Smaller-sized pearls are obtained from the common oyster, the British river mussel (Mar. garitana margaritif era), also in the AnodonU cygnea, the Pinna nobilis, the Mytilus edulh or common European mussel, in the Perna anc Spondylus gmderopus. In these they are generally of a green or rose colour ; the pearls found ir. Arca nom are violet, and Anomia cepa purple They are similar in structure to the shell, and like it consist of three layers ; what is the innermost layer in the shell is placed on the outside in the pearl. The mother-of-pearl shell is extensively fished for in the straits and seas south of Singa. pore ; the diving-bell is utilized, and the divers an natives of the Pacific islands. - Cameo ornaments are 'Obtained by • carving shells. The inner strata of porcellanous shells are differently, coloured from the exterior, and the makers • of shell cameos avail themselves of this difference to produce_ white or rose-coloured figures on a dark ground. Cameos are used ai brooches, pins, bracelets, etc., and the most beautiful are cut on a large species of Cassis (C. rufa), known as the bull's-mouth, and found in the Mediterranean ; but any shell can be made ,into cameo, the term meaning any small carving on a solid object. The queen-conch or helmet-shell, Cassis Madagascariensis, and other large species of Cassis, also species of Chama, are used in the manufacture of the shell cameos. Strombus gigas, L., the fountain-shell, is imported in immense quantities into Europe from the Bahamas, for the manufacture of shell cameos. Stone cameos are cut from the onyx, agate, and jaspers, and cost up to £40; a shell cameo, £2 to £4.
The shells of nearly all the Turbiniche are brilliantly pearly when the epidermis and outer layer of shell are removed. Many of them are used in this state for ornamental purposes. The Chinese carve a variety of patterns in the outer opaque layer of the nautilus shell, relieved by the pearly ground beneath. Species of the genera I'rochus and Phasianella are used as beads. Cyprma tigris, which is prettily spotted with black, is frequently made into snuff-boxes in England. The mantle is so large as to cover all the shell, on the back of which there is often a longitudinal line which marks where its two folds meet. This , membrane continually secretes an abundance of viscid fluid which lubricates the shell, and preserves the beautiful polish which has procured for them the name of porcelain shells.
The shells of species of Nautilus and Carinaria are prized for ornamental purposes. The beautiful paper Nautilus, Argonauta argo, is admired by all who see it for its graceful form, delicate structure, and pure colour. The argonaut or paper sailor is thin and translucent. A. hyans, Solander, is still living in the China seas, and fossil in the sub-Apennine tertiaries of Piedmont. The ear shells, species of Haliotis, are largely used for ornament and inlaying. When polished, they present varied and beautiful tints, with mother of-pearl lustre. Cone-shells are also ornamental, as also are species of Tellina,Murex, and Bliccinurn.
The money cowrie, Cyprma moneta, of eastern seas, is used as small change throughout British India, and on the east coast of tropical Africa. It is also largely utilized in the ornamentation of horse and elephant trappings. C. annulus is used by the Asiatic islanders to adorn their dress, to weight their fishing-lines, and for barter. The smaller cyprma are made into clasps, buttons, ear rings, bracelets, etc. The larger species were consecrated by the Greeks at Cnidos in the temple of Venus. At the present day Muhammadans of India suffering from guinea-worm make as a charm a string of human hair, to which they attach the eye of a peacock's feather, a piece of the _root of AMOMUM zerumbet, and a cowrie. The cyprrea, cones, olives, and ovulus are called love-shells.
Many species of Purpum secrete a fluid which gives a dull crimson dye ; it may be obtained by pressing on the operculum.
Murex brandaris and M. trunculus are supposed to be the species of the Gasteropoda from which the Tyrian purple dye was obtained, but Purpura patula and others have also been indicated. The Ianthina also yields a colour.
The calcareous internal shell (Sepiostaire) of the Sepiidre is the cuttle-bono in use by painters • as pounce', also in casting counterfeits. It was formerly used in medicine as an antacid. That of a Chinese species of sepia attains 1 feet in length.
Potamides telescopium (Terebralia telescopium) is so abundant near Calcutta as to be made into lime after exposure to the sun to kill the animals. The dead and living shells of species of the Conchifer•e are largely converted into lime at Madras, for the beautiful plaster called chunam.
The great Tridacna gigas of the Indian Ocean, China seas, and Pacific is a marvel to behold. A pair of valves may weigh 500 lbs. and, the animal, about 20 lbs. in weight, is good to eat. Some Christian churches, as in St. Sulapice in Paris, use them as benetiers. If a man were to put his hand inside and the animal shut its valves, he would be unable to withdraw it.
The chank-shell of the Indian Ocean and Bay of Bengal, Turbinella pyrum, long the war trumpet of the ancient Hindu races, is still represented in the hand of their deity Vishnu and other of their gods, and it is used as a trumpet in the Hindu temples and in their funeral processions. The Australasian and Polynesian islanders utilize the Triton tritonis similarly. The Buccinum whelk, employed similarly, has its Latin name from Buccina, a trumpet or triton's shell. At Dacca, in Bengal, chauks are cut into necklaces, bracelets, armlets, and anklets, often of several hundred rupees value. Veneration is paid all over India to the large chanks, but especially those with the spiral line and mouth turned to the left. Chanks are used for beetling fine cloths ; also as oil lamps in Hindu temples. In some years, above four millions of chank-shells are obtained in the Gulf of Manaar, of the value of £10,000.