OF SUBAPENNINE, SHELLS. 303 
APPENDICE. 
P. 627. DENTALIUM TETRAGONUM. 
Not D. quinquangulare of Forbes, or Siphonodentalium pentagonum 
of M. Sars. See Part v. of my papers in the ‘ Proceedings of the 
Zoological Society of London,’ on the Mollusca of the ‘ Lightning’ 
and ‘ Porcupine’ Expeditions. 
P. 666. CarRpIUM PUNCTATUM. 
A single valve, and decorticated or deprived of the greater part of 
the outer layer. It appears to be C. papillosum, Poli. 
It would be impossible to make a satisfactory analysis of all the 
species named or described by Brocchi, so as to ascertain which of 
them are now known to be living, and which of them are supposed 
to be extinct, because thirty at least of all these species are marked 
“ smarrita” or “ citazione ” on the tablets in the collection without 
any specimens. Perhapsa similar analysis could be attempted on a 
more extensive scale, as regards all the shells from the Pliocene 
formation in Italy, by a careful examination and comparison of 
modern collections in the University and private museums by some 
conchologist who was conversant with the living species of the North 
Atlantic and Mediterranean seas. Such an undertaking would 
require much time, but would be exceedingly useful to naturalists 
as well as paleeontologists. 
The lines of demarcation between the upper, middle, and lower 
sections of the Pliocene formation in Italy have not yet been well 
defined. At Castrocaro in the Bolognese district the “ sabbiosa ” 
and “ argillosa ” divisions of the lower Pliocene are distinguishable, 
but not the lower from the upper Pliocene, which are intermixed 
like our Coralline and Red Crag in so many places. As a general 
rule the upper Pliocene appears to contain by far the greater pro- 
portion of living or existing species and no tropical forms. The 
succession of these fossiliferous strata and of their organisms is 
still to be investigated. It might throw an immense flood of 
light on the difficult problem of the devolution or descent of species 
accompanied by a certain degree of modification or change, which 
is a very different phenomenon from what is popularly known as 
“ evolution.” 
My examination of Brocchi’s collection, as well as of several other 
and more extensive collections of Pliocene shells in Northern and 
Central Italy, has induced me to draw two inferences, viz.— 
1. That they represent deposits made in comparatively shallow 
seas, probably not exceeding fifty fathoms in depth. The only ex- 
ception seems to be the late discovery of Sequenzia formosa (a deep- 
water shell) in the Valle de Savena. In Calabria and Sicily, how- 
ever, there are deep-water formations evidenced by the nature of 
their Molluscan remains. According to Manzoni and other palx- 
ontologists the Miocene formation in Central Italy also denotes 
Q:J.G.5> No. 157. D 
