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The Voyage of the Beagle by Charles Darwin
page 291 of 731 (39%)

In Tierra del Fuego, as well as in the Falkland Islands,
made many observations on the lower marine animals, [11] but
they are of little general interest. I will mention only one
class of facts, relating to certain zoophytes in the more highly
organized division of that class. Several genera (Flustra,
Eschara, Cellaria, Crisia, and others) agree in having singular
moveable organs (like those of Flustra avicularia, found
in the European seas) attached to their cells. The organ, in
the greater number of cases, very closely resembles the head
of a vulture; but the lower mandible can be opened much
wider than in a real bird's beak. The head itself possessed
considerable powers of movement, by means of a short neck.
In one zoophyte the head itself was fixed, but the lower jaw
free: in another it was replaced by a triangular hood, with
beautifully-fitted trap-door, which evidently answered to the
lower mandible. In the greater number of species, each cell
was provided with one head, but in others each cell had two.

The young cells at the end of the branches of these corallines
contain quite immature polypi, yet the vulture-head
attached to them, though small, are in every respect perfect
When the polypus was removed by a needle from any of the
cells, these organs did not appear in the least affected. When
one of the vulture-like heads was cut off from the cell, the
lower mandible retained its power of opening and closing.
Perhaps the most singular part of their structure is, that
when there were more than two rows of cells on a branch,
the central cells were furnished with these appendages, of
only one-fourth the size of the outside ones. Their movements
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