PROFESSOR OWEN ON THE BELEMN1TE. 75 
stratum and restricted locality, admits of no reasonable doubt of their belonging to 
one and the same species of true Belemnite. 
The two flattened fibrous bodies, (e,e) with well-defined semi-oval external and appa- 
rently free margins, — the one on the right side entire, the one on the left having the 
contour of the defective part of the margin indicated by the dark carbonaceous stain 
in the matrix, — are the parts which I regard as the lateral fins of the mantle. They 
have been slightly displaced transversely and pressed inwards upon the yielding 
viscera; their original cartilaginous basis would favour their encroaching in that 
direction if subjected to equable surrounding pressure : the lateral fin which is pre- 
served in the first specimen * has been pushed more deeply inwards. 
The large end of the semi-oval free border is the anterior one, where the fin is 
broadest ; it gradually becomes narrower posteriorly. The muscular fasciculi are 
strongly marked, and are arranged transversely to the long axis of the fin, as in exist- 
ing Decapodous Cepbalopods. It is interesting to find a rounded contour associated 
with an advanced position of the lateral fins in the ancient Belemnites, as in the modern 
Rossia and Sepiola, the rhomboidal form being most common in those fins which are 
placed at the end of the body, as in the Onychoteuthis and Loligo ; the only exception, 
indeed, being presented by the Loligopsis, which has terminal and rounded fins. 
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 Bridgewater Treatise; and, like it, differs from 
Mr. Miller’s restoration, 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 discovery of the 
united fractures of the spathose guard, has objected 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 swim- 
ming, would soon have fallen a prey to its numerous enemies, and would not have 
survived to exemplify the reparative powers of those ancient Cephalopods. M. Duval, 
however, modestly concludes by confessing that he should not have dared himself to 
figure from the known analogies, the animal to which the Belemnite ought to have 
belonged ; for “l have not,” he says, “a sufficiently exact knowledge of the organic 
laws of the Cephalopoda.” It seemed vain to hope that the soundness of the prin- 
ciples on which the classification of the Belemnites with the dibranchiate Cephalo- 
pods had been definitely proposed, should ever be vindicated by the demonstration of 
parts, apparently so perishable as the fleshy mantle, the fins, and the slender flexile 
arms of these ancient Mollusca^. 
* PI. III. 
t Sur les Belemnites, 4to, PL 7. fig. 10. 
+ Cuvier, in the second edition of the ‘ Rbgne Animal,’ places the Belemnites between the Orthoceratites 
and the Ammonites, and observes, “Us appartiennent probablement encore <1 cette famille, mais il est impossible de 
s'en assurer, puisqu on ne les trouve plus que parmi les fossiles,” tome iii. p. 19,— which teaches how liable the 
best authoiities are to err, when they would set bounds to the possibilities in Nature. 
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