FAMILY BULLIINE Genus BULLA, Linn.
Shell thin, smooth, ventricose, almost globular; spire pol ished, deeply pitted; lip plain; body large, fleshy, partially enveloping the shell by reflexing the two wing-like parapodia. Eyes prominent on frontal disc. Quantities of mucus are se creted by the skin to keep it moist while the tide is out.
The food of Bulla is molluscan; the creature burrows in the sandy mud and captures small bivalves and snails which it swal lows whole and grinds to fragments between the strong walls of the gizzard. The mantle flaps are used in swimming.
The Cloudy Bubble Shell (B. nebulosa, Gld., B. Gouldiana, Pils.) 1 have often found on the mud flats of San Pedro, and watched the captive slowly stow away the viscid bulk of its great foot within the ample shell. 1 have washed away the slimy mud, and admired the cloudy splotching of yellow and brown on its 244 The Shell-bearing Sea Slugs polished surface. I have boiled my bubble shells with the utmost care, and delicately set about extracting the fleshy parts from shells. Alas ! every time they went the way of all bubbles. In fragility, as well as in form and coloration they are like the shells of certain birds' eggs. Like other collectors, I have grate fully accepted shells cleaned by the little black side-stepping crabs that throng the rocks of the breakwater and the old jetty. Length, 2 inches.
Habitat.— Southern California.
The largest bubble shell is B. ampulla, Linn., from the Philippines, as big as a hen's egg. The most vivid in colouring is B. cruentata, A. Ads., "the blood-stained Bulla," from the Moluccas.
The Florida Bubble (B. occidentalis, A. Ads.) is small,
but it has the characteristic apical pit, and gaping mouth as long as the thin, oval shell. The body is large, the foot lobes turning back so as to envelope the shell almost completely. The surface is polished, minutely scored both ways, pale mottled with warm brown in a vague pattern. On the gulf coast of Florida the beach is sometimes strewn thickly with these shells after a storm. They are West Indian, and venture no further north than Florida, chiefly on sandy beaches toward the southern end. Length, I inch.
Genus HAMINEA, Leach H. solitaria, Say, is a little bubble shell, bluish white or brownish, thin and fragile, finely striated, found in muddy, sheltered bays south of Cape Cod. In the neighbourhood of Woods Holl, Mass., and along the shallow borders of Vineyard Sound it is abundant. Length, a inch.
Habitat.— Atlantic coast.
H. vescicula, Gld., is a fragile, pale yellowish green species of the west coast. It has the form of the typical bubble shell, and, lives in muddy shores near the mouths of rivers, mingling with a vegetable diet such small crustacea and shell fish as it is able to capture and swallow. The powerful gizzard, armed with teeth, does the rest.
The Green Bubble Shell (H. virescens, Gld.) prolongs the lip into a scoop which is quite inadequate to protect the 245 The Shell-bearing Sea Slugs body. Length, inch. It is found well concealed on mossy rocks on Southern California coast.
Thin, handsomely banded bubble shells, partially internal, are included in genus Aplustrum and a sub-genus, Hydatina.