XXXI.—On the Genera Lycopodites and Psilophyton of the Old Red Sandstone Formation of Scotland

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Abstract
Towards the close of the Upper Silurian period certain traces of land plants appear, but in the flora of the succeeding Devonian period we find a more exuberant and varied representation of the earliest terrestrial plants which occur in the stratified rocks of the globe. The Devonian flora of Scotland, like that of Central Europe, is met with in an obscure and imperfectly preserved condition. It is in the sandstones of Gaspé and New Brunswick where the plants which it comprises more abundantly occur. Sir William Dawson refers to the occurrence in the Devonian of North America of upwards of a hundred species of plants, showing in some instances fruit and internal structure in a very perfect state of preservation.* Before discussing the affinities of Psilophyton and Lycopodites as typical plants of the period the stratigraphical position and relationships in the Old Red Sandstone assigned by geologists to the deposits of Midland Scotland, and those of the Caithness area, may be briefly adverted to. Sir R. I. Murchison held that the three groups of the Devonian system represent the Lower, Middle, and Upper divisions of the Old Red Sandstone—the Lower occurring in Forfarshire, and the Middle in Caithness.† Sir A. Geikie, however, dissents from this view, and classes the deposits of Midland Scotland and those of the Caithness area into Lower and Upper Old Red Sandstone.‡ From a stratigraphical point of view this classification apparently leaves little to be desired, but an examination of the palæontological evidence shows that the This 250-word extract was created in the absence of an abstract

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