The Pliocene deposits of the East of England have been studied for many years, and by many competent observers, but, unfortunately, no general consensus of opinion has been arrived at, either as to their systematic arrangement, or the conditions under which they originated: the views, for example, of Sir Joseph Prestwich, which have obtained considerable acceptance, differing in many important respects from those of the equally eminent authorities Mr. Searles V. Wood and his son. Prestwich, in his well-known paper, divided the Coralline Crag into eight constant and determinable zones, and, on the other hand, regarded the Red Crag as forming two divisions only: the lower, including the deposits of Walton-on-the-Naze, Sutton, Bawdsey, Butley, Sudbourne, and Aldeburgh, and the upper, consisting of what he originally called ‘the unfossiliferous sands of the Crag’ (now believed to be a part of the deposit which has been deprived of its shells by the infiltration of water containing carbonic acid) and of the Chillesford Beds. The Norwich Crag, with which he grouped some deposits containing Tellina balthica , he held to be equivalent, partly to his lower (namely, to the Crag of Walton, Sutton, Butley, etc.), and partly to his upper or Chillesford division. I still hold, for reasons to be given hereafter, that there is no sufficient evidence for dividing the Coralline Crag into the eight zones proposed by Prestwich; indeed, I now believe that the tripartite arrangement, formerly adopted by Mr. Wood, jun., and myself, can be no longer maintained, and that the