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Family Pleurotomidae

Genus PLEUROTOMA, Lam.

SHELL spindle-shaped, with anterior canal of more or less length; aperture oval; lip thin, notched near the suture; operculum usually present, horny, annular; head broad; tentacles wide apart, with eyes at base; siphon long; mantle border notched below notch in shell; radula present; teeth long, hollow, connected with poison gland. A large family of little known shells found in all seas.

The spindle-shaped shell, drawn out at both extremities, has the tell-tale anal slit, or notch, in the outer lip near its juncture with the spire. By this sign we know them. Some have the anterior canal short, but the spire is always elongated. Reeve lists 369 species. Many of these are described from single specimens, so the number is probably far too great.

The Great Notch-side (P. grandis, Gray), the largest species, is six inches long; its greatest diameter is about one inch. In this graceful spindle-shaped shell one sees the notch-sides at their best. The whorls are delicately chiselled in many sharp revolving ridges, with fine raised striae between. Broken longitudinal and spiral lines of brown handsomely decorate the yellowish exterior. The finest and closest dots follow the sutures.

Habitat.--China Seas.

The White Notch-side (P. Virgo, Lam.) shows a glossy white surface where the horny epidermis is removed. Its whorls are deeply cut into ridges, the central one forming a strong keel. A series of these shells exhibits considerable variation. The spire is in every case longer than the canal. The name "White Tower of Babel," has been given this species. Length, 3 to 4 inches.

Habitat.--West Indies.

Carpenter's Notch-side (P. Carpenteriana, Gabb.) has a regular spindle shape, tapering gracefully to base and apex. But it is not drawn out into needle-like extremities as some species are. Its whorls are flat, sculptured by revolving grooves and marked by brown lines that follow the strongest ridges. The ground colour is yellow, with a tinge of red. The notch is a mere sutural curve in the lip. The aperture widens below. Length, 2 to 3 inches.

Habitat.--California.

The Left-handed Notch-side (P. perversa, Gabb.) coils its ten or twelve rounded whorls so that the aperture is on the left side, contrary to the usual univalve rule. This is a slim little shell with very graceful curves, including a very decided S shape in the lip which forms a deep notch below the suture. Wavy longitudinal striations cross the whorl which are sculptured with fine spiral lines. The colour is reddish brown with an indistinct band of white in the middle of the whorl. Over all, in life, is a greenish gray epidermis. Length, 1 to 2 inches.

Habitat.--Southern California.

The Tipsy Notch-side (P. vinosa, Dall) is a shorter, stouter shell, with rounded whorls and deep sutures. It is sinistral and has a wide notch formed by the S-curved lip. Length, about 1 inch.

Habitat.--Aleutian Islands.

The Girdled Notch-side (P. circinata, Dall) is a well proportioned spindle shell, coiled dextrally; each whorl has a central raised girdle or keel. The lip flares outward to form the notch. Half the length of the shell is occupied by the large aperture. Length, 2 to 3 inches.

Habitat.--Behring Sea.

The Unarmed Notch-side (P. inermis, Hds.) represents a section of the genus distinguished by the slender spire, short curved canal, thick lip, and a sinus near (but not reaching) the suture. The pinkish gray exterior is cut by fine revolving ridges and cross grooves with a sharp angle at the middle of each whorl, giving it the appearance of "herring-bone" decoration. The colour shades deeper in the hollows. Length, 1 2/3 inches.

Habitat.--Southern California.

The Carved Notch-side (P. incisa, Carp.) is shaped like the preceding species, but smaller, with more convex whorls, and sculptured with fine revolving chestnut lines. It is a fraction over an inch in length.

Habitat.--Puget Sound.

P. maesta, Cpr., is found on Southern and Lower California beaches under stones when the tide is out. Its brown shell is strongly cross-ribbed, with beaded and spotted sutures between the whorls. Length, about 1 inch.

P. torosa, Cpr., is cross-ribbed along the shoulder of the whorls, the protuberances contrasting with the brown ground colour. Length, over 1 inch.

Habitat.--Southern California.

Genus DRILLIA, Gray

Allied to Pleurotoma, and closely resembling it, but smaller and more delicately made throughout. Well represented on our west coast.

The Pencilled Drillia (D. pencillata, Cpr.) I first found alive on the sand at Terminal Island, below San Pedro harbour. It had been a notable day, for I found a large Pomaulax alive on the rocks at Dead Man's Island. The old jetty had yielded living Pectens, Pteronoti, Olivellas, bubble shells, and even a devil-fish of handy size to carry home. My good luck as a collector came from having as a guide Mrs. Oldroyd, whose wide knowledge of the molluscan life of the Pacific coast is recognised by all modern conchologists. She had her reward in the discovery of a rare species of Thracia, and in showing a stranger the rich fauna of San Pedro.