A marine shell, with a circular aperture like the Cyclostoma, but easily
distinguished by its turreted form; longitudinal, elevated ribs, never
connected together, rather oblique, and sharp; the shape of the shell is
elegant, being a spiral cone, formed by gibbous whorls, unconnected by a
columella, gradually increasing from the apex to the base. The colour is
generally yellowish or brownish white. When perfect and of good size,
they are of great value and highly prized.
Shell sub-turreted, the whorls of the spire more or less pressed and
garnished with interrupted longitudinal ribs, formed by the successive
preservation of the reflected margin of the aperture, which is small,
perfectly round, with edges united, thickened, and outwardly reflected;
operculum horny and thin.
Scalaria pretiosa.
S. lamellosa.
S. coronata.
S. varicosa.
S. communis.
S. Australis.
S. raricosta.
_S. pretiosa._ The precious Scalaria, more commonly called the Wentle
Trap, or Winding Staircase. Pl. 23, fig. 1.
This shell has its spiral whorls separate, and appears like an
attenuated tube evolved round a cone; spire detached, with a deep
umbilicus; volutions connected by longitudinal ribs; body extremely
ventricose; colour cream yellow.
_S. communis._ The common Scalaria, or false Wentle Trap.
More taper and elongated than the S. pretiosa. It has no umbilicus, and
the whorls are closely united.