Below the “Coniston Limestone Series”—if we include under this general title not only the Coniston Limestone proper, but also the “Style End Grassing Beds” of Long Sleddale and the “Dufton Shales” of the Cross Fell area—no fossiliferous beds have hitherto been detected in the Lake—district till the horizon of the Upper Skiddaw Slates (Llanvirn Series) is reached. Between these two horizons are placed the thick and varied volcanic rocks which have usually been grouped together under the name of the “ Borrowdale Series ” (the “ Green Slates and Porphyries ” of Prof. Sedgwick); though it may be taken as certain that this name covers more than one series of volcanic ejecta. Up to the present time, no strata containing fossils have been detected in connection with any of the rooks which have been included under the general title of the “ Borrowdale Series.”