We now enter upon the third and concluding term of Linnarsson's geological career. This extended from the commencement of the year 1876 to the date of his untimely death in September, 1881. Hitherto, he had been occupied mainly in the development of the grander natural divisions of the Lower Palæozoic Succession of Sweden. This final period was devoted to the task of elaborating their minor subdivisions and best-characterized zones of life.

The geology of the neighbourhood of Birmingham is one of more than ordinary interest, owing to the great variety of geological formations exposed within its area. Its rocky structure was investigated about thirty years since by the officers of the Geological Survey of Great Britain, and its several geological formations laid down upon their maps, and described in detail in their various explanatory memoirs. Some of these publications—notably the maps and descriptions of the South Staffordshire Coalfield—have subsequently become classic in the literature of Geology. Since these publications were issued, however, the science of Geology has made great advances, more accurate and detailed methods of research among the older rocks have been developed, and their application to the study of the strata of the Birmingham district has recently resulted in the detection of several most interesting facts which escaped the notice of the earlier investigators.

Prof. Prestwich, in his paper in the January Number of this MAGAZINE on the “Causes of Volcanic Action,” assumes the existence of hot reservoirs or cavities filled with molten rock, and cold reservoirs or cavities, nearer the surface, filled with water; and he supposes the shrinkage of the Earth to squeeze up the molten rock till it meets with the water, which then explodes, producing a volcano.