2. The Muricidæ, of which the Murex (an extraordinary form of this is the "Venus' comb," Murex tenuispina, [Fig. 9]), the Mitre-shells, and the Red-Whelks (Fusus) are examples.
3. The Buccinidæ, taking its name from its type, the Common Whelk (Buccinum undatum), and including such other forms as the Dog-Whelk (Nassa), the Purpura, the strange Magilus, and the lovely Harp-Shells and Olives ([Fig. 10]).
Fig. 9. Murex tenuispina.
4. The Cassididæ, or "Helmet-Shells." Cassis rufa, from West Africa, is noted as the best species of shell for cameo engraving; with it are classed the "Tun" (Dolium) and the great "Triton" (Triton tritonis), such as the sea-gods of mythology are represented blowing into by way of trumpet, and which are used by the Polynesian Islanders to this day instead of horns.
Fig. 10. Oliva tessellata.
5. The Conidæ, whose type, the "Cone-shell" ([Fig. 11]), is at once distinctive and handsome, but which in the living state is covered by a dull yellowish-brown periostracum that has to be carefully removed before the full beauties of the shell are displayed.