5. Genus Planaxis. Pl. [XI].

Animal. Unknown.

Shell. Ovate conical, solid; aperture ovate, sublongitudinal, columella flat and truncated at the base, separated from the right margin by a narrow sinus. Interior surface of the right margin furrowed or lineated, and a callosity running under the summit. Inhabits the American and W. Indian seas. Four species.

6. Genus Phasianella. Pl. [XI].

Animal. Spiral; foot oval; upon each side an appendage ornamented with filaments; head edged anteriorly with a kind of veil formed by a double, bifid, fringed lip; two, long, conical tentacula; eyes borne upon short peduncles and situated at the external part of their base; mouth between two vertical subcornate lips.

Shell. Marine; many of them very rare and valuable; their beauty of colouring disposed so as to resemble the plumage of a pheasant. Oval, rather thick, smooth and glossy, spire pointed; columella uniting itself with the left edge, forming interiorly a longitudinal callosity; aperture oval, larger before, with edges disunited; operculum calcareous, oval, oblong, subspiral, the summit at one extremity. Inhabits the British coast. Twelve species.

7. Genus Turritella. Pl. [XI].

Animal. Spiral; foot fringed anteriorly by a transversely wrinkled band; tentacula long, very fine towards their extremity, somewhat thick at their base, and having the eyes upon an inflation; the head skirted with a veil or fringe garnished with filaments.