They have increased and multiplied and filled the mud.
"Requiescat in pace."
But zooelogy has its tragedies as well as human history. Let us turn
to the development of a third molluscan line terminating in the
cuttle-fishes. The ancestors of these cephalopods, although still
possessed of a shell and a high visceral hump, regained the swimming
life. First, apparently, by means of fins, and then by a simple but
very effective use of a current of water, they acquired an often
rapid locomotion. The highest forms gave up the purely defensive
campaign, developed a powerful beak, led a life like that of the old
Norse pirates, and were for a time the rulers and terrors of the
sea. With their more rapid locomotion the supra-oesophageal
ganglion reached a higher degree of development, and it was served
by sense-organs of great efficiency. They reduced the external
shell, and succeeded, in the highest forms, of almost ridding
themselves of this burden and encumbrance. Traces of it remain in
the squids, but transformed into an internal quill-like, supporting,
not defensive, skeleton. They have retraced the downward steps of
their ancestors as far as they could. And the high development of
their supra-oesophageal ganglion and sense-organs, and their
powerful jaws and arms, or tentacles, show to what good purpose they
have struggled.
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