II] WHERE PEARLS ARE FOUND 11 



CHAPTER H 



WHERE PEARLS ARE FOUND 



Pearls are found in the soft parts of aquatic 

 animals known scientifically as molluscs, and 

 popularly as shellfish. Inasnuich, however, as our 

 English Board of Agriculture and Fisheries lists 

 together such creatures as shrimps, periwinkles, 

 crabs, lobsters and oysters as shellfish, it will be 

 advisable, for our purpose, to use the much more 

 correct term, Mollusca. The molluscs are known to 

 everyone by their shells, but to very few by the 

 much more important part — the animal that made 

 the shell. The shell is merely an external covering, 

 a. secretion of the outer layer of the animal's body — 

 of the animal's "skin," to speak popularly. Xow 

 if we were to try and enumerate the molluscs in 

 which pearls occur we should probably have to give 

 the names of almost all the bivalves. There is no 

 reason why the sequence of events which produce 

 pearls in one species should not occur, if not regu- 

 larly, at odd intervals in other species. Not all pearls 

 however are valuable. Most of these structures are 

 dull and worthless. We shall therefore turn our 

 attention to those molluscs in which are found 



