After having examined the manner in which one instrument, the hand, is modified and adapted to a variety of purposes in different animals, there remains only this mode of elucidation—that we contrast it with its imperfect substitutes in other creatures. I might, indeed, have shown in the insect tribes the most curious examples of instruments for similar purposes with the hand and fingers of man; but I have intentionally confined this inquiry to the higher classes of animals.

The habits of some fishes require that they should cling firmly to the rocks or to whatever presents to them. Their locomotive powers are perfect; but how are they to become stationary in the tide or the stream? I have often thought it wonderful that the salmon or the trout, for example, should keep its place, night and day, in the rapid current. In the sea, there are some fishes especially provided with means of clinging to the rocks. The lump-fish, cyclopterus lumpus fastens itself by an apparatus which is on the lower part of its body. The sucking fish, remora, has a similar provision on its back. It attaches itself to the surface of the shark and to whatever is afloat; and, of course, to the bottoms of ships. The ancients believed it capable of stopping a ship under sail, and Pliny, therefore, called it remora.