The earlier part of this paper is devoted to a short epitome of the stratigraphical evidence that the Yoredale rocks of Wensleydale are only the equivalents of the upper part of the Carboniferous Limestone, and that the so-called Yoredale Beds of South Yorkshire, Lancashire, and Derbyshire are an entirely different series, which occupy a position above the Carboniferous Limestone. After all, the important point is the palæontological evidence, which, to my mind, is absolutely conclusive.