26
The Ancient Fauna of Essex.
wearing action ; for all the angles and ridges of the bones
still retain their original natural sharpness."13
If we could once more restore the physical features of the
Valley of the Thames as it existed in Pleistocene times, we
should doubtless find that all those places along its lower
course, where considerable deposits of brick-earth occur and
where the remains of the larger Mammalia are found in such
abundance, as at Ilford, Grays, Erith, &c, mark the sites of
ancient bays formed by the debouchment of side-valleys into
the principal one, giving rise in flood-times to eddies into
which the floating carcases of land-animals would indubitably
be drawn, and would in course of time sink and become
entombed in the soft and yielding argillaceous mud beneath.
That many of the remains of land-Mammalia met with in
these deposits may have lain for a very long period of time
upon the surface of the dry ground before being carried down
by floods and entombed in their present resting-place is, I
think, rendered highly probable by the following interesting
observation made by Mr. Wm. Davies, F.G.S., of the British
Museum of Natural History, who writes as follows:—
"During the preparation of fossil remains from the brick-
earth, I have had frequent opportunities of noticing points
which would otherwise have passed altogether unobserved by
any one, as they could only have been seen at the time the'
specimen was being actually cleared and developed from its
sandy or argillaceous matrix.
"I observed, for example, in the skulls of several fossil
Oxen numerous shells of the common Land Snails, Helix
nemoralis and H. hortensis, in one instance more than thirty
examples, all in good condition.
"I cannot help imagining that these snails, whilst still
living, may have found their way into the hollow cavity of
the skull through the only aperture (the foramen magnum)
for the purpose of hybernation—as is common with all
Helices now living in this country—whilst the skull was still
lying on the dry land, where it may have been left for a long
time after a flood; or, the animal to which it belonged may
13 See "Notes on the Pleistocene Deposits yielding Mammalian remaine
in the vicinity of Ilford, Essex." By Henry Woodward,- F.R.S., and
William Davies, F.G.S. (Geol. Mag., 1874. Decade II., vol. i., pp.
390—398).