Bats, or Cheiroptera, are particularly distinguished from all other creatures which suckle their young, by possessing the power of flight. A Lemur Galeopithecus, which exists in the Eastern part of the globe, takes long sweeps from tree to tree, and owes this faculty to the extension of its skin between its fore and hind limbs, including the tail; but it cannot be really said to fly. The Bats, then, alone enjoy this privilege; and the prolongation of what, in common parlance, we should call the arms and fingers, constitutes the framework which supports the skin, or membrane forming the wings. The thumbs, however, are left free, and serve as hooks for various purposes. The legs, and tail (when they have any), generally help to extend the membrane of the wing; and the breast-bone is so formed as to support the powerful muscles which aid their locomotive peculiarities. They climb and crawl with great dexterity, and some will run when on the ground; but it is difficult for most of them to move on a smooth, horizontal surface, and they drag themselves along by their thumbs. A portion of the Cheiroptera feeds on insects, and another on fruits; one genus subsists chiefly on blood. The first help to clear the atmosphere of those insects which fly at twilight; the second are very destructive to our gardens and orchards; the last are especially the object of that superstitious fear to which I have already alluded. They are all nocturnal or crepuscular, and during the day remain suspended by the sharp claws of their feet to the under-branches of trees, the roofs of caves, subterranean quarries, or old ruins, hanging with their heads downwards; multitudes live in the tombs of Egypt.