The largest and heaviest shells, which yield fine mother-of-pearl most abundantly are confined almost entirely to the Pacific Ocean within twenty degrees south of the equator. The best white shells come from the northern shores of Australia and the Aroo islands. The best black shells are found about Tahiti, the Gambier Islands, and the Tuamotu Archipelago. Of the big yellow variety, the best are obtained in the Merguian Archipelago and Dutch Indies. The shells of this district at Ceram, Batjan, and elsewhere, vary somewhat but the bulk of them are yellow. Beginning with the east coast of Africa, the pearl oyster is found in the Red Sea, where it has been fished for ages. The shell here is of medium size and weight; much larger than those of Venezuela, Ceylon, or the Persian Gulf and smaller than the shells of the Pacific. The mother-of-pearl is not of the finest quality and is used now for inferior work only. It was more used formerly but since the fresh-water unio shell of the United States came into the market, it has displaced to a great degree the Egyptian and Panama shells. The inner edge of the Red Sea shell is of a greenish-gray color. South of the Red Sea, on the East of the African coast, pearl oysters are found in a number of places between Zanzibar and Inhambane, particularly at the Bazaruto Islands, but nowhere in sufficient abundance to develop the fishing for them into a regular industry. Good mother-of-pearl is abundant on the German East African coast, but the oysters carry few pearls. Travelling east, they are next found in large numbers in that arm of the Arabian Sea known as the Persian Gulf. Here they have existed for many centuries. The mollusk is of the smaller species and the shells are known in the market as Lingahs, from the name of the centre of the pearl trade in this district. The shells are of no commercial importance. After these come the ancient fisheries of India, the most prolific in the world. The oysters here are smaller than those of the Arabian Sea and the shells are of no value, but they mature rapidly and yield great quantities of pearls. Myriads of them cover the shoals and banks between the coast of India, at the South-eastern point, and Ceylon, and as the beds are under government supervision, they cannot be destroyed by the reckless fishing of immature oysters. Crossing the Bay of Bengal and the Malay Peninsula, between longitudes 100 and 120 degrees E., there are pearl oysters on the coasts of China, the Merguian Archipelago and western Australia. Between longitudes 120 degrees E. and 150 degrees E., these mollusks flourish on many coasts, including those of Japan, the Sulu Archipelago, the Dutch Indies, the Spice Islands, the Banda Islands, the Aroo Islands, New Guinea and northern Australia.