follows
that the deposited nacre roughly assumes the irregular outline of the
inclosed object. This is strikingly shown in pearls covering a minute
fish, a crayfish, or a small crab. Several specimens have been found in
which the species could be identified by examination through the
nacreous coating.
In
the American Unios there is a strong tendency to produce elongated
pearls near the hinge of the shell, which are consequently known as
"hinge pearls." The occurrence and form of these suggest that their
origin may not be due to nuclei, but that they result from an excess of
carbonate of lime in the water, and that the animal stores a surplus of
nacre in this convenient form. There are several standard forms of
these hinge pearls. Many are elongated or dog-toothed, some are
hammer-shaped, others resemble the wings of birds, the petals of
flowers, the bodies of fish, and various other objects. A large
percentage of the pearls found in Unios of the Mississippi Valley are
of these types.
Some
irregular pearls or baroques are very large, weighing an ounce or more.
A well-known example is the Hope pearl, described on page 463, which
weighs three ounces. These monster pearls sometimes assume odd shapes,
such as clasped hands, the body of a man, lion, or other animal, etc.
Although
baroques may have a pearly luster, they are not highly prized unless
unusually attractive, and they have little permanent value, apart from
their estimation in the eyes of admirers of the curious and unique.
They are used largely in l'art nouveau, and in forming odd and
fanciful objects of jewelry, the designer taking advantage of the
resemblance which they bear to common objects of every-day life, and by
additions of gold and other ornaments completing the form which nature
had merely suggested.
Some
remarkable examples of baroque mountings have been produced, and a few
are to be found in most of the large pearl collections. In a single
case in the Imperial Treasury at Vienna are baroques forming the
principal parts or figures of a horse, stag, lamb, tortoise, lizard,
cock, dragon, butterfly, gondola, hippopotamus, female bust, and three
mermaids. Other well-known collections are those of the royal family of
Saxony in the Grüne Gewölbe at Dresden ; those in the Palace of
Rosenberg at Copenhagen; in the Waddesden (Rothschild) collection of
the British Museum; among the jewels in the Louvre in Paris; with the
treasures of the Basilica of St. Mark in Venice; and in the museum of
the University of Moscow.
A remarkable pearl-like ornament more common in Asia than in the Occident, is the coque de perle, which is an oval section of the globose whorl of the Indian nautilus. The exterior or convex surface is highly
