hair, called
eyelashes. The opening of the pupil is in general circular; but to some
species, as in those of the Cat and Hare, it is contracted into a
perpendicular line, whilst in the Horse, the Ox, and a few others, it
forms a transverse bar. The _ears_ are openings, generally accompanied
with a cartilage which defends and covers them, called the external
ears. In water-animals the latter are wanting; sound, in them, being
transmitted merely through orifices in the head, which have the name of
auditory-holes. The most defenceless animals are extremely delicate in
the sense of hearing, as are likewise most beasts of prey. Most of the
mammiferous animals _walk_ on four feet, which, at the extremities, are
usually divided into toes or fingers. In some, however, the feet end in
a single corneous substance called a hoof. The toes of a few end in
broad, flat nails, and of most others, in pointed claws. Some, again,
have the toes connected by a membrane, which is adapted to those that
are destined to pass a considerable portion of their lives in water.
Others, again, as in the Bat, have the digitations of the anterior feet
greatly elongated, the intervening space being filled by a membrane,
which extends round the hinder legs and tail, and by means of which they
are enabled to rise into the air. In Man, the hand alone comprises
fingers, separate, free, and flexible; but Apes, and some other kinds of
animals, have fingers both to the hands and feet. These, therefore, are
the only animals that can hold movable objects in a single hand. Others,
such as Rats and Squirrels, have the fingers sufficiently small and
flexible to enable them to pick up objects; but they are compelled to
hold them in both hands. Others, again, have the toes shorter, and must
rest on the fore-feet, as is the case with dogs and cats when they wish
to hold a substance firmly on the ground with their paws. There are
still others that have their toes united and drawn under the skin, or
enveloped in corneous hoofs, and are thereby enabled to exercise no
prehensile power whatever.

588. ACCORDING TO THE DESIGN AND END OF NATURE, mammiferous animals are
calculated, when arrived at maturity, to subsist on various kinds of
food,--some to live wholly upon flesh, others upon grain, herbs, or
fruits; but in their infant state, milk is the appropriate food of the
whole. That this food may never fail them, it is universally ordained,
that the young should no sooner c