(See Encycl.). Two new species of this genus of insects were discovered by La Martinière, the naturalist who accompanied Peroufe on his last voyage of discovery. For the information of such of our readers as are entomologists, we shall give the author's description of these species. Of the first, which he says only nearly answers to the generic character of oniscus, E (fig. 1.) is a view of the upper part of its body, and at F of the lower. Its body is crustaceous, and of an opaque white, with two round pink-coloured spots on the anterior part of its corset; two others, much larger, in the form of a crescent, are on the elytra; its fluid is also of the same colour. The under part of the thorax is furnished with four pair of legs: the first and third of which are terminated with sharp claws; the second, from its form, serves it to swim with; the fourth is very small, consisting of two membranaceous threads. Some scales, also membranaceous and very channelled, may also perform the office of legs: of these the two lower are the largest. Its belly is filled with vermicular intestines of the size of a hair; its mouth is placed between the first and second pair of legs, and is of the form of a small trunk placed between two lips, joined only at the upper extremity.

Fig. 2. represents an insect of the genus oniscus flem. Its body is nearly of the form, confidence, and colour, of the oniscus aeflum, except that it is not divided Opaque, vided by segments as this last is. It has a double tail, three times as long as the body; from the insertion of which, at the hinder part of the body, spring two legs, used chiefly by the animal in swimming upon its back.

The insect, viewed on the lower part H, presents five pair of legs; the two first of which terminate in very sharp and thick points; it makes use of the third to swim with, and to balance its body, together with that pair which is inserted at the base of the tail; the fourth pair, and the largest of all, is armed with two very sharp points, which the animal forces into the body of any fish on which it seizes; the two last pair are nothing more than very finely divided membranes. Between the two first is situated its trunk, smooth, and about half a line long; at the base of the third pair are two points, of a horny consistence, very hard, and firmly fixed. The two horns also below the large pair of legs are, in like manner, very firmly united to its body. Martiniere imagines it to be by means of these darts that it pierces the body of the fish on which it is found, and that then, changing its situation, it finds means to introduce its trunk into the holes thus formed. When put into a glass it sinks to the bottom, and rises again to the surface with the greatest ease, advancing with the edge of its body, and describing curves. Its two long tails are very easily pulled off, without the animal appearing to suffer any pain.