INHABITING MULTILOCULAR SHELLS. 455 
The filaments in the ink-pen of the cephalopod terminate on each 
side in a straight line, which makes an acute angle with the outer 
edge of a marginal band, separating the filaments from the body of 
the shaft. The shaft itself is divided lengthways into two parts, 
and is formed of thin horn-like plates laid on each other, and com- 
posed of alternate longitudinal and transverse fibres. The whole 
contrivance is connected with a bag containing the ink (which is of 
the consistence of pap, and suspended in the cells of a thin net-work, 
filling up the interior of the bag); and at the least alarm it is 
spirted out, and discolours the surrounding fluid. The rich brown 
colour called sepia, and the still darker one known as Indian ink, are 
manufactured from cephalopodous animals now living in the Indian 
seas ; and, as we have already observed, the dried carbonaceous mat- 
ter in the pouches of similar animals found fossil might be, and 
indeed has been, worked up into a pigment, and is then not distin- 
guishable from the best of that which is commonly to be cbtained. 
Having described this contrivance in known animals, we come 
next to consider whether there is proof that in the genus before us 
—that of Belemnites—a similar contrivance existed ; and, if so, how 
far the now extinct animal may have resembled the yet living sepia 
and other Cephalopoda. 
Till lately, no absolute proof had completely silenced the doubt as 
to whether the fossil pouches and ink-pens had once belonged to the 
shell called Belemnite ; for the horny termination of the calcareous 
sheath had not been found connected with the fossil. The matter, 
however, is now entirely set at rest by the discovery, first, of the 
horny sheath forming a continuation of the calcareous part to a dis- 
tance equal to the length of that solid portion ; and secondly, and 
most conclusively, by two complete specimens, noticed first by Prof. 
Agassiz, each containing an ink-bag within this anterior horny por- 
tion. More recently, the ink-bag has often been obtained in connec- 
tion with the horny sheath, and the horny continuation has been 
found in many individuals of well-known species of Belemnite ; so 
that the fact of the co-existence of all these parts in the same ani- 
mal is no longer to be doubted. It may be observed, lastly, that 
casts of the chambers are very commonly found in the open end of 
the fossil ; and we have, therefore, now gone through, and con- 
nected, the chief points in the natural history of the animal, so far 
as it is indicated by organic remains still existing. 
It will be seen, from this description, that the natural family of 
Belemno-sepia, thus brought under our notice, appears to form a 
link uniting the peculiarities of the common sepia, and other free- 
