ous matter which we
observe on the surface and in the upper beds of the earth.

"Nevertheless there is in the sea, for the formation of calcareous
matter, a cause which is greater than shelled molluscs, which is
consequently still more powerful, and to which must be referred
ninety-nine hundredths, and indeed more, of the calcareous matter
occurring in nature. This cause, so important to consider, is the
existence of _coralligenous polyps_, which we might therefore call
_testaceous polyps_, because, like the testaceous molluscs, these
polyps have the faculty of forming, by a transudation or a continual
secretion of their bodies, the stony and calcareous polypidom on
which they live.

"In truth these polyps are animals so small that a single one only
forms a minute quantity of calcareous matter. But in this case what
nature does not obtain in any volume or in quantity from any one
individual, she simply receives by the number of animals in
question, through the enormous multiplicity of these animals, and
their astonishing fecundity--namely, by the wonderful faculty they
have of promptly regenerating, of multiplying in a short time their
generations successively, and rapidly accumulating; finally, by the
total amount of reunion of the products of these numerous little
animals.

"Moreover, it is a fact now well known and well established that the
coralligenous polyps, namely, this great family of animals with
coral stocks, such as the millepores, the madrepores, astraeae,
meandrinae, etc., prepare on a great scale at the bottom of the sea,
by a continual secretion of their bodies, and as the result of their
enormous multiplication and their accumulated generations, the
greatest part of the calcareous matter which exists. The numerous
coral stocks which these animals produce, and whose bulk and numbers
perpetually increase, form in certain places islands of considerable
extent, fill up extensive bays, gulfs, and roadsteads; in a word,
close harbors, and entirely change the condition of coasts.

"These enormous banks of madrepores and millepores, heaped upon each
other, covered and intermingled with serpulae, different kinds of
oysters, patellae, barnacles, and other shells fixed by their base,
form irregular mountains of an almost limitless extent.

"But when, after the lapse of considerable time, the sea has left
the places where these immens