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 vf 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. t Syst. of Geol., vol, i, chap. xv. 
