My friend Mr. O9Reilly, Professor of Mineralogy to the Royal College of Science, Dublin, has kindly permitted me to examine a collection of fossil remains made by himself and Professor Sullivan, of Queen9s College, Cork, when engaged in surveying the mineralogy and geology of the province of Santander. The conditions under which the remains were found are fully detailed in the able reports of these gentlemen, published in the 4th volume of the ‘Atlantis,’ and reprinted in a separate volume entitled ‘Notes on the Geology and Mineralogy of the Spanish Provinces of Santander and Madrid.’ It appears that, during the sinking of a shaft in search of calamine in limestone underlying the dolomite of the valley of Udias, the workmen,at about 12 metres from the surface, suddenly broke into a cavern of considerable dimensions. At the north end of the cavity was a mound of soil which had fallen down a funnel blocked up at the time of the discovery by surface-soil and debris. Close to this mound were found many bones of mammals and birds. The remains were either partially or entirely buried in calamine, which covered the floor and formed an enormous bed of variable thickness. It appears, therefore, not only from the large funnel, which was evidently the original opening, but also from the remains, that the cavern was an enlarged joint or rock-fissure, into which the entire carcasses or else the live animals had been precipitated from time to time. The following, I am informed, does