its nymph state, which it retains for the space of about three months, during which period it is nearly as active as in its former state, and takes in food the whole time, though it neither increases in size nor varies materially from its former shape; in which respects it differs greatly from those classes of insects that afsume the form of a chrysalis (Vol. II. page 361); and Z represents it in its perfect, or imago state. In its larva state the most striking peculiarities are a a the antennæ, cc two strong crooked horny claws, which it can move like forceps, and with which it digs out the earth. Its mouth is below, and thus concealed from this point of view. ii the eyes, gg, kk, ll, its three pairs of legs. dd, ss, the body covered with a particular set of members, which will be noticed soon. fef three remarkable filamentous projections forming the tail. The variations that take place between these two different states of the same insect are so perceptible to the eye that glances at the two figures, as not to require to be indicated by words, farther than barely to remark, that the part m m on the upper part of the body B indicates the cover under which the wings of the embryo fly lie concealed until it throws off this its last case, and afsumes its imago form,

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The whole body consists of nine rings, which are here concealed by a series of flexible membranes o o ss, folded over each other in some measure like the gills of fishes, and are like them perpetually agitated

with a very brisk motion; and this peculiarity serves well to discriminate the ephemera from every other clafs of insects. For, although these members appear under many different forms in the different varieties; in one species, for instance, these spring out from each side one between every pair of rings like so many pairs of oars, and on others they rise up from the body like thin fialamentous fins of fishes; yet under every variety of form the same unceasing motion is observable. These, it is conjectured, serve for the purpose of the inspiration and expiration of air. The tail likewise, which consists of three ribs, from the sides of which spring out many smaller feather-like filaments, each of which, when examined by a microscope, is found to contain two hollow tubes, is also conceived to be of use for distributing the same fluid through the body, for some necessary purpose in the economy of this animal.

When the time of its last metamorphosis is arrived, and it is about to emerge for ever from the water in which it has till now subsisted, and afsume its station in the air, it puts off the whole of this casing, and then afsumes the form it bears at Z, in which the rings of its body are plainly perceptible. Its head now afsumes a form considerably different from that which it formerly bore. The strong forceps are now entirely dropped. In their place we find two delicate antennæ a ɑ, two large netted eyes y y, and three other smooth eyes i i i, placed in a triangular form. The two fore legs g g now stretch forward on each side of the head to a great distance. The other legs are shorter, and serve occasionally to support the body.

wings of a whitish colour, being of a middle nature between those of flies and butterflies, wanting the pure transparency of the oné, as well as the downy scales of the other. A strong rib runs along the fore part of each upper wing from the corcelet towards the extremity, from which other lefser ribs diverge, spreading over the whole wing, and bearing some resemblance to the feathers of some birds, as may be more distinctly recognised by inspecting the figure. The under wings n n are small, and, joining closely with the others, seem to form one undivided whole upon a slight inspection.

Having thus given the reader a general idea of the form and transformations of this singular insect, it is proper that I should make him acquainted with some of the principal phenomena that occur respecting it during the short but busy period of its existence in the fly state. To Mr. Reaumur we are indebted for the animated detail he has given of it, a detail which cannot surely be deemed superfluous, when the reader shall be told, that though this philosophical investigator had lived in Paris for the greatest part of his life, it was not until the year 1738, when he was then far past his prime, that he seems to have known that such a thing could ever be seen there; and I think it is not at all improbable, that many millions of persons both before and since that time may have inhabited that metropolis for many years, without having either seen or heard of it.

"It was now," says he, "the time when they had made me expect that I should see millions of ephemera come out of the river, and rise aloft into the air. The sun was now ready to set, having sunk entirely

beneath the horizon. I saw, indeed, then a few flies of that sort here and there above the surface of the river; but this was far short of the promised spectacle. I remained upon the Seine even till half an hour past seven o'clock, without observing the number sensibly to augment; I then went into the Marne, where there were still fewer. In short, the night was closed in, and lightnings foretold an approaching storm, which induced me, about eight o'clock, to enter into that branch of the Marne which flows past the stairs at the bottom of my own garden. Although a good deal disappointed at having seen so few ephemera, I made them carry into the garden the tub which contained a great many lumps of earth taken from the banks of the river, full of holes, containing great numbers of ephemera in their nymph state. Scarcely had it been placed on one of the steps of the stair, when those who had charge of it, cried out, "What a vast quantity of ephemera are here!" I seized one of the lights which they carried before me to show the way during the dark night, and ran to the tub. I saw every part of those clods of earth which rose above the surface of the water covered with ephemera, some of which had just begun to put off their coverings, others had almost entirely effected it, and others had completed it and were just taking wing; they were seen also in different parts of the surface of the water, busied about the same operations in different degrees of forwardness. While I enjoyed this spectacle, more agreeable than any thing I had expected,-while I had the pleasure of seeing so many aquatic beings changed into winged insects, and much nearer than I could have expected

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A

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The Ephemera. A the larva in its worm state, B ditto in its nymph

state, Z ditto in its imago state.

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