the boat-fly; a genus of insects belonging to the order of hemiptera. Barbut gives the following character of this genus. "The rostrum is inflected; the antennae are shorter than the thorax; the four wings, which are coriaceous from their base to their middle, are folded together cross-wise; the hind feet are hairy, and formed for swimming." To which may be added, that the tarsi are composed of two articulations, and all the six feet are equally formed for swimming. The abdomen terminated by four little horns or appendages." He also describes the notonecta glauca, Linn. no. 1. in these words. "This insect has a head somewhat round, of which the eyes seem to take up the greatest part. Those eyes are brown and very large, the rest of the head being yellow. In the fore part it has a sharp trunk that projects, and is reflected between the fore feet. On the sides are seen the antennae, very small, yellowish, and that spring from under the head. The thorax, which is broad, short, and smooth, is yellow on the fore and black on the back part. The elytrae are large, of a rough black, and as it were nappy. The elytra, rather large, and crossed over each other, are a mixture of brown and yellow, not unlike the colour of rust, which makes it look cloudy. The under part of the body is brown; and at the extremity of the abdomen are to be seen a few hairs. The feet, fix in number, are of a light brown, the two hindermost having on the leg and tarsus hairs that give them the shape of fins, nor are they terminated by nails. The four anterior ones are somewhat flat, and serve the animal to swim with; but at their extremity they have nails and no hairs. This insect is seen in stagnating waters, where it swims on its back, and presents its abdomen upwards; for which reason it has been called by the Greek name of notonecta. The hinder feet, longer than the rest, serve it as paddles. It is very nimble, and dives down when you go to take hold of it; after which, it rises again to the surface of the water. It must be cautiously handled if one would avoid being pricked by it, for the point of its rostrum is exceeding sharp and intolerably painful, but it goes off in a few minutes. The larva very much resembles the perfect insect." Such is the account that Mr. Barbut gives of this beautiful nimble little creature, which we thought it our duty to lay before our readers, as this gentleman seems to have been particularly attentive to the subject. To this account, however, we shall add the following. Its legs are long; when taken out of the water it hops; it is very common in the ponds of water in Hyde-park, and in several other places about London. It is of a very particular form, being flattish at the belly, and rising to a ridge on the middle of the back; so that when it swims, which is almost always on the back, its body has much the resemblance of a boat in figure, and whence its vulgar name. It is eight lines long, three broad, and two and a half thick. The belly is jointed, striated, and, as Barbut observes, hairy. Nature has provided it with an offensive weapon resembling a sting, which it thrusts out when hurt from a large opening at the tail. The head is large and hard. The eyes of nearly a triangular form. The nose is a long, green, hollow proboscis, ending in a hard and sharp point, which in its natural posture remains under the belly, and reaches to the middle pair of legs. The outer pair of its wings are of a pale flesh-colour, with spots of a dead white; these are long, narrow, and somewhat transparent; they terminate in a roundish point, and perfectly cover the whole body. The triangular piece which stands between the top of the wings is hard, and perfectly black; the inner wings are broader and shorter than the outer ones; they are thin and perfectly transparent, and are of a pale pearl colour. The hinder pair being greatly longer than all the rest, they serve as oars; and nature has tufted them with hair at the end for that purpose. This creature mostly lives in the water, where it preys on small insects, killing them and sucking their juices with its proboscis, in the manner of the water scorpion and many other aquatic insects; and it seizes its prey violently, and darts with incredible swiftness to a considerable distance after it.

Though it generally lives in the water, it sometimes, however, crawls out in good weather; and drying its wings by expanding them in the sun, takes flight, and becomes an inhabitant of the air, not to be known for the same creature, unless to those who had accurately observed it before; when tired of flying, or in danger of an enemy, it immediately plunges into the water. We are told that there are 14 species of it, seven of which are common in Europe in waters, &c.