MAMMALIA, dbl 
CLASS I. 
MAMMALIA. 
THE mammalia are placed at the head of the animal kingdom, not only 
because it is the class to which man himself belongs, but also because it is 
that which enjoys the most numerous faculties, the most delicate sensa- 
tions, the most varied powers of motion, and in which all the different 
qualities seem combined in order to produce a more perfect degree of in- 
telligence, the one most fertile in resources, most susceptible of perfection, 
and least the slave of instinct. 
As their quantity of respiration is moderate, they are designed in gene- 
ral for walking on the earth, but with vigorous and continued steps. The 
forms of the articulations of their skeleton are, consequently, strictly de- 
fined, which determines all their motions with the most rigorous pre- 
cision. 
Some of them, however, by means of limbs considerably elongated, and 
extended membranes, raise themselves in the air; others have them so 
shortened, that they can move with facility in water only, though this does 
not deprive them of the general characters of the class. 
The upper jaw, in all of these animals, is fixed to the cranium; the 
lower is formed of two pieces only, articulated by a projecting condyle to 
a fixed temporal bone: the neck consists of seven vertebra, one single 
species excepted, which has nine; the anterior ribs are attached before, 
by cartilage, to a sternum consisting of several vertical pieces; their an- 
terior extremity commences in a shoulder-blade that is not articulated, 
but simply suspended in the flesh, often resting on the sternum by means 
of an intermediate bone, called a clavicle. This extremity is continued by 
an arm, a fore-arm, and a hand, the latter being composed of two ranges 
of small bones, called the carpus, of another range called the metacarpus, 
and of the fingers, each of which consists of two or three bones, termed 
phalanges. 
With the exception of the cetacea, the first part of the posterior extre- 
mity, in all animals of this class, is fixed to the spine, forming a girdle or 
pelvis, which, in youth, consists of three pairs of bones—the ilium which 
is attached to the spine, the pubis which forms the anterior part of the 
girdle, and the ischium, the posterior. At the point of unicn of these 
