in zoology, a genus of insects belonging to the order of hemiptera. The rostrum is inflected; the antennae are shorter than the thorax; and the hind-feet are hairy, and fitted for swimming. There are seven species. The four wings are folded together cross-wise, with the anterior part coriaceous. The two fore feet are cheliform, or resemble the claws of a crab; the other four are formed for walking. We have but three species of this genus, all three of which are found in the water, where they dwell, as do their larvae and chrysalids. It is likewise in the water that we find the eggs of the water-scorpion. Those eggs, of an oblong shape, have at one of their extremities two or more bristles or hairs. The insect sinks its egg into the stalk of a bull-rush or some other water-plant, so that the egg lies concealed, and only the hairs or bristles stick out, and are to be seen. One may easily perceive in water those stalks loaded with eggs, and see the young water-scorpions hatched under one's own roof, or at least their larvae. These insects are voracious, and feed on other aquatic animals, which they pierce and tear with their sharp rostrum, while they hold them with the forceps of their fore-feet.—They fly well, especially in the evening and night, and they convey themselves from one pool to another, especially when that they are in begins to dry up. Mr Geoffroy affirms, that the pedes cheliformes, or fore-feet of the nepa, are the antennae of the insect, which, according to him, has but four feet.