After some prefatory remarks on the general character of the greywacké formations in the south of Scotland, on their entire destitution of organic remains, or even decided impressions, and on the general prevalence of marks, produced apparently by shallow water, a singular series of schistose strata is described, of little more than two feet in thickness altogether, presenting everywhere peculiar features. First, there are two opposed surfaces, the one sprinkled over with thin, short, raised streaks, and the other with small cylindrical grains, all lying perfectly parallel to each other, and consisting of a hard substance, differing from the material and colour of the greywacké rocks. Next, there are a few seams of fine schist, and then a surface, covered with minute, sharply-defined indentations, having every one a lip turned up on one side, and sometimes clinging to the lip, a small speck of the same hard brown substance, which appears on the two surfaces first mentioned.