The Sea Bottle Shells

THE SEA BOTTLE SHELLS Genus MYTILIMERIA, Conr.

Shell bivalve, rounded-oval, thin, fragile, usually inflated, with terminal spiral beaks, somewhat distant. Hinge without teeth; epidermis thin. Species few.

Nuttall's Mytilimeria, or Sea Bottle Shell

(M. Nuttalli, Conr.), thin and fragile, is the type. The peculiarity of the whole genus is that the mollusks live together and make a common nest. This species nests among the colonies of sea-bottles, or compound ascidians. The delicate, white, bladder-like shell is protected by a brown epidermis, and by the ascidians which conceal it. Length, i inch.

Habitat.— California.

The Mytilimeria (M. saxicola, Baird) has a protean form, as it grows to fit the hole it enters. Pear-shaped when not crowded too much, the shell has a narrow and short anterior end; it is broadened, swollen and abruptly truncated at the posterior end. The brown epidermis is rough. The hinge plate, large, thick and concave, replaces an ossicle.

This is the mollusk, without a doubt, that Baird called Lyon sia, and Keep calls by the sub-generic name Entodesma, Phil., the Rock Entodesma, E. saxicola, Baird. Length, 4 to 5 inches.

Habitat.— Puget Sound.

Genus PANDORA, Hwass Shell unsymmetrical, right valve flat, left one convex, close shut, attenuated behind; two diverging grooves from apex of left valve. A small genus widely scattered, chiefly in cold waters. About twenty-five species.

The Pandora (P. trilineata, Say) is a delicate little bivalve, in its pellucid white shell, too thin, almost, to cast a shadow. The lining of the shell is iridescent. Its hinge line 33o The Duck-bill Shells and Lantern Shells is concave, the other margins rounded. At the extreme posterior end the valves are spread apart to let the short, forked siphon tube through. The foot is finger-like. The muscles are weak, the body thin and inactive. The three lines are parallel with the margin, extending all the way around from the beak.

About Cape Cod this mollusk is plentiful. It frequents oyster beds and sandy or muddy bottoms, burrowing at varying depths. Length, I inch.

Habitat.— Maine to Florida.

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