FOR a long time these curious little animals puzzled the Naturalists.
Aristotle defined them as Birds with wings of skin. After him, Pliny and
other Naturalists fell into the same error of classifying them with the
Birds; but after many centuries the different characters that fix the
rank of these animals in the scale of created beings are well known, and
they are placed where they belong, in the great family of Mammals, and
classed as the Cheiroptera, or animals with winged-hands—as the word
Cheiroptera comes from two Greek words meaning wing and hand.
All the fingers of the hand (with the exception of the thumb, which is
short, has a nail, and is quite free) are immoderately long, and united
by means of a transparent membrane which is without hair. This membrane
covers also the arm and forearm, and is simply a prolongation of the
skin of the flanks, composed of two very thin layers. It also extends
down the hind legs, where it is more or less developed, according to the
species; but it never reaches the toes of the feet, which are short and
have nails.
It is owing to this membranous sail that Bats direct their course
through the air in the same manner as Birds. When they are at rest they
fold their wings around them, covering their bodies as if in a mantle,
similar to our closing an umbrella to diminish its volume when it is no
longer required. This comparison is still more exact when we note that
the curiously long fingers of the animal perfectly correspond to the
ribs or rods of the umbrella.
Bats do not descend to the ground if it can possibly be helped, for they
are very awkward and slow in attempting to walk along the ground; and
besides this, when on the ground they find themselves in a very
inconvenient position to resume their flight. Their case is then almost
the same as that of high-soaring Birds, which, full of grace and
assurance aloft, are compelled to resort to the most painful efforts to
ascend again from low levels.
The Bats are classed as nocturnal animals, as they hunt their prey at
night, and spend the day in caverns, lofts, church spires and old ruins,
or the trunks of trees. Their eyes, although small, are organized for
seeing, not in complete darkness but in the twilight, or in the feeble
light of the moon and stars.