Shell rather thick, oval, smooth, without epidermis, spire pointed; aperture oval, larger in front, with disunited edges; the right sharp; the columella uniting itself a little with the left edge, and offering interiorly a longitudinal callosity; operculum calcareous, oval, oblong, sub-spiral, the summit at one of its extremities. Phasianella bulimoides. P. rubens. P. variegata. P. elegans. P. Peruviana. P. lineata. P. nebulosa. P. sulcata. P. Mauritiana. P. angulifera. _P. picta._ The painted Phasianella. Pl. 24, fig. 2. Species smooth, oval, glossy, volutions inflated; reddish white, with crimson or reddish brown spots; aperture sub-ovate. 7. Turritella. The Screw Shell. Thirteen species. This genus is easily distinguished from all screwlike shells by a sinus on the right margin of the aperture, not existing in any other shell of similar form. Shell marine, turreted, not pearly, rather thin, striated according to the turning of the spire, which is very pointed, and has numerous whorls; aperture rounded; the edges disunited posteriorly; the right extremity thin, and, when perfect, having a light sinus about the middle; operculum horny. Turritella duplicata. T. terebra. T. imbricata. T. replicata. T. fuscata. T. cornea. T. brevialis. T. bicingulata. T. trisulcata. T. exoleta. T. carinifera. T. Australis. T. Virginiana. _T. bicingulata._ The twice-girdled Turritella. Pl. 24, fig. 5. Species that answers to the above description. _T. terebra._ The auger Turritella. Taper, pointed, acute transverse striæ, the intermediate spaces prominent and acute; white, reddish, or cream coloured. FAMILY XVI. CANALIFERA. Eleven genera. 1. Cerithium. Thirty-six species. A beautiful and numerous genus of turreted shells, with an expanded outer lip and short beak; the greater part are marine; many are found at the mouths of rivers, and a few in lakes, though none can properly be called river shells. In appearance they are like an elongated pyramidal cone, and the spire is at least two thirds the length of the shell. The exterior is seldom smooth, but striated, tuberculated, granulated, or spinous.