THE PEARL OYSTER. 911 



merchant, in consequence of the correctness of judgment 

 which is requisite in classing them according to their 

 value. 



From the size of the ornaments made of this nacre, or 

 mother-of-pearl, some idea of the magnitude attained by 

 the shell fbj may be appreciated. Were it only for the 

 production of this article, so much in request for all kinds 

 of " bijouterie," this shell would form an important object 

 of commerce ; but yielding as it does its nacreous lining in 

 such abundance and solidity, it affords also those more 

 valued nacreous drops or nodules called pearls, estimated in 

 the East, time immemorial, as "of great price " the orna- 

 ments of Kings. 



The article called mother-of-pearl is not a product of 

 the pearl mussel, but the substance of the shell of another 

 genus, found in warm seas, where the water is not very 

 deep ; it is obtained in the Indian Ocean ; but more abun- 

 dantly, and of the finest colours, in the Red Sea, the seas 

 on the coasts of China, and the waters of the Eastern Isles. 

 It is named Nautilus Pompilius, or great chambered sailor 

 fish. The inner side is exquisitely polished by nature, of 

 the whiteness and water of pearl itself ; and the outside, 

 after the external coating has been removed by aqua-fortis 

 and the lapidary's wheel, has a similar lustre. It is cut 

 into pieces with a saw, and made into many sorts of trin- 

 kets. It is also used with great advantage as buhl, in in- 

 laying the nicer sorts of cabinet work. 



(b) Commenting upon the Geology of Patagonia, Darwin says : 

 " The most common shell is a massive gigantic oyster, sometimes even 

 a foot in diameter." "Voyage of a Naturalist," p. 170. Whether 

 these belonged to the Common or Pearl-Oysters is not stated ; most 

 probably both. 



