VI Occurrence of Volida Lamherti on the Suffolk Coast. 



remarking that, " since the commencement of the tertiary 

 strata, the temperature has been constantly diminishing ; 

 passing in our climates from the equatorial to that which we 

 now enjoy." * Two statements could not well be more dia- 

 metrically opposed to each other ; and to increase the diffi- 

 culty, M. Deshayes has left out all reference to the crag, 

 although he alludes to nearly every well known European 

 tertiary deposit. To say the least of it, this omission looks 

 singular, especially when M. Deshayes had so recently been 

 engaged in the examination of the crag fossils. 



In whatever light we regard the crag, it appears to be a 

 most mysterious deposit, and the present investigation of its 

 history seems likely to be attended in one sense with most 

 unfortunate results. Professor Agassiz has declared the fish 

 to be those of tropical climates, whilst the Mollusca, by equally 

 eminent naturalists, are said to indicate a temperature ap- 

 proaching that of the polar regions; and, to complete the 

 anomaly, we have associated with them the mammiferous 

 species which now inhabit this island. These are facts of the 

 highest importance in reference to such geological deductions 

 as may have been based upon individual opinion, or upon the 

 examination of only one class of fossil organisms. I am, 

 however, sanguine enough to hope that the discrepancies will 

 be in some measure reconciled, when the tertiary formations 

 in Norfolk and Suffolk are no longer referred to by geolo- 

 gists as " the crag," and when the nature of the separate 

 deposits, and their relation to one another, are more clearly 

 established. 



The circumstance of meeting with these volutes upon the 

 coast, along with the shells of living Mollusca, illustrates in a 

 most forcible manner how fallacious may be the conclusions 

 founded upon association, and upon the assumption that all 

 the organic remains embedded in one deposit must have 

 existed contemporaneously. The most casual observers of the 

 causes now in operation upon the earth's surface must per- 

 ceive that the formations at this time in progress necessarily 

 contain the remains of beings which belong to different periods, 

 and yet, day after day, are inferences based upon the supposi- 

 tion, that, in whatever stratum a fossil is found, at that particular 

 period it must have existed. In this respect the examination 

 of the crag has demonstrated the fallacy of the per-centage 

 test, as a general rule for determining the age of the supra-cre- 

 taceous rocks, since it has been clearly shown that one forma- 

 tion may derive a large proportion of its fossils from deposits 



* See Art. II. in our present Number, p. 10. 



