24 



POPULAK CONCHOLOGY. 



purpose ; and from several species of Mollusca 

 may be procured a strong colouring matter of 

 a purple hue, which formerly was used as a 

 dye, but has now been supplanted by other 

 animal, mineral, and vegetable productions, 

 which are easier of access. Secondly, as regards 

 the shell; in many countries, particularly in 

 China and Japan, the valves of some of the 

 genus Placuna, which are extremely thin and 

 semi-transparent, are used instead of glass, to 

 serve as windows. Lime may be burned from a 

 great many varieties, and is so procured, in 

 America and elsewhere, particularly in Holland, 

 where many vessels are employed in fishing 

 for shells, which are afterwards brought to 

 Haarlem, where the lime-kilns are situated. In 

 the Hebrides, Antilles, and many other islands, 

 no other lime is known than that procured 

 from shells. Some shells are used as money in 

 different countries, particularly the CyprcBa ; 

 and in conclusion, pearls and mother of pearl, 

 both the productions of this class of animals, 

 are well known valuable and beautiful objects. 



To counterbalance in some measure these 

 benefits which are derived by mankind from 



