The Pinna is a marine shell; most of the species are large, and the
shells very thin in proportion to their size. That represented in the
engraving is found in the American seas, and is sometimes as much
as a foot and a half in length; it is by no means rare. There is a
species found in the Mediterranean, in about five or six fathoms water,
which is much sought after by the inhabitants of Sicily and Calabria,
not only as an article of food, but also for the sake of its beard,
or byssus, of which, in many places, a kind of cloth is made, very
remarkable for its softness and warmth. The fishermen, to obtain the
Pinna, make use of a kind of iron rake, called a _crampe_, with teeth a
foot in length; when the shells are drawn up, the beards are found to
be torn in some part of their substance. If a sufficient length remains
attached to the animal, to render the fibres available for the purpose
of spinning, they are cut off close to the shell: they are then dried
and spun, and afterwards woven into gloves, stockings, caps, and even
garments of much larger size.
[Illustration: _Pinna rudis._]
The threads of which the byssus is formed are extremely fine, and of
equal thickness throughout their whole length, very strong, and of a
dark morone colour, which is exceedingly permanent.
This curious kind of cloth was long since known to the ancients; but
at present its manufacture is very limited, from the great scarcity of
the Pinna, and the number of beards necessary to make even so small an
article as a pair of gloves. But it is supposed, that if the shells
were placed in more favourable circumstances, in preserves, &c., they
would increase much more rapidly.
These shells are found in the seas of all hot climates, but the British
shores possess but one species, the _Pinna lævis_ of Donovan; this is
of a horny colour, clouded with brown, and attains a considerable size.