thousands
are annually taken for the shell, which forms quite an article of
commerce. The flesh is esteemed as food and is also used for bait ; and
it is particularly in preparing for these purposes that the pearls are
found, as no established fisheries exist for the pearls alone.
The
ear-shells or abalones (Haliotidae) found on the coasts of California,
Japan, New Zealand, and other localities in the Pacific, secrete pearly
concretions, sometimes with fine luster, but usually of small value.
These shells resemble in general outline the form of the human ear.
Distinguishing characteristics are the flatly-spiral bowllike shape,
and the regular series of holes in the back near the distal margin, for
the admission of water to the respiratory organs. The holes are on the
left side and parallel with the columellar lip, and those nearest the
apex close up as the shell increases in size. The shells are rough
externally, but beautifully nacreous within. In variety and intensity
of coloring, the nacre is superior to that of the pearl-oysters, but it
is not so harmonious, and it does not form so thick and flat a layer.
Abalone
pearls are especially interesting on account of their brilliant and
unusual colors. Green predominates, but blue and yellow also occur.
Although commonly very small, some of the well-formed ones exceed
seventy-five grains in weight, and those of irregular shape may be very
much larger. The ear-shells also produce many irregular pearly masses.
Although these are without an established commercial value, their
beautiful greenish or bluish tints adapt them for artistic jeweled
objects, such as the body of a fly or of a beetle.
Similar concretions are found in species of turbos and turbinella, especially the Indian chank (Turbinella rapa), which yields pink and pale red pearls. The pearly nautilus (Nautilus pompilius) yields
a few yellowish pearls, especially those taken in Australian waters ;
but from the paper nautilus—"the sea-born sailor of his shell canoe"—
no pearls are obtained, owing to the non-lustrous nature of the shell.
In
bygone days, especially in Asia, and also to some extent in Europe,
pearls were credited as coming from many non-molluscan sources. The
Rabbis had the idea that they came also from fish, as noted in the
story of a tailor who was rewarded by finding a pearl in one which he
bought (Gen. R. xi. 5). The Raganighantu of Nara-hari, a Kashmir
physician of about 1240 a.D., reported them as coming from bamboos, cocoanuts, heads of elephants, bears, serpents, whales, fish, etc.;1
although it conceded that these were deficient in luster, which is
recognized as the characteristic feature of pearls. We understand,
therefore, that this use of the word signifies only
1 Garbe, "Die Indischen Mineralien," Leipzig, 1882.
