OSTREAD^. OYSTER, 
83 
los ReL Descalzos de S. Francisco/ etc., 1738, mentions 
the use of great oyster-shells for holy water,^^ and 
speaks of one known to be ninety years old, by the 
layers of its shell. But I fancy he must mean the shell 
of the Tridachna gigas, as we know it is used for that 
purpose ; and in the church of St. Sulpice in Paris are 
two of these shells resting upon rock- work in marble, 
by Pigalle ; they were given to Francis I. by the Re- 
public of Venice. In the Intellectual Observer/ vol. i. 
p. 483, is an account of an oyster-shelF^ island by M. 
Aucapitaine, on the east coast of Corsica, composed of 
layers of shells, bearing some resemblance to the shell- 
mounds of St. Michel- en-F Her m, in La Vendee. This 
island is formed of still-living species, and is between 
three hundred and four hundred yards in circumference, 
the greatest elevation about thirty yards, and the mean 
elevation rather more than two yards above the level 
of the sea. The Romans are said by the fishermen to 
have deposited the shells of the oysters there, which 
they salted for exportation, but M. Aucapitaine does 
not believe in the artificial origin of this island. 
According to M. de Quatrefages, the shell -mounds of 
St. Michel-en-FHerm are composed of oyster, mussel, 
and scallop shells, of the same species as those living 
now in the neighbouring seas. Many of them have 
their valves still connected by the ligament which forms 
the hinge, and they have not even changed colour. 
The three banks of St. Michel-en-FHerm are about 
seven hundred and thirty yards in length, three hundred 
in width, and rise about ten to fifteen yards above the 
level of the surrounding marshes. 
Mr. Buckland mentions a large heap of oyster-shells 
in Galway Bay, at a place called Creggauns; another 
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