GENERAL INTRODUCTION
19
like the anemones but consist oimany individuals united
.
“together.
Of such are the little Hydroids which .have
_branching stems dotted with many little polyps, like owers,
each ’one resembng a minute anemone, which are united,
to one another by a common canal which traverses the stem.
The framework is usually of a thin, transparent, horny'
“material, though in a few cases it is of limy substance, the
'result being a kind of coral.
Some of these are not attached
at all, have
and swim freely in the sea, an
example being the Portuguese Man—o’—War. Allied more
closelyto the anemones are the false corals or Alcÿonarians}
_
consisting of many individuals with a common skeleton
-
of thick horny substance or of tinyspicules or other material, .
and also the true corals (Madreporaria) with massive 1imy:
skeletons.
-
_
-
The worms are divided into“many groups with 1ittle
resemblance other than in shape.
There are the little
TURBELLARIA, seldom more than an inch long,
very at and almost
to which are allied many
parasitic worms which, though commonly found in marine
animals, need ,not concern us here.
There are also the
._NEMERTINA, soit—bodied worms with a long probôscis which
they can prbtrude or draw in at will, and without that
division of the body into a series of transverse segments
which is so striking a feature
the most highly-organized
worms.
These are known as the ANNELIDA and include
the common earthworm (inwhich the segments wehave just .
spoken of are very easily seen) and the bristle—worlS
(Polychætes)
,
which are almost exclusively marine, being
'
everywhere abundant and constituting the great‘majority
of
the, marine worms.
Besides segmentation they are
characterized by the presence of long. bristles which project
from the sides of; the body. ,_Sonie wander about at will
—
,
and are called errant worms, but others live always in