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by which respiration was performed. In this experiment, the distance from the bottom to the surface was two inches, and, of course, the tails were of an equal length. To discover how far the animals could extend their tails, this ingenious and indefatigable naturalist gradually augmented the height of the water, and the tails uniformly rose to the surface till it was between five and six inches high. When the water was raised higher, the animals quitted their station at the bottom, and either mounted higher in the water, or fixed themselves upon the sides of the vessel, in situations which rendered it convenient for them to reach the surface with the points of their tails. These tails consist of two tubes, each of which is capable of extension and contraction. The first tube is always visible; but the second, which is the proper organ of respiration, is exerted only when the water is raised beyond a certain height. Through this tube the air is conveyed into two large tracheæ, or wind-pipes, within the body of the animal, and thus maintains the principle of life. When the tails are below the surface, the animals occasionally emit small bubbles of air, which are visible to the naked eye, and immediately afterwards they repair to the surface for fresh supplies.

So admirably has Providence furnished animals, in every state of their existence, with the means of obtaining air, that, after the transformation of many insects into chrysalids, they are provided with instruments for that purpose, which did not exist previously to their transformation. These Rat-tailed Worms, soon after they ⚫ are transformed into chrysalids, instead of a soft, pliable skin, are covered with a hard, crustaceous substance, seemingly impervious to the air; and the tail, which was the wind-pipe of the animal in its first state, gradually disappears. In a few hours, four hollow horns shoot out, two from the fore and two from the under part of what was the head of the animal. These horns, which are hard and tubular, are real wind-pipes, destined for the introduction of air into the chrysalis. They

terminate in as many trachea within the body of the animal. This fact affords a strong example of the necessity of air for sustaining the principle of life, even in its lowest condition. After these animals pass from the chrysalid state to that of flies, they are deprived both of their tails and horns. But the Creator, in this last stage of their existence, has not left them without proper resources for the introduction of air into their bodies. Instead of protuberant trachea, in the form of tails or horns, they now, like other flies, receive air by means of stigmata or holes, variously disposed over different parts of the body.

These Rat-tailed Worms pass the first and longest part of their lives, which is supposed to be several months, under water. When the time of their transformation approaches, they leave that element, retire into the ground, and there become chrysalids. From this state they are changed into flies, and pass the remainder of their existence in the air.

OF THE TABANUS OR WHAME-FLY

TRIBE*.

The insects of the present tribe subsist on the blood of animals, which they suck with great avidity, by means of their proboscis. They are chiefly active during the hottest weather of summer. In most of the species the eyes are beautifully coloured. Wet meadows and moist woods are the places in which they principally abound. The larva of some of the species live underground.

The mouth is furnished with a straight, exserted, membranaceous proboscis, which terminates in an ovate knob, and two equal lips. The sucker projects, and is placed in a groove at the back of the proboscis, with a single-valved sheath and five bristles. There are two equal palpi or feelers, which are clavate, and each terminates in a point. The antennæ are short, ap proximated, and have an elevated tooth at the base.

THE HORSE-FLY*, AND GREEN-EYED WHAME-FLY †.

The puncture of both these insects is extremely keen and painful. During the summer-time, the former torment horses and cattle in such a degree, as sometimes to throw them into a state of the utmost agitation and alarm. They are more abundant in wet meadows and pastures than in other places. Mankind are also not unfrequently attacked by them.

The Green-eyed species often torment mankind. Those persons who are accustomed to walk in shady lanes and in woods, during the hot weather of June and July, know well what it is to suffer from their attacks. They conceal themselves in crevices of the bark of trees, or among the foliage, until about noon, from which time until five or six o'clock in the evening, they are often very troublesome. Both species delight in the hottest sunshine, and indeed seldom fly abroad except in fine weather.

In these insects, as in the Gnats, it is to be remarked that the females only are troublesome. The males are found on flowers, from which they appear to derive their whole nourishment. The latter, towards the close of the day, are frequently observed to fly round and round in the air, apparently for the purpose of inviting the females.

M. De Geer was the first naturalist who described

DESCRIPTION. The length of this insect is about eleven lines. The eyes are of a greenish brown colour; and the back of the abdomen is marked with white triangular spots. SYNONYMS. Tabanus bovinus. Linnæus.-Le Taon des

Bœufs. Tigny. Cuvier.

+ DESCRIPTION. The length is about five lines. The head is yellowish, with three black shining dots, forming a triangle on its anterior part. The eyes are of a brilliant yellowish green colour, with some black specks.

Linn.-Le Taon aveu

SYNONYMS. Tabanus cæcutiens. glant. Tigny.-Le Taon aveugle. Cuvier.

the larvæ of this tribe of insects. Those of the Horsefly, as he states, live under the surface of the earth. They are of a yellowish white colour, and destitute of feet, but furnished with a series of fleshy tubercles, which supply the place of feet. Their body is cylindrical, and terminates before in a conical point. The head is small and scaly, furnished with two large hooks, by means of which it is supposed they are enabled to dig their holes in the ground.

They change into pupa under the surface of the earth. After continuing in this state about a month, they break out from their shell, through a longitudinal orifice. which they make in the upper part of the thorax, and become perfect insects.

OF THE GNATS IN GENERAL*.

These insects principally frequent woods and watery places, and, in many parts, are known to the country people by the name of Midges. They live by sucking the blood and juices of the larger animals.

Their larvæ are very common in stagnant waters. The bodies of these are composed of nine segments, the last of which is furnished with a small cylindrical tube, through which they breathe; and they frequently rise to the surface of the water for that purpose. The head of the chrysalis is bent towards the breast, so as to throw the thorax in front: in this the respiratory tubes are situated, near the head. The last segment of the abdomen terminates in a kind of flat fin, by means of which the creature performs all its motions in the water.

*The mouth of the Gnats has a long, slender trunk, or flexile sheath, including five pointed bristles; it has also two feelers. The antennæ are generally thread-shaped, but those of some of the males are feathered.

THE COMMON GNAT *.

Few insects are better known than this species of Gnat, and there are not many that afford a more interesting history.

The female deposits her eggs on the surface of the water, and surrounds them with a kind of unctuous matter, which prevents them from sinking; and she at the same time fastens them with a thread to the bottom, to prevent them from being floated away from a place, the warmth of which is proper for their production, to any other where the water may be too cold, or the animals, their enemies, too numerous. In this state, therefore, they resemble a buoy that is fixed by an anchor. As they come to maturity they sink deeper; and at last, when they leave the egg, they creep, in the form of grubs, at the bottom.

From the beginning of May, innumerable larvæ of Gnats may be seen in stagnant waters, with their heads downward, and the extremity of their abdomen at the surface; from the side of this arises a hollow tube, through which they respire. Their heads are armed with hooks, by which they are enabled to seize on insects and bits of grass, on which they feed; and on their sides are four small fins, by the help of which they swim and crawl along. These larvæ retain their form during a fortnight or three weeks, after which they turn into chrysalids; and all the parts of the winged insect are now distinguishable through their thin exterior covering. The place and shape of their respiratory tube are also altered: this is now divided into two parts, and is situated near the head. The chrysalids abstain from eating, and reside almost constantly at the surface of the water; but, on the least motion, they may be seen to unroll themselves from their spiral posi

*SYNONYMS. Culex pipiens. Linn.--Le Cousin commun.

Cuvier.

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