Ch. XV.] EOCENE AND MIOCENE STRATA. 187 



for the discovery of gradations from Miocene to Eocene, and for the 

 probable necessity of including hereafter in the Miocene series some 

 fossiliferous groups which may diverge in their characters from the 

 standard first set up, or from the type of the faluns of Touraine. But I 

 have seen, as yet, no sufficient evidence that such a passage, as is here 

 spoken of, has been made out. The limits of the Eocene series have 

 been extended, without as yet filling up the gap between that series 

 and the faluns of Touraine. I am desirous at the same time to explain, 

 that the important point now at issue is not simply one of nomenclature. 

 The difficulty is the same, whether we use the terms Lower and Middle 

 Tertiary, or Eocene and Miocene. To one or other of the periods so named 

 we must refer the Limburg and Hempstead beds, and the sands of the 

 Forest of Fontainebleau. Can we, without doing violence to paleonto- 

 logical principles, refer all these to the same period as the faluns of 

 Touraine ? If so, it would be immaterial whether we called them 

 Middle Tertiary, Miocene, or " Falunian," or by any other general name. 

 The question is, whether, in the present state of our information, the 

 mass of characteristic fossils of the groups alluded to resemble more 

 nearly the Eocene or the Falunian. I adhere at present to the nomen- 

 clature formerly adopted by me for strata described in this chapter, 

 calling them Upper Eocene — not because of the small number of living 

 species of shells found in them, although this is certainly one point of 

 agreement between them and the " nummulitic" Eocene beds, but be- 

 cause of the aspect of the whole fauna, which seems to me to be Eocene 

 rather than Falunian. Among other illustrations of this affinity, I may 

 refer the reader to the numerous and excellent figures of species of the 

 genus Voluta given by M. Beyrich from the Limburg beds of North 

 Germany — forms strikingly characteristic of the Barton clay in Hamp- 

 shire, a regular member of the Middle Eocene group. The faluns are 

 devoid of such forms. Until, therefore, the time arrives when the break 

 between the Limburg beds and the faluns has disappeared more com- 

 pletely, it appears to me safer to include the Limburg and all contem- 

 poraneous formations in the TCbcene. 



At the same time I have drawn the line between Middle and Upper 

 Eocene, as in former editions, excluding from the latter the Bembridge 

 beds of the Isle of "Wight, or the gypseous series of Montmartre. A 

 preference is given to this last method, simply for convenience sake, in 

 order that the Upper Eocene of this work may coincide exactly with 

 the strata classed by so many distinguished geologists as Lower Miocene. 

 I am bound, however, to state, that the parting line between the Bem- 

 bridge and Hempstead series, in the Isle of Wight, has been shown by 

 Professor Forbes to be an arbitrary one — a purely conventional line, 

 if any thing, less marked than the line separating the Bembridge series 

 from the underlying St. Helen's group. (See Table, p. 209.) If re- 

 tained as more useful, it is, as before hinted, for the sake of confor- 

 mity with a system of classification adopted by many able geologists, 

 who selected it before the uninterrupted continuity of the Eocene series 



