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Published online by Cambridge University Press: 01 May 2009
page 21 note 1 We do not here discuss the breaks in time either physically or palæontologically; it is too large a subject.
page 22 note 1 Camarium, Eatonia, Eichwaldia, Lingulepis, Pholidops, Rhynchospira, Tropidolepsus, Zygospira, Meganteris, Skenidium, Strophodonta, Trimerella, Rennselœria, Trematospira.
page 23 note 1 See the works of Hall, Haydan, Meek, Billings, Schúmard, Worthen, De Koninck.
page 23 note 2 21 Genera are common to the Western and Eastern hemispheres; 35 are peculiar to America; and 23 are European.