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IV.—On the Relative Ages of the American and the English Cretaceous and Eocene Series
Published online by Cambridge University Press: 01 May 2009
Extract
I have been desired by the Council of the British Association to contribute some account of the later Fossil Floras of Europe and America, with a view to determining, more precisely if possible, their relative ages.
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References
page 492 note 1 “Island Life,” p. 358.
page 494 note 1 An account has been published since this paper of the non-marine mollusca of the series, probably strengthening my views.—J. S. G.
page 504 note 1 “Your letter has of necessity, remained unanswered, for the question of the relations of the Cretaceous and the Tertiary Echinoidean faunas is one 1 and Sladen are still trying to investigate. Alex. Agassiz's statements regarding the alliances of the deep-sea forms with those of the Cretaceous are diminishing in value in our eyes, and the subject is still in too crude a condition for any satisfactory argument to be developed. Take, for instance, the genus Salenia, the Tertiary and the recent species do not belong to the same group of forms which characterize the Cretaceous; and they differ from the Secondary group, more than these differ amongst themselves. The same holds good for the species of Cidaris. Certainly no Cretaceous species survives, and I am not sure that any one is common to the Secondary and Tertiary faunas. There are many genera of Corals that are common to the Cretaceous, Tertiary and the recent seas; but not any well-defined species. Unfortuntely, the American fossil faunas do not assist in the research. In fact, the break of marine life is vast, and the only connexion is by some Forams and genera of Planté.—P. M. Duncan.”