ON ACEPHALA. 389 
which may be found there. They choose, moreover, the finest 
shells, most proper for the production of nacre, and leave the 
rest. In spite of the pestilential exhalations which result 
from such a considerable mass of dead mollusca, the poor of 
the country come afterwards to glean what the rich by chance 
may have left behind. 
The free pearls thus obtained are then sifted and selected 
carefully, and even drilled, and strung by negro workmen, 
who are extremely adroit in this sort of operation. As to the 
adherent pearls, they must be first detached and then rounded> 
and polished at the place of their adherence, which is like- 
wise done in the same country, by means of a powder, fur- 
nished by the pearls themselves. 
The commerce of pearls appears to be of the highest anti- 
quity. History, in fact, apprizes us, that from time imme- 
morial, the princes and princesses of the East have sought 
after this kind of ornament with a sort of passion, and em- 
ployed it in all parts of their dress, and even in instruments, 
furniture, &c. The Persians, according to the report of 
Athenzus, paid for pearls with their weight in gold. The 
pearl mussels, therefore, must be like our common mussels, 
which, in spite of the prodigious quantity which have been 
eaten for so many ages, do not appear to suffer any sensible 
diminution. It is, nevertheless, said that the Dutch having 
fished too often on the coasts of Ceylon, the pearl fishery is 
not now so lucrative in the hands of our government as it was 
formerly. 
We should hope that the facility for this business, given by 
the invention of the diving bell, may not contribute to hasten 
the destruction of those pearl-banks, but that it will be rather 
employed to regulate the fishery still better than has hitherto 
been done. 
In Europe also a certain number of pearls are derived from 
the Unio margaritifera, a large species, which is found in 
