152 The Commercial Products of the Sea. 



navigators and inhabitants of seacoasts. A very beautiful 

 purple dye was formerly procured to some extent from 

 certain molluscs. Sepia and Indian ink are obtained from 

 the peculiar dark fluid of the cuttle-fish. The gall of the 

 carp is used in Turkey as a green paint and in staining 

 paper. The byssus of certain species of Pinna affords 

 a kind of brown silky fibre which may be worked up into 

 useful articles. Many kinds of shells contain pearls. Red 

 coral is an important article of trade, particularly in the 

 East Indies. Several kinds of shells, either entire or 

 divided, pass current as money in Africa, India, and other 

 remote nations. From portions of shells the North 

 American Indians made their wampum a sort of currency 

 which serves the purpose of records. Many savage people 

 use mussel, snail, oyster, and tortoise shells for drinking- 

 vessels, spoons, etc. In regard to works of art, the mother- 

 of-pearl oyster and many mussel and snail shells are cut 

 like onyx into cameos, and used for making buttons. The 

 cuttle-fish bone is employed by artists and workmen. 

 Sponge serves a variety of domestic purposes. Madrepore 

 is employed for paving and building on the coasts of the 

 Red Sea. Numerous shells and corals are burnt for lime. 

 Some large thin shells are used as glass in the south of 

 China and in India. Shells are among the most common 

 ornaments of savage nations ; and shell flowers, shell 

 earrings, shell brooches and bracelets are worn even by 

 females in the more civilized countries. 



It is not as nourishment only that fish is made sub- 

 servient to commerce. The preparation of isinglass affords 

 to some countries the means of extensive trade and specu- 

 lation. Sole skins, if clean, sweet, well prepared, and 

 dried, can be used as a fining agent, and are sometimes 

 employed in households to clarify coffee. It may be 



