On the Orvjin and Distribution of the British Flora. 78 



plants; and at Bournemouth this group occurs, with figs, 

 bays, and Papilioiiaceo}, 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 (Eninghen, 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. ^'^ 

 At Breslau, at Dantzic, at Bovey Tracey, and in the Island 

 of Mull, Ave have some of the same forms ; ^^* 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 ;^^ 

 whilst in Spitzbergen, more than 8° further north, occur 

 water-lilies and swamp-cypress with pines and sequoias ;" 

 and even in Grinnell-land, within 8^° of the Pole, occur elms, 

 guelder-roses, the Norway spruce, and the swamp-cypress.^^ 

 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,'^*^ 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,'^^ 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.' ^'^* Heer, 'Miocene Baltische Flora'; 

 Pengelly and Heer, 'Phil. Trans.,' 1863; Duke of Argyll, 'Quart. Journ. 

 Geol. Soc.,' 1851 ; LyeU, op. cit., pp. 214— 2'23. 



1-^ Heer, 'Fossil-Flora von Alaska,' 1869; 'Flora fossilis Arctica'; 

 Lyell, op. cit., p. 215. 



1^ Heer, op. cit. 



15 Wallace, op. cit., pp. 177—179. 



16 Wallace, op. cit., pp. 183—192. 



17 Translated by Mr. W. S. Dallas, London, 1876. 



I 



