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called the shelly covalves. A common shelt
If in the sea the mangled parts you cast,
Move as before, nor life nor vigour lose* 2. Mollusca testacea, or soft-bodied animals furnished with shell's, are divided into three assortments, called univalves, bivalves, and multivalves; meaning, that the shelly cover consists either of one, two, or several parts or válves. A univalve shell may be exemplified by that of the common snail; for the shell is simple or undivided. A bivalve shell may be exemplified by a muscle, in which, as every one knows the shell is composed of two pieces or valves; and, lastly, a multivalve shell may be exemplified by any species of lepas or bernacle, in which the shelly covering of the animal is formed of several pieces or divisions. The shell-animals are produced fram eggs, which, in some species, are gelatinous, or gluey; and, in others, covered with a hard or calcareous sliell: and the young animali emerges from the egg with its shell on its back. The most familiar and convincing proof of this may be abtained, by observing the evolution or hatching of the eggs of the common garden-snail, as well as of several of the water-snails, which deposit eggs, so transparent, that the motions of the young, with the shell on its back, may be very distinctly seen several days before the period of hatching.
All the shell-animals are of such a constitution as perpetually to secrete or exude from their bodies a viscid moisture, and it is with this, managed according to the exigencies of the animal, that the shell is, throughout life, increased in dimensions, and repaired when accidentally broken in any particular part. The growth of shells proceeds from the edges of the mouth or opening, and thus the spires or turns of the univalve shells are gradually increased in number and size, till the animal has arrived at its
* Bingley's Animal Biography, vol. jii, pp.435, 436.
full set by the the principio Dentalium Hof each are-ijelix, snoteredo , VALVES ther-of ch
full growth. The bivalves are increased in a similar manner, by the gradual enlargement of the outline of each valve. The principal genera in the UNIVALVES are-1. Argonauta. 2. Nautilus, pearlynautilus. 3. Helix, snail*. 4. Dentalium, toothfish. 5. Serpula. 6. Teredo, ship-worm. 7. Sabella. 8. Patella, limpet. BIVALVES-1. Anomia. 2. Pinna. 3. Mytilus, muscle and mother-of-pearl shell. 4. Mya, pearl shell. 5. Spondylus. 6. Chama, clamp shell.' 7. Solen, razor sheti. 8. Ostrea, oyster. 9. Cardium, cockle. MULTIVALVES-1. Pholas. 2. Chiton. 3. Lepas, bernacle shell.
Learn of the little Nautilus to sail,
Spread the thin oar, and catch the driving gale. The argonauta, known to shell collectors by the name of the paper-nautilus, is supposed to have given to man the first idea of navigation. When it means to sail, it discharges a quantity of water from its shell, by which it is rendered lighter than the surrounding medium, and, of course, rises to the surface. Here it extends two of its arms upward, which are each furnished at their extremity with an oval membrane, that serves as a sail. The other six arms hang over the sides of the shell, and supply the place either of oars or rudder. It is an inhabitant of the Mediterranean and Atlantic seas.
Two feet they upward raise, and steady keep;,
* And then the whining school-boy with his satchel,
And shining morning face, creeping like snail
No more they wanton drive before the blasts,
And dash them down again to sands below. When the limpet is properly cleaned, the shell is sometimes found of a beautiful purple tint, and sometimes emïts rays of reflected light of an uncommon brilliancy. They are found on the rocks, which are incessantly beaten by the surges and breakers on the sea shores of almost every country in the world. The rays of variegated colours which issue from their centre-tops, are sometimes found of the most vivid colours ; and the animal that lives under this magnificent roof and versicolor canopy, is a kind of slug, as disagreeable to the eye for its shape, as its flesh is for its taste insipid to the palate, It is not by any glutinous liquid, as it has been asserted, that this fish adheres so strongly to the rock, but by the simple process of sucking the air between its body and the ground, to which it affixes itself.
Oysters breathe by means of gills. They draw the water in at their mouth, a small opening in the upper part of the body; drive it down a long canal that constitutes the base of the gills, and so out again, retaining the air for the necessary functions of the body.
Lonely dependent from weed-fringed rocks, Unmoved she dares the storin's tremendous shocks. The principal breeding time of oysters is in the months of April and May, when they cast their spawn, or spats, as the fishermen call them, upon rocks, stones, shells, or any other hard substance that happens to be near the place where they lie, to which the spats immediately adhere. . These, till they obtain their film or crust, are somewhat like the drop of a candle, but are of a greenish hue. The substances to which they adhere, of whatever nature, are called cultch. From the spawning-time until about the end of July the oysters are said to be
thahe substae called ch of July 2
sićk, but, by the end of August, they become perfectly recovered. During these months they are out of season, and are bad eating.
The oyster fishery of our principal coasts is regulated by a court of admiralty. In the month of May, the fishermen are allowed to take the oysters, in order to separate the spawn from the cultch, the latter of which is thrown in again, for the purpose of preserving the bed for the future. After this month it is felony to carry away the cultch, and otherwise punishable to take any oyster, between whose shells, when closed, a shilling will rattle. The reason of the heavy penalty on destroying the cultch is, that, when this is taken away, the ouse will increase, and muscles and cockles will breed on the bed and destroy the oysters, by gradually occupying all the places on which the spawn should be cast. There is likewise some penalty for not treading on, and killing, or throwing on shore, any Star-fish (Asterias of Linnæus) that happen to be seen.
The prickly star creeps on with full deceit,
And empty shells the sandy hillocks grace *. IV. VERMES, or worms. Their forms are various, and their natures extraordinary. The major part of them are the inhabitants of living animal bodies; their introduction into which is one of those inscrutable mysteries which must for ever evade the power of human intellect. They exist in most animals; some kinds in the intestines, and some in the other viscera. The external worms possess an elongated body, composed of rings; have cireulating yessels, but no heart. No nerves have been discovered in the intestinal worms.
* Bingley's Animal Biography, vol. iii, p. 452.
ORDER I. INTESTINI, or intestinal worms inhabiting the bodies of animals. The genera are :-1. Gordius, guinea-worm. 2. Ascaris, thread-worm, round-worm. 3. Tricocephalus. 4. Fasciola, Auke. 5. Tænia, tape-worm. 6. Hydatis, hydatid.
ORDER II, EXTERNI, or external worms. The genera are:-1. Aphrodite, sea-mouse. 2. Sipunculus. 3. Hirudo, leech. 4. Planaria. 5. Lumbricus, earth-worm. 6. Furia.
At once came first whatever creeps the ground,
INSECTS are distinguished from other animals by their being furnished with several feet; never fewer than six, and sometimes with many more; by their breathing, not through lungs, but by spiracles or breathing-holes, situated at certain distances along each side of the body; and, lastly, by the head being furnished with a pair of antenne, or jointed horns, which are extremely various in the different tribes. The first state in which the generality of insects appear, is that of an egg. From this is hatched the animal in its second state, in which it is often, but improperly, called the caterpillar. The insect, in this state, is the larva, or larve, being a mask or disguise of the animal in its future form. The larve differs in its appearance, according to the tribe to which it belongs. When the time arrives for the larve to change into its next state of chrysalis, or pupa, it ceases to feed, and, having placed itself in some quiet situation for the purpose, lies still for several hours; and then, by a kind of laborious effort, frequently repeated, divests itself of its external skin, or larye-coat, and immediately appears