Книга только для ознакомления
.
In all these animals there is a fin, encircling the sac. In the
Poulps and the Sepias this fin is unbroken and continuous, as is
also the case in the larger calamaries known as Teuthi. But in the
smaller kind, called Teuthides, the fin is not only broader than in
the Sepias and the Poulps, where it is very narrow, but, moreover,
does not encircle the entire sac, but only begins in the middle of the
side. The use of this fin is to enable the animal to swim, and also to
direct its course. It acts, that is, like the rump-feathers in
birds, or the tail-fin in fishes. In none is it so small or so
indistinct as in the Poulps. For in these the body is of small bulk
and can be steered by the feet sufficiently well without other
assistance.
The Insects, the Crustacea, the Testacea, and the Cephalopoda,
have now been dealt with in turn; and their parts have been described,
whether internal or external.
10
We must now go back to the animals that have blood, and consider
such of their parts, already enumerated, as were before passed over.
We will take the viviparous animals first, and, we have done with
these, will pass on to the oviparous, and treat of them in like
manner.
The parts that border on the head, and on what is known as the
neck and throat, have already been taken into consideration. All
animals that have blood have a head; whereas in some bloodless
animals, such as crabs, the part which represents a head is not
clearly defined
|
