“Look, here are two projecting parts with a hollow part between. The projecting parts are called the teeth, and you see they are so placed that the teeth of one valve fit into the hollow part of the other. The creature, which is something like an oyster, and is eaten, can open and shut these valves at pleasure, and it can push out a long elbow-like part of its body and spring forward to a considerable distance when it wishes to leave the sand and return to the sea. Look, too, how delicately this valve that you have found, is ribbed, and observe the form of the shell. You see it bears some resemblance to a heart, and hence the scientific name of the genus is Cardium, which signifies a heart.”
Agnes now picked up another shell, and her mother smiled when she discovered that it was a Whelk, or Buckie. “My dear Agnes,” said she, “you certainly cannot boast of finding any very rare shells in your travels; for the whelk is nearly as common as the cockle. However, there is a material difference between them, for the whelk, or buccinum, is a univalve, that is, its shell is only in one part, like that of the snail. Look at this shell, and you will perceive a curious little notch at the lower end; and when there is this mark we know that the animal inhabiting the shell is carnivorous, that is, it lives on other creatures of its own kind. The common garden snail, which, you know, lives on vegetables, has no notch.”
Agnes now saw several shells lying scattered about, but she scarcely condescended to look at them, till at last, one appeared so curious that she could not help calling her mamma’s attention to it. It was a long narrow shell, something resembling the handle of a pocket knife. What she picked up, however, was only the half of what was evidently a bivalve-shell, and to Agnes’s great annoyance, it was by no means perfect. Mrs. Merton, however, told her that it was what was called a Solen, or Razor-shell, or, sometimes, a Sheath-shell, from its resemblance to the handle, or sheath of a razor. She also showed her the hinge that united the two valves together, and which, though very slight, was curiously formed.
While Mrs. Merton was speaking, Agnes saw another shell nearly similar to the first, but smaller and prettier, and the little girl ran with great delight to pick it up. Just before she reached it, however, she saw it raise itself on one end, and then instantly disappear in the sand.