156 OLDER PLIOCENE PERIOD. [Ch. XII. 



he added, some species of fossil shells which are found in these 

 deposits throughout the whole of Italy. 



In a catalogue, published by Lamarck, of 500 species of 

 fossil-shells of the Paris basin, a small number only were enu- 

 merated as identical with those of Italy, and only 20 as agreeing 

 with living species. This result, said Brocchi, is wonderful, 

 and very different from that derived from a comparison of the 

 fossil-shells of Italy, more than half of which agree with spe- 

 cies now living in the Mediterranean, or in other seas, chiefly of 

 hotter climates *. 



He also stated, that it appeared from the observations of 

 Parkinson, that the clay of London, like that of the Subapen- 

 nine hills, was covered by sand (alluding to the Crag), and that 

 in that upper formation of sand in England the species of shells 

 corresponded much more closely with those now living in the 

 ocean than did the species of the subjacent clay. Hence he 

 inferred that an interval of time had separated the origin of the 

 two groups. But in Italy, he goes on to say, the shells found 

 in the marl and superincumbent sand belong entirely to the 

 same group, and must have been deposited under the same 



circumstances t- 



Notwithstanding the correctness of these views, Brocchi con- 

 ceived that the Italian tertiary strata, as a whole, might agree 

 with those of the basins of Paris and London, and he endea- 

 voured to explain the discordance of their fossil contents by 

 remarking, that the testacea of the Mediterranean differ now 

 from those living in the ocean J. In attempting thus to 

 assimilate the age of these distinct groups, he was evidently 

 influenced by his adherence to the anciently-received theory of 

 the gradual fall of the level of the ocean, to which, and not to 

 the successive rise of the land, he attributed the emergence of 

 the tertiary strata, all of which he consequently imagined to 

 have remained under water down to a comparatively recent 

 period. 



Brocchi was perfectly justified in affirming that there were 

 * Conch. Foss. Subap., torn. i. p. 148. f Ibid., p. 147. J Ibid., p. 166. 



