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. 3. Delphinula. Three species. A marine shell, which, like the Scalaria, has a round aperture, but its solidity and pearly substance distinguishes it from the Cyclostoma, which is terrestrial. Shell thick, pearly in the interior, sub-discoid or conical; the spiral whorls sometimes detached, rounded, spiny, with a large umbilicus; aperture round or multrigonal, not modified; edges perfectly united with a small spire, tuberculated exteriorly. Delphinula laciniata. D. distorta. D. turbinopsis. _D. laciniata._ The fringed Delphinula. Pl. 23, fig. 5. Shell depressed, umbilicus large, surrounded by large vaulted scales in spiral rows; strong waved spiral striæ; colour reddish purple, variegated with white. FAMILY XV. TURBINACEA. Seven genera. 1. Solarium. Seven species. Some shells of this genus are highly valued for their beauty and rarity. Shell orbicular, involuted almost in the same plane; Planorbis-shaped; the spire of the right side very depressed; umbilicus large and conical, with edges denticulated or not at the entrance; aperture not modified by the last whorl of the spire, which is entirely flat; no columella. Solarium perspectivum. S. granulatum. S. lævigatum. S. stramineum. S. hybridum. S. variegatum. S. luteum. _S. perspectivum._ The perspective Solarium. Pl. 23, fig. 4. Species very carinated in their circumference; the aperture square; umbilicus large and crenated; colour yellowish, with brown and white bands on the sutures of the volutions. _S. variegatum._ The variegated Solarium. Species sub-carinated, aperture sub-orbicular. 2. Trochus. The Top Shell. Sixty-nine species. This genus derived its name from its resemblance to a top. The shells are marine, found in almost all parts of the world; some are smooth, but the greater number are covered, with knobs, spines, tuberculations, or undulations.