They are common enough in some parts of England; and, in the
condition in which they are ordinarily found, it might be
difficult to give satisfactory reasons for denying them to be
merely mineral bodies.

They appear, in fact, to consist of nothing but concentric
layers of carbonate of lime, disposed in subcrystalline fibres,
or prisms, perpendicular to the layers. Among a great number of
specimens of these Belemnites, however, it was soon observed
that some showed a conical cavity at the blunt end; and, in
still better preserved specimens, this cavity appeared to be
divided into chambers by delicate saucer-shaped partitions,
situated at regular intervals one above the other. Now there is
no mineral body which presents any structure comparable to this,
and the conclusion suggested itself that the Belemnites must be
the effects of causes other than those which are at work in
inorganic nature. On close examination, the saucer-shaped
partitions were proved to be all perforated at one point, and
the perforations being situated exactly in the same line, the
chambers were seen to be traversed by a canal, or
siphuncle, which thus connected the smallest or aphical
chamber with the largest. There is nothing like this in the
vegetable world; but an exactly corresponding structure is met
with in the shells of two kinds of existing animals, the pearly
Nautilus and the Spirula, and only in them. These
animals belong to the same division--the Cephalopoda--as
the cuttle-fish, the squid, and the octopus. But they are the
only existing members of the group which possess chambered,
siphunculated shells; and it is utterly impossible to trace any
physiological connection between the very peculiar structural