PROFESSOR OWEN ON THE BELEMNITE. 
71 
tion, suffices to prove that the weight and solidity of the guard had received no 
augmentation by inorganic influences after death*. 
That the shell of the Belemnite was due to the formative forces of the mantle of 
a molluscous animal, was the sound speculation as to its nature, which our country- 
man Joshua Platt first recorded in the Transactions of the Royal Society for 1764. 
The presence of a camerated and siphonated structure in this complicated shell, led 
Walch^~ and Guettard^, and after them most subsequent conchologists, to class 
the Belemnites with the Baculites, Orthoceratites, and other more simple chambered 
shells. Mr. Miller, having detected evidence of the internal position of the belem- 
nitic shell, compared it, as Deluc§ on other grounds had done, with the internal shell 
of the Cuttle-fish, and first ventured on a conjectural restoration of the entire animal. 
He thought the Belemnite to have been an intermediate form in the Cephalopodal 
class, uniting the internal multilocular shell of the Spirula with the laminated calca- 
reous plate of the Sepia, to which the belemnitic guard appears to correspond ; and, 
believing that the Nautilus, Ammonite, Sepia and Loligo, had the same organization 
(only the Dibranchiate type of Cephalopodal structure being then known), Mr. 
Miller placed the belemnitic shell in the body of a Calamary (Loligo), assigning to 
the terminal fins the office of clasping the guard and retaining it in its proper position ; 
which last idea M. De Blainville very justly rejected. 
The subsequent discovery of two grades of organization in the class of Cephalopods, 
consequent on the dissection of the Nautilus Pompilius ||, called for a closer investi- 
gation of the affinities of the Belemnites, and led to an attempt to establish a more 
definite approximation of these with the other families of siphoniferous Cephalopods, 
now ranked under two distinct orders of the class. 
The first evidence that bore directly upon the question of the position of the Belem- 
nite in this class, was detected by Dr. Buckland^[ and M. Agassiz** in specimens 
of Belemnite from the lias at Lyme Regis, in which the fossil ink-bag was preserved 
in the basal chamber of the phragmocone, or that formed by the anterior prolonga- 
tion and expansion of its capsule. 
The importance of this discovery depends chiefly on the facts, that the secreting 
gland and reservoir of the inky secretion common to all the naked Cephalopods do 
not exist in the recent Nautilus Pompilius, and that no trace of them has ever been 
* Such was Mr. Miller’s opinion ; but, as it was unsupported by microscopic investigation, or by any facts 
like that above cited, it was not accepted by Prof. De Blainville and Dr. Buckland. 
f In Knorr’s ‘ Recueil de Monumens des Catastrophes que le Globe de la Terre a essuyees,’ &c. fol. 1768. 
I Memoires sur differentes parties des Sciences et des Arts, t. v. 9 e Memoire, 1783. 
§ Memoires sur les Belemnites, in Journal de Physique, 1799, 1801, 1802. 
t) Owen, Memoir on the Pearly Nautilus, 4to, 1832. 
Philosophical Magazine, N.S. 1829, p. 388. [One of the specimens discovered by Miss Mary Anning 
of Lyme, on which Dr. Buckland’s observations were made, has been presented, since the reading of the pre- 
sent memoir, by the Earl of Enniskillen to the College of Surgeons.] 
** Ibid. 1834. 
