their growth by the quantity of fresh water poured by rivers into
that inland sea.* (* See "Principles of Geology" chapter 30.) Hence
we may confidently infer that in the days of the aboriginal hunters
and fishers, the ocean had freer access than now to the Baltic,
communicating probably through the peninsula of Jutland, Jutland
having been at no remote period an archipelago. Even in the course
of the nineteenth century, the salt waters have made one irruption
into the Baltic by the Lymfiord, although they have been now again
excluded. It is also affirmed that other channels were open in
historical times which are now silted up.* (* See Morlot "Bulletin
de la Societe Vaudoise des Sci. Nat." tome 6.)

If we next turn to the remains of vertebrata preserved in the
mounds, we find that here also, as in the Danish peat-mosses, all
the quadrupeds belong to species known to have inhabited Europe
within the memory of Man. No remains of the mammoth, or rhinoceros,
or of any extinct species appear, except those of the wild bull
(Bos urus, Linn., or Bos primigenius, Bojanus), which are in such
numbers as to prove that the species was a favourite food of the
ancient people. But as this animal was seen by Julius Caesar, and
survived long after his time, its presence alone would not go far
to prove the mounds to be of high antiquity. The Lithuanian aurochs
or bison (Bos bison, L., Bos priscus, Boj.), which has escaped
extirpation only because protected by the Russian Czars, surviving
in one forest in Lithuania) has not yet been met with, but will no
doubt be detected hereafter, as it has been already found in the
Danish peat. The beaver, long since destroyed in Denmark, occurs
frequently, as does the seal (Phoca Gryppus, Fab.), now very rare
on the Danish coast. With these are mingled bones of the red deer
and roe, but the reindeer has not yet been found. There are also