PULMONATA n.
An extensive division, or sub-class, of hermaphrodite gastropods, in which the mantle cavity is modified into an air- breathing organ, as in Helix, or land snails, Limax, or garden slugs, and many pond snails, as Limnæa and Planorbis.
RHACHIGLOSSA n.
A division of marine gastropods having a retractile proboscis and three longitudinal rows of teeth on the radula. It includes many of the large ornamental shells, as the miters, murices, olives, purpuras, volutes, and whelks. See Illust. in Append.
RIVER n.
-- River pirate (Zoöl.), the pike. -- River snail (Zoöl.), any species of fresh-water gastropods of Paludina, Melontho, and allied genera. See Pond snail, under Pond. -- River tortoise (Zoöl.), any one of numerous fresh-water tortoises inhabiting rivers, especially those of the genus Trionyx and allied genera. See T…
SCALARIA n.
Any one of numerous species of marine gastropods of the genus Scalaria, or family Scalaridæ, having elongated spiral turreted shells, with rounded whorls, usually crossed by ribs or varices. The color is generally white or pale. Called also ladder shell, and wentletrap. See Ptenoglossa, and Wentletrap.…
SCREW n.
, a steam vessel propelled by a screw. -- Screw shell (Zoöl.), a long, slender, spiral gastropod shell, especially of the genus Turritella and allied genera. See Turritella. -- Screw steamer, a steamship propelled by a screw. -- Screw thread, the spiral which forms a screw. -- Screw stone (Paleon.), the fossil stem…