Family II. Vespertilionidæ.
(Insect-eating Bats.)
The great majority of the numerous species of the Cheiropterous order belong to this Family, the food of which consists, for the most part,[1] of insects. ‘The true molars, of which there are six in each jaw, are set with conical points: the forefinger has no nail, and no more than two phalanges: the interfemoral membrane is commonly large, the tail long, and, either wholly or in part, enveloped in the membrane. Many of the species have cheek-pouches; and most of them utter a peculiar clicking sound, which, as it is frequently emitted when the mouth is wide open, is probably produced in the throat. The Marmoset Monkey (Jacchus) we have heard utter a similar sound.
One large division of the Family have an extraordinary development of the skin of the face, sometimes taking the form of a leaf or an arrowhead, standing up from the nose; at others assuming an appearance too complicated for description. The ears, also, are, in general, large, and in many species, the tragus is so lengthened as to seem a second ear. The membranes of the ears, in some cases, meet above the head, and in others are produced, with strange convolutions, along the cheek
HEADS OF BATS;
Rhinolophus ferrum-equinum, and Megaderma frons.
to the muzzle. These expansions of naked and sensitive skin, in addition to the volar membrane, no doubt increase the peculiar capacity which the Bats are known to possess, of receiving impressions from the impact of the air.
This family is known to be spread over all parts of the world; and doubtless very many species yet remain to be described.
Genus Vespertilio. (Linn.)
Twelve species of this extensive genus have been recognised as inhabiting this island, and perhaps more may yet be discovered. They are distinguished by having a simple muzzle; teeth, inc.2-23-3; can.1-11-1; false mol.variablevariable; Mol.3-33-3 ears
PIPISTRELLE.
separate, scarcely larger than the head; and the tail enveloped in the membrane. The pretty little Pipistrelle (Vespertilio pipistrellus, Geoff.), one of the smallest as well as most common of our English Bats, will illustrate the genus. The length of its head and body is about an inch and a half, and that of the tail less than an inch and a quarter more; while the expanse of the wings in flight does not much exceed eight inches. It is of a reddish-brown hue, the under parts being paler than the upper.
This little bat resorts to the eaves and crevices of buildings for concealment by day, and during its winter torpidity. It is more easily roused than our other species, and is active at a lower temperature; hence it is occasionally seen abroad on fine days very late in the season, pursuing the gnats and tipuladæ[2] which often dance in the winter’s sun. We have repeatedly seen bats, doubtless of this species, coursing through the most thronged streets of the metropolis, on an afternoon in November; and Mr. Bell mentions a specimen which was shot just before Christmas. As early as the middle of March it is again active, and commences its long summer-campaign against the humming swarms of the evening air. To us there has always seemed something particularly pleasing in the flight of the little harmless Bats. We naturally associate with them the soothing quietude of evening, the warm sunset with its gilded clouds fading into night, the placid face of the moon, the brawling of the pebbly brook, the darkening surface of the pool, the solemn eushes of the nightingale’s song, the spark of the glowworm in the herbage, and the thousand mingled perfumes that come from the hedgerow and the field. Then comes the little Bat flitting around us on silent wing, seen for a moment, then lost in the increasing gloom, now skimming along the brim of the brook, now coursing round the tops of the trees, now darting through the lanes, and now wheeling in tortuous mazes among the insect swarms above our heads.
The common error that Bats cannot rise from the ground to flight, but require to throw themselves from an elevation into the air, has been so often contradicted, that it seems needless to refer to it, but that even such naturalists as M. Geoffroy repeat it. We can testify from personal observation, that several tropical genera have the same facility in flying from the ground as those common in Europe. "This observation," remarks Mr. Bell; of the error of Geoffroy, "is totally incorrect as to the present, and probably every other species. I have seen the Pipistrelle rise from a plain surface with a sort of spring, instantly expand its wings and take flight." The same naturalist notices a curious peculiarity of this species, before unobserved. "It is the prehensile character of the extremity of the tail. A small portion of the tail in this, and in most other species of this family is exserted beyond the margin of the interfemoral membrane. Not only does the animal employ the tail in horizontal progression,—in which case it assists in throwing forward the body, by being brought into contact with the ground on either side alternately, corresponding with the action of the hinder foot on the same side,—but in ascending and descending a rough perpendicular surface, this little caudal finger holds by any projecting point, and affords an evident support. This is particularly conspicuous when the Bat is traversing the wires of a cage, in which situation I first observed the fact.” [3]
Genus Plecotus. (Geofe.)
The ears in this genus are greatly elongated, ordinarily erect, but capable of falling into elegant curves with minute transverse wrinkles: the aural membranes are united over the head, and the tragus is long and tapered to a blunt point. The muzzle is simple, the tail long, wholly enveloped. The teeth,—inc.2-23-3; can.1-11-1; f. mol.2-23-3; mol. 3-33-3ː=36.
LONG-EARED BAT.
Our common species, known as the Oreillard, or Long-eared Bat, (Plecotus auritus, Geoff.) is scarcely less abundant than the Pipistrelle; it is of a dusky grey hue, paler on the belly, with ears more than twice as long as the head, and nearly as long as the head and body together. Like the preceding, it is active on the ground, but has a different mode of proceeding. "In crawling or walking along a horizontal surface, it has the anterior part of the body considerably elevated above the ground, and its progression is effected by a succession of abrupt impulses or leaps of one. side after the other; whilst the Pipistrelle, which never raises the head from near the ground, runs along in an almost prostrate position, but with much celerity and freedom."[4]
Timid as the Bats are, gentleness will render them confiding and familiar. The present species is active and playful in confinement, and may readily be trained to take a fly from the hand. Mr. Bell speaks of one which, "when at liberty in the parlour, would fly to the hand of any of the young people who held up a fly towards it, and pitching on the hand, take the fly without hesitation. If the insect were held between the lips, the Bat would then settle on its young patron’s cheek, and take the fly with great gentleness from the mouth: and so far was this familiarity carried, that when either of my young friends made a humming noise with the mouth in imitation of an insect, the Bat would search about the lips for the promised dainty."[5]
None of our native Bats are in any respect injurious to man; but on the other hand, as the destroyers of numberless insects which in one stage or other are noxious, we cannot but consider them as absolute benefactors.