CHEIROPTERA. 



595 



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- 

 jtiana, 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 escu- 

 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. The 

 latter genera are not even on the confines 

 of their respective orders, nor do they offer 

 any important aberration 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 natural group to be found in the whole 



class of the Mammifera. 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 truncated 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. Vesper tilionida, Gray,) 

 have the molares furnished with acute points, 

 similar to those of other insectivora. 



Osteology. The evident object in the general 

 structure of the skeleton of the Cheiroptera 

 (jig. 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 (jig. 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. 



The cranium is generally rounded, and rather 

 broad. The posterior aspect more or less con- 

 vex in different groups ; in some overhanging 



Skeleton of Pterojtiu. 



