In making the excavations now in progress for the formation of the great South High Level Sewer in the neighbourhood of Peck-ham and Dulwich, the works have been carried through a series of deposits, constituting part of the lower London, Tertiaries, and distinguished by Mr. Prestwich as the “Woolwich and Reading series.” As I learn from Mr. Charles Rickman, the able and zealous curator of the Lambeth Museum of Natural. History who has laboured assiduously in collecting the fossil remains found in them, these deposit at Dulwich, at the depth of twenty-five feet from the surface, comprise a bed of grey sand, and below this, at a depth of about forty feet, and intercalating a bed of clay containing, shells and a bed of Ostreæ, a band of hard compact sandstone, very slightly calcareous, apparently identical with that at Lee, referred to by Mr. De la Condsmine as known there by the name of the “cookle.”