CIIEIROPTERA, (from xEce, 771a77US)IrrEgotly ala,) Bats, Fr. Chauvesouris, Germ. Fledernuiu ser, an order of mammiferous quadrupeds, consisting of such as have a generally in sectivorous type of dentition, with the extremi ties connected together by an aliform expansion of the integuments, for the purpose of flight. The question whether this group, as well as that of the CARNIVORA and that of the IN SECTIVOP.A5 ought to be considered as forming a single order according. to the method of Cuvier, has been already sufficiently adverted to under the head CARNIVORA ; and it needs only to be now observed that if there were sufficient ground for giving to the last-men tioned group a separate consideration, either on account of expediency and convenience, or on that of natural arrangement, the same reasons hold good, in the present case, in an equal, if not a superior degree.
The distinctions by which the present order is Separated from all others are so marked, and the general similarity in the organization of its component groups is so striking, as greatly to facilitate and shorten the necessary detail of the organization.
There appears to be a great and obvious objection to the usual location of the remark able genus Galeopithecus amongst the Cheiro ptera ; there are so many important parts of its organization in which it clearly resembles the more insectivorous forms of the Quadru mana, not only in the peculiarities of its osteology, but in many other not less essential points, that I have preferred following the change suggested by Blainville, and subse quently adopted by Temminck, to the arrange ment of Cuvier and of most other zoologists. It may undoubtedly be considered as an oscu lent form, leading from the Quadrumanous order, by the Makis, &c. to the present group ; but it cannot but be acknowledged by any one who has attentively marked its anatomical structure, that the affinity of this genus to the Quadrumana is more intimate than that by which it approaches the Bats ; though perhaps it would be going too far to say, with Temminck, that it bears the same relation to the Quadrumana as Petaurista to the Mar supiata, or Pteromys to the Rodentia. Tbe latter genera are not even on the confines of their respective orders, nor do they offer any important abermtion from the typical struc ture; but in the present case there are several characters which indicate an interesting ap proach towards the order from which it has very properly been removed.
Omitting, then, the genus Galeopithecus, the Cheiroptera form, without perhaps a single exception, the most distinctly circumscribed and natuml group to be found in the whole' class of the Manimafera. The characters by which the order thus restricted is distinguished are as follow :— General form disposed for flight ; an ex pansion of the integument stretched between the four members, and the fingers of the an terior extremities, which are greatly elongated for that purpose; the flying membrane naked, or nearly so, on both sides. Mamma pectoral, clavicles very robust ; fore-arm incapable of rotation, in consequence of the union of the bones of which it is composed.
The Cheiroptera consist of two distinct groups ; of which the first, containing the genera Pteropus and Cephalotes, is frugivorous, and distinguished by the molar teeth being obliquely tnincated and longitudinally grooved, and by the existence of a third phalanx, which is in general provided with a little nail on the index or second finger, and by the absence or rudimentary condition of the tail. The second, consisting of the insectivorous bats, ( Chauve souris vraies, Cuv. Vespertilionidee, Gray,) have the molares furnished with acute points, similar to those of other insectivora.
evident object in the general structure of the skeleton of the Cheiroptera (fig. 280) is to combine as great a degree of lightness as possible with great extension of the anterior extremities, for the purposes of flight. The general form of the head differs in the two grand divisions of the Cheiroptera by the different lengths of the cranium ; and this diversity is exactly conformable with that which exists in other families. The frugivorous group (fig. 281, 282, 283) has a much more elongated form than the insectivorous (fig. 284, 285, 286), arising principally, though not wholly, from the form of the maxillary and, intermaxillary bones.