64 MAMMALIA. 
THE FIRST FAMILY OF CARNARIA. 
———— 
THE CHEIROPTERA 
Retain some affinities with the Quadrumana by the pendulous penis, and 
by the mamme which are placed on the chest. 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 scapule 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 the 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 thickness 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 cecum in their intes- 
times. 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 obscure places. They generally produce two young ones at a birth, 
which they keep fastened to their mamme, 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 
Preropus, Briss. 
The Bats called the Rowssettes, have trenchant incisors in each-jaw, 
and grinders with flat crowns*; their food, consequently, consists chiefly 
* The grinders have properly two longitudinal and parallel projections separated 
by a groove, which wear away by attrition. 
