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shall conclude our account of chambered shells with a brief notice of Belemnites. This extensive family occurs only in a fossil state, and its range is included within that series of rocks which in our section are called Secondary. These singular bodies are connected with the other families of fossil chambered shells we have already considered; but differ from them in having their chambers inclosed within a cone-shaped fibrous sheath, the form of which resembles the point of an arrow, and has given origin to the name they bear.

M. de Blainville, in his valuable memoir on Belemnites, (1827) has given a list of ninety-one authors, from Theophrastus downwards, who have written on this subject. The most intelligent among them agree in supposing these bodies to have been formed by Cephalopods allied to the modern Sepia. Voltz, Zeiten, Raspail, and Count Münster, have subsequently published important memoirs upon the same subject. The principal English notices on Belemnites are those of Miller, Geol. Trans. N. S. London, 1826, and that of Sowerby, in his Min. Conch. vol. vi. p. 169, et seq.

A Belemnite was a compound internal shell, made up of three essential parts, which are rarely found together in perfect preservation.

First, a fibro-calcareous cone-shaped shell, terminating at its larger end in a hollow cone (Pl. 44, Fig. 17. and Pl. 44', Fig. 7, 9, 10, 11, 12.