
than now; great forests largely prevalent. Incoming and spreading of existing
fauna.
‘ 9. Period of final insulation of Britain; the climate being moist, the great
forests tending to disappear, and peat mosses prevalent.
‘ 10. The present condition of things.’
Dr. Wallace, in his ‘ Island Life,’ evidently differs from this view of the order
of things, for he is of opinion that Britain underwent an entire submergence to a
depth of two thousand feet, and that this submergence occurred during the latter
part of the Glacial period and destroyed the entire fauna of the country, while most
authorities are agreed that the destruction of the animals was due to the rapid
development of the second Ice-sheet itself—a most reasonable conclusion, considering
the manner and position in which most of the great creatures which inhabited
Great Britain during the warm snap between the two eras of Glacial cold are found
buried.
Both Dr. Wallace and Professor Geikie are, however, agreed that Britain was
connected with the Continent at two distinct periods, and that the present fauna
did not make its appearance until the second continental period ; but this theory
has been disputed by Mr. Bulman, who contends1 that part of the original fauna
survived the second Glacial period, owing to the fact that the Ice-sheet did not extend
further south than the latitude of London, and that possibly it stopped short of this
point. This would, of course, leave a great area of country, including the southern
counties, which might have been free from ice, and so formed an asylum for the
surviving animalltt Mr. Bulman’s contentions are thus lucidly summed up by
Mr. Lydekker, who both as zoologist and geologist is qualified to criticise the
subject from both standpoints.
‘ Without offering a definite opinion on a question so bristling with difficulties
as the above, we may say that, so far as Mammals are concerned, we do not
think that anything decisive one way or the other can be declared from the considerations
referred to. If the ancestors of our present Mammals did survive
the whole Glacial period in the south of England, there would of course be no
difficulty in regarding them as having repopulated England and Scotland at its
close. The case is, however, more difficult with regard to Ireland, which, on
this hypothesis, must at the same time have been separated from the sister-island,
since here, too, we must have had an area in which the present Irish Mammals
1 Natural Science, October 1893.