VERTEBRATED ANIMALS. Q5 
tavity, without an outlet. The lowest in the series, which are also the 
iast of the animal tribes, exhibit nothing but a homogeneous pulp, possessed 
of motion and sensibility. In the preceding divisions, the organs of move- 
ment and sense are disposed symmetrically, on both sides of an axis; but 
in this, they have a circular arrangement, around a common centre. Th‘3 
form of existence Cuvier arranges under the head of RapiareD ANIMALS. 
(Animalia Radiata.) 
The term Zoology, includes the whole of the Animal kingdom ; besides 
wnicn, different departments have received particular names; such as Orni- 
thology, for the birds; Ichthyology, for the fishes; Entomology, for insects; 
and Conchology, for the testaceous Mollusca. 
FIRST DIVISION. 
VERTEBRATED ANIMALS. 
Tue body of vertebrated animals is sustained by a skeleton, composed 
of many pieces, connected together and moveable upon one another. The 
body is composed of a head, a trunk, and limbs. The head is formed of the 
cranium, which incloses the brain, and of the face, composed of two jaws. 
In the face are the organs of sense. The trunk is sustained by the spine 
and ribs. The spine is composed of vertebrae which move upon one another, 
all of which have a cylindrical opening in the centre,-forming together, a ca- 
nal, containing the portion of nervous matter called the spinal marrow. The 
ribs are semicircular, and protect the sides of the cavity of the trunk. They 
are generally articulated, by one extremity, to the vertebral column, and by 
the other, to the sternum. In some species, they are scarcely perceptible. 
The vertebrated animals have never more than two pair of limbs; some- 
times, indeed, one or other of these pairs is deficient, and sometimes both. 
According to the motions to which these limbs are destined to be subser- 
vient, the anterior ones assume the form of hands, feet, wings, <x fins; the 
posterior, of feet or fins. 
The blood of the vertebrated animals is always red, and seems, by its 
composition, adapted to sustain energy of sensation anc muscular vigor. 
The correspondence of the blood with the respiration, necessary to the 
several species of these animals, has suggested their division into classes. 
The external organs of sense, in all vertebrated animals, are two eyes, 
two ears, two nostrils, the teguments of the tongue, and the teguments of 
the whole body. The nerves unite with the nervous matter in the vertebra, 
end terminate in two meduJlary masses, in the cranium, the volume of 
which is generally proporticned to the extent of the intellectual capacity. 
There are always two jaws, an upper and under one. The principal 
motion exists in the lower, ‘which has the power of elevanon or depression. 
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