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b. Hemiptera; insects smaller than the preceding, with four wings: the two superior semi-crustacious, and the interior edges lying one upon the other.
c. Lepidoptera; insects with four wings, all of them imbricated with scales.
d. Neuroptera; insects having four wings interwoven with veins, like a piece of net-work, and no sting. e. Hymenoptera, insects agreeing in their characteristics with the preceding, except that these are armed with a sting.
f. Diptera, insects having two wings, and two elevated alteres (or balances), behind each.
g. Aptera, insects destitute of wings.
503, Every insect is furnished with a head, antennæ, or horns, and feet. All insects, likewise, have six or more feet. They respire through pores on their sides, called spiracles. Their skin is extremely hard, and serves them instead of bones, of which they have
The head also, the trunk, the proboscis, the feelers, the breast, the belly, the limbs, the tail, and the wings, are all objects of notice to the entomologist.
See the proud giant of the beetle-race!
504. Worms are, according to the Linnæan system, the sixth class. Some of them have only two senses; others no head; and most of them, no feet.
They are divided into five orders:
1. Intestinal worms; as tape-worms, leeches, &c. 2. Molluscous worms; chiefly inhabiting the sea. 3. Testaceous worms; as muscles, cockles, aysters, snails, &c.
4. Zoophytes; between animals and vegetables. And 5. Animalcules; generally invisible to the naked eye.
505. The Indian thread worm eats into the skin in the West Indies, and its extraction occasions great trouble. The furia does the same in Sweden. The common hair-worm is said to occasion whitlows. Garden or dew-worms, are useful to vegetation, by loosening the soil. The heads and tails of snails will grow again. The Nereis is the sea glow-worm.
Full nature swarms with life; one wonderous mass
Waiting the vital breath, when PARENT-HEAVEN
506. Young snails come forth with their shells on their backs; and the shells are enlarged with the animal, by means of a secretion for the purpose, by which also they repair the shells when broken. The shell so effectually preserves them, that they have revived in water after being kept dry in a box for twenty years; and even after being immersed in boiling water.
Corals are shells produced by an insect within them; and they grow in such quantities, and to such heights in some seas, as to create islands inhabited by men. The Friendly Islands, in the Pacific Ocean, were thus raised by corals from the depth of that sea. Ships have often been lost on coral-rocks.
Obs. 1.-The wisdom of BEES, the harmony of their government, their persevering industry, and wonderful economy, have been celebrated in every age. Their combs or nests, are composed of cells or six sided figures, so finely finished, that the most expert workman would find himself unqualified to construct a similar habitation. By applying hexagonal cells to the sides of each other, no void spaces are left between them; and, though the same end might be accomplished by other figures, yet they would require a greater quantity of wax. A comb consists of two rows of cells applied to each other's ends. This arrangement both saves room in the hive, and gives a double entry into the cells: the bases of the cells in one row of a comb, serving for bases to the opposite row. It is difficult to perceive, even with the assistance of glass hives, the manner in which bees operate. They are so eager to afford mutual assistance; and, for this purpose, so many of them crowd together, that their individual operations can seldom be observed. It has, however, been discovered, that their two teeth are the instruments they employ in modelling and polishing the wax. The combs are generally arranged in a direction parallel to each other. An interval, or street, between the combs, is always left, that the bees may have a free passage, and an easy communication with the different combs in the hive. These streets are sufficiently wide, to allow two bees to pass one another. Besides these parallel streets, to shorten their journey when working, they leave several round cross passages, which are always covered. The honey bees not only labour in common with astonishing assiduity and art, but their whole attention and affections seem to centre in the person of the queen or sovereign of the hive. When by any accident she dies, the whole community are instantly in disorder-all their labours cease; no new cells are constructed; and neither honey nor wax are collected.
To their delicious task the fervent bees
2. The labors of WASPS, though not beneficial to mankind, are not less ingenious nor less worthy of admiration.
Wasps associate in great numbers, and construct a common habitation with much dexterity and skill. The cells of the wasps are formed of a kind of paper, which, with great dexterity, is fabricated by the animals themselves. The hole which leads to a wasp's nest is about an inch in diameter, being a kind of gallery mined by the insects; and the whole nest is of a roundish form, and sometimes above twelve inches in diameter. The subterraneous city, though small, is extremely populous; in a middle-sized nest there were at least 10,000 cells. The different stories of combs are always about half an inch high! these intervals are so spacious, in proportion to the bulk of the animals, that they may be compared to great halls, or broad streets. Each of the larger combs is supported by about fifty pillars, which at the same time, give solidity to the fabric, and greatly ornament the whole nest. Boys, and even men, are guilty of great and undeserved cruelty to these ingenious insects, who never sting, unless they are irritated and attacked.
3. The association of ANTS merits no less admiration than those of the bees and wasps. The form of their nest, or hill, is somewhat conical; and, of course, the water, when it rains, runs easily off, without penetrating their abode. Under this hill, there are many galleries or passages, which communicate with each other; and resemble the streets of a city. They go to great distances in search of provisions; and their roads, which are often winding and involved, all terminate in the nest.
507. The study of shells is called Conchology. There are more than a thousand species of shells, and they are separated into three divisions-multivalves, bivalves, and univalves, accordingly as the shells consist of many parts, of two, or of a single part.
Multivalves consist of many plates or shells, connected in some species like the different parts of a coat of mail.
Bivalves consist of two shells, connected by a hinge; as the muscle, oyster, &c.
And the Univalves comprehend those that have a regular spiral, which is a numerous division, including the snail, periwinkle, &c. and those also without a regular spiral.
Obs.-Pearls are found in oysters and muscles. They are calcareous concretions, formed of the liquid of which the inner surface of the shell is composed, and are an effect of accidental injury to the shell. The Chinese increase the number of pearls, by catching muscles and perforating the shells; and then replace the muscles in the water. After a certain time, on opening them again, they discover pearls attached to the part injured. The substance of the shells of these animals, when chemically examined, is found to be a mild calcareous earth, deposited in a mass of net work, composed of animal matter. The shining matter, left in the tracks of snails, is this very substance; which, when deposited in strata above one another, hardens and forms a shell.
2. Many hundreds of unknown species of mineral shells are found in the strata of the earth, the remains of seas and shores now no more.