V. WADERS (_Grallæ_) Have a roundish bill, a fleshy tongue, and the legs
naked above the knees, as the _herons_, _plovers_, and _snipes_.
VI. SWIMMERS (_Anseres_) Have their bills broad at the top, and covered
with a soft skin; and the feet webbed, as the _ducks_ and _geese_.
7. Under the third class, or AMPHIBIA, are arranged such animals as have a
cold, and, generally, naked body, a lurid colour, and nauseous smell. They
respire chiefly by lungs, but they have the power of suspending respiration
for a long time. They are extremely tenacious of life, and can repair
certain parts of their bodies which have been lost. They are also able to
endure hunger, sometimes even for months, without injury.
The bodies of some of them, as the turtles and tortoises, are protected by
a hard and horny shield or covering; those of others are clad with scales,
as the serpents, and some of the lizards; whilst others, as the frogs,
toads, and most of the water-lizards, are entirely naked, or have their
skin covered with warts. Many of the species shed their skins at certain
times of the year. Several of them are furnished with a poison, which they
eject into wounds that are made by their teeth.
They chiefly live in retired, watery, and morassy places, and, for the most
part, feed on other animals; though some of them eat water plants, and many
feed on garbage and filth. None of these species chew their food; they
swallow it whole, and digest it very slowly.
The offspring of all the tribes are produced from _eggs_, which, after they
have been deposited by the parent animals in a proper place, are hatched by
the heat of the sun. The eggs of some of the species are covered with a
shell: those of others have a soft and tough skin or covering, not much
unlike wet parchment: and the eggs of several are perfectly gelatinous. In
those few that produce their offspring alive, as the vipers, and some other
serpents, the eggs are regularly formed, but are hatched within the bodies
of the females.