rents laden with mud or sand, is a minute shell, a species of modiola; a mussel, but
with the strange habit of the individuals aggregating in a sort of
blanket, into which minute fragments of coral, shells, &c. are
embodied. We have always compared this aggregation to the red spider on
vegetation. Up to the age of one year the young oysters are in millions
upon millions, destroyed by this suran as the Tamils call it.
If, however, the pearl oysters can only manage to survive beyond the
critical period of one year, they turn the table on the modiola and,
instead of allowing themselves to be smothered, they eat up their
enemies, literally "feeding fat" their grudge against them. The species
of batistes called the "trigger" or "old woman" fish is also supposed to destroy far more of the modiola than
of the oyster spat. But the Hon. Mr. Thomas, of the Madras Civil
Service, following an idea started by Capt. Phipps of the Indian Pearl
Banks, has introduced an element of doubt in the question of what is
pearl oyster spat, asserting and quoting British Museum authorities in
favour of his opinion, that what has always been taken for oyster spat
was not "the real Simon Pure," but the young of quite a different
mollusk. The correctness even of a portion of the beautiful drawings,
engraved in Tennent's Natural History, is impeached. Versus Phipps
and Thomas of Madras and the scientists, those with fullest practical
knowledge of the Ceylon fisheries, Mr. Twynam and Capt. Donnan, still
hold the faith which old Master Attendant Steuart held and expressed.
They state that, if the masses of spat they have hitherto regarded as
embryonic pearl oysters are not that, they should like to see
separately the genuine spat, and this they told us they had not seen
up to the date of the Jubilee fishery. The scientists, as we have said,
have sided with Mr. Thomas, amongst them Mr. Haly of our Ceylon Museum,
but certainly a constructive should follow a destructive theory. That
the pearl oysters produce spat in enormous quantities, and that masses
of such spat go floating over the Gulf of Mannar, and, perhaps, beyond
its bounds is certain. But it would appear that, simultaneously, masses
of the mature shell of Avicula vexiUum float about and get
mixed up in every sense with the oyster spat, specimens of both being
placed by Mr. Thomas in the British Museum. His reference lo the Museum
authorities led to another result, viz., that we ought no longer to
call our small pearl oyster Avicula (meleagrina) margaritij'era that
being the proper name of the large shells so extensively fished off
the coasts of Australia and which yield the mother-of-pearl, out of
which so many ornamental and useful articles are manufactured,
including knife handles, buttons, papier mache inlaying, &c. Our
small oyster (3^ inches in diameter at its largest, instead of 1 foot
and more) ought to be distinguished as Avicula (meleagrina) fucata. In
each case the lovely lustre, white with just a suspicion of pink, is
dye not te any pigment in the mucus secreted and calcified, but to the
deposition of the nacre in films of almost inconceivable thinness, one
over the other and with slight corrugations in the enamel to the
interior of the shell and the pearl. Although fine pearls are
occasionally found in the great aviculos they are chiefly
valuable for their shells, which are cut up', fashioned and polished by
cunning workmen, into objects which rival gold and gems in beauty. Our
small oyster is valuable not for its shells but for the gems it
produces. The general opinion of scientists is that each pearl is
formed over a nucleus of some minute irritating substances, on which
nacre was originally laid to prevent inconvenience to the soft-fleshed
animal. The nuclei have been recognized as grains of sand and diatoms,
and Dr. Kelaart found on one occasion the eggs which had escaped from
the creature's own ovary, coated with nacre and destined in time
perhaps to assume the dimensions of valuable pearls. But in some pearls
no foreign nucleus can be traced, and Captain Donnan has formed a
strong opinion that the majority of pearls owe their origin to an
instinct which leads the nacre secreting animal to utilize any excess
of the carbonate of lime mucus in the formation of the separate
beautiful spherical objects which are prized as
the most chaste of " gems of purest ray serene." It seems probable too (and this (act, if it be a fact, is of great practical value as applied to fisheries,
