In the greater number of species of B., the wing-membrane extends not only to the hind-legs, but beyond them to the tail, which is included in it, a peculiar bone (e in fig. of skeleton) also arising from each heel to afford further support to this part of it, which seems to serve purposes analogous to the tail of birds, acting as a rudder, and enabling the animal to make those rapid evolutions in the air, which it is so pleasing to see as bats flit about in the summer evening. The fruit-eating bats of tropical regions, which have no need to perform such evolutions, are destitute of this interfemoral part of the mem brane; and according to the habits for which each species has been designed, the tails are long or short, entirely included iu the membrane, or only for part of their length, or produced a very little beyond it, and terminating in a hard tip, so that the tail is capable of being used to aid in creeping or climbing, evidently possessing consid erable power, and being curved and moved iu a manner which suggests a slight analogy to the prehensile. tails of monkeys.
Bats were placed by Linnaeus in his order primates, along with monkeys and lemurs, with which they agree in their pectoral teats and in other characters, particularly of the organs of reproduction. In one genus (dysopus), there is an additional resemblance to the primates in the partially opposable thumbs of the hind-feet, and a trace of this char acter is to be found in the fore-thumbs already noticed. Bats are now, however, generally placed by naturalists in the order fern' or carnaria, although, like many other animals of that great order, most of them are by no means exclusively carnivorous. The greater part of them feed chiefly on insects, some chiefly on fruits. They exhibit con siderable variety both in the !umber and character of their teeth, as might be expected in animals which differ so much in their food. All of them have four rather large canine teeth; the incisors vary much in size and form, as well as in number. The digestive apparatus exhibits a variety corresponding with that of the teeth; the intestinal canal of the vampires (q.v.). which live by sucking the blood of animals, proceeding almost in a straight line from one extremity of the body to the other, whilst that of some of the frugivorous bats, as the kalong (q.v.) (pteropus) of Java, is seven times as long as the body.
Except in the power of flight and things essential to it, bats present no resemblance to birds. The old English name flittermouse, and the German fledermaus, indicate an early popular recognition of their true place in creation. They are generally nocturnal animals, or, at least, prefer the twilight, although one of the British species may occa sionally be seen pursuing insects during winter at midday. They generally- spend the day in caves, hollow trees, and other dark recesses, often under roofs of houses, and in crannies of ruined or deserted buildings. They are found in almost all parts of the world, except the very:coldest, but are most numerous and of greatest size within the tropics. Those of temperate climates generally spend the winter in a state of torpidity.
in which, although circulation continues very languidly-, respiration does not ordinarily take place. The whole number known to Linnreus amounted to a very few species, not half so many as are now known to inhabit Great Britain alone. Upwards of 130 species have been described, and there is great probability that the actual number existing is very much greater. It isnot unlikely that some exaggerated accounts of the great bats of warm climates gave rise to the fable of the Harpies, which 1 irgil introduced into the _Eaeid, The bats of Europe are all small; the body of the largest British one is not so large as a mouse, and the fullest stretch of its wings about 15 in., whilst the com mon British species are much smaller; but in the kalong, already mentioned, the stretch of wing is 5 feet. Of British species. the largest is the noctule B. (rIspertilia9ioetube), a very focal species, found chiefly in the s. of England; the pipistrelle II. (V. prstrellus) is perhaps the most common. It was long confounded by British Muralists with the common B. of the continent of Europe (V. mu rinus), which is much larger and very rare in Britain. In some parts of the country, the long-eared 13. (pleeotas auritus) is very common. It Is distinguished by its enormously large and very beau tiful ears, which, when it is asleep, are folded up in a remarkable manner under the arm, the long tragus then resembling a slender ear. This great development of the ears is characteristic of certain genera of B., that part of the ear called the tragus attaining also a remarkable size, so that it seems like a smaller ear in front of each large one. In many species, only two of which are found in Britain, there is a still more remarkable membranous or leaf-like appendage on the nose, which in some 'is simple, in some complex, and often of large size, giving an extraordinary appearance to the face. Some of the larger species, having a nasal crest, are called specter bats (q.v.). Only two species of B. (rhinolophus), possessing such an appendage, are found in Britain, both of them very rare; from the form which it assumes, they are called horseshoe bats. It is supposed that this nasal appendage is of use as a very deli cate organ of touch, perhaps also of smell; as the great ears may be of use both for touch and hearing. These senses must often guide bats when that of sight cannot be employed; and the sense of touch appears to be possessed in no ordinary degl-ee even by the winged membrane. BY supposing it to be affected by the pulsations of the air, envier accounted for the power displayed by bats which had been cruelly deprived of sight, of avoiding objects amongst which they flew, without the necessity of ascribing to them, as Spallan zani had done, the possession of a sixth sense.