National Geographic : 1949 Jul
The National Geographic Magazine wooalr(al(lge \llllams A "Naked Clam," Wearing Its Shell Inside, Lives in Mission Bay, California This queer mollusk, although it closely resembles the gastropods such as small cowries, is a bivalve called Chlamydoconcha orcutti. Buried as if swallowed in the top layer of tissue known as the mantle is an internal rudimentary shell. The creature, an inch and a half long and an inch wide, moves by means of a hatchet-shaped foot which protrudes from a slit in the body. At the base of this organ is a large gland capable of spinning a tuft of fine, tough filaments used for anchoring. Photograph first published in Pacific Discovery, March-April, 1949. tongue to puncture and eat mussels and clams. Shell experts call them by their scientific names for accurate identification. But when you find Turkey Wings, Nutmegs, Rose Petals, Angel's Wings, and Chinese Alphabets lurking among the sands and driftwood you may remember more easily. Color Page 46 Here you see examples of the different shapes and the range of brilliant colors easily found by the amateur collector. Note the different tones of the two valves of the Calico Scallop. The right hand valve is the lower one, and in this species it is usually much lighter, almost white. Here is the Violet Snail. It averages one inch across. In contrast to common snails, it has a thin shell so fragile that it would be quickly broken except for this creature's peculiar way of life. The Violet Snail floats upside down sus pended from a gelatinous cushion, filled with air bubbles for buoyancy, that is part of its body. One observer says that he saw millions of these snails coloring the sea violet. The Wing Shell is characterized by unequal valves and a straight hinge line. This is the same family as the pearl-bearing oyster. (There are po true pearl-bearing oysters around Florida.) The Wing Shell has an inner coating of beautiful, iridescent mother-of-pearl. Color Page 47 These are selected to reveal a variety of delicate tints. In the upper left-hand corner you see the famous Keyhole Limpet. The limpet is unique in that it is a gastropod, a single shell, although not coiled like a snail. This one is distinguished from the regular limpets by the hole at the apex. It is most common in the Bahama Islands, but many are found on the Florida coast. The Rose Cockle is one of the joys of the amateur collector. Note that it makes a heart shaped outline. The Flesh Marginella is like an agate with beautifully polished enamel. This is sometimes called the Ruddy Rim Shell. or the Gem Shell. For those who search only in the day time it is hard to find. Dr. Bales said that he found many more of these choice Marginellas when he went after them at night with a gasoline lantern that shed a bright white light. The Marginellas are abundant on the beaches of South Africa. There is a record of 79 different species picked up on one beach at Port Alfred. In the lower left-hand corner you see the Banded Thais. This is the Florida type of the Thais, so common on the Maine coast.