100 
CASE O. 
(All the specimens in Cases O and M are from the clay of 
Fisherton, unless the contrary is stated). 
The hones in the subjoined catalogue are, with a very few ex¬ 
ceptions, from the brick-fields of Fisherton, about a mile to the 
west of Salisbury. The clay from which they are obtained belongs, * 
geologically speaking, to that division of the tertiary formations 
which is technically known as the Mammalian drift or Pleistocene * 
The gracefully-sloping hill sides of the various ranges of chalk 
which bound the river Avon, and its tributary streams the Wiley, 
Nadder, and Bourne, are in many places covered with detached 
patches of clay and gravel ; but in this neighbourhood they are 
more conveniently exposed, and of far greater extent at Fisherton 
than elsewhere. Here the gravel, clay, and brick earth, are deposited 
upon the south side of the northern boundary of the river Nadder ; 
the deposits vary considerably in thickness, in parts vertical sec¬ 
tions show a height of about 30 feet; they everywhere gradually 
thin out towards the valley. At the base of the clay in some of 
the pits may be detected a very thin band of light coloured marl, 
which contains a large number of both land and freshwater 
shells, all of species similar to those now found inhabiting the 
streams and meadows of the valley below, and hence it is very clear 
that these beds of gravel, clay and sand, are the result of fresh¬ 
water action, not a single marine shell has hitherto been discovered. 
The bones and teeth themselves occur scattered through the 
clay and gravel, but are met with most abundantly low down, 
generally a few feet from the base of the deposits. From the great 
lapse of time which must have occurred since these bones were 
first buried where they are now found, considerable alteration in 
their chemical composition has taken place, nearly all traces of 
gelatine are lost, only the earthy salts remaining; and hence, when 
the bones are dry, they very readily absorb moisture, sticking to 
the wetted finger like a piece of dry chalk or lime: this is a rough, 
but often a very useful, test of the genuineness or otherwise of the 
remains of such animals as are still living, the ox, horse, and others. 
The bones exhibited give but an imperfect idea of the state in 
which they usually occur ; these specimens have been selected from 
a large number, many having undergone extensive repairs, the 
majority being fragmentary and very much broken, although 
scarcely ever water-worn ; it is quite the exception to meet with 
any of the long bones of the extremities entire. 
* The terms Eocene, Miocene, Pliocene, and Pleistocene, employed by Sir 
Charles Lyell to designate the different tertiary strata, are derived from the 
Greek words 7]cos } eos, dawn ; fieiov, meion, less; irAeiop, pleion, more; 7 tA€ i<ros, 
pleistos, most; and kolivos , kainos, recent; each being intended to express the 
relative proportions of recent and extinct shells found in the several strata. 
Thus the shells of the Eocene period contain a very small number of living 
species, and may be looked upon as indicating the dawn of the existing state of 
the testaceous fauna. In the Pleistocene, on the other hand, all, or nearly all, 
the shells belong to existing species. 
