THE EOCENE FLORA AND FAUNA.
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The London Clay at Walton is the typical stiff bluish-black
clay, turning brown where exposed to atmospheric agencies, and
containing thick bands of hard argillaceous limestone full of
curious vermiform concretions which stand out in relief on
weathered blocks.
Plant remains were chiefly represented by twigs and pieces
of wood, some of which were riddled with the tubes of a boring
mollusc, Teredo antenautae. Of determinable vegetable remains I
have a very fine cone of Petrophylloides richardsoni. I also found
a beautiful cast in pyrites of an acorn, but although it must still
be in my collection somewhere, I have not yet been able to lay
my hands on it : so minutely had the replacement of the organic
structure by the mineral taken place, that I was able to lift it
out and replace it in the "cup."
The Hydrozoan Graphularia wetherelli occurred in abundance,
forming the axis of cylindrical nodules of hardened clay.
The Crinoid Balanocrinus subasaitiformis was the commonest
of all the fossils, but unfortunately I have not kept any examples.
I trust that the next time a member of the Essex Field Club
visits the locality, he will remember the Museum.
The small crab Plagiolophus wetherelli is represented by a
complete carapace. The local barber had a lovely specimen of
the Eocene lobster, Hoploparia gammaroides, on the outside of a
nodule of London Clay, and I myself obtained claws both of this
species and of H. belli.
The Brachiopoda are represented by a single species,
Terebratulina striatula.
Of the Mollusca, besides the Teredo antenautae already referred
to, I obtained an internal cast of another Pelecypod, and one of
a Gastropod, but they could not be satisfactorily determined.
The Cephalopoda are represented by the genus Nautilus of
which the local barber had several examples both large and
small.
The Selachian (Sharks) remains were mostly in a good state
of preservation and so have escaped the fate of the majority. In
nomenclature I have followed Mr. A. S. Woodward's "Notes on
the Teeth of Sharks and Skates from the English Eocene
Formations."1
1 Proc. Geologists' Assoc., vol. xvi. (1899).