Abstract
The selection of a base for the Devonian System has evoked much controversy, and summaries of the literature are given in several papers. The subject has acquired a new significance recently through the work of Ch. Barrois and his coadjutors in the north of France, and that of W. W. King and L. D. Stamp in England. The matter has been argued at length in the papers referred to, and it is impossible to appreciate all the factors involved without reference to them.

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