, at least a noticeable
likeness to families familiar to the modern algaeologist. The cord-like
plant, _Chorda filum_, known to our children as "dead men's ropes,"
from its proving fatal at times to the too adventurous swimmer who gets
entangled in its thick wreaths, had a Lower Silurian representative,
known to the Palaeontologist as the _Palaeochorda_, or ancient chorda,
which existed apparently in two species,--a larger and smaller. The
still better known _Chondrus crispus_, the Irish moss or carrageen of
our cookery-books, has likewise its apparent though more distant
representative in _Chondritis_, a Lower Silurian algae, of which there
seems to exist at least three species. The fucoids, or kelp weeds,
appear to have had also their representatives in such plants as
_Fucoides gracilis_ of the Lower Silurians of the Malverns; in short,
the Thallogens of the first ages of vegetable life seem to have
resembled, in the group, and in at least their more prominent features,
the algae of the existing time. And with the first indications of land we
pass direct from the Thallogens to the Acrogens,--from the sea weeds to
the fern allies. The Lycopodiaceae;, or club mosses, bear in the axils of
their leaves minute circular cases, which form the receptacles of their
spore-like seeds. And when, high in the Upper Silurian System, and just
when preparing to quit it for the Lower Old Red Sandstone, we detect our
earliest terrestrial organisms, we find that they are composed
exclusively of those little spore receptacles. The number of land plants
gradually increases as we ascend into the overlying system. Still,
however, the Flora of even the Old Red is but meagre and poor; and you
will perhaps permit me to lighten this part of my subject, which
threatens too palpably to partake of the poverty of that with which it
deals, by a simple illustration.

[Illustration: Fig. 7.

LYCOPODIUM CLAVATUM.]

[Illustration: Fig. 8.

EQUISETUM FLUVIATILE.]

We stand, at low ebb, on the outer edge of one of those iron-bound
shores of the Western Highlands, rich in forests of algae, from which,
not yet a generation bygone, our Celtic proprietors used to derive a
larger portion of their revenues than from their fields and moors. Rock
and skerry are brown with sea weed. The long cylindrical lines of
_Chorda filum_, many feet in length, lie aslant in the tideway; long
shaggy bunches of _Fucus serratus_ and _Fucus nodosus_ droop heavily
from the r