It is a well-known fact that river diamonds and the diamonds of each mine are quite distinct in character from each other. The Old De Beer’s stones are much more like those of the river than are those of Kimberley. An experienced buyer can tell at a glance in most cases where a diamond was found, and many buyers, diggers and other experts have on oath expressed their conviction as to the source of certain stones before courts of law. There are no rents or large fissures in the hard containing rocks of the Kimberley mine, but the joints and bedding remain undisturbed, thus showing that earthquakes have not acted upon them, at least to any appreciable extent. There can be little doubt but that the pits or craters were formed by volcanic agency, but it does not follow that the contents thereof were thrown up at one and the same time, nor indeed that the present contents were derived from the craters at all. After denudation had taken place, calcareous tufa was deposited from the waters, and then the ferruginous red sand. It does not appear probable, as suggested by Mr. Kitto, that “the diamond was formed by a rock being crushed between other rocks previously to its being brought to the surface by volcanic agency,” as the rock would thus be merely broken into small fragments, whereas it is in the form of an impalpable powder, intimately mixed with boulders, nodules and crystals of foreign rocks. [Illustration: Pl. III. ] Had diamonds been formed in this rock, and the rock crushed, the brittle diamond would not, in my opinion, have escaped being also crushed. It seems a more feasible theory that the rock when first elevated was in a heated state, and brought into contact with water then covering the land, and the sudden cooling caused its sudden disintegration, and that the diamonds and other materials foreign to it got mixed with it subsequently. However, in either case, the diamonds and other materials contained therein would still have to be accounted for, and it does not appear probable that these should have all been formed with or within one single rock, or that they are all of the same period and were elevated at one and the same time. If diamonds were formed by heat, it was not in the Kimberley mine, as the shale walls and the agglomerate within the mine show no signs of having there been subjected to any great heat; on the contrary, water and air seem to have been here the active agents. From the foregoing extracts it will be seen that no theory as to the formation of the diamond hitherto advanced is completely, if at all satisfactory, and the mystery, if penetrable, must be left to the geologist of the future. GEOLOGY, FOSSILS, ETC. DESCRIPTION OF PLATES. PLATE I.