No other part of Sweden affords more favourable opportunities for studying the earliest fossiliferous deposits and their relations to each other than Vestrogothia, with its unusually complete, undisturbed, and, in many natural sections, exposed series of strata. Its two lowest principal layers, consisting of sandstone and alum-slate, are to be referred to the Cambrian system, if that system, as proposed by Sir Charles Lyell, Salter, and others, be extended over the “Primordial zone,” which is easily distinguished by its organic remains from the overlying Silurian deposits. This sandstone has long been known as the oldest stratum of Vestrogothia above the Fundamental Gneiss. Traces of seaweeds were found in it by our earlier geologists, and caused it to receive the name, still commonly used, of Fucoid sandstone. Deposits of the same period are distributed over large parts of Scandinavia; and Professor Angelin, who, like his predecessors, had found them to be the oldest portion of the whole “Transition formation” of Scandinavia, included them all in his regio Fucoidarum, no other Fossil having as yet been found in them. Norwegian authors have proposed the denomination “Sparagmite stage,” for the rock prevailing in Norway, which has not as yet afforded any fossils, a term also adopted by Professor Torell.