CHIEROPTERA—ANIMALS WITH WINGED-HANDS.
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.