The _Protozoans_ are represented by
_Foraminifera_ and _Sponges_, and the _Coelenterates_ by a small
number of _Corals_; but these require no special notice. It may be
mentioned, however, that the great Palaeozoic group of the _Rugose_
corals has no known representative here, its place being taken
by corals of Secondary type (such as _Montlivaltia, Synastoea_,
&c.)
The _Echinoderms_ are represented principally by _Crinoids_,
the remains of which are extremely abundant in some of the
limestones. The best-known species is the famous "Lily-Encrinite"
(_Encrinus liliiformis_, fig. 142), which is characteristic of the
Muschelkalk. In this beautiful species, the flower-like head is
supported upon a rounded stem, the joints of which are elaborately
articulated with one another; and the fringed arms are composed
each of a double series of alternating calcareous pieces. The
Palaeozoic Urchins, with their supernumerary rows of plates, the
Cystideans, and the Pentremites have finally disappeared; but
both Star-fishes and Brittle-stars continue to be represented.
One of the latter--namely, the _Aspidura loricata_ of Goldfuss
(fig. 143)--is highly characteristic of the Muschelkalk.
[Illustration: Fig. 142.--Head and upper part of the column of
_Encrinus liliiformis_. The lower figure shows the articulating
surface of one of the joints of the column.
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