In Canton, many houses are illuminated almost entirely by skylights and windows made of shells, probably the semitransparent valves of Placuna placenta. In China lime is commonly made of ground cockle-shells, and, when mixed with oil, forms an excellent putty, used for cementing coffins, and in forming a surface for the frescoes with which the gables of temples and private houses are adorned. Those who suffer from cutaneous diseases, and convalescents from small-pox, are washed in Canton with the water in which cockles have been boiled.[211]
A recent issue of the Peking Gazette contains a report from the outgoing Viceroy of Fukhien, stating that he had handed over the insignia of office to his successor, including inter alia the conch-shell bestowed by the Throne. A conch-shell with a whorl turning to the right, i.e. a sinistral specimen, is supposed when blown to have the effect of stilling the waves, and hence is bestowed by the Emperor upon high officers whose duties oblige them to take voyages by sea. The Viceroy of Fukhien probably possesses one of these shells in virtue of his jurisdiction over Formosa, to which island periodical visits are supposed to be made.[212]
Shells appear to be used occasionally by other species besides man. Oyster-catchers at breeding time prepare a number of imitation nests in the gravel on the spit of land where they build, putting bits of white shell in them to represent eggs.[213] This looks like a trick in order to conceal the position of the true nest. According to Nordenskjöld, when the eider duck of Spitzbergen has only one or two eggs in its nest, it places a shell of Buccinum glaciale beside them. The appropriation of old shells by hermit-crabs is a familiar sight all over the world. Perhaps it is most striking in the tropics, where it is really startling, at first experience, to meet—as I have done—a large Cassis or Turbo, walking about in a wood or on a hill side at considerable distances from the sea. A Gephyrean (Phascolion strombi) habitually establishes itself in the discarded shells of marine Mollusca. Certain Hymenoptera make use of dead shells of Helix hortensis in which they build their cells.[214] Magnus believes that in times when heavy rains prevail, and the usual insects do not venture out, certain flowers are fertilised by snails and slugs crawling over them, e.g. Leucanthemum vulgare by Limax laevis.[215]
Mollusca as Food for Man.—Probably there are few countries in the world in which less use is made of the Mollusca as a form of food than in our own. There are scarcely ten native species which can be said to be at all commonly employed for this purpose. Neighbouring countries show us an example in this respect. The French, Italians, and Spanish eat Natica, Turbo, Triton, and Murex, and, among bivalves, Donax, Venus, Lithodomus, Pholas, Tapes, and Cardita, as well as the smaller Cephalopoda. Under the general designation of clam the Americans eat Venus mercenaria, Mya arenaria, and Mactra solidissima. In the Suez markets are exposed for sale Strombus and Melongena, Avicula and Cytherea. At Panama Donax and Solen are delicacies, while the natives also eat the great Murex and Pyrula, and even the huge Arca grandis, which lives embedded in the liquid river mud.
The common littoral bivalves seem to be eaten in nearly all countries except our own, and it is therefore needless to enumerate them. The Gasteropoda, whose habits are scarcely so cleanly, seem to require a bolder spirit and less delicate palate to venture on their consumption.
The Malays of the East Indian islands eat Telescopium fuscum and Pyrazus palustris, which abound in the mangrove swamps. They throw them on their wood fires, and when they are sufficiently cooked, break off the top of the spire and suck the animal out through the opening. Haliotis they take out of the shell, string together, and dry in the sun. The lower classes in the Philippines eat Arca inaequivalvis, boiling them as we do mussels.[216] In the Corean islands a species of Monodonta and another of Mytilus are quite peppery, and bite the tongue; our own Helix revelata, as I can vouch from personal experience, has a similar flavour. Fusus colosseus, Rapana bezoar, and Purpura luteostoma are eaten on the southern coasts of China; Strombus luhuanus, Turbo chrysostomus, Trochus niloticus, and Patella testudinaria, by the natives of New Caledonia; Strombus gigas and Livona pica in the West Indies; Turbo niger and Concholepas peruvianus on the Chilian coasts; four species of Strombus and Nerita, one each of Purpura and Turbo, besides two Tridacna and one Hippopus, by the natives of British New Guinea. West Indian negroes eat the large Chitons which are abundant on their rocky coasts, cutting off and swallowing raw the fleshy foot, which they call ‘beef,’ and rejecting the viscera. Dried cephalopods are a favourite Chinese dish, and are regularly exported to San Francisco, where the Chinamen make them into soup. The ‘Challenger’ obtained two species of Sepia and two of Loligo from the market at Yokohama.
The insipidity of fresh-water Mollusca renders them much less desirable as a form of food. Some species of Unionidae, however, are said to be eaten in France. Anodonta edulis is specially cultivated for food in certain districts of China, and the African Aetheriae are eaten by negroes. Navicella and Neritina are eaten in Mauritius, Ampullaria and Neritina in Guadeloupe, and Paludina in Cambodia.
The vast heaps of empty shells known as ‘kitchen-middens,’ occur in almost every part of the world. They are found in Scotland, Denmark, the east and west coasts of North America, Brazil, Tierra del Fuego, Australia and New Zealand, and are sometimes several hundred yards in length. They are invariably composed of the edible shells of the adjacent coast, mixed with bones of Mammals, birds, and fish. From their great size, it is believed that many of them must have taken centuries to form.
Pre-eminent among existing shell-fish industries stands the cultivation of the oyster and the mussel, a more detailed account of which may prove interesting.
The cultivation of the oyster[217] as a luxury of food dates at least from the gastronomic age of Rome. Every one has heard of the epicure whose taste was so educated that