Notice of a Fossil Nautilus from the Isle of Sheppy. 105 



interstratified layers of concretionary nodules, commonly 

 called septaria or cement stones. This clay belonged to the 

 lower tertiary formation, and formed a part of the London 

 basin — one of those isolated fluvio-marine deposits which took 

 place in hollows of the chalk subsequent to the cretaceous 

 epoch. On the north side of the island, and eastward from 

 Sheerness, the cliffs rise to the height of from one to two 

 hundred feet, and, chiefly from atmospherical causes, were 

 constantly crumbling down in large prismatic masses, which 

 gradually broke up, and formed a flat shore of fine silt. Mud 

 banks extended off shore for about half a mile, and at low 

 water workmen were employed in procuring the cement stones. 

 The beach was not more than from ten to twenty yards wide, 

 on which were strewed abundance of fossil fruits, wood, Crus- 

 tacea, and mollusca, which had fallen out of the clay. Dr 

 M'Bain said, he had frequently obtained upwards of a hundred 

 Eocene fossils in a single excursion, and that the remains of 

 fish and reptilia were also of frequent occurrence in the Lon- 

 don clay of the Island of Sheppy. He added, that many of 

 these Eocene fossils became mixed with recent organisms, and 

 were buried together in the re-composed silt, which the hasty 

 generalization of some palaeontologist, in a future new geolo- 

 gical epoch, might consider as a sufficient proof that they also 

 lived together at the same time in the Cainozoic period. 



(2.) Notice of the Nucula decussata, found in the so-called Raised Sea- 

 beach Bed at Leit'i. By James M'Bajn, M.D., R.N. 



The members of the Society, Dr M'Bain said, were no 

 doubt familiar with a bed of sand and gravel extending along 

 the shores of the Forth in a more or less continuous manner, 

 and generally known as the raised sea-beach bed. This de- 

 posit had been considered by several eminent geologists to re- 

 present an ancient sea-beach, which, in consequence of a gene- 

 ral elevation of the land, had been raised twenty feet or more 

 above the level of the sea, at a comparatively recent geologi- 

 cal period. This view was strenuously opposed by the late 

 Professor John Fleming, who maintained that this so-called 

 raised sea-beach bed and other accumulations of a similar 



VOL. II. 



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