PERIWINKLE.
This is the commonest representative which we have of the family Turbinidæ, which comprehends, according to Cuvier, all the species which have the shell completely and regularly turbinated, that is, if we translate the Latin word into English, twisted. The little Periwinkle, (here he is,) is by no means a handsome mollusk, but some of his relatives are very beautiful as we shall presently show. He is called by naturalists T. littoreus, from littoralis—belonging to the shore, and often eaten by boys and girls with great relish; but he is not very digestible, and sometimes occasions dangerous disorders. The Swedish peasants believe that when the Periwinkle crawls high upon the rocks, a storm is brewing from the south; but Linnæus quotes a Norwegian author to shew that according to popular belief, it foretells the approach of a land wind with a calm on shore. Man may learn much of elemental changes from an observation of the movements and habits of all living creatures, which are instructed by God to provide for their safety and wants, and often perceive, long before man himself does, the indications of calm and tempest, rain and drought, etc. But our little Turbo, what of him? will you boil him, and pick out his curled-up form with a pin? or let him go crawling about the rocks, feeding upon the delicate earlier growth of marine vegetation? In the former case, you will have to reject the little kind of horny scale attached to his foot, which forms, when he retires into his habitation, a closely-fitting door to make all snug.
Several species of this genus are found on our shores; one of those is the Turbo rudis, or Red Turbo, which has a very thick periwinkle-like shell, about three-quarters of an inch long; the colour is dull red, fawn, or drab.
Of the foreign Turbinæ, sometimes called Turban Shells, we will now introduce two or three species, which will be found on [Plate III]. Fig. 3 is the Marbled Turbo, (T. marmoratus,) from the Latin marmor—marble; a large handsome shell well known to conchologists, and a native of the Indian seas. Fig. 4 is the Twisted Turbo, (T. torquatus;) this shell, when deprived of its outer coat or layer, is beautifully nacreous, or if we may so speak, mother-of-pearly. The specimens which have reached England were brought from King George’s Sound. Fig. 5 is called Cook’s Turbo, (T. Cookii:) this is a handsome South Sea shell, oftentimes of large size. It has been found in great numbers on the coast of New Zealand.
On [Plate IV], we have placed two very curiously formed and marked shells, called Wentletraps, also belonging to the family Turbinidæ. The scientific name is Scalaria, from the Latin scala—a ladder, which the ribbed shells are supposed to resemble. Of this genus there are about eighty distinct species known; they are mostly deep-sea shells found in warm latitudes, although several inhabit the European seas, and one, the Common False Wentletrap, (S. communis,) Fig. 1, may often be picked up on our own shores. Fig. 2, the Royal Staircase Wentletrap, is a rare and valuable shell, generally brought from India and China; the scientific name is S. pretiosa, given to it by the French Naturalist Lamarck, on account of the high price which it fetched, pretiose, in Latin, meaning costly, valuable. As much as £100 have been given for a single specimen of this shell; and a fine one, especially if it exceed two inches in length, yet commands a considerable sum, although not nearly so much as that. A good deal like the False Wentletrap in general outline, is the Awl-shaped Turritella, found in the African and Indian Seas. This is the T. terebra of naturalists; the first name referring to the turret shape common to the genus, and the last being the Latin word for an auger, or piercer. The Roseate Turritella, (T. rosea,) is also sometimes seen in collections; the beautiful rosy tint of the live shell changes to a dull red or brown, on the death of the mollusk.
TROCHUS, OR TOP-SHELL.
“Of the shelled Mollusca which the dredge ever and anon brings up,” says Mr. Gosse, in his delightful volume on the Aquarium, or Aqua-vivarium, as the glass tank in which living marine animals and vegetables are kept, is called, from the Latin aqua—water, and vivo—to live, “the Trochi are among the most conspicuous for beauty. The chief glory of this genus is the richly-painted internal surface of their shells, in which they are not excelled by any even of the true margaritiferous or pearly bivalves.”
Of this Trochidæ family, a few of the members must be introduced to our readers; it is rather a numerous one, consisting of more than one hundred species, which are scattered nearly all over the world, few seas being without some of them. They are found at various depths, from near the surface to forty-five fathoms down, creeping on rocks, sand, masses of sea-weed, etc. We will first speak of those found on our own shores, the two commonest, as well as the smallest of which, are the Grey and the Spotted Trochi, scientifically named T. cinerarius and T. maculata, the translation of the first Latin specific name being ashy or ash-coloured, and that of the second, spotted. Trochus, in the same language signifies a top, and has reference to the shape of most of these shells, which are something like a boy’s whip-top.
Children on the coast sometimes call the last-named of the above species Pepper-and-salt Shells, because in colour they resemble the cloth so named. The Muddy-red Trochus, (T. ziziphinus,) so called, perhaps, because in colour it resembles the ziziphia, or fruit of the jujube tree, is also common with us. This shell is about an inch long, of a grey tint dashed with dark spots, these follow the line of the spiral turnings, which are very regular, proceeding from the opening below to the apex or point. Seen on shore, its colours are dull and faint, but beneath the water, inhabited by a living mollusk, it looks as though made of pearl, and studded with rubies; the animal, too, is richly coloured, being yellow with black stripes.—See [Plate IV], Fig. 3.