Note 24 — Chapter III

See the important memoir of Barrande on the Silurian Brachiopods, in which, as the result of the most elaborate and detailed comparisons, he concludes that in the case of these shells, as in that of the Cephalopods and Trilobites, the introduction of species in geological time has not occurred by modification, but must have depended on a creative process. It is such painstaking researches as those of the great Bohemian palæontologist which must finally settle these questions, in so far as geology is concerned.