314 PHILOSOPHICAL TRANSACTIONS. [aNNO 1747. 



bular, in different degrees. Now one kind of petrifaction, or any other change 

 in the earth, which they might have undergone, could never have given so re^ 

 gular a texture and substance, and cause such different effects as solidity and tu- 

 bularity. And if, on the other hand, we allow it to be inconsistent, as it is, to 

 form the idea of a shell of the tubulus kind, by a solid body, without that body 

 having suffered some change in the earth, while buried in it, we must either deny 

 all solid belemnites to be such tubulin and run to subterfuges, by owning them to 

 be natural fossils ; or else allow a great inconsistency, to uphold a wrong system. 



That the belemnites are not a tubular case, which is part of, and covers a 

 shell of the nautilus kind, as is its alveolus. The variety of circumstances already 

 alleged of the belemnites serve to demonstrate the improbability also of this opi- 

 nion, as it has done of the other two. The numbers of belemnites of all kinds, so 

 plentiful every where, and the consideration of how few are furnished with alveoli. 



Numbers indeed have conic cavities ; but that those cavities never did contain 

 alveoli, is evident ; that the sides of the said cavities are even, and without any 

 circular or other impressions, which a belemnites that has ever contained an al- 

 veolus must have ; that body being in close contact to all parts of the investient 

 belemnites, must consequently impress it with its concamerations ; which im- 

 pressions must be therefore found on the sides of the cavities of all belemnites 

 which ever contained them. 



As for asserting, that all the alveoli, which are now found loose, were origi- 

 nally lodged in belemnites ; it cannot be, without inferring also that all belem- 

 nites, which are now devoid of alveoli, contained such formerly ; which, by 

 some external or other agent, have been forced out and loosened from them. 



To consider such an agent, we must also conclude its force to have been ex- 

 ceedingly great, to loosen out the nucleus of a body in close contact with all its 

 investing parts ; and strengthened further to it by ridges and grooves ; such a 

 force must have compressed, shattered, and otherwise broken and destroyed the 

 belemnites that contained them ; which is contrary to observation. Further, 

 forcing out the alveolus might perhaps easily have happened to the conic belem- 

 nites ; which has a basis of a larger diameter than the middle, where the alve- 

 olus is lodged ; but we cannot conceive the same by the cylindric, fusiform, and 

 other belemnites, of which the 2 ends or extremes terminate pointed ; while 

 the middle, where the alveolus is lodged, is thick and swelled. 



To force an alveolus out of such shaped belemnites, it is evident that the nar- 

 row ends of the said belemnites must be quite forced open, broken, and shat- 

 tered, before a broader and more capacious body could be forced through, 

 especially to such a brittle shattery fossil as the belemnites is. The evident facts 

 to the contrary of this are also too common to insist on, since all these belemnites 

 are ever found regular, perfect, and entire. 



Further, let us consider the alveoli which are now found in belemnites, they 



