Among the important results of Sir Roderick Murchison’s establishment
of the Silurian system is the following:
That as the Lower Silurian group, often of vast dimensions, has
never afforded the smallest vestige of a Fish, though it abounds
in numerous species of the _marine_ classes,--corals, _crinoidea_,
_mollusca_, and _crustacea_; and as in Scandinavia and Russia,
where it is based on rocks void of fossils, its lowest stratum
contains _fucoids_ only,--Sir R. Murchison has, after fifteen years
of laborious research steadily directed to this point, arrived at
the conclusion, that a very long period elapsed after life was
breathed into the waters before the lowest order of vertebrata was
created; the earliest fishes being those of the Upper Silurian
rocks, which he was the first to discover, and which he described
“as the most ancient beings of their class which have yet been
brought to light.” Though the Lower Silurian rocks of various parts
of the world have since been ransacked by multitudes of prying
geologists, who have exhumed from them myriads of marine fossils,
not a single ichthyolite has been found in any stratum of higher
antiquity than the Upper Silurian group of Murchison.
The most remarkable of all fossil fishes yet discovered have been found
in the Old Red Sandstone cliffs at Dorpat, where the remains are so
gigantic (one bone measuring _two feet nine inches_ in length) that
they were at first supposed to belong to saurians.
Sir Roderick’s examination of Russia has, in short, proved that _the
ichthyolites and mollusks which, in Western Europe, are separately
peculiar to smaller detached basins, were here (in the British Isles)
cohabitants of many parts of the same great sea_.