II] WHERE PEARLS ARE FOUND 15 



Pearls occur in Anodonta, a large bivalve, common 

 in many of our English ponds and lakes. The pearls 

 from this mollusc provided material for the work of 

 Home and Filippi (1826 and 1852), on the origin of 

 pearls. In Chinese rivers and lakes an allied genus — 

 Dipsas, is of great importance commercially, and has 

 been cultivated in enclosed waters. It is in this shell- 

 fish that the Chinese insert little images of Buddha 

 or some other deity, which are eventually coated over 

 with mother of pearl. 



A considerable fishery for fresh-water pearls is 

 carried on in the rivers of the United States of 

 America. In fact this fishery is much more important 

 than that of Europe. It dates back some considerable 

 time before the white people took possession of the 

 countries of the West. One of the most recent and 

 greatest fisheries was that in the State of Arkansas 

 in 1897. The genera of shellfish (which are again 

 members of the family Unionidae) include Quadrula, 

 Pleurohena, Lampsilis and Tritlgonia. 



Pearls occur very frequently in the common edible 

 mussel (Mytilus edulis) of our sea coasts, and especially 

 in those from certain areas. Numbers up to twenty- 

 six often occur in a single mussel, and Johnstone and 

 Scott, on one occasion at Piel, obtained 390 pearls 

 from sixty-one mussels examined. Lest anyone should 

 imagine that a gold mine exists in the shape of pearls 

 in our mussel beds, we must add that the greatest 



