\Si*lu"ri*an\, a. [From L. Silures, a people who
anciently inhabited a part of England and Wales.] (Geol.)
Of or pertaining to the country of the ancient Silures; -- a
term applied to the earliest of the Paleozoic eras, and also
to the strata of the era, because most plainly developed in
that country.
Note: The Silurian formation, so named by Murchison, is
      divided into the Upper Silurian and Lower Silurian. The
      lower part of the Lower Silurian, with some underlying
      beds, is now separated under the name Cambrian, first
      given by Sedwick. Recently the term Ordovician has been
      proposed for the Lower Silurian, leawing the original
      word to apply only to the Upper Silurian.

\Si*lu"ri*an\, n.
The Silurian age.