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ticularly the fusiform, have a longitudinal sulcus, and others have been 
seen with two ; but what has been the use of these sulci is not known. 
So perplexed were the earlier writers on this fossil, respecting its 
nature and origin, that they were even puzzled to ascertain under 
which of the natural kingdoms to place it. Not only the earliest 
writers on mineralogy considered it as originally belonging to the 
mineral kingdom, but even Woodward supposed it to be a stone, sui 
g eneris. Langius considered it as a stalactite ; Libavius believed it 
to be indurated amber ; and even M. de Costa supposed it to be a 
natural fossil, or lapis sui generis, composed of talc and spar, and 
compared its cavity to that of stalactites; adding — “As for that 
marine body, the alveolus, I cannot think otherwise than that it is of 
the Nautilus kind, which, at the concretion or formation of the 
belemnite s, became accidentally lodged in its cavity, in the same 
manner as all other marine bodies became lodged in the various 
fossil substances we now find them in.” Phil. Trans. 174/ • Stobaeus 
and Hellwing were of opinion that it was of vegetable origin. 
Among those who conceived it to be of animal origin, we find no 
small discordance of opinion ; some believing it to have been the 
horn, and others the tooth, of an animal. Of those who entertained 
the latter opinion, some supposed it to be the tooth of a crocodile, 
and others of a physeter; Lhwydd believing it to be the tooth a 
particular species of the whale, resembling the narwhal. Some were 
of opinion that it was the spine of a particular species of echinus. 
M. Titius conjectured it to be one of the extremities of a species of 
Stella marina. M. de la Tourette believed it to have been a species 
of Polype ; and Waller and others a species of Holothuria. 
Later oryctologists, particularly Rosinus, Erhart, Breyn, Klein, 
and Linnaeus, have agreed, that this body must be considered as the 
remains of the chambered shell of a marine animal, the recent analogue 
of which is unknown. With this opinion M. Walch perfectly agrees, 
believing it. to be supported by the circumstance of the nacre having 
