PREFACE. 
ix 
at Parma, where I studied, in the cabinets of Signor 
Guidotti, a beautiful collection of Italian tertiary 
shells, consisting of more than 1000 species, many 
of which had been identified with living testacea. 
Signor Guidotti had not examined his fossils with 
reference to their bearing on geological questions, 
but computed, on a loose estimate, that there were 
about 30 per cent, of living species in the Subapennine 
beds. I then visited Florence, Sienna, and Rome, 
and the results of my inquiries respecting the ter- 
tiary strata of those territories will be found partly in 
the body of the work, and partly in the catalogues 
given in Appendix II. 
On my arrival at Naples I became acquainted with 
Signor O. G. Costa, who had examined the fossil 
shells of Otranto and Calabria, and had collected 
many recent testacea from the seas surrounding the 
Calabrian coasts. His comparison of the fossil and 
living species had led him to a very different result 
in regard to the southern extremity of Italy, from that 
to which Signors Guidotti and Bonelli had arrived in 
regard to the north, for he was of opinion that few of 
the tertiary shells were of extinct species. In con- 
firmation of this view, he showed me a suite of fossil 
shells from the territory of Otranto, in which nearly 
all the species were recent. 
In October, 1828, I examined Ischia, and obtained 
from the strata of that island the fossil shells named 
in Appendix II., p. 57. They were all, with two or 
