76 
PROFESSOR OWEN ON THE BELEMNITE. 
But we derive from the present remarkable specimens ample confirmation of the 
association of the ink-bag with the higher grade of the circulating and respiratory 
organs, which grade is necessarily associated with the high development of the loco- 
motive system, as demonstrated by the muscular mantle and its appended fins; 
whilst the preservation of the latter organs in situ establishes the soundness of M. 
Duval’s objections to their position in all the published conjectural restorations of 
the Belemnite. 
In the specimen under consideration * the fins are crossed by a narrow tract of grey 
transversely fibrous substance, probably part of the mantle, near the anterior termi- 
nation of which an oblong flattened tract of similar substance extends forward, 
slightly expanding as it advances to a position opposite the neck of the Belemnite, 
where it is terminated by a slightly concave truncation : longitudinal fibres may be 
discovered decussating the more abundant transverse fibres of the part which is 
most probably the remains of the infundibulum. A short flattened band of fibres (y) 
connects this part with the neck of the Belemnite, having the exact position and pro- 
portion of the retractor or levator muscles of the infundibulum of the naked Cepha- 
lopods'j-. The traces of muscular tissue in the situation of the head are much more 
obscure ; two short processes from the anterior part of this mass are evidently the bases 
of tentacula or cephalic arms. 
At the middle of the visceral mass, in the interval of the two lateral fins, there lies 
a compressed body of a horny texture and sub-bilobed form (m), on which may be 
clearly distinguished striae passing outwards in opposite directions from a middle 
line and diverging from each other in their course, which resembles that of the fibres 
of the digastric muscle in the gizzards of the Nautilus and other Cephalopods : this 
apparent remnant of the stomach lies about half an inch in advance of the ink-bladder, 
in a position corresponding with that of the gastric organ in naked Cephalopods. 
There is strong negative evidence that the Belemnite possessed horny mandibles like 
the other naked Cephalopods, since no calcareous beaks, or Rbyncholites, have been 
discovered associated with the specimens from the Oxford clay, or with those from 
the lias. 
The thickness of the layer of dried and compressed grey fibrous matter to which the 
mantle is reduced is half a line, and we may infer from this, that in its soft and re- 
cent state, when permeated by its sanguiferous vessels, it must have equalled in thick- 
ness that of a Calamary of the same size. In fact the mantle of true Teuthidce 
(Calamaries with horny pens), preserved in the same matrix as the Belem nites here 
described, has been reduced to a compact fibrous layer of the same thinness: a 
specimen of one of these ^ displays by a fracture of the layer of the clay in which it 
was imbedded, the anterior and posterior walls with the intervening cavity of the 
abdomen, exposing the ink-bag and duct in situ. 
* PI. IV. fig. 1. 
t Compare fig. 10, <7, with Cuvier’s PI. 1. fig. 2, m, n, Mernoire sur le Poulpe, 4to. 
J PI. IV. fig. 2. 
