rigin of high-level shelly
gravels and sands seems to me by far the simpler of the two theories,
and the most consistent with the facts and phenomena which the labours
of a succession of enthusiastic geologists have made us acquainted
with."

Among those geologists, and they form the majority, who hold that
Ireland was covered by land-ice, there is a great diversity of opinion
as to its extent. Messrs. Close, Kinahan, J. Geikie, and others believe
that the ice covered practically everything, whilst others who claim to
have examined the ground with equal care, such as Professor Carvill
Lewis, were led to believe that the south of Ireland, with the exception
of a few local glaciers, was free from ice. The glacial phenomena of
the country can therefore be interpreted in different ways, even by
those who are convinced that they are due to land-ice and not to
icebergs or mud-glaciers.

SUMMARY OF CHAPTER III.

The history of the British fauna is not only of interest to us from a
sentimental point of view, it is a convenient starting-point in the
study of the larger European problem. The fauna, broadly speaking, is
composed of three foreign elements, viz., the northern, eastern, and
southern, to which may be added a small endemic one. Examples are given
of the more noteworthy forms belonging to each of these. This leads us
to the subject of the natural divisions of the British Islands according
to their animal inhabitants. Zoologists attempted at first to subdivide
these countries, on the lines laid down by botanists, into a large
number of provinces. Forbes proposed ten such divisions for mollusca,
and subsequently five, which were ultimately reduced by others to two or
three.

The opinions of biologists are almost unanimous in attributing the bulk
of the British fauna and flora to migrations by land from the Continent,
but two other theories, viz., those of Professor Cole and Messrs.
Kinahan and Lamplugh, are also referred to. The first believes in a
possible migration eastward from Western Europe, and the latter support
the view of the former existence of ice-bridges to assist the fauna in
their migrations.

An endeavour is next made to determine at what geological periods the
various migrations entered the British Islands. There is considerable
difference of opinion on this subject. Some believe that the British
fauna is altogether post-glacial; a few think that it is partly so and
the remainder glacial; others a