r8_
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THE SEAS
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common in the sea ; some are minute scraps of living matter,
such as the marine amœbæ, quite unprotected and moving
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about on the sea bottom by a kind of owing motion;
others possess elaborate little shells of limy matter and are
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-
called Forarhinifera, or of silica and are known as Radi—
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olariäans, both occurring in countless numbers in the surface
Others
again, called Ciliates, though without
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‘
shells, are of more complicated structure, being covered
with ne hairs by the heating of which they move and draw
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in
food.
As widespread near the surface as the Radi—
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olariäms- and Foraminifera, are the DinoageHates or
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Peridinians which have two whip—like processes for loco—
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motion, may or may not be covered with skeletal plates, and
often contain green colouring matter so that it is unce'rtain
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whether they are animals or plants.
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:
'The spdnges or PORIFERA are animals of so simple a
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Structure that they give the impression of being little more
,
than aggregations of Protozoans.
They are always attached
and have a supporting Skeleton, of homy matter in the
sponge of commerce, but in the majority of cases consisting
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'of immense numbers of tiny spicules of many beautiful
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shapes and formed in some cases of limy material and '
Others of silica.
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.
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.
The CŒLENTERATA include a large number of relatively
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simple anim‘als whose bodies are eSsentially bag—shaped,
c0ntaining Only One CaVity which COmbin'es the functions
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of thèstomach cavity and the general body cavity of the
jremaining, more ”highly-organized, animals.
They are all
,
built on a circular plan, i‘.e. there are not two symmetcaî
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Sides. " They are almost entirely marine and are universally
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distribüted.
They include many common animals and
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inay be said to be of two general types, attached like the”
and
freely swimming like the
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Many
attached kinds are not solitary individuals