CHAPTER III. SHELLS AND MOLLUSCOUS ANIMALS. Even as the rainbow-tinted shell which lies Colours of skies, and flowers, and gems, and plumes." IT is an interesting question, and one which yet is not fully answered, how far living creatures can exist below the surface of the deep. The wondrous architects of the coral reef cease to live at 100 feet below that surface, and so vast a number of shell-fish and crustaceous animals, of corallines and other zoophytes, dwell within a few yards of it, that the statement seems probable, that below the depth of a few hundred feet life ceases in the ocean, from the want of air and light, and from the pressure of the waters. Yet the words of the poet are true enough. Miles deep at bottom of the sea, must lie the structures of myriads of once living animals; and shells of graceful form and glowing colours add to the constantly accumulating substance at the base of the ocean. Many are strewed upon our sandy shores, and so beautiful are they, that we wish, in our summer rambles, that the waves would bring them up to us in greater numbers, or that we could look down on a clear day into those recesses where "" Buoyant shells, On stormless voyages, in fleets and single, We gather up those which we find, and looking at their structure would fain know something of the inmate of such a dwelling. All nature proclaims the goodness of God. We hear that the bird which wings its way over our heads has a song of joy; the bee hums delightedly by us; and the little shrimp which darts in the clear pool, seems full of merriment. Was the inmate of the shell less cared for by its Maker? No doubt the little builder had some sense of joy, as he framed from his own substance the house which excites our admiration. Doubtless his existence, short and sluggish as it was, had its own consciousness of pleasure; and obscure as is his history, and little calculated as such a creature might seem to perform an important part in the economy of creation, yet we know that he had a work to do, not only for the living creatures of the sea, but for the well-being of man himself. Those living mollusks which glide along in such multitudes in the waters, are among the appointed messengers of death to the smaller animals, whose numbers would else exceed their destined limits; they, like other inhabitants of sea and earth, are the equalisers of life and death. In their turn they serve as food for the rich man, and are often the only meal of the peasant, or of the savage. The land bird stays his song, as he descends to pick up the limpet from the rock; and the sea bird, white as the foam over which he skims, dips among the shell-fish for his food; while to fishes they furnish the daily meal. Thus much is evident to any observing person; but science has revealed to us other important uses of shells. Those shells are made of carbonate of lime, which, by some mysterious process, the mollusk derived from the materials forming his food: materials which in themselves possess scarcely any portion of this substance, and yet which, when mingled with animal matter, serve to compose the calcareous habitation: and those towering chalk cliffs on which the short grass is now growing, or that long stratum of limestone, extending for miles away, is formed almost entirely of shells mingled with the skeletons of zoophytes and sea urchins, and other marine animals. The block of marble, hard as it seems, reveals, by the aid of the microscope, masses of shells, some of them perfect and unbroken, and rivalling in symmetry the loveliest shell in the cabinet of the collectors: while the myriads of shells lying in crushed heaps among the mountains, are hourly undergoing those processes by which they shall, after the lapse of ages, form the component parts of the gem to deck the coronal of princes, or the marble statue to be reared to the memory of worth or genius. Fossil shells were elegantly termed by Bergman the "Medals of Creation." The geologist reads in the masses of species of shells now extinct, histories of by-gone times and of earth's changes; and distinctly deciphers traces of revolutions, of which, but for their aid, we should know nothing. Fossil shells are among the most valuable records of the earth on which we live. Though the study of the shells of land or sea is important to science, yet Conchology is much less popular than most of the other departments of Natural History. It may be that it is owing to the costliness of the pursuit. Foreign shells are expensive, and even a good collection of native shells is not to be procured without considerable trouble, as there are many parts of the coast on which few marine shells can be gathered. They are not like the wild-flowers, which grace every way-side; or the song-birds of the woodlands; or the insects of our summer pools; and comparatively few are among the common things of earth. But perhaps the study of conchology has been in former times rendered uninteresting by the neglect of the animal inhabiting the shell. The collector had long prided himself on the beauty of the rare shells brought from distant seas, or on some well arranged cabinet of native species. He could descant on their rarity and beauty of form and tell their names and classification; but he had nothing to relate of the animal within. Until the labours of recent naturalists, scarcely anything was known respecting the structure or habits of the shell-fish; and even yet, the details which can be given of them are very few, not only from the difficulty of making observations, but from their having less activity and fewer modes of life than most living creatures with which we are familiar. Nor are they so easy of description as are most other natural objects; and the terms of science, often unpleasing and perplexing to all but the student, are almost necessary here, if we would convey a good idea in writing, either of the animal or its dwelling-place. And yet those who do examine the contents of the shell find matter of deep interest, and now that many are engaged in this pursuit, and monographs with beautifully coloured plates are publishing on different tribes of the molluscous animals, we shall gradually learn more of their nature and history. Most of the common shell-fish are of a greyish or brownish white, or of a straw colour, sometimes clouded with dark spots. Yet some of them exhibit great beauty of tint, in which every shade of red, and orange, and yellow, and blue, may be seen. A writer in Loudon's Magazine of Natural History says of our native Cowry (Cypraea europaea), that it is a most beautiful creature, viewed from beneath, with colours unrivalled among the order to which it belongs. "The proboscis is dark vermilion ; the tentacles yellowish red, spotted with yellow; the upper part of the foot streaked longitudinally with yellow and brown, and the mantle greenish brown, edged with brownish red; but notwithstanding, the shell is of a dull uniform white." This writer tells us too of other shell-fish, which have fins or lateral expansions elegantly speckled with bright yellow, and the fleshy parts of the body marked with pink colour: while another is dotted over with milk-white spots, and others are mottled with black and white. Then the part called the foot of the mollusk is in some tropical species of blackish red; in some, green; in others, black; in some deep red, with faint designs resembling those of the shell; and in others it is bright yellow and deep brown. The inmate of the beautifully marbled harp shell, he says, "glories in a rich vermilion-red skin." This writer also quotes a passage from a paper of Broderip in the Zoological Journal. "In the Mauritius," writes this gentleman, "it is the amusement of the place to watch over the trim apparatus of lines, hung over some sand-bank to tempt the various species. of Oliva which there abound, or to wait for the more rare approach of the harp shell, till the |