, on this “law of the succession of types,”⁠—on “this wonderful relationship in the same continent between the dead and the living.” Professor Owen has subsequently extended the same generalisation to the mammals of the Old World. We see the same law in this author’s restorations of the extinct and gigantic birds of New Zealand. We see it also in the birds of the caves of Brazil. Mr. Woodward has shown that the same law holds good with seashells, but, from the wide distribution of most molluscs, it is not well displayed by them. Other cases could be added, as the relation between the extinct and living land-shells of Madeira; and between the extinct and living brackish water-shells of the Aralo-Caspian Sea.