but having from thirty-four to thirty-six ribs, with no depressed line down their middle, nor vestiges of spines; Mactra solida, Venus exolata, Venus scotica ? Venricardia senilis, Lam. Arca glycemeris, Arca nucleus.
Besides these remains of marine animals, the fossil hollow tubercles, having lost the spines, of the thornback are here found; also fragments of the fossil palate, (Scopula littoralis of Lhwydd) and fossil remains of sponge and alcyonia, particularly a very fair specimen of the reticulated alcyonium. Org. Rem. vol. II. pl. IX. fig. 9.
In this bed, among the gravel and the shells, are frequently found fragments of fossil bone, which possess some striking peculiarities. They are seldom more than half an inch in thickness, two inches in width, and twelve in length ; always having this flat form, and generally marked with small dents or depressions. Their colour, which is brown, light or dark, and sometimes inclining to a greenish tint, is evidently derived from an impregnation with iron. From this impregnation they have also received a great increase of weight and solidity; from having been rolled they have acquired a considerable polish; and on being struck by any hard body they give a shrill ringing sound. These fragments, washed out of the stratum in which they had been imbedded, are found on the beach at Walton, but occur in much greater quantity at Harwich.
Of the flat rounded pieces described above, no conjecture can be formed as to the particular bone or particular animal to which they belonged. But within these few years an Essex gentleman found, on the beach at Harwich, a tooth which was supposed to have belonged to the mammoth. This fossil was kindly obtained at my request, for the purpose of being exhibited to the members of the Geological Society, by my late friend Dr. Menish; and certainly it appeared to be part of a tooth of that animal. It had been
