Select the best conjunctive adverb in the sentence below.
In some cases not one species is identically the same, but they belong to the same families, genera, and sections of genera, and sometimes are similarly characterised in such trifling points as mere superficial sculpture;
, other forms, which are not found in the Chalk of Europe, but which occur in the formations either above or below, occur in the same order at these distant points of the world.
Darwin, Charles Robert. The Origin of Species. New York: P.F. Collier & Son, 1909–14,