62 ECONOMIC ZOOLOGY 



The oldest pearl fisheries are on the north coast of the island of 

 Ceylon, where pearls have been collected since the beginning of the 

 Christian era. 



Since the British occupation the fisheries have been under govern 

 ment control and have been a great source of revenue. 



At certain intervals the government will advertise an open season 

 for pearl diving and the natives flock to the fishing grounds by the 

 thousands. At a given signal, each day the boats set out, and at the 

 end of the day a second signal recalls them to shore. Small boats are 

 used, each with 10 divers, in two gangs, an equal number of helpers, 

 and two or three sailors. The diver descends to the bottom, 30 to 

 50 feet, with the aid of a heavy stone, works for 30-90 seconds and 

 is drawn up with his basket of oysters. At the end of the day the oys- 

 ters are taken to shore and placed in bins to decay. When thoroughly 

 decayed they are carefully washed and examined for pearls; the stench 

 may be imagined. The government claims a certain proportion of the 

 shells and the divers take the rest. It makes an interesting form of 

 gamble, as a collection of shells may have $10,000 worth of pearls or 

 it may contain none. For miles the shore is covered several feet deep 

 with shells. 



In America the most important pearl fisheries are in the Gulf of 

 California, centering about La Paz. These fisheries were operated by 

 Indians in the time of Cortez and were exploited by the Spanish govern- 

 ment. The season here is from June to December. The expert Indian 

 and Mexican divers, who were said to work on an empty stomach to 

 increase the lung capacity, have been largely replaced by the present 

 operators, chiefly San Francisco firms. Each boat now has a diving 

 outfit, with one diver and a proper number of pump men and other 

 helpers. About 300 oysters per day are collected by such a boat. 



There are also 'fisheries on the coasts of Panama, Guatamala, Red 

 Sea, South Sea Islands, Australia, the Sulu Islands, and elsewhere. In 

 the latter two regions the shells are particularly fine and are collected 

 for mother-of-pearl. At the town of Jolo, capital of the Sulu group 

 the writer was asked one peso (50 cents) for a single valve of a large 

 pearl oyster. 



Some of the fresh-water mussels (Unionidae), Fig. 28, of Asia, 

 Europe and America are valuable both for pearls and for use in making 

 pearl buttons. On account of their unusual color the pearls are often 



