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.