types, encrinital remains forming the greater proportion of the mass.
There are occasional plant remains which bear evidence of having drifted
for some distance from the shore. But next to the _encrinites_, the
corals are the most important and persistent. Corals of most beautiful
forms and capable of giving polished marble-like sections, are in
abundance. _Polyzoa_ are well represented, of which the lace-coral
(_fenestella_) and screw-coral (_archimedopora_) are instances.
_Cephalopoda_ are represented by the _orthoceras_, sometimes five or six
feet long, and _goniatites_, the forerunner of the familiar _ammonite_.
Many species of brachiopods and lammellibranchs are met with. _Lingula_,
most persistent throughout all geological time, is abundant in the
coal-shales, but not in the limestones. _Aviculopecten_ is there abundant
also. In the mountain limestone the last of the trilobites (_Phillipsia_)
is found.

[Illustration: FIG. 27.--_Fenestella retipora_. Mountain limestone.]

[Illustration: FIG. 28.--_Goniatites_. Mountain limestone.]

We have evidence of the existence in the forests of a variety of
_centipede_, specimens having been found in the erect stump of a hollow
tree, although the fossil is an extremely rare one. The same may be said
of the only two species of land-snail which have been found connected
with the coal forests, viz., _pupa vetusta_ and _zonites priscus_, both
discovered in the cliffs of Nova Scotia. These are sufficient to
demonstrate that the fauna of the period had already reached a high stage
of development. In the estuaries of the day, masses of a species of
freshwater mussel (_anthracosia_) were in existence, and these have left
their remains in the shape of extensive beds of shells. They are familiar
to the miner as _mussel-binds_, and are as noticeable a feature of this