But of all the bats, the most conspicuous from its size and numbers, and the most interesting from its habits, is the rousette of Ceylon[1];--the "flying fox," as it is called by Europeans, from the similarity to that animal in its head and ears, its bright eyes, and intelligent little face. In its aspect it has nothing of the disagreeable and repulsive look so common amongst the ordinary vespertilionidæ; it likewise differs from them in the want of the nose-leaf, as well as of the tail. In the absence of the latter, its flight is directed by means of a membrane attached to the inner side of each of the hind legs, and kept distended at the lower extremity by a projecting bone, just as a fore-and-aft sail is distended by a "gaff." [Footnote 1: Pteropus Edwardsii, _Geoff_.] [Illustration: FLYING FOXES.] In size the body measures from ten to twelve inches in length, but the arms are prolonged, and especially the metacarpal bones and phalanges of the four fingers over which the leathery wings are distended, till the alar expanse measures between four and five feet. Whilst the function of these metamorphosed limbs in sustaining flight entitles them to the designation of "wings," they are endowed with another faculty, the existence of which essentially distinguishes them from the feathery wings of a bird, and vindicates the appropriateness of the term _Cheiro-ptera_[1], or "winged hands," by which the bats are designated. Over the entire surface of the thin membrane of which they are formed, sentient nerves of the utmost delicacy are distributed, by means of which the animal is enabled during the darkness to direct its motions with security, avoiding objects against contact with which at such times its eyes and other senses would be insufficient to protect it.[2] Spallanzani ascertained the perfection of this faculty by a series of cruel experiments, by which he demonstrated that bats, even after their eyes had been destroyed, and their external organs, of smell and hearing obliterated, were still enabled to direct their flight with unhesitating confidence, avoiding even threads suspended to intercept them. But after ascertaining the fact, Spallanzani was slow to arrive at its origin; and ascribed the surprising power to the existence of some sixth supplementary sense, the enjoyment of which was withheld from other animals. Cuvier, however, dissipated the obscurity by showing the seat of this extraordinary endowment to be in the wings, the superficies of which retains the exquisite sensitiveness to touch that is inherent in the palms of the human hand and the extremities of the fingers, as well as in the feet of some of the mammalia.[3] The face and head of the _Pteropus_ are covered with brownish-grey hairs, the neck and chest are dark ferruginous grey, and the rest of the body brown, inclining to black. [Footnote 1: [Greek: cheir] the "hand," and [Greek: pteron] a "wing."] [Footnote 2: See BELL _On the Hand_, ch. iii. p. 70;]