in zoology, a genus of insects belonging to the order of aptera. It has 14 legs, bristly feelers, and an oval body. There are 15 species; of which the most remarkable are,

1. The entomum, or sea wood-louse, is white; eyes black; convex above, beneath flat, margin acute; Antennae 4: Four hind pair of legs largest, hairy. Body of 10 segments. Length 1½ line. Found on the coast. It accompanies the herring, and is an enemy well known to our fishermen; these insects will frequently eat up a whole fish while it hangs in the net.

2. Oniscus aquaticus, is of an ash-colour, and tolerably smooth. Its body is composed of seven articulations, exclusive of the head and tail; which last part Onkelos is much larger than the other segments, round at the extremity, and from which issue two appendices, each divided into two threads. This insect has in common with some sea-onisci, but differs from them by the sea ones having ten segments. This has seven legs on each side; the last of which gradually increase in length, and are constantly larger than the foremost. The antennae have but three long articulations, the last of which is much longer than the rest. This insect is found in pools, small rivulets, and especially in springs.

3. *Afellus, milleper,* or wood-louse, is oval; the tail obtuse, with two undivided bristles; various as to colour; length; 5 lines. Their use in medicine is well known.

4. *Oniscus armadillo* is broad, very glossy, and smooth; its colour is black, with a small portion of white on the edge of the segment, which colour often varies; but still the insect is glossy and smooth. Its body is composed of ten segments, besides the head and tail. Of the ten segments, the first seven are broad, and the last three short. The first of these three appears divided in the middle, which is broader than the rest, into three more. These last short segments, with that of the tail, form the extremity of the animal's body, which is round, without any appendix, and constitutes the specific character of this insect. It has fourteen feet, seven on each side. This oniscus, when touched, rolls itself up into a ball, bringing its head and tail together like the animal called armadillo, and neither antennae nor feet are seen: it might be taken for a round, shining pearl. This oniscus is found in woods.