a genus of fishes belonging to the order of apodes. The principal characters of this genus are the following. The head is somewhat naked; the The teeth are in the jaws, palate, and fauces; the body long; the fins of the back, tail, and anus, confounded in one; no fin on the under part of the body; and the eyes covered by the common skin. Of this genus there are several species, of which the most curious is the *ophidium barbatum* of Linnæus, thus described by Dr. Proustnet in the 7th volume of the Philosophical Transactions.

"The scales of the ophidium (says he) are irregularly placed and dispersed over the whole body. Their form is sometimes round, sometimes nearly oval. They are larger near the head, and in the lower part of the body; but are hardly to be distinguished near the tail. They adhere to the body by means of a particular transparent skin, which is in general very thin, but somewhat thicker near the neck, and extended loosely over the whole head: this skin is very easily destroyed, after which the scales falling, the body appears spotted (fig. 1.) When you look at them with the naked eye (fig. 2.) they appear as covered with very small grains; but viewed through a microscope (fig. 3.) the middle of them appears more elevated than the margin; and from the centre to the margin, close by each other, there are many lines or rays formed by small scales placed upon one another, like tiles upon a roof, the superior being always the nearer to the centre. This sort of scales, which may be called umbonate, are fastened to the body by very small vessels which are inserted in their middle; they are to be seen on the body only, not on the head nor the fins."

The anatomy of this fish comprehends some very remarkable circumstances, which, our author thinks, were never observed in any other species. When the skin is drawn off, there appears a thin membrane of a silver colour, which covers the muscles. The muscles being removed, we find the peritoneum, which lines the abdominal cavity, and is adherent to the swimming bladder by some elongations. It is of a silver hue, with some very small black points. The ventricle is not to be distinguished from the intestines by any other mark but by its size; its form is oblong; it is extended almost to the anus, from whence the intestinal duct has a retrograde course, and then defecates again, having a little dilatation near the anus. On the vertebra next the anus on the outside of the peritoneum is a kind of cavity of an oblong form, containing a reddish viscous, which he takes to be the kidney.

The first vertebra from the head has nothing very remarkable in its structure. The second has on each side an elongated and sharp apophysis, to the apex of which is annexed a small ligament. The third is very flat, and has on each side a kind of triangular and sharp apophysis, to which adheres a ligament as to the second. The fourth is remarkable in having a sharp apophysis on each side, articulated with the body of the vertebra; and under each of them is another articulated apophysis, flattish, thick, roundish at its extremities, and forked at its basis (fig. 5.) The fifth, which is strongly adherent to the former, has in its middle a bifid process. The sixth has in its middle a flattish elevation, sharp on each side. Between the extremity of the larger apophysis of the fourth vertebra is a bone, or rather a hard cartilage, which bears the figure of a kidney (fig. 6.) its convexity being turned towards the body of the vertebra; its position is parallel to the bodies of the vertebrae; its motion is half circular; one of its parts, viz. the lowest, being in the cavity of the swimming bladder, to which it adheres by a thin membrane, so that no air can escape at that part. It is covered by membranes, which adhere strongly to its middle; in this part are fastened the two ligaments of the apophysis of the second and third vertebrae, of which we spoke before, and which are of a great tenacity. In the same point are fastened also two ligaments, each of which belongs to an oblong muscle parallel to each other, and fixed to the bones of the lowest and posterior part of the head (fig. 4.)

All this apparatus is certainly subservient to the purpose of swimming; but it is very remarkable, that if these parts are necessary to some animal function, they should not be found in all the individuals; "for I have seen (says our author) two, of which the vertebrae were not different from the vertebrae of the other species; which difference depends, perhaps, on the difference of sex. I am inclined to believe so; but the generation in this fish seems to be no less mysterious than that of the eel: I could never distinguish a male from a female in this species."

This fish commonly grows to the size of eight or nine inches. It is to be found in all the Mediterranean sea, and in great plenty in the Adriatic: its flesh is not of a good taste, rather coarse, as is that of all the species of fishes which, having no ventral fins, are obliged to make great efforts in swimming, and have consequently the muscles harder.