158 PLEISTOCENE MAMMALIA. 
§ 3. Range in Time in Britain —We have now to discuss the paleontological value 
of the remains of the animal in determining the age of the deposits in which they are 
found. On a reference to the foregoing Table it will be seen that the animal occurs more 
or less abundantly in Bone-caves and River-deposits that are beyond all doubt of Post- 
glacial age, that is to say, which contain the remains of the arctic group of animals that 
invaded Western Hurope during the great refrigeration of temperature at the close of the 
Pliocene epoch, such as the Mammoth, Musk-sheep, and Reindeer, and that spread over _ 
the area that had been occupied by the Glacial sea as the land gradually rose again above 
the waves. There are, however, in Britain certain deposits which contain the remains of 
Post-glacial mammals associated with those which have been considered characteristic of 
the Pliocenes of France, Germany, and Italy, and which, therefore, stand intermediate in the 
geological scale between Pre- and Post-glacial deposits properly so called. In two of these 
the Cave Lion has been found, in the ancient river-bed at Clacton, and in the Lower Brick- 
earths of the Thames Valley, at Ilford in Essex, and Crayford in Kent. We will, therefore, 
sum up the whole of the paleontological evidence as to their place in the geological scale. 
The occurrence at Clacton of Rhinoceros leptorhinus of Owen (R. hemitechus of Fal- 
coner), of Llephas antiquus, Hippopotamus major, Vvish Elk, Horse, and of Urus, 
may be accounted for equally well by the assumption of its Pre- or Post-glacial age, for 
these Pliocene animals dwelt side by side in the same area with the arctic group of 
mammalia during the Post-glacial epoch. A new species of Deer, Cervus Brownit, 
is closely allied to the Fallow Deer, that is now found wild only in the districts adjacent 
to the shores of the Mediterranean. The Bison is the only animal that points in 
the Post-glacial direction, and this even will very probably be proved by future 
investigations on the Continent to have lived in France, Germany, and Italy during 
the Pliocene period. With its exception, therefore, there is nothing to forbid the 
supposition of the Phocene age of the deposit; but, nevertheless, as the characteristic 
mammals of the Pliocene, so abundant in the Forest-bed of Norfolk and Suffolk, are 
absent, it would be hazardous to ascribe it to that age. And in the same way, since the 
Reindeer, Mammoth, tichorhine Rhinoceros, and other equally common and characteristic 
Post-glacial mammals, are also absent, it cannot be said to belong to the class of deposits 
containing their remains. We are, therefore, justified in assuming that it represents, in 
point of geological time, an epoch during which some of the more hardy Phocene species 
lived under a temperature too severe for the more delicate of their congeners, and not 
cold enough for the invasion of the Reindeer and the allied arctic mammals. 
The Lower Brickearths of the Thames Valley at Ilford and Crayford contain the 
remains of Rhinoceros meyarhinus, which has not yet been found in France, Germany, or 
Italy in any strata later than the Pliocene age, and are therefore brought into more 
intimate relation with that epoch than any other of the deposits undoubtedly Post-glacial. 
Nevertheless, strange to say, since the Essay on the “ Lower Brickearths’? was written, 
1 «Quart. Geol. Journ.,” May, 1867, “On the Age of the Lower Brickearths of the Thames Valley,”’ 
by W. Boyd Dawkins, M.A., F.G.S. 
