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]
LOCUST SCREW.
Along the margins of these shallow rock-pools with sandy bottoms, we see many little grey shrimp-like creatures, with thick-set arching bodies, which swim rapidly, and with much vibration of the abdominal feet, from weed to weed. If we catch one and lay it on the rock or on the wet sand, it appears very helpless, for its vertically thin shape and arched attitude preclude the possibility of its crawling: it falls upon its side, and vainly struggles round and round as on a pivot, or makes aimless jerks by throwing out the tail. It is of a greenish blue, or glaucous colour, marked with red dots. This is the common Locust Screw,[75] which is so confined to sea-water, that it has been affirmed that if put into fresh water it presently dies. But the experiments of Mr. Robertson negative this statement:[76] he has found that five out of seven, after being eighteen hours in rain-water, continued to live upon being returned to salt water.
I delight to trace the manifestations of parental love in these tiny forms of animal life. It had long been known that the females of this species display a solicitude for their infant offspring, which they carry for some time about with them; but the following very pleasing details of maternal manners have recently been observed by my relative, Dr. James Salter, and by him communicated to the learned zoologists who are now engaged upon the history of this order:—