use a certain bed
at Claiborne in Alabama, which contains "_four hundred_ species of
marine shells," includes among them the _Cardita planicosta_, "and _some
others_ identical with European species, or very nearly allied to them,"
Sir C. Lyell says it is "highly probable the Claiborne beds agree in age
with the central or Bracklesham group of England." When we find
contemporaneity alleged on the strength of a community no greater than
that which sometimes exists between strata of widely-different ages in
the same country, it seems as though the above-quoted caution had been
forgotten. It appears to be assumed for the occasion, that species which
had a wide range in space had a narrow range in time; which is the
reverse of the fact. The tendency to systematize overrides the evidence,
and thrusts Nature into a formula too rigid to fit her endless variety.

"But," it may be urged, "surely, when in different places the order of
superposition, the mineral characters, and the fossils, agree, it may
safely be concluded that the formations thus corresponding date back to
the same time. If, for example, the United States display a succession
of Silurian, Devonian, and Carboniferous systems, lithologically similar
to those known here by those names, and characterized by like fossils,
it is a fair inference that these groups of strata were severally being
deposited in America while their equivalents were being deposited here."

On this position, which seems a strong one, we have, in the first place,
to remark, that the evidence of correspondence is always more or less
suspicious. We have already adverted to the several "idols"--if we may
use Bacon's metaphor--to which geologists unconsciously sacrifice, when
interpreting the structures of unexplored regions. Carrying with them
the classification of strata existing in Europe, and assuming that
groups of strata in other parts of the world must answer to some of the
groups of strata known here, they are necessarily prone to assert
parallelism on insufficient evidence. They scarcely entertain the
previous question, whether the formations they are examining have or
have not any European equivalents; but the question is--with which of
the European series shall they be classed?--with which do they most
agree?--from which do they differ least? And this being the mode of
inquiry, there is apt to result great laxity of interpretation. How lax
the interpretation really is, may be readily sho