From an attentive examination of the different Conchological authors, it does not appear to us that the shell before us has hitherto been figured, and we have reason also to believe that it has never been described. These circumstances are the more probable since, as we have before observed, the shell is at this time very little known among the Continental Cabinets. The nearest approach, so far as we can judge from the description, unassisted by any figure, is the Marteau Normal (Malleus Normalis) of Lamarck, a species defined by him as _testa biloba_; _lobo basis unico anticali ad normam_, our shell is certainly bilobate, for it has only one lateral lobe at the beak, and that moreover advances from the beak, pretty nearly, though not exactly, in a right line; but its general description does not sufficiently accord with our shell to authorise as a conclusion that they are the same. Lamarck informs us that there are two varieties of his Malleus Normalis, one of which is a native of the ocean of the Great Indies, the other of the seas of New Holland. The first, or Indian kind, he describes as being on the inside as well as outside of a black colour, with a longish lobe at the base of the shell.[22] The New Holland kind is described of a whitish colour, with the lobe at the base abbreviated.[23] The two last-mentioned shells which Lamarck concludes to be varieties of the same species, may perhaps prove hereafter to be species distinct from each other, as Lamarck has himself shewn to be the case with respect to the common black and the white hammer shells. The black supposed variety of Malleus Normalis we apprehend to be distinct from the shell before us, but it is possible that the New Holland shell which he describes as being whitish, with the lobe at the base abbreviated, may be a worn or much depauperated specimen of our present shell; it certainly does not accord with our shell in any tolerable state of preservation. Lamarck says nothing of any ruddiness or testaceous hues in his New Holland variety of _Normalis_, and admitting these colours to indicate that the shell had been found with its animal in a living state, we can scarcely conceive the dark fuscous spotting which is so conspicuous in the species could by any ordinary accident be so entirely obliterated as appears to be the case in Lamarck’s specimen, if his New Holland variety of Malleus Normalis be really of this species; and it may be further added that if our present shell was actually intended by his Malleus Normalis, the defects of his shell has necessarily influenced his specific character and rendered it imperfect.