But we have also an example of a much rarer shell, the Torbay Bonnet,
or Cap of Liberty.[73] The shape, which is exactly that of the ancient
Phrygian bonnet, or the modern emblem of liberty, is sufficiently
commemorated in all the appellations by which it is known, both
scientific and popular. This specimen is but an empty shell, but the
freshness of the colours, and the beautiful polish of the interior
show that the animal cannot have been long dead, for the porcellaneous
smoothness and gloss of shells very soon become defaced after their
exposure by the death and decay of the soft parts. The interior of this
shell is of a most lovely rose-pink, very glossy, and the exterior is
nearly of the same hue, though this is concealed by a horny skin which
closely invests it, and is covered with a shaggy pile that projects
even beyond the edge, in the form of a ragged yellow fringe. This rough
epidermis is of a hue varying from a bright yellow-olive to a dull
wood-brown; it is frequently rubbed off in the upper parts, when the
natural hue of the shell is there seen.
This species is rare enough, and large enough, and handsome enough to
be a prize worth finding, when picked up in so fresh a condition
as this; but, of course, it is more valuable when it occurs in a
living state. But this scarcely ever happens except by dredging, or by
trawling. I have frequently had it brought to me by trawlers both at
Weymouth and Tenby, oftenest by the former, who get it in deep water,
from thirty to fifty fathoms, on the western side of Portland.
The living animal is not unworthy of its elegantly painted house. Its
colour is usually pale yellow, with a rose-pink mantle, bordered by a
fine orange-coloured fringe. The head is large and swollen, furnished
with tentacles, which carry the eyes at their bases. The tongue-ribbon
carries seven rows of teeth, of which the central one differs in shape
from the rest.
I have kept a specimen in the aquarium for a considerable time, with
very little addition to my knowledge as the result. It remained
adhering to the scallop shell on which it was found almost all the time
I had it, occasionally shifting a hair’s-breadth to the one side or
the other. Almost always the fringed edge of the shell was so closely
applied to the support as absolutely to forbid intrusion; but now and
then a very slight lifting of the edge all round gave me the narrowest
possible peep at the broad cream-coloured foot adhering to its rest.
Thus it went on tantalizing me, till after some months I lost it, I
forget how.
A close ally of this form is a pretty shell which we often obtain by
dredging, called the Cup-and-Saucer Limpet. It is a pretty little white
porcellaneous cone, with a curved plate of thin shell projecting from
the side of the interior, like a semi-cup within the cup. It is named
_Calyptræa_. Both this and the Torbay Bonnet have been ascertained
to manifest domestic instincts, in sitting on their eggs till they
are hatched. According to MM. Audouin and Milne Edwards, the parent
_Calyptræa_ “disposes them under her belly, and preserves them, as
it were imprisoned, between the foot and the foreign body to which
she adheres, her patelloid shell thus serving not only to cover and
protect herself, but as a shield to her offspring. These eggs are oval
bodies of a yellow colour, enclosed in membranous capsules, which
are elliptical, flattened, translucid, and filled with an albuminous
matter. The number of these little capsules varies from six to ten;
they are connected among themselves by a footstalk, so as to represent
a sort of rosette; each of them contains from eight to ten eggs. It
appears that the young _Calyptræa_ are developed under this sort of
maternal roof, and do not quit it until they are in a condition to
affix themselves, and are provided with a shell sufficiently hard to
protect their own bodies.”[74]