MOLLUSCA. 157 



Oliva, Ovula, etc., sometimes quit their old shells, 

 and produce new ones. 



The Conch-shell, the product of Strombus gigas, 

 is much prized as an ornament when the aperture 

 is of a fine rose colour. This large shell is a 

 common chimney-piece ornament, but it is also 

 used for making cameos ; and the inferior kinds are 

 purchased also by the masters of potteries as a 

 source of pure lime, or for other purposes. Great 

 numbers are sold for ornament. It is taken prin- 

 cipally on the shores of the West Indies, and is 

 imported from time to time into Liverpool, at the 

 rate of from 6000 to 11,000 shells per annum. 



The allied Mollusc, Cassis (or Helmet shell), is 

 sometimes preferred for cutting cameos. Cassis 

 ru/a is exported from the Maldives to Italy for this 

 purpose in considerable quantities. 



Certain species of Murex and Buccinum are also 

 purchased as decorative ornaments.* 



The Gasteropod known as Turbinella pyrum (or 

 Valuta gravis, Linn., Fig. 17), produces a large 

 pear-shaped shell, which is much prized in India for 

 making bracelets and other ornaments. This shell 

 has acquired a certain commercial importance, and 



* Most of the shells mentioned in this work are to be seen in 

 the collection at the British Museum, and many have been elabo- 

 rately drawn and coloured in Lovell Reeve's extensive work on 

 Mollusca, in 20 vols. 



