Page:Popular Science Monthly Volume 9.djvu/551

Rh Some twenty-five years later, Ray gave them their true position among quadrupeds—a position which they have ever since retained.

The Teutonic mind seems early to have appreciated the true nature of bats, as we may judge from the German name, Fledermaus and the old English term, flittermouse.

Let us look a little closely at our subject of to-day—the bat.

In the first place, there is a little rounded body, covered with soft fur, which is indeed, what Shakespeare calls it, "wool," when giving the ingredients of the caldron of Macbeth's witches.

There is a small head, little eyes, large ears, a tail, and two pairs of limbs of very unequal size. The hind-pair (the legs) are of moderate length and singularly disposed, so that the knees are turned almost backward, like our elbows.

Each leg terminates in a foot, furnished with five toes, each with a long, curved claw, all of about the same length. These toes are not webbed, like those of a duck, but are free.

The other pair of limbs (the arms and hands) are of exceeding length. Both the arm and forearm are long—especially the latter—but it is the fingers which are so wonderfully drawn out, and they are webbed, like the toes of a water-fowl. Moreover, the web not only connects these long fingers together, but also connects them with the sides of the body and with the legs (as far as the ankle); and does not stop even here, but continues on to the tail, thus connecting it with the two legs.

This large web or membranous expansion has two names. The part belonging to the hand and joining the sides of the body (which is supported by the fingers as an umbrella by its rods) is termed the alar membrane. The part connecting the legs with the tail is called the interfemoral membrane.

Looking more closely, however, we find that, though the four fingers of each hand are thus bound together, the thumb is free, standing out at a wide angle, and furnished with a very long and strong-hooked claw. Of the four fingers, it is only the first which is clawed.

The uses made by the bat of its singularly-formed limbs are, of course, in exact correspondence with their structure. The fore-limbs are true organs of flight; the hind-limbs and tail have a rudder-like action. Besides flight (their predominant mode of motion), bats can crawl upon the surface of the earth with an awkward, shuffling gait. When so crawling, the wings are closed (the long fingers then lying side by side), and the animal rests on its wrists and hind-feet, the body being dragged forward by the help of the strong, hooked thumbnails, which also help it to climb with ease up any rough surface, even though perpendicular.

When at rest, bats usually hang suspended, head downward, by the claws of their feet, though occasionally they turn round and hang from the claws of their thumbs.