2 Mr. Charlesworth on the Crag^ and on ascertaining 



and the superior beds, depended upon the abrasion or natural 

 degradation of one deposit during the formation of the other. 

 I then referred to the large proportion of Red Crag fossils 

 which M. Deshayes had identified with species now known to 

 inhabit the German Ocean (4-0 per cent.): consequently, if my 

 idea of the removal of the fossils from an older to a more recent 

 bed were disputed altogether, the number common to the two 

 crag series would at any rate indicate no nearer approxima- 

 tion of the periods during which these Testacca existed than 

 that established by M. Deshayes between those of the red crag 

 and the Mollusca of our present seas. Under these circum- 

 stances, it was certainly with some degree of surprise that 

 I found Mr. Lyell opposing the opinion 1 had advanced, upon 

 no other ground than that of this very occurrence of analogous 

 species in the two deposits*. 



To say nothing of those Sicilian strata, which contain 

 ninety-five per cent, of existing species, it is palpably evident that 

 if a per centage of analogous forms, to the amount of thirty or 

 forty, place in one and the same geological period the races 

 of organized beings occurring in rocks naturally separated by 

 superposition and mineral character, by the same line of rea- 

 soning must the red crag, in common with all the other plio- 

 cene deposits, be looked upon, geologically speaking, as part 

 and parcel of the formations now going forward in the adja- 

 cent seas, although these very deposits have been referred to 

 a distinct epoch by Mr. Lyell from the very circumstance of 

 their containing 40 per cent, of existing species. Paradoxical 

 as it may appear, the facts which in one instance are made 

 use of to prove the wide interval which has elapsed between the 

 deposition of certain marine strata, are on another occasion 

 brought forward to establish diametrically opposite conditions. 

 Thus a division called older pliocene is made for those beds 

 which contain so few as 40 per cent, of species common to 

 that period and the present, while the red and coralline crag 

 must be identified, — because their fossils indicate just this same 

 degree of approximation to one another. I apprehend that 

 this is no other than a fair statement of the case, and that I 

 have not pushed analogy beyond reasonable limits ; for if we 

 admit, with Mr. Lyell, that the formations of the present day 

 constitute one link of the entire series, and originate in the 



mtinued operation of those causes which have been in ac- 

 tivity, at least during the deposition of the supracrt-taceous 



)cks, we are surely justified in drawing analogous inferences, 

 whether we are comparing the present deposits with the newer 

 members of tlie tertiary series or the individual members con- 

 stituting the tertiary group with one ^i;^gther. 



* Lyell's Geology, 4tli edit., vol. iv. p. 87. 



