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 their inhabitants before they rested there. In the clay at Shotover near Oxford, they have a curious smooth surface, but are otherwise imperfect: at Stonsfield, in the slate-stone, they are generally crushed : those approaching nearest to perfection, which I have seen, came out of the sand, under the bed of stone at Garsington-pitts near 0xford: the outer part is quite perfect, and the verge of the conical cavity is as thin as paper, but the alveolus is destroyed, except the apex or point. At Thame, in digging for stone, several small ones were found in a stratum of blue clay of a more cylindrical form ; some of which have the pearly substance still remaining; an incontestable proof of their being marine productions.

How much of the cavity is occupied by the alveolus, cannot be truly ascertained, until a perfect one can be found, which it will be hard to do in the fossil-state; but if we may judge from the nautilus, the walls are carried to a distance from the last formed valve, much greater than that, at which the valves are placed from each other; as in ﬁg. xiii. from a, to b, which gives the animal all the convenience of forming a new valve or diaphragm, c. This circumstance has been very ingeniously cleared up by a learned physician in one of our monthly papers.

The recent nautili are very common in the eastern seas; and in the fossil state are frequently found with the Belemnites at Garsington near Oxford. Why may we not therefore expect to find a recent Belemnite,

Rh