Only two examples of those reversed shells have occurred to our observation: both were of that kind in which the spire is elongated; the high spired Turnip Shell of the English cabinets. One of these reversed shells we saw in the year 1797, in the celebrated collection of Mon de Calonne, ci-devant Minister of France, and which passed, at a considerable price, into the collection of the Earl of Tankerville. The other occurred in the late Leverian Museum, which was distributed by public auction, in the year 1806. This last-mentioned shell was in a less perfect condition than might be wished; it was worn and mutilated, and for this reason did not obtain by any means such a price as was expected from its rarity: it produced only _seven guineas_, a sum considered much beneath its real value, even in its injured state.[16] In the month of April, in the year 1815, the same shell appeared in the sale of certain effects, the property of the Duke de Bourbon, at his residence in Great Ormond Street, Portman Square, where it was sold, we believe, at an advanced price. It is the figure of this last-mentioned shell that appears in the present plate. We have delineated the specimen with all faults for the sake of greater accuracy, and from a persuasion that the Naturalist would prefer a correct representation from an undoubted original, to any figure in which its actual defects might have been amended by the pencil of the artist. The shell is depicted in its natural size, and it will hence appear, is little inferior in point of magnitude to the generality of those shells of the same species which are not of the reversed kind. The species is sometimes known to grow to the length of seven or eight inches, but such examples are not common. Of the reversed kinds the Leverian specimen, as it has been emphatically denominated, is probably one of the largest known. The smaller figure in the lower part of our plate is a representation of the same species in its usual form, and appears clothed or covered with the thick filmy epidermis, of a brown colour, with which the shell is naturally covered when in a living state. From this figure it will be perceived that the direction of the spiral wreath or whorls in the larger shell is exactly reversed, and that the mouth or aperture of the shell, which in the smaller figure appears on the right side, is seen in the reversed shell on the left. Thus upon the least comparison of the two figures, the true character of the reversed shell will be distinctly perceived.