G4 MAMMALIA. 



THE FIRST FAMILY OF CARNARIA. 



THE CHEIROPTERA 



Retain some affinities with the Quadrumana by the pendulous penis, and 

 by the mammae which are placed on the cliest. Their distinguishing 

 character consists in a fold of skin, commencing at the sides of the neck, 

 and extending between the four members and fingers of the anterior 

 feet, supports them in the air, and even enables such of them to fly as 

 have their hands sufficiently developed for that purpose. This disposition 

 required strong clavicles and large scapula to give the necessary solidity 

 to the shoulder, but it was incompatible with the rotation of the fore-arm, 

 which would have diminished the force of the effort requisite for flight. 

 They have all four great canines, but the number of their incisors varies. 

 They have long been divided into two genera, founded upon the extent of 

 their organs of flight ; but tlie first of these requires several subdivisions. 



Vespertilio, Lin. 



The Bats have the arms, fore-arms, and fingers excessively long, form- 

 ing, with the membrane that occupies their intervals, true wings, possess- 

 ing even a greater extent of surface than those of Birds — they conse- 

 quently fly very high, and with great rapidity. The tliickness of their 

 pectoral muscles is proportioned to the motions they have to execute, and 

 there is a ridge in the middle of the sternum like that of Birds, to which 

 they are attached. The thumb is short and armed with a claw, by which 

 they are enabled to creep and to suspend themselves. Their hind feet are 

 weak and are divided into five toes, almost always of equal length, armed 

 with trenchant and pointed nails. They have no caecum in their intes- 

 tines. Their eyes are excessively small, but their ears are frequently 

 very large, and together with the wings form an enormous membranous 

 surface, which is almost naked, and so extremely sensible, that the Bats 

 are conducted through all the sinuosities of their labyrinths, even after 

 their eyes have been plucked out, probably by the diversity of the im- 

 pressions of the air. They are nocturnal, and in our climate pass the 

 winter in a state of lethargy. During the day they suspend themselves 

 in obscui'e places. They generally produce two young ones at a birth, 

 which they keep fastened to their mammae, and whose size is consider- 

 able in proportion to that of the mother. This genus is very numerous, 

 and offers many subdivisions. We must begin by separating from it the 



Pteropus, Briss. 



The Bats called the Boussettes, have trenchant incisors in each jaw, 

 and grinders with fiat crowns*; their food, consequently, consists chiefly 



* The grinders have properly two longitudinal and parallel projections separated 

 by a groove, which wear away by attrition. 



