All the
mountain-chains--such as the Alps, Pyrenees, Carpathians, and
Himalayas--into the composition of whose central and loftiest parts
the Nummulitic strata enter bodily, could have had no existence
till after the Middle Eocene period. During that period, the
sea prevailed where these chains now rise; for Nummulites and
their accompanying Testacea were unquestionably inhabitants of
salt water."
[Illustration: Fig. 214.--_Nummulina loevigata_. Middle Eocene.]
The _Coelenterates_ of the Eocene are represented principally
by _Corals_, mostly of types identical with or nearly allied to
those now in existence. Perhaps the most characteristic group
of these is that of the _Turbinolidoe_, comprising a number of
simple "cup-corals," which probably lived in moderately deep
water. One of the forms belonging to this family is here figured
(fig. 215). Besides true Corals, the Eocene deposits have yielded
the remains of the "Sea-pens" (_Pennatulidoe_) and the branched
skeletons of the "Sea-shrubs" (_Gorgontidoe_).
The _Echinoderms_ are represented principally by Sea-urchins, and
demand nothing more than mention. It is to be observed, however,
that the great group of the Sea-lilies (_Crinoids_) is now verging
on extinction, and is but very feebly represented.
Amongst the _Mollusca_, the _Polyzoans_ and _Brachiopods_ also
require no special mention, beyond the fact that the latter are
greatly reduced in numbers, and belong principally to the existing
genera _Terebratula_ and _Rhynchonella_.
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