MOLLUSCA. ot 
occur on our own shores, are very rich in this 
respect, and the widely-gaping Har-shells (Haliot?s) 
are most gorgeous. 
The elegant articles called cameos, so much used 
as clasps and brooches, are formed out of the 
substance of large shells: the ponderous Helmets 
(Cassis) of the West Indies are chiefly used for this 
purpose. A great excellence in the art consists in 
the careful cutting away of the material so that the 
ground shall display one colour, commonly a dark 
hue, while the design is carved in another, commonly 
the pure white, which overlays the brown. 
Shells, being composed of carbonate of lime, are 
capable of being burned to a quick-lime, having all 
the essential properties of that made from stone. 
On some parts of our own shores where limestone 
is scarce, shell-lime is extensively burned; but in 
other countries, as Holland and the United States 
of America, scarcely any other is used, either for 
building purposes or for manuring land. 
Among the subordinate uses of shells may be 
mentioned that in China 
and Japan the valves of 
a sort of Oyster (Placuna), 
which are as large as a 
plate, flat, and transparent, 
are used in windows and for 
other purposes where we 
employ glass; and among 
the semi-barbarous nations 
of Africa, a little species of Cowry (Cyprea moneta) 
is universally recognised as a money currency. 
The natural secretions of the Mollusca are not 
much used among us. The Indian ink used by 
artists is generally understood to be in part, at least, 
MONEY COWRY. 
