Page:Quarterly Journal of the Geological Society of London, vol. 27.djvu/627

 that is not denuded. Between Hasborough and Sherringham, the latter usually lies at too low a level to be exposed. When it does appear, the relations to the Norwich Crag and to the Westleton beds remain constant, in the same way as at Coltishall, Wroxham, and Thorpe.

I have, in my last paper, noticed that the rich fossiliferous beds of the Red Crag of Walton, Sutton, and Butley become poorer after passing beyond that area, that at Chillesford the number of species is much less, and that the same poverty characterizes the few pits on the west flank of the Coralline ridge of Sudbourne.

North of this ridge the Crag at Aldborough is still poorer ; but still the fossils are all Bed-Crag species. At Thorpe the facies of the fauna seems different ; but this is chiefly due to the difference in the relative proportion of the species. There is not a single new species of Mollusca ; but such species as are found on the beach of a sandy bay abound. The Littorina littorea, scarce at Chillesford, Butley, and Aldborough, is here abundant, as are also the Mya arenaria, Mactra ovalis, and Cardium edule, whilst Natica, Cerithium, and Turritella become much more common. At the same time some fragmentary mammalian remains, vertebrae and teeth of fish, and fragments of Crustacea are also more numerous. At Sizewell the Conovulus pyramidalis is a common shell. At Bulchamp and at Easton Bavent freshwater shells increase in number, and the Corbicula fluminalis* and the Astarte borealis make their first appearance. But of 43 other species of marine shells I have collected at Thorpe, Sizewell, Bulchamp, and the neighbourhood of Southwold, there is not a single species which is not found also in the Red Crag. In both also some species, such as the Tellina obliqua, T. lata, and Purpura lapillus, continue to be very abundant, and the Cyprina islandica is common. In lithological character the only difference is the greater extent of gravelly (flint) beds and the absence of the ferruginous colouring, though that exists at Sizewell and Bulchamp. Neither of these characters is of any importance.

Probably Thorpe, Wangford, and Bulchamp (in part) may be regarded as the equivalents of the lower division of the Bed Crag, whilst Sizewell and Easton Bavent should be referred to the upper division or Chillesford sands.

This upper division is better exposed at Aldeby, where a large addition is made to the number of species ; several new forms appear, while some old forms of the Red and Coralline Crags reappear. In the neighbourhood of Norwich the Rhynchonella psittacea† comes in, and on the coast at Sherringham the Tellina balthica is added to the fauna. In the upper bed of the Norwich Crag at Bramerton and Thorpe many of the species found in the lower bed are wanting, but, with the exception of the accurate fists of fossils from the Bramerton pits made by Mr. Reeve, we are yet without fully sufficient separate lists of the two divisions of the Crag, whether in Norfolk or in


 * Mr. Bell has lately found this shell in the Red Crag at Waldringfield.

† Also lately found by Mr. Bell in the Red Crag at Shottisham.