Habitat.— Nova Scotia to Cape Hatteras, west coast of Florida.
Sub-genus CALLISTA, March The Giant Callista (C. gigantea, Gmel.) is shaped and painted like a sunset shell, but the plaid pattern is oftenest developed in dull blue, lilac or gray, on a pale ground. A brown band of some width is set a little back from the margin. The hinge is nearer the anterior end. The posterior end is elongated, and pointed to a slight degree. The china-like shell is covered with a livid or pink epidermis. This species is especially abundant on the beaches of western Florida. Length, 5 to 6 inches; width, 3 inches.
Habitat.— Cape Hatteras to Texas.
The Spotted Callista (C. maculata, Linn.) is oval, ventricose, with a shiny surface, fawn-coloured, with broken radiating bands of violet-brown, and chevron prints in the spaces between the bands. A horny epidermis covers the shell. The flesh is edible as is also the giant Callista's, but both have a peppery taste one must learn to like. Length, 4 inches; width, 3 inches.
Habitat.— Cape Hatteras to Texas.
Sub-genus TIVELA, Link.
The Thick-shelled Tivela (C. crassatelloides, Conr.) is one of the finest, as well as largest, of California clams. Walk along the beach at ebb tide, and you may see a depression like a thumb print, deep in the sand. Dig a few inches with a convenient shell scoop, and you reach the great three-angled clam, which reminds you of the surf clam, Mactra solidissima, of the east coast. The thick valves are scored with growth lines, yellowish but painted with streaks or rays of purple and hints of red. The lips of the valves are thick and rounded. A single clam often weighs a pound.
349 The Venus Clams and Carpet Shells Yet a walk of half a mile on the sand at Long Beach often yielded five Tivelas, quite enough to make a royal chowder for a family of ten. In some places the farmers run ploughs through the beach sand, and turn clams out like potatoes in a field. They are often in the markets. Street venders sell them from push carts at five cents each. Length, 5 inches.
Habitat.— Southern California.
Sub-genus DIONE, Gray Venus Dione (C. Veneris, Desh.) represents a beautiful
group of Cythereas whose distribution centres in Australia. The rosy pink polished shell is a compact, ventricose little box, with the posterior area set off by abrupt angular ridges. These two ridges bear long, curving spines in two rows. The surface of the valves is scored concentrically and lamellar ridges rise between the sulci. The colour sometimes shades into deep violet. This is one of the most striking and handsome of bivalve shells. Length; 2 to 3 inches.
Habitat.— West Indies, Central America.
The Orange Dione (C. aurantia, Desh.) is a larger shell with bold ovate-globose form, the angled ridges spineless and scarcely showing at all. The smooth, polished surface is a rich orange colour. Length, 4 inches.
Sub-genus AMIANTIS, Cpr.
The White Amiantis (C. callosa, Conr.) is a pure white, oval shell, covered with concentric, lamellar ridges, often double. The hinge is set forward a trifle. Length, 3 to 4 inches.
Shells of sub-genus Circe show beautiful chevron markings.
Genus DOSINIA, Scop.
Shell orbicular, compressed, concentrically lamellate or striated, a deep lunule under the small beaks; hinge teeth, three in each valve; ligament external, partly concealed; siphons united; mantle margins plaited; foot large, squarish.
The Disk Dosinia (D. discus, Rve.) is shaped like the discus 35o The Venus Clams and Carpet Shells used in the Olympian games. The minute umbones top the circle with an acute point. The surface is finely scored with concentric lines. The epidermis is transparent and yellowish on the white valves. Diameter, 3 inches.
Habitat.— Virginia to West Indies, Texas.
The Heavy Dosinia (D. ponderosa, Gray) is yellowish-brown and smooth outside, except for fine growth lines. The deep lunule is cordate. The valves are white and thick, but the lips are thin as knife blades. Diameter, 4 inches.
Habitat.—Peru to San Pedro Bay, Cal.