minutes. The insect itself is very
beautiful: it has four delicate, yellowish, lace-like wings, freckled
with brown spots, and three singular hair-like projections hanging out
beyond its tail. It never touches food during its mature life, but
leads a short and joyous existence. It dances over the surface of the
water for three or four hours, dropping its eggs as it flits, and then
disappears for ever. Myriads come forth about the hour of eight in the
evening; but by ten or eleven o'clock not a single straggler can be
found alive.

From the egg which the parent May-fly drops into the water, a
six-legged grub is very soon hatched. This grub proceeds forthwith to
excavate for himself a home in the soft bank of the river, below the
surface of the water, and there remains for two long years, feeding
upon the decaying matters of the mould. During this aquatic residence,
the little creature finds it necessary to breathe; and that he may do
so comfortably, notwithstanding his habits of seclusion, and his
constant immersion in fluid, he pushes out from his shoulders and back
a series of delicate little leaf-like plates. A branch of one of the
air-tubes of his body enters into each of these plates, and spreads
out into its substance. The plates are, in fact, gills--that is,
respiratory organs, fitted for breathing beneath the water. The
little fellow may be seen to wave them backwards and forwards with
incessant motion, as he churns up the fluid, to get out of it the
vital air which it contains.

When the grub of the May-fly has completed his two years of probation,
he comes out from his subterranean and subaqueous den, and rises to
the surface of the stream. By means of his flapping and then somewhat
enlarged gills, he half leaps and half flies to the nearest rush or
sedge he can perceive, and clings fast to it by means of his legs. He
then, by a clever twist of his little body, splits open his old fishy
skin, and slowly draws himself out, head, and body, and legs; and,
last of all, from some of those leafy gills he pulls a delicate
crumpled-up membrane, which soon dries and expands, and becomes
lace-netted and brown-fretted. The membrane which was shut up in the
gills of the aquatic creature, was really the rudiment of its now
perfected wings.

The wings of the insect are then a sort of external lungs, articulated
with the body by means of a movable joint, and made to subserve the
purposes of flight. Each wing is formed of