298 ON THE ZONAL STRATIFICATION OF THE
state of the univalves, a state that seems to have continued
during the deposition of the overlying silts and sands of the
Walton beds.
The presence of such shells at Boyton as Buccinum c.f.
inexhaustum Verk.. Trophon clathratus, several Betas, and other
boreal species, gives also a datum line for the opening of the
Northern barrier usually placed at a later period.
The fossils in the appended lists are from Boyton only.
(See end of paper.)
The next zone in succession to the above is the Waltonian of
Mr. Harmer or lowest Red Crag, a zone in which the reversed shell
Neptunea contraria makes its first appearance. At Walton-on-
the-Naze this form of Neptunea is the only one, but in the
upper portion of the Waltonian zone at Little Oakley, the
dextral forms of Neptunea antiqua and N. despecta, come in.
The Walton section as seen many years ago exhibited in
succession the basement bed followed by bands of Pectunculus,
Artemis and Mactra with seams of comminuted shelly silt full
of small and well preserved shells nearly all common to the
Gedgravian zone. The whole appears to have been accumulated
as a littoral deposit in a small and sheltered bay. The univalves
at this spot were abundant, and unworn, unlike the majority of
the Red Crag remains.
In working out his theory of the continuity of the Crags,
Mr. Harmer sought to find some deposits that would carry on
the succession by connecting the faunas of the Walton-Naze
deposit and the Coprolite-bearing beds of Waldringfield in
the Deben-Orwell district, and these he found at Little Oakley
and Beaumont. As he is shortly publishing a full report on the
Waltonian zone, dealing more especially with his work at the
former place, which he considers to be an upper horizon of the
Waltonian Crag, I do not propose going into any further details
in this paper. I have visited the excavations with Mr. Harmer
several times and seen his large and varied collections from the
place, which contain between 600 and 700 species and well
marked varieties of Mollusca, Polyzoa, Corals, etc.
Further changes in the relations of sea to land seem to have
set in towards the close of the Walton-Naze series, as the
Oakley fauna presents an increased number of northern and
boreal forms, the northern barrier being largely broken down,