VOL. XLIV.] PHILOSOPHICAL TRANSACTIONS, 315 



are very seldom if ever found as mere shells, but ever differently changed or pe- 

 trified. They are moulded of stone, pyrites, crystal, &c. Now it can never be 

 argued, that the contained bodies can ever be so differently changed or petrified 

 in their covers or shells, and those covers or shells which admitted such different 

 petrifying particles to undergo no change or petrification whatever. 



Another proof against this opinion, is the diverse forms of alveoli now disco- 

 vered by naturalists, as conic, cylindric, curved, spiral at the apex, &c. whereas 

 all belemnites, which have cavities, have none but conic ones. 



These cylindric, &c. alveoli are now found in Pomerellia in Poland, in the 

 marble of the island of Oeland, in the Baltic sea, belonging to Sweden, and in 

 the marble of Sweden ; in Gothland in masses of building stone ; in Ingria, in 

 several parts of Prussia, &c. and are commonly of an immense size, to several 

 feet in length, and proportionably thick, yet not perfect. For such alveoli, 

 which are only nuclei, we must suppose immense large belemnites ; and such 

 we have never heard of, so with probability we may conclude none such to exist. 



The very view of a belemnites sufficiently evinces its mineral origin, and shows 

 it evidently composed of 2 fossil substances, a talc, and a spar, or bastard crystal ; 

 of which the former is the basis, and from which principle he attributes its striated 

 texture. Most of the talcy bodies are of a fibrous nature, and several are com- 

 posed of crusts inclosing each other, in the same manner as the septa of the 

 ludus helmontii, some of the asbestos kind, the hasmatites crusts, &c. Of the 

 stalactites tribe there are several, which so entirely approach the texture and 

 constitution of the belemnites, that were their shapes a little more regular, the 

 most experienced lithologist might easily be deceived. And he remembers when 

 abroad, to have seen such, of a prodigious size, which, though he was then 

 somewhat conversant in the fossil study, he could not help taking for belemnites. 

 He does not therefore wonder, that Petrus Assaltus, in notis ad Metallothecam 

 Mercati, p. 282, and Langius, Hist. Lap. Figurat. Helvetiae, p. 133, should 

 judge them a native figured fossil, formed in the earth, of the stalactites kind, if 

 that terni for the belemnites might with propriety be used. 



The cavities of stalactites in some measure illustrate, and are adequate to the 

 cavities of belemnites ; they are placed in as various positions, and are only dif- 

 ferent from them by not being exactly conic. As for the regular figure of the 

 belemnites being excepted against, he believes few fossilists will argument that, 

 when we see as perfect regular figures in the fossil kingdom, as in any other 

 parts of the creation ; as witness the salts and crystals of all kinds ; the rhom- 

 boid, hexagonal, columnar, and other selenites; the cubic, octangular, dode- 

 caedral, and other pyrites ; the quadrangular pyramids of tin, the rhombs of 

 iron, cubes of lead, and infinite other native fossils, which are far more perfect 

 figures than the belemnites are. Chymical and other trials and tests demonstrate 



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