V.—Palæontological Considerations on the Old Red Sandstone of Scotland

Abstract

However paradoxical it may appear, we have reason to believe that the occurrence of so-called ganoidian fishes—of a freshwater type—in the Old Red Sandstone affords the strongest evidence in favour of its marine origin. That recent representatives of the ganoids of the Old Red Sandstone inhabit rivers and lakes of the globe, is by no means a proof of the fresh-water origin of the latter fishes. The immense interval of time implied by the comparison renders its value somewhat problematical. Sir A. Geikie, in referring to the fishes of the Old Red Sandstone, says: “That some of the fishes found their way to the sea, as our modern salmon does, is indicated by the occasional occurrence of their remains among those of the truly marine fauna of the Devonian rocks.”