394 POPULAR SCIENCE MONTHLY. 



waters off the coasts of equatorial South. America, the West In- 

 dies, Panama, and southern California. The Aztec kings pos- 

 sessed pearls of great beauty and price, obtained, it is supposed, 

 from Panama. The palace of Montezuma, when despoiled by the 

 Spaniards, is described as " studded with pearls," along with em- 

 eralds. 



Some fine pearls are produced in inland waters by the fresh- 

 water mussel (Unio margaritifera). Most of the river pearls are 

 found in China, though at some periods the pearl industries in 

 England and Scotland have been important. The rivers of Ger- 

 many and parts of Russia are also pearl-producing. The prin- 

 cipal river-pearl fishery in the United States is in the Little 

 Miami in Ohio. 



The marine mollusks yielding pearls are the Avicula (Melea- 

 grina) margaritifera, Avicula macroptera, and Avicula fucata. 



In the Persian Gulf the Avicula fucata is specially fished for 

 gem pearls, as it produces more and of finer quality than the 

 other varieties, though it is smaller and of less value for the 

 mother-of-pearl lining of its shell. All three varieties mentioned, 

 however, are found on the famous Great Pearl Bank, which lies 

 along the west coast of the gulf. There the pearling industry 

 from remote times has so dominated the people that it has passed 

 into a proverb, "All are slaves to one master, Pearl/' 



The great Ceylon pearl fisheries are now a monopoly, under 

 the supervision of the British Government, as formerly under 

 that of the Portuguese and the Dutch. The fishing seasons occur 

 at irregular and infrequent periods, only half a dozen having 

 been sanctioned by the inspecting officer in the quarter century 

 between 1863 and 1887. The value of the pearls from these sev- 

 eral fishings varied from fifty thousand to three hundred thou- 

 sand dollars, with a total of about one million dollars. The Cey- 

 lon fishing season runs from four to six weeks. The latest of 

 which there is data was that of 1889, when in twenty-two days 

 fifty divers brought up eleven million oysters, which yielded the 

 Government fifty thousand dollars and the divers about fifteen 

 thousand dollars. In Ceylon it is the custom to land the cargoes 

 of oysters on the shore to die and decay. When sufficiently de- 

 composed they are opened and then washed and searched for the 

 more valuable loose pearls, after which the boutons are clipped 

 from the shells, and the larger of the shells themselves selected 

 for their mother-of-pearl. 



Diving for pearls is perhaps the most perilous of occupations, 

 with the possible exception of its antithesis that of aeronautics. 

 There are the terrible physical tortures of the first descents 

 from the pressure of water ; the bleeding from nostrils, ears and 

 mouth ; the bursting of small blood-vessels in the lungs ; and the 



