y only procure a small quantity of
oxygen from the air which is diffused in the water; which also is
further confirmed by an experiment with the air-pump, as fish soon die
when put in a glass of water into the exhausted receiver, which they
would not do if their gills had power to decompose the water and
obtain the oxygen from it.

The lamprey, petromyzon, is put by Linneus amongst the nantes, which
are defined to possess both gills and lungs. It has seven spiracula,
or breathing holes, on each side of the neck, and by its more perfect
lungs approaches to the serpent kind; Syst. Nat. The means by which it
adheres to stones, even in rapid streams, is probably owing to a
partial vacuum made by its respiring organs like sucking, and may be
compared to the ingenious method by which boys are seen to lift large
stones in the street, by applying to them a piece of strong moist
leather with a string through the centre of it; which, when it is
forcibly drawn upwards, produces a partial vacuum under it, and thus
the stone is supported by the pressure of the atmosphere.

The leech, hirudo, and the remora, echeneis, adhere strongly to
objects probably by a similar method. I once saw ten or twelve leeches
adhere to each foot of an old horse a little above his hoofs, who was
grazing in a morass, and which did not lose their hold when he moved
about. The bare-legged travellers in Ceylon are said to be much
infested by leeches; and the sea-leech, hirudo muricata, is said to
adhere to fish, and the remora is said to adhere to ships in such
numbers as to retard their progress.

The respiratory organ of the whale, I suppose, is pulmonary in part,
as he is obliged to come frequently to the surface, whence he can be
pursued after he is struck with the harpoon; and may nevertheless be
in part like the gills of other fish, as he seems to draw in water
when he is below the surface, and emits it again when he rises above
it.

ADDITIONAL NOTE. VI.

HIEROGLYPHIC CHARACTERS.

So erst as Egypt's rude designs explain.
CANTO I. l. 351.

The outlines of animal bodies, which gave names to the constellations,
as well as the characters used in chemistry for the metals, and in
astronomy for the planets, were originally hieroglyphic figures, used
by the magi of Egypt before the invention of letters, to record their
discoveries in those sciences.

Other hieroglyphic figures seem to have been desig