These have been designated by Jameson as M. margaritifera persica and M. margaritifera erythrœensis. These
are much larger than the Lingah shell of the Persian Gulf, but are
smaller than the Australian species. The percentage of pearls in them
is less than in the Lingah species, but from a commercial point of view
this is to some extent offset by the greater value of the shell. The M. m. persica is more numerous in the gulf than the M. m. erythrœensis, and
large quantities of the shell are marketed in Europe. Formerly the
shipments were made principally by way of Bombay, hence the shell is
known in the mother-of-pearl trade as "Bombay shell." The exterior is
of a light grayish or greenish brown color, with yellowish white radial
bands. The nacre has a slightly roseate tint, and the margin is
greenish yellow. The pearls found herein are more yellowish in color
and attain a larger size than those from the Lingah oyster.
The M. m. erythrœensis occurs
also in the Red Sea and along the shores of the Arabian Sea. Among
mother-of-pearl dealers it is known as "Egyptian shell" or "Alexandria
shell," owing to the fact that prior to the opening of the Suez Canal
shipments were commonly made by way of Alexandria. The color of the
nacre is darker than that of its related variety in the Persian Gulf.
In the trade, three grades of this shell are recognized, classed
according to the shade of color. The fightest comes from Massowah and
near the southern end of the Red Sea, and the darkest from farther
north, in the vicinity of Jiddah and Suakim.
The islands of the southern Pacific, and of eastern Polynesia especially, yield another variety of M. margaritifera, to which the name M. m. cumingi has
been given. The nacre is of a dark metallic green, and in the
mother-of-pearl trade the shell is designated as "black-edged." It
attains a large size, only slightly smaller than the large Australian
species; many individual specimens measure ten inches in diameter, and
weigh six or seven pounds for the two valves. Belonging to this
variety are those oysters whose shells are known in the markets of
Europe and America as "Tahiti," "Gambier," and "Auckland" shells, the
name designating the port of shipment.
Yet another subspecies, the M. m. mazatlanica, occurs
on the coasts of Panama and Mexico, and especially in the Gulf of
California. This is likewise green-edged, and the exterior color is
yellow or light brown. This shell has been marketed in quantities since
1850, and is known in the mother-of-pearl trade as "Panama shell." It
is smaller than the Australian species, specimens rarely exceeding
eight inches in diameter. It yields a large percentage of the black
pearls that have been so fashionable in the last fifty years.
Since 1870, the largest pearls have been found mainly in a very
