The first-mentioned of these
formations has also yielded the curious, furrowed and striated
stems which have been described as a kind of land-plant under
the name of _Eopkyton_ (fig. 28). It cannot be said, however,
that the vegetable origin of these singular bodies has been
satisfactorily proved. Lastly, there are found in certain green
and purple beds of Lower Cambrian age at Bray Head, Wicklow,
Ireland, some very remarkable fossils, which are well known under
the name of _Oldhamia_, but the true nature of which is very
doubtful. The commonest form of _Oldhamia_ (fig. 29) consists of
a thread-like stem or axis, from which spring at regular intervals
bundles of short filamentous branches in a fan-like manner. In
the locality where it occurs, the fronds of _Oldhamia_ are very
abundant, and are spread over the surfaces of the strata in tangled
layers. That it is organic is certain, and that it is a calcareous
sea-weed is probable; but it may possibly belong to the sea-mosses
(_Polyzoa_), or to the sea-firs (_Sertularians_).
Amongst the lower forms of animal life (_Protozoa_), we find the
Sponges represented by the curious bodies, composed of netted
fibres, to which the name of _Protospongia_ has been given (fig.
32, a); and the comparatively gigantic, conical, or cylindrical
fossils termed _Archoeocyathus_ by Mr Billings are certainly
referable either to the _Foraminifera_ or to the Sponges.
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