upwards ; these lines however are not seen in old shell, as they are soon destroyed by decay.
Great
differences are presented by the appearance of the oyster when opened,
the outer edge of the " mantle " being in some cases black, and in
others orange, speckled with either black or white spots. In fact the Meleagrinœ are
subject to much local variation, and the appearance of the shell will
generally allow a tolerably close conjecture as to « whence it came.
The black-edged variety is the most distinct both in the oyster and in
the shell. In some shells the palliai line is more strongly marked than
in others ; in the Sooloo shell, the impressions of the adductor
muscles are comparatively faint and almost smooth, whilst in the
Australian shell a rough, uneven surface is more commonly found.
Mother-of-Pearl shells vary in weight, when clean and dry, from 400 to 4,000 pairs (i. e., single oysters) to the ton, but occasional specimens have weighed as much as 14 lbs.
The
valuable white shell is obtained chiefly from Tahiti and Macassar, the
trade port of the Aru Islands, near New Guinea. It seems to exist in
close proximity to the other varieties, without losing its distinctive
peculiarity, for it is found year after year to the south side of
Tapul, an
