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Any small creeping marine gastropod, as the species of Littorina, Natica, etc.

s in a sewing machine. -- Shuttle shell (Zoöl.), any one of numerous species of marine gastropods of the genus Volva, or Radius, having a smooth, spindle- shaped shell prolonged into a channel at each end.

One of the tubes or folds of the mantle border of a bivalve or gastropod mollusk by which water is conducted into the gill cavity. See Illust. under Mya, and Lamellibranchiata.

Any one of numerous species of limpet-shaped pulmonate gastropods of the genus Siphonaria. They cling to rocks between high and low water marks and have both lunglike organs and gills. -- Si`pho*na"rid, a.

A tribe of gastropods having the mantle border, on one or both sides, prolonged in the form of a spout through which water enters the gill cavity. The shell itself is not always siphonostomatous in this group.

An artificial division of gastropods including those that have siphonostomatous shells.

rolonged in the shape of a channel for the protection of the siphon; -- said of certain gastropods.

Any species of Pleurotomaria, a genus of beautiful, pearly, spiral gastropod shells having a deep slit in the outer lip. Many fossil species are known, and a few living ones are found in deep water in tropical seas.

Any one of numerous species of terrestrial air-breathing gastropods belonging to the genus Helix and many allied genera of the family Helicidæ. They are abundant in nearly all parts of the world except the arctic regions, and feed almost entirely on vegetation; a land sanil.

The anterior prolongation of the head of a gastropod; -- called also rostrum.

llusca belonging to the Isopleura. A narrow groove takes the place of the foot of other gastropods.

Any marine gastropod of the genus Fusus. Dead spindle (Mach.), a spindle in a machine tool that does not revolve; the spindle of the tailstock of a lathe. -- Live spindle (Mach.), the revolving spindle of a machine tool; the spindle of the headstock of a turning lathe. -- Spindle shell. (Zoöl.) See Spindle, 7. above.…

Any marine gastropod shell of the genus Apporhais having an elongated siphon. See Illust. under Rostrifera.

Any one of several species of handsome gastropod shells of the genus Trochus, or Imperator. The shell is conical, with the margin toothed somewhat like the rowel of a spur.

of leather, or strip of wood covered with a suitable material, for sharpening a razor; a strop.

An extensive division of gastropod Mollusca in which the loop or visceral nerves is twisted, and the sexes separate. It is nearly to equivalent to Prosobranchiata.

A genus of marine gastropods in which the shell has the outer lip dilated into a broad wing. It includes many large and handsome species commonly called conch shells, or conchs. See Conch.

A mountain range owing its origin to the progress of a geosynclinal, and ending in a catastrophe of displacement and upturning. Dana.

An extensive division of gastropod mollusks in which the odontophore is long and narrow, and usually bears seven rows of teeth. It includes a large number of families both marine and fresh- water.

An order, or suborder, of gastropod Mollusca in which the gills are usually situated on one side of the back, and protected by a fold of the mantle. When there is a shell, it is usually thin and delicate and often rudimentary. The aplysias and the bubble shells are examples.