In reviewing the first DIVISION of the animal kingdom, namely, the
vertebral animals, we cannot fail to have been delighted with the
wonderful and appropriate faculties bestowed upon each individual;
but, beautiful and well adapted to the use of their possessors as
these faculties may have appeared, our pleasure must be still greater
in tracing the powers with which those creatures are endowed, which
constitute what we have been accustomed to call the lower orders of
animated nature.
When contemplating the graceful form of the horse or the stag, or
the beautiful plumage of the feathered tribes, or when we notice the
terrific appearance of the crocodile, or the elaborate finish and
metallic lustre of the scales of fishes, we are led to expect that
equal care has been bestowed upon the rest of the organization of the
different individuals, and that equal attention has been paid to the
various instincts and powers that are necessary to their preservation;
but when we observe a snail, or a worm, and compare their more simple
appearance, and the perfect absence of what we have been accustomed to
consider the organs of motion, namely, feet and hands, we are apt to
look on them as having been created for some very subordinate purpose,
and, therefore, less carefully formed than the vertebral animals. How
much greater then must be our delight, when we find them possessed
of every power necessary to their state of existence, as beautifully
developed, and as carefully adapted to their necessities, as the
highest instincts of other classes are to their possessors. Nor is
their organization to be considered less perfect, because we are unable
to trace it in all its ramifications; the minute branches of the nerves
of the human body are, not only invisible to the naked eye, but even
to the most acute observer when assisted by the magnifying power of
the microscope, but we are certain that they do exist, from the pain
we feel when they are injured. Until lately, the _Infusoria_, those
microscopic animals that are found in infusions of vegetable substances
in water, were supposed to be possessed of neither nerves nor stomach,
and to be fed by absorption; but the ingenious experiments of a learned
foreigner have proved, that, instead of being without a stomach,
they are provided with as many as five or six: it is true, that the
nerves have not yet been detected, but we have a right to infer their
existence from their effects; so that these minute creatures, which we
have been accustomed to consider as nearly destitute of organs, are, in
fact, beautifully formed, and as perfect in their kind as any other of
the Creator’s works.
The second DIVISION of the objects of natural history, namely, the
INVERTEBRAL animals, which we have now to describe, are placed by
themselves, on account of their being without an internal skeleton,
consisting of a series of vertebræ, or bones of the back. This
distinction is explained in the introductory chapter to the Book of
Animals. They have been separated, by Lamarck, into Eleven CLASSES,
namely:—
1. MOLLUSCA, (_soft-bodied animals_,) in general covered
with a shell; as, for instance, a snail; or without a
shell, as a slug.
2. CONCHIFERA, (_shell-bearing animals_,) with a shell,
consisting of two valves, as an oyster or mussel.
3. CIRRHIPEDA, (_with feet like cirri, or hairs_.) The inhabitant
of the acorn-shell, found on the back of the larger kind of
shell-fish, &c., is an instance of this class.
4. ANNELIDA, (_with body formed of rings_;) of this class
the leech and the earth-worm are instances.