Ch.XIL] SUBAPENNINE STRATA. 157 



some species of shells common to all the strata called by 

 him Subapennine ; but we have shown that this fact is not 

 inconsistent with the conclusion, that the several deposits may 

 have originated at different periods, for there are species 

 of shells common to all the tertiary eras. He seems to have 

 been aware, however, of the insufficiency of his data, for in 

 giving a list of species universally distributed throughout Italy, 

 he candidly admits his inability to determine whether the shells 

 of Piedmont were all identical with those of Tuscany, and 

 whether those of the northern and southern extremities of Italy 

 corresponded *. 



We have already satisfactory evidence that the Subapennine 

 beds of Brocchi belonged, at least, to three periods. To the 

 Miocene we can refer a portion of the strata of Piedmont, 

 those of the hill of the Superga, for example ; to the older 

 Pliocene belong the greater part of the strata of northern 

 Italy and of Tuscany, and perhaps those of Rome ; to the 

 newer Pliocene, the tufaceous formations of Naples, the 

 calcareous strata of Otranto, and probably the greater part of 

 the tertiary beds of Calabria. 



That there is a considerable correspondence in the arrange- 

 ment and mineral composition of these different Italian groups 

 is undeniable; but not that close resemblance which should 

 lead us to assume an exact identity of age, even had the fossil 

 remains been less dissimilar. 



Very erroneous notions have been entertained respecting 

 the contrast between the lithological characters of the Italian 

 strata and certain groups of .higher antiquity. Dr. Macculloch 

 has treated of the Italian tertiary beds under the general title 

 of c elevated submarine alluvia,' and the overlying yellow sand 

 and gravel may, according to him, be wholly, or in part, a ter- 

 restrial alluvium f . Had he visited Italy, we are persuaded 

 that he would never have considered the tertiary strata of 

 London and Paris as belonging to formations of a different 

 order from the Subapennine groups, or as being more regu- 



* Conch, Foss, Subap., torn. i. p. 143. f Syst. of Geol., vol. i. chap. xv. 



