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already described': immense multitudes of them, sufficient to darken the air, have, sometimes, been observed in England.

The spider-flies (hippobosca) inhabit woods and marsby places; the forest-fly (h. equina), found in abundance in the New Forest in Hampshire, and in several other parts of England, is particularly tormenting to the noble animal after which it is named. So hard and tough are the skins of these determined blood-suckers, that it is almost impossible, by crushing, to kill them; and the only effectual mode of destroying them is by tearing off their heads. Forest flies are occasionally found upon cattle; and in open countries even upon dogs.

Order VII.-APTERA, Or insects without wings, in both sexes. This order comprehends all kinds of spiders, the lice of different animals, and also lobsters, crabs, shrimps, &c., which last are all of the genus cancer. The ominous companion of the true death-watch, referred to at p. xxiv, is the termes pulsatorium, which belongs to this order, and is of a greyish white colour, much resembling the common louse; it is found in dry wood, or in books not often used. It has an oval body, with long antennæ; runs with great rapidity, and, like its congener, shuns the light. Some ento mologists have described it as the pediculus of old wood. The writer has, with his companions, frequently witnessed the alarming labours of this puny insect, giving its responses to a noise, imitated by striking leisurely with the nail on a glass half filled with liquid, or placed on a marble slab, to lessen the sharpness of the sound. Sometimes the insect would suddenly stop his ticking, but instantly re

See Time's Telescope for 1820, Introduction, p. xlix ; and Mr. Wood's excellent Illustrations before noticed, vol. ii, pp. 94-97.


sume his note on mimicking the sound, which it continued for a considerable time. The sound was full as loud, but more regular than the ticking of a watch. It was correctly ascertained to proceed from a picture hanging in the room, whence the sound would continue to be distinctly emitted, if the picture was laid on the table or chair, and disturbed as little as possible in the moving. On a very careful examination, no other insect was discovered but the termes pulsatorium, these being very numerous; and the observer was surprised that there was not a chorus of this tinckling music.

The nets spread out by spiders, to catch their unwary prey, are composed of similar materials to the silk of the silkworm, and are spun from the animal's body nearly in the same way. How artfully they are contrived, and how cunningly the spider lurks unseen, but continually watches the approach of its prey, must so often have been the subject of observation and admiration, as to make any description unnecessary.

The common house-spider (aranèa domestica), fig. 7 in our Frontispiece, belongs to a numerous and well-known genus, the terror of many and the antipathy of all. It is a proscribed race, which we think ourselves entitled to destroy whenever we have an opportunity, from feelings of disgust, rather than from the operation of reason. This feeling seems implanted as it were in our nature, from which even the naturalist is not wholly exempt; and it tends, together with other causes, to check the multiplication of an insect which would otherwise become by far too numerous. The eight eyes with which the spider is provided are fixed points, disposed in a different order in different species, insomuch that authors have taken advantage of the cireumstance, to divide the genus into families. They are hard, smooth, and brilliant, and are always placed on the head, i.e. before the two oblique lines which are seen between


the head and the thorax. The inconvenience which might arise from their want of motion is remedied by their number and position, which is well calculated to comprehend every view compatible with the wants or safety of the animal. There is little doubt that the spider can inject a venomous liquor into the wound made with its fangs. Instances, and those related by authors of credit, have occurred, of inHammation succeeding the bite of a spider on the human body.

The female spider lays a number of eggs, of which she takes the greatest care, as well as of the young when they are hatched, exposing herself to every danger when it becomes necessary to defend them. At other times spiders are very fearful, and fly with precipitation whenever they are approached; but if by any chance, while the female is carrying her little ones on her back, one of them should fall off, she would rather perish than abandon it, and will wait with firmness till all danger be passed; after which the young one will remount, and the mother continue her journey. She is devoted to her eggs, which she never abandons. If they are taken from her, she exhibits the greatest degree of inquietude, moving about with rapidity from place to place in search of them: if they are restored, she seizes them with precipitation, and runs off as fast as possible. This fondness of the spiders for their young is the more remarkable, as they are a solitary race, appearing to avoid and hate their fellows, and even devouring each other when they have an opportunity'.

The cobwebs of other spiders, called gossamer, are frequently seen floating in the air in a sunny day, and are sometimes so abundant as to fall in showers. Each of these may be compared to a balloon, trans

See Mr. Wood's Illustrations of the Linnæan Genera of Insects, vol. ii, p. 134; Time's Telescope for 1820, Introduction, p. lii, and the previous volumes.

porting the little aeronaut that formed it, by means of its specific lightness. This species of spider, attaching its first formed thread to the leaf or branch of a tree, by dropping to a certain distance, lengthens it; then running up the thread, and dropping again, draws out another, and so on, till a sufficient quantity of this silk is formed to buoy up the spider in the air. He then separates the whole from the leaf, and, running down to his seat at the bottom, trusts himself and his balloon to the mercy of the wind. It is thus that these animals are transported from tree to tree, and from wood to wood, in search of food. The cobwebs that are spread over the surface of the grass, and that offer so beautiful an object to the eye early in a summer's morning, through the brilliancy of the dew-drops formed and suspended on their silken threads, and the reflection of the sun's rays from each of these crystal gems, are the work of another species of spiders.

All lice live by suction; some on the blood of man, others on that of quadrupeds and birds. The microscope shows the instrument by which this purpose is effected. It is a proboscis, generally concealed in its sheath, very sharp, and provided, towards one end, with some reversed prickles. These insects are oviparous, and multiply amazingly. The young soon issue from the eggs (or nits as they are called), and, after having changed the skin two or three times, are ready to produce in their turn. Experience has shown that, in six days, a louse will produce fifty eggs. The young leave the shell about the same period of time, and in about eighteen days more are in a state for reproduction. From these observations, and the calculations arising from them, it appears that two females may have 18,000 little ones in the space of two months.

Hottentots and monkeys seem to delight in the filthy custom of eating these insects, and there is reason to believe that the same nauseous inclination

prevails among the lower class of the Russians. Most of the quadrupeds and birds seem to have their peculiar species of this disgusting genus, and even fish and insects are not totally exempt from them.

The flea (pulex) has more strength and agility in proportion to its size than any other animal. “A flea, by a dexterous contrivance, has been fastened to a small cannon, which it has dragged along without difficulty; and it is not uncommon to find it exhibited at country fairs, either drawing a chain fixed to its scaly body, at least thirty times heavier than itself, or springing along with a little ivory chariot behind it.See Time's TELESCOPE for 1820, Introduction, p. lị.

The cheese-mitę (acarus siro), which belongs to the tribe of ticks, appears to the naked eye little more than a moving particle of dust; but, on the application of the microscope, is found to be a perfect insect, performing all its regular functions. The minute scarlet insect, so troublesome to haymakers and reapers, called commonly harvest bug, is of the same family, and is not very unlike a spider, It burrows into the skin, and raises a considerable tumour, which itches much, and is often painful, See p. 247.

Having described the principal British species of the genus cancer in our previous volumes, we shall merely observe, that their shells afford a material constituent in the formation of chalk-beds and beds of marl, which are formed at the bottom of the sea. We frequently meet with specimens of entire shells in chalk-pits, which are now inland; and there is little doubt that, in a comminuted state, they form a principal ingredient in most calcareous earth.

The genus monoculus presents a singular species, in the water-flea (m. pulex), which is familiar even to the unscientific observer. When submitted to the microscope, the body of this flea appears to be inclosed in a bivalve sheath, from the opening of which

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