1853.] FORBES — ISI.E OF WIGHT. 269 



each end of the Isle of Wight can now be made out very clearly, the 

 bands of peculiar Nummulites having been found in the course of 

 my work in WhiteclifF even as in Alum Bay. 



The Barton series is distinctly linked with the Middle Headons 

 by not a few fossils. The relations to the marine beds of the Bern- 

 bridge series are not so evident, but, strange to say, they are clearly 

 enough shown to exist with the uppermost marine beds of all those 

 that cap Hempstead Hill, in which the most plentiful fossil is a 

 Barton Corhula, accompanied by a Barton and Headon Natica. The 

 connection between the Headon, St. Helens, Bembridge, and lower 

 portion of the Hempstead beds is maintained without a break by the 

 Avell-marked WIelania muricata, whilst Melania fasciata links all the 

 series still more completely. Cyrena obovata ranges through the 

 Headon, St. Helens, and Bembridge series, mingling in the latter 

 group vdth Cyrena semistriata, which ascends to the upper division 

 of the Hempstead group. Paludina lenta ranges through all. 



The differences are most strikingly marked by the species of Ce- 

 rithium and by the land and freshwater shells. The CharcB of the 

 different groups appear also to be very distinct. The distinctness of 

 the Vertebrata found in each division has already been noticed. 



There is evidently no break in this series of deposits, and it would 

 be harsh and forced to place one portion of them in the Eocene and 

 another in the Miocene, as has been generally done on the Con- 

 tinent. In the Isle of Wight we have really the true clue to their 

 relations clearly exhibited in unmistakeable and perfect sections. 

 The importance of this clue in its bearing on Continental geology 

 may probably be estimated very highly. In the accompanying table 

 I have endeavoured to indicate the probable relations of the Isle of 

 Wight section to some of the principal Eocene groups of the Conti- 

 nent and Mediterranean. As we might expect, a great portion of our 

 fresh and brackish water beds is represented abroad by marine strata. 

 Certain bands of well-marked fossils seem, however, to be so widely 

 extended that we are enabled to indicate very definite horizons. Per- 

 haps the most constant is the zone of Cerithium plicatum ; well- 

 marked among the tertiaries of France, Belgium, and Germany ; and 

 equally well-marked in the Isle of Wight. The relations of that 

 zone to the marine beds containing Pecten laticostatus and gigantic 

 Echinoderms, as seen in the south-west of France, enable us to fix 

 the position of the Maltese and other Mediterranean tertiaries hitherto 

 classed as Miocene, and thus to obtain a key to one of the most 

 widely-spread and well-marked tertiary formations in the old, and 

 apparently also in the New World. 



