“New times demand new measures and new men; the world advances, and in time outgrows the laws that in our fathers’ day were best; and doubtless, after us, some purer scheme will be shaped out by wiser ones than we, made wiser by the steady growth of truth.” (Lowell.)

Two papers in which the boundary between the Ordovician and Silurian systems is discussed were recently published in this country. The first, written by Prof. O. T. Jones, of Manchester University, England, appeared in the May–June issue of the Journal of Geology; the second, by Prof. Charles Schuchert, of Yale University, appeared in the Bulletin of the Geological Society of America, volume 36, number 2. In both papers the authors disagree with conclusions previously published by me after exhaustive study of the organic and physical evidence bearing on the question of the most natural, the most widely recognizable, and . . .

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