404 The Commercial Products of the Sea. 



America, we may be able to form a slight conception of 

 the great importance of pearls in an artistic and commercial 

 point of view. The 10 fisheries for pearls carried on, on 

 the coast of Ceylon, between 1833 and 1863, brought in to 

 the Ceylon Government 300,000, but what the speculators 

 made by the pearls they obtained it is quite impossible 

 to state. 



The ordinary pearls of commerce are an excretion of 

 superimposed concentric laminae, of a peculiarly fine and 

 dense nacreous substance, consisting of membrane and 

 carbonate of lime. The best are obtained from bivalves, 

 but some are formed by univalves, which are more curious 

 than valuable. 



In the class of mollusca which inhabit the seas and 

 fresh waters, most of those with shells secrete a horny and 

 calcareous substance, that is, combined animal and mineral, 

 formed on the interior of the shell during their growth, and 

 they also form that admired substance known as mother-of- 

 pearl. The superabundance of this secretion is often pro- 

 duced in drops, balls, or tuberosities, adhering to the in- 

 terior of the valves, or lodged in the fleshy part of the 

 animal. In the latter instance they are of a spherical 

 shape, and increased annually by a layer of pearly matter ; 

 they remain brilliant, translucid, and hard. 



At the Maritime International Exhibition which was 

 held at Naples in 1871, the various ocean treasures em- 

 ployed in art were displayed in great profusion and 

 magnificence. Even the Italian journals became poetical 

 and enthusiastic upon the manifold attractions of the hall 

 of pearls and coral. Marchisini, of Florence, showed a 

 wonderful collection of pearls ; among others, a brown 

 pearl, valued at 5000, and three necklaces of large white 

 oriental pearls, finished and ornamented with brilliants, etc. 



