According to the Linnæan classification, the shelly covering of this animal is a Voluta; and so far as the most prominent criterion of the Voluta genus, the folds or plaits upon the pillar lip be considered, this character is unequivocal. Linnæus regarding this as one of its most essential definitions, has overlooked the differences that prevail in the structure of the spire and beaks, or includes them only as distinctions of the different families into which his Volutæ are divided. Later writers differ upon this subject; these differences are considered by many as generical, and thus the Linnæan Volutæ have become separated into several distinct genera. In the shell before us, the beak is lengthened or produced, and canaliculated; and thus constitutes in the classification of Lamarck, a species of his TURBINELLA; and is the shell in particular which he adopts as the type of that genus. The character of that genus, as proposed by this Conchologist, in his work entitled _Animaux sans vertèbres_, is thus expressed, Turbinelle (Turbinella) a shell turbinated or subfusiform, canaliculated to the base, and having upon the column from three to five plaits or folds of a compressed form and placed transversely. Murex scolymus of Martini, Voluta ceramica of Lister, and Voluta capitellum of the same author, are comprehended with the Linnæan Voluta pyrum in this genus Turbinellus. It has been observed by De Montfort that Lamarck has made a group of those shells which accord with the above character, and which he himself adopts with some small variations: according to this writer, the genus Turbinelle, of which our Voluta Pyrum is considered as the type, has the shell heavy, univalve, with an obtuse spire ending in a nipple; the mouth sloping and lengthened; the pillar denticulated with large equal folds or plaits, the outer lip strait and cut off, and the base lengthened. After all the pains, however, which Lamarck and other Continental Naturalists have taken to establish the genus Turbinella, Cuvier in his Règne Animal observes that the shells of this genus differ in no other respect from the Conic Volutes than in the prolongation of their opening, forming a kind of canal, and adding that it is not easy to trace the limits between the one and the other.