1852.] 



LYELL BELGIAN TERTIARY FORMATIONS. 



321 



Table XI. (continued). 





Limburg 

 Divisions. 



British and other Localities. 



Typhis cuniculosus 



U. M. L. 

 U. M. L. 



L. 



L. 

 U. M. 



L. 

 U. M. L. 

 M. 

 M. 



L. 



L. 



L. 



L. 

 U. 



Barton ? 



Barton, Highgate. 



Barton. 



Barton ; Calc. gross. 



Highgate. 



Barton. 



Barton. 



Barton. 



Barton. 



Barton. 



Barton; Bracklesham. 



Barton. 



Barton ; Calc. gross. 



Highgate; Sheppey. 



Triton argutum *•.... 



Rostellaria ampla 







Cassidaria ambigua 



Buccinum Gossardii 





Conns lineatus ? 



Terebellum fusiforme ? 



Ancillaria canalifera 





80. Nautilus ziczac 





7. Nomenclature of the Limburg Tertiary Strata; and whether 

 they should be referred to the Upper Eocene or Lower Miocene 

 periods. 



My original reasons for not classifying the upper marine strata of 

 the Paris basin, commonly called " sables de Fontainebleau/' &c., and 

 the upper marine and freshwater of the Isle of Wight as Miocene, 

 were threefold. 



1st. Because many of the shells were identical with fossils from 

 the Calcaire grossier. Barton clay, and other Eocene beds, while the 

 general aspect of the fauna resembled that of the lower, rather than 

 of the upper tertiary strata. 



2ndly. Because of the great distinctness of the fauna from that of 

 the faluns of Touraine, which contained above 300 species of shells, 

 and which I had chosen as the type of the Miocene period. 



3rdly. Because the proportion of recent species did not appear to 

 be sensibly greater than in the Eocene strata, regarded as a whole. 



Geologists will be enabled by means of the Tables given above to 

 appreciate the true merits of this question. It will be seen that out 

 of 20 1 species of Limburg moUusca, eighty are identical with fossils 

 commonly regarded by English geologists as Eocene. Even if 

 we omit seventeen species which occur, fifteen of them in the upper 

 marine of Hampshire, and two in the associated freshwater beds, still 

 we have sixty-three Eocene species in a list of 201. Ten of these 

 identifications, however, are given doubtfully, because the means of 

 comparison were more or less deficient. If we exclude all these, we 

 have still fifty-three remaining. I am, however, by no means disposed 

 to exclude the Upper Marine of Hampshire from the Eocene period, 

 as the number of species common to it and to the Barton beds is 

 shown by old and modern researches, especially by Dr. Wright*, to 

 be considerable. 



* Proceedings of the Cotswold Naturalists' Club for 1850, p. 87 e/ seq. ; and 

 Ann. and Mag. N. Hist. 2 ser. vol. vii. p. 14 e^ seq. 



