35 1 
1878.] Superficial Gravels and Clays. 
This was probably the time of the greatest range of the 
Hippopotamus which ascended the great river to the Ger- 
manic lake. Possibly the river, by the lowering of the sea 
level, flowed as far southward as the Bay of Biscay, and if, 
as Dr. Gwyn Jeffreys supposes, theJMediterranean then com- 
municated with the Atlantic to the north of the Pyrenees, 
the hippopotamus would not have to travel far from the 
Mediterranean area, where we know it abounded, to the 
mouth of the great river. 
Palaeolithic man appears to have penetrated into Britain 
at this stage, as his implements are found associated with 
the older mammalian fauna in the caves of the west. 
E. Newer Mammalian Fauna . — The last stage gradually 
merged into the present one by the climate — affeCted by the 
continued advance of the northern ice — becoming too cold 
for the southern fauna, which retired further south ; its 
place being taken by the mammoth, the woolly rhinoceros, 
and the reindeer. The great ox, the wild horse, the bison, 
the red deer, the Irish deer, the lion, the bears, and the 
hyaenas appear to have lasted on from the former period, 
and the three first to have abounded. The hippopotamus 
still occasionally came up the great river in the early part 
of the period. The mammoth, which during the time of 
the deposition of the brick-earths had reached as far south 
as the Thames in its winter migrations, now became a more 
permanent resident. The most characteristic mammals are 
the woolly rhinoceros and the reindeer, though even they, 
in the early part of the period, must have overlapped in 
their winter migrations the range of the more southern 
animals in their summer wanderings. The reindeer is 
absent from the Lower Brick-earths, and from the beds 
containing the older fauna at Brentford, excepting a 
small portion of an antler found by Colonel Lane Lox, 
which may have been drifted at the time of the debacle, 
when the remains of the two faunas were partially mixed 
together. In the section at Brentford, described by Prof. 
Morris, the reindeer was abundant, and was associated with 
the mammoth and woolly rhinoceros. Not a fragment of 
the southern shells, Hydrobia marginata, Unio littoralis, 
and Cyrena] fluminalis, occurred at this’ spot, whilst in the 
older sands in the same district the two first-named are 
abundant. 
Mr. Godwin Austen has described peat and sedimentary 
beds of this age underlying the gravels at Pease Marsh, 
