Mammiferous Animals. 511 
sequent classes. The class of mammiferous animals ought to 
be placed at the head of the animal kingdom, not only because 
it is the class to which we ourselves belong, but because it is 
that which possesses the most numerous faculties, the most 
delicate sensations, and the greatest variety of action, and in 
which the assemblage of all their qualities appear so combined, 
as to produce an intelligence more perfect, more fertile in 
resources, less the slave of instinct, and more capable of pro- 
gressive perfection, than what is found in any of the other 
classes. 
As the quantity of respiration in mammiferous animals is 
comparatively moderate, they are generally constituted for 
walking firmly, with a continued motion, and all the joints of 
their skeletons are fitted with a precision which determines 
the regularity of their movements. Some animals of this class, 
however, are able to raise themselves in the air by the aid of 
membranes extended on the prolongation of their members, 
of which the common bat furnishes a well known example. 
Other animals of this class have their limbs so shortened and 
contracted, that they can only move with ease when in water. 
Cetaceous animals, as whales and seals, afford instances of 
such a formation; but they do not on this account lose the 
general character of mammiferous animals. 
In all animals of this class the upper jaw is fixed to the 
cranium, or skull; the lower is composed of only two pieces, 
and is articulated by a prominent joint or condyle (from the 
Greek /ondylos, a knuckle) to the temporal bone. ‘The neck 
is composed of seven vertebra, except in one species, which 
has nine. ‘The head of mammiferous animals is always arti- 
culated by two condyles to the first vertebral bone called the 
atlas. Their tongue is always fleshy, and attached to a bone 
called hyoides, which is composed of smaller pieces, and is 
suspended to the skull by ligaments. ‘Their two lungs are 
divided into lobes, composed of an infinite number of cells, 
and are always enclosed, without adherence, in a cavity formed 
by the ribs and the diaphragm. ‘Their organ of voice is always 
at the upper extremity of the trachea or windpipe. 
Their residence, being on the surface of the earth, exposes 
them less to alternation of temperature than many of the ani- 
mals in the other classes. Their bodies have only a light co- 
vering of hair, which is generally very thin in warm climate 
Cetaceous animals, which live entirely in water, are abso- 
lutely without hair. 
In all mammiferous animals, the generation is essentially 
viviparous ; and, as before stated, they nourish their young 
with their milk. There has, baer er, been one singular ani- 
LL 4 
