FAMILY MYIDIE Shell strong, opaque, unequal, gaping; cartilage process flattened on left valve; ligament internal; epidermis wrinkled; mantle edges united except at pedal aperture; foot small; siphons long, united, retractile; gills two on each side, elongated.
Genus MYA, Linn.
Shell oblong, thin, soft, chalky; left valve smaller; gape at both ends; pallial sinus large; foot tongue-like; palpi free. Three living species; seventeen fossil in United States and Europe.
The Clam (M. arenaria, Linn.) is found on gravelly mud flats of river mouths from South Carolina to Green land and Great Britain; by colonisation it has become estab lished in San Francisco Bay. Its normal station is between high and low tide marks. Even rocky shores may harbour it, the mollusk burrowing in the sediment deposited in crevices. The animal lies head downward, its siphon tube extending upward into the water, if the tide is in; in any case, to the surface of the sand, or mud, to get a supply of food and oxygen. The limit of depth reached is about one foot.
Walk over the territory of the sand clam, at low tide, and little vertical spurts of water show where the siphons have been suddenly drawn down as a measure of safety. The length of the siphon exceeds that of the shell, which is as big as the palm of your hand. The mantle is prolonged into a tough protective sac to the fringed tips of the united siphons. A small hole at the
opposite end gives egress to the pointed foot, the organ by which the mollusk travels through sand and mud.
Inferior to the quahog in popularity, the sand clam is, never theless, an important food mollusk. Up and down the Atlantic coast, in San Francisco and in British coast towns, the demand 324 The Soft-Shell Clams. Sand Clams for it is steady and large. It was the original basis of the famous Rhode Island clam chowders. In the fishing banks it is used, fresh and salted, for bait. In Greenland the walrus,Arctic fox and many birds are especially fond of it. The Pilgrims learned its value from the Indians. John Winthrop listed among the ani mals of Plymouth in 1634: "Clams—white. Their broth is most excellent in all intermitting fevers, consumption, etc. These clams feed only on sand." The Indian name, "maninose," corrupted to "nannynose," is often used on the east coast. "Sand clam" and "soft-shell clam" are oftener heard. In English markets ask for "sand gaper" or "old maid," and you will get the familiar Mya arenaria.
The Truncated Mya (M. truncata, Linn.), with its posterior end abruptly squared, but otherwise agreeing with the characters of the better-known species, inhabits northern seas.
Habitat.— Puget Sound.