of the District around Colchester. 97
The above list is as complete as I have been able to make
it. Of course there are portions of the district that I have
not explored, as my engagements have prevented me making
long excursions; but as far as I have gone I think I have
searched over the ground somewhat minutely and carefully.
It will no doubt be remarked that there is almost an entire
absence of species of the genera Pupa, Vertigo, and Clausilia
in my catalogue. I suppose this fact may be accounted for
by the deficiency of calcareous strata in the district. All the
names of shells which appear in the list are inserted after a
personal examination of the specimens and localities, and
may be relied upon. I have carefully verified every shell
named, and to insure correctness in doubtful cases I have
had my opinion confirmed by some of the best authorities.
I cannot leave this subject without calling attention to an
extraordinary deposit of land and fresh-water shells, in a
fossil condition, in the brickyards at Copford. This Shell
Marl was fully described by the late John Brown, F.G.S., in
the 'Journal of the Geological Society of London' for August
1852, vol. viii., p. 184. He shows that more than sixty-nine
species are there represented, only two of which (Helix in-
carnata and H. ruderata) are extinct in this country.
From a personal examination I can testify to the number
of Vertigos, both as regards species and individuals, as well as
other rare shells, contained in this deposit.