In order not to occupy too much time or confuse my auditors with details, it has seemed best to give a brief summary of the known fossil floras bearing on the problem of intercontinental land connections between North and South America, followed by the conclusions which it has seemed might be legitimately drawn from their evidence.

This evidence is not presented in detail, since it has been given at length in publications recently printed or now in press.2

Upper Cretaceous

The flora which commenced to radiate from Arctogæa in the Cenomanian, and which during the Turonian and Emscherian covered most of North America and Europe, and presumably Asia, penetrated as far as southern South America before the close of the Upper Cretaceous, and at least 26 typical species have been recorded from Argentina.3 This would seem to indicate that there was some land connection between North and South America throughout . . .

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