Haliotis, the ear-shell, is remarkable for its brilliant colours, and for a line of singular perforations in many of the species.
The seventh family, Turbinidæ, contains Trochus, Turbo, Protella, Monodonta, and Delphinula.
The genus Trochus are found in all seas, and near to the shore in the clefts of rocks, especially in places where sea-weeds grow luxuriantly. Some of these thick, cone-shaped shells are extremely beautiful, being richly nacred inside, and remarkable for the beauty and diversity of colour exhibited. Generally smooth, the great spiral is, nevertheless, sometimes edged with a series of regular spines. The form is conical, the spiral more or less raised, broad and angular at the base; the opening entire, depressed transversely, and the edge disunited in the upper part.
Fig. 219. Trochus niloticus (Linnæus). Fig. 220. Trochus virgatus (Gmel.).
Fig. 221. Trochus inermis (Gmel.). Fig. 222. Trochus Cookii (Chemnitz).
Fig. 223. Trochus imbricatus (Gmel.). Fig. 224. Phorus conchyliophorus (Borfu).
The animal which inhabits this shell is also spiral; its head is furnished with two conical tentacles, having at their base eyes borne on a peduncle; its foot is short, round at its two extremities, edged or fringed in its circumference, and furnished with a horny operculum, circular and regularly spiral.
The family is divided into many sub-genera. Among the Trochi, properly so called, we may notice Trochus niloticus (Fig. 219), T. virgatus (Fig. 220), T. inermis (Fig. 221), and T. Cookii (Fig. 222).
Fig. 225. Turbo margaritaceus (Linnæus). Fig. 226. Turbo argyrostomus (Linnæus).
