Pvn H,i I'UitlS

X INTRODUCTION.
up only stones and earth from the land, like the moraine
of a glacier, such a conjecture does not seem to be en-
titled to much weight. An iceberg might certainly be
stranded, and thus pick up shells ; but it would in all
probability be dissolved on the spot in the course of time.
Its bulk and weight are too great to admit of its floating
off again under such circumstances as I have supposed.
It is, indeed, within the bounds of possibility that the
shells might have been collected on the shore by coast-
ice, and carried off to sea ;
but Dr. Wallich informs me
that this kind of ice has never been known to travel so far
southward as the locality above mentioned. There is
much greater probability that the mollusca in question
lived and died on the sea-bottom where their remains
were found. Every one who considers the importance of
these researches ought to read and study Wallich's trea-
tise on the North-Atlantic Sea-bed, and especially the
limits of animal life in the
chapter on the bathymetrical
ocean. He will find the subject treated in a philosophical
and the account of living starfishes
and masterly style ;
having been discovered at a depth of 1260 fathoms in
the open sea, and also the geological application of that
discovery, especially
years the use of the dredge,
deserve attention. Until of late
as an instrument of zoolo-
gical research, was nearly unknown. All that natu-
ralists did in former times was to examine the refuse of
trawl nets, which seldom reached a depth of 20 fa-
thoms ; or now and then fishing-lines of more than twice
that length brought to the surface a few shells and
corals which were accidentally detached from the bottom
of the sea. These specimens (as Professor Forbes said)
" only served to whet our curiosity, without affording
the information we thirsted for." Now-a-days, how-
ever, the dredge is a scientific necessity ; and scarcely