Economic Uses of Shells, and their Inhabitants. 171 



thousand men. The entire amount of revenue derived from 

 the pearl-fisheries of Ceylon in nine years (from 1828 to 1837) 

 amounted, according to Mr. James Steuart, the Inspector of 

 Pearl Banks, to £227,131, but it has since decreased very 

 considerably. 



The shells of nearly all the Turbinidce are brilliantly pearly 

 when the epidermis and outer layer of the shell are removed. 

 Many of them are used in this state for ornamental purposes. 



The shell of Haliotis is also much used for inlaying" papier- 

 mache work, etc. 



Nor have we yet exhausted the list of uses to which the 

 mollusca are applied. In many districts where lime is scarce, 

 shells are used instead. Yast quantities are thus consumed on 

 the coast of Chili and Peru. 



The Cerithium (Terebralia) telescojrium is so abundant near 

 Calcutta as to be used for burning into lime. Great heaps of 

 it are first exposed to the sun, to kill the animals, and then 

 burnt. In some places they are so plentiful as to be used for 

 road making. 



Sir Charles Lyell tells us there are banks of the dead shells 

 of Gnathodon cuneatus, three to four feet thick, twenty miles 

 inland. Mobile is built upon one of these shell-banks. The 

 road from New Orleans to Lake Pont-Chartrain, a distance 

 of six miles, is made of Gnathodon shells, procured from the 

 east end of the lake, where there is a mound of them a mile 

 long, fifteen feet high, and twenty to sixty yards in width; in 

 some places it is twenty feet above the level of the lake. 



If anyone should reflect upon the Mollusca as undeserving 

 so much notice, and mention the Teredo as an instance of a 

 destructive member of the class, let him read of the utility of 

 another, the common mussel, in maintaining the long bridge 

 of twenty-four arches across the Torridge river, near its 

 junction with the Taw, at the town of Bideford in Devonshire. 

 At this bridge the tide runs so rapidly that it cannot be kept 

 in repair with mortar. The corporation, therefore, keep boats 

 employed to bring mussels to it, and the interstices of the 

 bridge are kept filled with mussels. It is supported 

 from being driven away by the tide entirely by the 

 strong threads of the byssus which these mussels fix to the 

 stonework. 



The Pinna of the Mediterranean spins a byssus so long and 

 fine that it is mixed with silk, and spun into gloves, caps, etc., 

 at Taranto. 



Although the British Museum collection has far higher 

 claims upon the scientific man than upon the mere utilitarian, 

 yet, as a large proportion of the visitors to that institution are 

 not scientific, wo cannot but feel indebted to Dr. Gray for the 



