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. The earthy character of its bone is a clear
indication of this. For in the Poulp there is no bone at all, and in
the Calamary it is thin and cartilaginous. Why this bone should be
present in some Cephalopoda, and wanting in others, and how its
character varies in those that have it, has now been set forth.
These animals, having no blood, are in consequence cold and of a
timid character. Now, in some animals, fear causes a disturbance of
the bowels, and, in others, a flow of urine from the bladder.
Similarly in these it produces a discharge of ink, and, though the
ejection of this ink in fright, like that of the urine, is the
result of necessity, and, though it is of excremental character, yet
it is used by nature for a purpose, namely, the protection and
safety of the animal that excretes it.
The Crustacea also, both the Caraboid forms and the Crabs, are
provided with teeth, namely their two anterior teeth; and between
these they also present the tongue-like piece of flesh, as has
indeed been already mentioned. Directly after their mouth comes a
gullet, which, if we compare relative sizes, is but small in
proportion to the body: and then a stomach, which in the Carabi and
some of the Crabs is furnished with a second set of teeth, the
anterior teeth being insufficient for adequate mastication. From the
stomach a uniform gut runs in a direct line to the excremental vent.
The parts described are to be found also in all the various
Testacea
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