46 Mr. Henry Walker's Lecture:
oxen of colossal size were selected and established; the
enormous "Irish elk" was supreme among the Cervidae of
the period, and other giant animals were on their way to
these western feeding grounds and fastnesses. The land had
recovered from the depopulation, extinction, and wreck of
the great submergence, and the glaciation which succeeded.
The great Europasian invasion had begun.
THE SOUTHERN AND SUB-TROPICAL ANIMALS.
We have thus far accounted for the presence of the
northern and Arctic group of animals found fossil at Ilford.
We have seen the remarkable geographical surroundings
amid which they lived, and we may see all around us in
Essex the surviving memorials of the climate of the
mammoth, and the woolly rhinoceros. The problem pre-
sented by the southern and sub-tropical fauna still remains
to be considered.
This group of the Ilford fauna consists of the lion, two
rhinoceroses (the "leptorhine," or small-nosed, and the
"megarhine," or big-nosed), the straight-tusked elephant,
the hippopotamus, and the little river mollusk, Cyrena
fluminalis.
Of this strange collection of British Pleistocene mam-
malia, the Elephas antiquus and the two rhinoceroses are
now extinct. The hippopotamus, which in Pleistocene
times ranged as far as Yorkshire and has been found in
valleys near Leeds, is not now found north of the Nile;
Britain" (Glasgow Science Series, 1878-9). At page 15, the lecturer
remarks:—"Modem civilisation, by extirpating beasts of prey, has
rendered it possible for us to leave herds and flocks of small oxen and
sheep out in the open. In times of ancient savagery, in which packs
of wolves held their own, none but big animals would be so left. In
those times also, the country was not mapped out by 'formal props of
restless ownership,' and these wild animals had a much wider range,
and having better pasturage grew larger accordingly. It is clear that
both causes—the presence of wild carnivora, and the absence of en-
closures—must have co-operated in increasing the size of the
graminivorous beasts. Those cattle were large because, if a small bull
encountered a pack, however small, of wolves, it was pulled down, and there
was an end of its existence, and of the chance which it had of propagating
small animals like itself."