“It is said,” returned Mrs. Merton, “that when a fisherman wishes to catch one of these creatures alive, he can bring it to the surface by throwing a little salt down the tube; but, strange to say, this plan is only successful once, and the fisherman must be on the watch to seize the shell the moment it makes its appearance, as if the animal becomes alarmed and descends a second time, the salt has no longer any effect upon it, and no efforts on the part of the fisherman can induce it to rise again.” “How very curious!” said Agnes; “but I do hope we shall find another of these creatures in time to seize it. Are they common on this coast, mamma?” “Not very, I believe,” said Mrs. Merton; “and I think the kind of which you have the half valve is not a British shell at all, but has been washed here from some other country.” They now walked on, and Agnes picked up the half of another bivalve shell, which her mother told her was called Mactra, or the Kneading Trough, from some fancied resemblance in the shape of the shell to that utensil. As this shell was not very beautiful, Agnes soon threw it away, but not before her mamma had made her observe that one of the teeth was shaped like the letter V. “There are many shells,” continued Mrs. Merton, “which are of nearly the same outward shape as this, and which can only be distinguished from each other by some peculiarities in the teeth or hinge.” Agnes now picked up another half of a bivalve shell, which she at first thought was another mactra, as the two shells bore considerable resemblance to each other; but when Mrs. Merton told her to look at the hinge she found that instead of being in the shape of a V there was a curious projection resembling a small spoon, which her mother told her fitted into a corresponding hollow in the other valve. “This shell,” continued Mrs. Merton, “is one of the kind called Gapers, because the two valves, instead of closing, are always open or gaping at one end: they are so far apart, indeed, as to admit of a large tube, containing two smaller ones, to pass through the opening. This tube the animal can draw into the shell at pleasure; but generally when the creature buries itself in the sand it allows its tube just to reach the surface in order that it may take its food by means of the small tubes within the large one. In some cases the animal buries itself so deeply in the sand that it is obliged to elongate its tube to an extraordinary length, in order to make it reach the surface; but in other cases the tube is very short. The scientific name of this shell is Mya; and the animal belonging to it is eaten in some parts of the world as an article of food.”