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The fossil records of the long ages during which the Mollusc, the Crustacean, and the Echinoderm slowly assumed their characteristic forms are hopelessly lost. But we are now prepared to return to the record which survives, and we shall find the remaining story of the earth a very ample and interesting chronicle of evolution.
A feature of another of the coral rock disintegrating agents is its extreme weakness. It is a rotund mollusc with frail white valves, closely fitting the cavity in which it lives. "Reasoning, oft admire How Nature, wise and frugal, could commit Such dispositions with superfluous hand."
A quotation from Lyell's "Principles of Geology" says that the perforations of Lithophagi in limestone cliffs and in the three upright columns of the Temple of Jupiter Serapis at Puzzuoli afford conclusive evidence of changes in the level of sea-coasts in modern times the borings of the mollusc prove that the pillars of the temple must have been depressed to a corresponding depth in the sea, and to have been raised up again without losing their perpendicularity.
Some of us might do well to use this hint in our treatment of acquaintances and friends from whom we are expecting gratitude because we are so very kind in thinking of them, inviting them, and even listening to what they say considering how insignificant they must feel themselves to be. Your mollusc, on the contrary, is inwardly objecting to every other grade of solid rather than to himself.
The evidence of the submergence of the pillars consists mainly of a zone commencing at the height of about 12 feet above their pedestals, and extending 9 feet upwards, in which are numerous perforations, made by a marine bivalve mollusc.
And will not the position of a mechanistic philosophy become still more difficult, when it is pointed out to it that the egg of a mollusc cannot have the same chemical composition as that of a vertebrate, that the organic substance which evolved toward the first of these two forms could not have been chemically identical with that of the substance which went in the other direction, and that, nevertheless, under the influence of light, the same organ has been constructed in the one case as in the other?
From the bases of the valves spring three or more pairs of hook-like processes which, if Fate decides upon a certain coral host, encircle a slim "twig," creating for the mollusc a curious resemblance to a short-limbed sloth hugging tightly the branch of a tree. When the spat happens to settle in places where coral is not available the hooks or arms are but crudely developed.
The grounds on which they base that supposition are these: That if you go through the enormous thickness of the earth's crust and get down to the older rocks, the higher vertebrate animals the quadrupeds, birds, and fishes cease to be found; beneath them you find only the invertebrate animals; and in the deepest and lowest rocks those remains become scantier and scantier, not in any very gradual progression, however, until, at length, in what are supposed to be the oldest rocks, the animal remains which are found are almost always confined to four forms 'Oldhamia', whose precise nature is not known, whether plant or animal; 'Lingula', a kind of mollusc; 'Trilobites', a crustacean animal, having the same essential plan of construction, though differing in many details from a lobster or crab; and Hymenocaris, which is also a crustacean.
"Just one finger and you'll feel 'em, nubbly like." "Pearls!" cried Carey, excitedly, and, forgetting all about the messiness of the great wet shapeless-looking mollusc, he used both finger and thumb. "Here, cut them out."
What is the meaning of the words "mollusc" and "octopus"? 2. How does the Octopus capture its prey? 3. How does the Octopus escape its enemies? 4. What creatures prey on the Cuttle and Octopus? Now and again Whales are washed up on our coasts, and then we can see how huge is this strange monster of the deep. It is by far the largest of all living animals.
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