On the Origin and Distribution of the British Flora. 73
plants; and at Bournemouth this group occurs, with figs,
bays, and Papilionaceae, the whole presenting a subtropical
and somewhat Australian aspect. It is, however, the
luxuriant and wide-spread flora of the Miocene period that
has chiefly forced upon geologists the question of climate in
the past. At OEninghen, in the North of Switzerland, we
have a flora including 465 species, of which 166 are trees
and shrubs, half of them being evergreens. They comprise
sequoias, cinnamons, tulip-trees, and many other American
genera, together with maple, ash, plane, oak, and poplar.12
At Breslau, at Dantzic, at Bovey Tracey, and in the Island
of Mull, we have some of the same forms;12* but even in
70° of north latitude, on the west coast of Greenland, is a
flora of a but slightly more northern character, including
evergreens, a walnut, a plum, vines, and a magnolia;13
whilst in Spitzbergen, more than 8° further north, occur
water-lilies and swamp-cypress with pines and sequoias ;14
and even in Grinnell-land, within 81/4° of the Pole, occur elms,
guelder-roses, the Norway spruce, and the swamp-cypress.15
The most satisfactory explanation of these wide-spread
indications of a warm climate in north temperate regions is
the theory, so ably advocated by Mr. Alfred Russel Wallace,
in his most suggestive 'Island Life,'16 of the lower elevation
of the land within the arctic circle, and the access of warm
currents from the Indian Ocean through the Red, Caspian
and White Seas, and from the Pacific, to Polar regions.
During the same period Professor Heer's valuable maps, in
his 'Primeval World of Switzerland,'17 indicate continuous
land from North-west Africa through Spain, and the Bay of
12 Lyell, op. cit., pp. 190—198; Wallace, op. cit., p. 177; and Heer,
'Flora Tertiaria Helvetia.' 12* Heer, 'Miocene Baltische Flora';
Pengelly and Heer, 'Phil. Trans.,' 1863; Duke of Argyll, 'Quart. Journ.
Geol. Soc.,' 1851; Lyell, op. cit-, pp. 214—223.
13 Heer, 'Fossil-Flora von Alaska,' 1869 ; 'Flora fossilis Arctica';
Lyell, op. cit., p. 215.
14 Heer, op. cit.
15 Wallace, op. cit., pp. 177—179.
l6 Wallace, op. cit., pp. 183—192.
17 Translated by Mr. W. S. Dallas, London, 1876.
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