72 Pearls. 



fish or molluscs. The Pearl-bearers of the sea are 

 commonly known as " Pearl oysters," though they 

 present but little resemblance to our " native oyster." 

 Indeed although popularly so called they are not 

 oysters in the scientific acceptation of the word, 

 but belong rather to the group of sea-mussels. The 

 term, however, is so commonly employed and 

 universally recognised, that it would be pedantry 

 to abandon it or to attempt to introduce any other 

 word as a substitute. 



For our purpose the Pearl-bearing molluscs 

 may be conveniently divided into two great 

 groups, viz. — 



I. The Marine. 

 11. The Fresh-water. 



All Pearls, whether marine or fluviatile, are 

 produced by organisms belonging to that great 

 group of bivalve shell-fish which was termed by 

 the famous French naturalist, Lamarck, the 

 Conchifera. This name however is by no means 

 well-chosen, inasmuch as it literally means '* Shell- 

 bearers" and might therefore with equal propriety 

 be bestowed upon other molluscs that secrete shells, 

 such as certain cephalopods and gasteropods. It has 

 hence become usual to replace the old term Con- 

 chifera by the better chosen name Lamellibranchiata, 



