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[ANNALS N. Y. ACAD. Sci., Vol. XIII, No. 1, pp. 1–72, July 18, ?cm.]

CORRELATION BETWEEN TERTIARY MAMMAL

HORIZONS OF EUROPE AND AMERICA

Ax INTRODUCTION TO THE MORE EXACT INVESTIGATION OF
TERTIARY ZOÖGEOGRAPHY. PRELIMINARY STUDY

WITH THIRD TRIAL SHEET

Two Presidential Addresses before the New York Academy of Sciences; first
address delivered February 27, 1899; second address delivered February 26, 1900.

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PART I. PARALLELS BETWEEN TERTIARY

HORIZONS.

INTRODUCTION.

This address is designed to reconsider an old subject in the new spirit and methods of modern palæontology. It does not pretend to cover the whole subject, but rather certain parallels between the mammalian fauna of America and Europe and between the later Tertiary fauna of Europe ; it is introductory to a more exhaustive treatment.

The work done hitherto in this field of commanding interest and importance serves mainly to pioneer the more exact comparisons between Europe and America which are now becoming possible.

I desire to enter an urgent plea for the establishment of uniform divisions of the Tertiary and for the international usage of common terms both as to life stages and life forms. As in military disarmament, this result is easier to propose than attain, because each is willing to disarm on his own basis, each is reluctant to part with either the language or perspective belonging to the historical development of the geology and palæontology of his own land. Yet in these matters patriotism and provincialism naturally should have no weight. Palæontology knows neither the divisions formed by the English channel, the Rhine, nor the Atlantic; it does not recognize the superiority of an English system, of a French or German system, or of an American system, but like all its sister branches of science in this time of absolute scientific good will it demands an international system. As during the Tertiary period animals migrated freely by land over the entire northern hemisphere, so our ideas and methods must enjoy a free migration and fall beneath the rigid operation of the law of the survival of the fittest. Since anatomical, descriptive, taxonomic and geologic terms are mere symbols for the expression of certain facts, ideas, hypotheses and theories, we should all employ the same symbols whatever our national sympathies. For my own part if an approximate synchronism can ever be established, I would go so far as to advocate the adoption of the standard European divisions for the American Tertiary as soon as the European stages and periods are finally determined upon.

In the meantime no one can oppose the immediate adoption of the fundamental principle that the old and new world palæontology should be studied as a unit.

If we are eager to solve the great number and variety of most interesting questions still unsolved as to the source, origin, filiation, migration and extinction of the noble races of animals which passed across the stage of the Northern Hemisphere or Ancient Holarctic Region, during the Tertiary we must hasten to use more exact methods, to agrec upon the synchronism of the Tertiary and the arbitrary limits which we shall assign to the Eocene, Oligocene, Miocene, Pliocene and Pleistocene periods and their subdivisions. The synchronism is a difficult subject, in fact it involves the main question ; the limits of the periods are largely arbitrary and are capable of being settled at once. Although the lower Tertiary of America from the base of the Eocene to the summit of the Oligocene is infinitely more complete, in fact an unbroken historic chapter, it will probably prove best that the beautiful series of Tertiary horizons of France should be adopted as the basis of division, partly because of their priority and completeness throughout, but chiefly because of the remarkable alternation of marine and freshwater deposits, whereby the vertebrate is checked by the invertebrate time scale. After we pass the summit of the Oligocene our country affords a series of vistas only while Europe offers a commanding view of the later Tertiary life periods. If France furnishes the initial basis, comparison with America will serve to check and amplify—thus the final basis for the division of the Tertiary will be comparative.

European Correlations :-In France GERVAIS, GAUDRY, FILHOL, LEMOINE, DEPÉRET, BOULE, and others have drawn the demarcations of the typical horizons. The parallels with Englant have been especially set forth by PRESTWICH and DAWKINS and with Germany by SchLOSSER, DEPÉRET and v. ZITTEL,

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