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whole belemnite ; in others, not a sixth part of the whole : but the 
upper chamber is equally proportionable to the bulk, or circumference 
of the belemnite, of whatsoever size or shape, and is the seat or 
dwelling place of the animal that forms the belemnite. 
Whoever (Mr. Platt says) considers the seam or sulcus in the 
belemnite, will, I think, conclude with me, that the outward lamina 
is formed latest, as in the cowree, and that the seam or sulcus is 
caused by the several additional coverings or laminae terminating 
there. As the oyster strengthens its shell, and excludes its first 
habitation, by additional laminae formed within, the belemnite incloses 
its dwelling, by adding new laminae without. Mr. Platt supposes, 
that the animal growing larger, when in its first former cell, forms 
then a second cell or chamber, and at the same time covers the first 
cell, by forming the appendage or guard, which is the first stage of 
the belemnite. In forming the third cell, fresh laminae or coverings 
are carried on, and so of the rest, the body of the belemnite gaining 
an increase of volume with each additional chamber. 
The siphunculus of the belemnite, he observes, is always upon the 
verge of the chamber or cell ; and, in this siphunculus, is a little gut 
or ductus, proceeding from the body of the animal, by dilating or 
contracting of which, the animal, it should seem, may go out or in to 
its cell at pleasure. This is the only stay which the animal has to 
secure its retreat. “ But I cannot agree (he says) with the learned 
Dr. Hooke, that the gut, or ductus, passes through all the cells to 
the end of the spiral cone, either in this shell or the nautilus. 1 
am apt to think (Mr. Platt says) that this gut, or ductus, as well as 
the body of the creature, is capable of being extended very consider- 
ably, to serve all the uses of forming the belemnite, without leaving 
the siphunculus ; and that the gut serves for the same purposes as 
the tendons of the oyster : the latter to open and shut the shell, 
the former to allow the animal to go out and in at pleasure. And as 
the oyster feeds altogether in the shell, by opening the verge, the 
belemnite (whose residence is in the great deep, which is seldom dis- 
