MELEAGRINA MARGARITIFERA. Lam. The pearl oyster, which furnishes the finest pearls and finest nacre. When secreted in the globular form, it is the pearl ; when on the inner walls of the shell, the nacre. The pearl oyster is met with in the Persian Gulf, Arabian coast, in the Japanese and American seas, on the shores of California, and near the islands of the South Seas, Bay of Bengal, Gulf of Manaar, Ceylon, and near the mouth of the Indus. Pearls are artificially produced by the Chinese, introducing beneath the mantle a grain of sand, around which the nacrous substance is thrown. Pearl mussel spat or spawn is thrown out in some years in great quantities, perhaps similar to the edible oyster of Britain, which threw much spat in 1849, and not again until 1860. The spat floats in and on the water, and attaches itself to anything with which it comes in contact, attaining, it is said, the size of a shilling in six months. In its seventh year the pearl ntollusc attains its maturity as a pearl pro ducer, pearls obtained from a seven-year oyster being of double the value of those from one of six years of age. In oysters under four years the pearls are not of any mercantile value, and after seven years the pearls deteriorate. Those from mussels of about four years old have a yellow tinge, and the older kinds a pinky hue, but pearls of a red and even black, as also with other colours, are also met with. Baghdad dealers prefer the round white pearl ; those of Bombay esteem pearls of a yellow hue and perfect sphericity ; while other nations choose the gems with a rich pink colour. There seem reasons to believe that pearl
mussel spat is migratory, forming colonies at places remote from the parent bed. Between the years 1732 and 1746, there was little pearl fishing at Ceylon, and there were long suspensions between 1768 and 1796, between 1820 and 1828, and between 1837 and 1854, and during the last period the expenses were covered. The late Dr. Kelaart is stated to have been of opinion that the molluscs are capable of leaving their shells. In the Persian Gulf the pearl banks extend 300 miles in a straight line, and the best beds are level and of white sand, overlying the coral in clear water, and any mixture of mud or earthy substance with the sand is considered to be detrimental to the pearl mollusc. In the Persian Gulf there is both a spring and a summer fishery, and as many as 5000 boats will assemble from Bahrein and the islands, and continue fishing from April to September. The net revenue from that of Ceylon, from 1828 to 1887, was £227,131. Each boat is manned with a crew of twenty-three persons, ten of whom are divers, two divers to each stone, of whicl there are five in the boat. When fishing for Government or for a speculator, those receive three-fourths of all the produce. Pearls are obtained also from the Avicula mar garitifera, the Unio margaritiferus, the common oyster, Anodonta cygnea, Pinna nobilis, Mytelus edulis, and Spondylus wederopus. Pearls found in Area note arc violet, and in Anomia cepa) purple. —Cornhill Magazine, August 1866.