SOLEN, the RAZOR-FISH, a genus of insects belonging to the order of vermes testacea. The shell is oblong, bivalved, and opening at both sides; the cardo has a subulated reflected tooth, not inserted into the opposite valve. There are eleven species, distinguished by peculiarities in their shells. Three of them, viz. the filiqua, vagina, and ensis, are found on the British coasts, and lurk in the sand near the low-water mark in a perpendicular direction. When in want of food, they elevate one end a little above the surface, and protrude their bodies far out of the shell. On the approach of danger they dart deep into the sand, sometimes two feet at least. Their place is known by a small dimple on the surface. Sometimes they are dug out with a shovel; at other times they are taken by striking a barbed dart suddenly into them. When the sea is down, these fish usually run deep into the sand; and to bring them up, the common custom is to throw a little salt into the holes, on which the fish raises itself, and in a few minutes appears at the mouth of its hole. When half the shell is discovered, the fisherman has nothing more to do than to take hold of it with his fingers and draw it out: but he must be cautious not to lose the occasion, for the creature does not continue a moment in that state; and if by any means the fisherman has touched it, and let it slip away, it is gone for ever; for it will not be decoyed again out of its hole by salt; so that there is then no way of getting it but by digging under it, and throwing it up with the sand. The fish has two pipes, each composed of four or five rings or portions of a hollow cylinder, of unequal lengths, joined one to another; and the places where they join are marked by a number of fine streaks or rays. Now the reason why the salt makes these creatures come up out of their holes, is, that it gives them violent pain, and
even corrodes these pipes. This is somewhat strange, as the creature is nourished by means of salt-water; but it is very evident, in that if a little salt be strewed upon these pipes in a fish taken out of its habitation, it will corrode the joinings of the rings, and often make one or more joints drop off: the creature, to avoid this mischief, arises out of its hole, and throws off the salt, and then retires back again. The use of these pipes to the animal, is the same with that of many other pipes of a like kind in other shell-fish; they all serve to take in water: they are only a continuation of the outer membrane of the fish, and serve indifferently for the taking in and throwing out the water, one receiving, and the other discharging it, and either answering equally well to their purpose.
When one of these fish is taken out of its hole, and laid upon the sand, if any thing touches it, it immediately gets in order for its progressive motion. It throws out a long cylindric part, of half the length of the shell, and of the shape of a clapper of a bell; this is suspended to the middle of the animal by a ligament, but in all other parts it is loose: this serves as a leg to the creature. As it lies upon the sand, it extends this about an inch from the end of the shell, and changes its cylindric figure to a flat one, which terminates in a point, flat and sharp at the edges; with this it opens its passage into the sand. When the opening is made, it extends this part still farther, and buries it deeper; and after this bends it back again in such a manner, that its point turns up towards the shell: thus it gives this part the figure of a hook, and by this hook it draws its whole body and shell down. In this attempt it brings the edges of the shells every where close together; and instead of lying flat upon the sand, it now by degrees gets into a vertical position, and then there remains nothing to do but to draw it deeper into the sand. To effect this, it now again extends its leg, which it easily passes into the sand in its flattened shape; and when it has thus pierced to its utmost length, the creature inflates, and extends it by degrees to the size of the shell, and to a round or cylindric figure; the consequence of which is, that there is now a hole made of the shape of the shell, and equal to its diameter, into which it can easily sink: to facilitate this, however, the creature swells out the extremity of the leg into a sort of button, which holding fast in its place, nothing more is necessary than to contract the rest of the leg, in order to pull down the shell after it. This operation is repeated as often as is necessary, and the creature, at every movement of this kind, getting down half the length of its shell, or thereabouts, is very soon plunged as deep as its occasions require.
When it has occasion to ascend out of its hole, the same leg serves for that purpose; nothing more being required, than the putting out the end of the leg, swelling it, and thus thrusting itself up to the length of that leg; then retracting it into the shell again, and thrusting out and inflating its end for a second movement of the same kind. These motions may be all perceived in the creature when out of the sand, particularly that by which it buries itself; for if held up in the fingers, it thrusts out the leg, and performs all the motions as if in the sand, making a fruitless attempt to save itself in its old way.
These fish were used as food by the ancients; and Athenæus, from Sophron, speaks of them as great delicacies, and particularly grateful to widows. They are often used as food at present, and are brought up to table fried in eggs.