us that the time has come when all the sciences and their results are so intimately connected that no one can be carried on independently of the others.  Since the study of the rocks has revealed a crowded life whose records are hoarded within them, the work of the geologist and the naturalist has become one and the same, and at that border-land where the first crust of the earth condensed out of the igneous mass of materials which formed its earliest condition their investigation mingles with that of the astronomer, and we cannot trace the limestone in a little Coral without going back to the creation of our solar system, when the worlds that compose it were thrown off from a central mass in a gaseous condition.

When the Coral has become in this way permeated with lime, all parts of the body are rigid, with the exception of the upper margin, the stomach, and the tentacles.  The tentacles are soft and waving, projected or drawn in at will, and they retain their flexible character through life, and decompose when the animal dies.  For this reason the dried specimens of Corals preserved in museums do not give us the least idea of the living Corals, in which every one of the millions of beings composing such a community is crowned by a waving wreath of white or green or rose-colored tentacles.

As soon as the little Coral is fairly established and solidly attached to the ground, it begins to bud.  This may take place in a variety of ways, dividing at the top or budding from the base or from the sides, till the primitive animal is surrounded by a number of individuals like itself, of which it forms the nucleus, and which now begin to bud in their turn, each one surrounding itself with a numerous progeny, all remaining, however, attached to the parent.  Such a community increases till its individuals are numbered by millions; and I have myself counted no less than fourteen millions of individuals in a Coral mass measuring not more than twelve feet in diameter.  These are the so-called Coral heads which form the foundation of a Coral wall, and their massive character and regular form seem to be especially adapted to give a strong, solid base to the whole structure.  They are known in our classifications as the Astraeans, so named on account of the star-shaped form of the little pits that are crowded upon the surface, each one marking the place of a single individual in such a community.

Thus firmly and strongly is the foundation of the reef laid by the Astraeans; but we have seen that for their prosperous growth they require a certain depth and pressure of water, and when they have brought the wall so high that they have not more than six fathoms of water above them, this kind of Coral ceases to grow.  They have, however, prepared a fitting surface for different kinds of Corals that could not live in the depths from which the Astraeans have come, but find their genial home nearer the surface; such a home being made ready for them by their predecessors,