CEPHALOPODA. 601 



branchiate order ; and I, therefore, separated tliese chambered and 

 siphoniferous shells from the Nautilus and the Ammonites in the 

 Classification of the Cephalopoda proposed in 1836.* 



Leopold Von Buch, who believed that he could trace in certain 

 slabs containing Belemnites the impressions of the Cephalopods to 

 which they belonged, concluded " that the body of the animal enve- 

 loped the greater part of the shell, and exceeded its length by eight 

 or ten times." f Other considerations, taken from the shell itself, 

 prove, as has already been shown, that it was wholly internal. 



M. Duval, the latest and most accurate author on fossil Belemnites, 

 reproduces the figure which M. D'Orbigny has published, and which 

 is essentially the same as that given by Dr. Buckland in his Bridge- 

 water Treatise ; and, like it, differs from Mr. Miller's restoration, 

 only in the position of the ink-bag and in the extended state of the 

 terminal fins. With respect to these parts, M. Duval, from his dis- 

 covery of the united fractures of the spathose guard, objects, with 

 much acumen, that, if the fins of the Belemnite had been placed at 

 the side of the guard, they must have been rendered useless by its 

 fracture, and the creature, thus deprived of its power of swimming, 

 would soon have fallen a prey to its numerous enemies, and would 

 not have survived to exemplify the reparative powers of those ancient 

 Cephalopods. It seemed vain to hope that the soundness of the 

 principles on which the classification of the Belemnites with the 

 dibranchiate Cephalopods had been definitely proposed, should ever 

 be vindicated by an example of parts apparently so perishable as the 

 mantle, the fleshy arms and fins of these Mollusca. I have, however, 

 been enabled to examine and describe a fossil specimen, in which 

 not only the ink-bag, but the muscular mantle, the head, and its crown 

 of arms, are all preserved in connection with the most essential cha- 

 racteristic of the Belemnitic shell, viz., the phragmocone. % It appears 

 to have been the peculiar property of the matrix, in which this and 

 many similar valuable and instructive specimens were entombed, to 

 favour the conversion of the muscular tissue into adipocire, and its 

 subsequent preservation to the present time. Yet this matrix is a 

 member of the Oxford-clay formation, belonging to the middle oolite 

 system ; older, therefore, than the Portland stone, the Wealden, and 

 the Cretaceous group. The Cephalopod, in which we may now study 

 the microscopic character of the muscular fibre §, must therefore have 

 existed at a period antecedent to the gradual deposition of these 

 enormous masses of the secondary strata, which themselves preceded 

 the formation of the entire tertiary series, and the overspreading un- 



* CCCXCVII. t Oken's Isis. Bd. xxi. p. 438. 



X CCCXCVI. pi. V. § lb. pi. vi. figs. 3 and 4. 



