OF THE BRITISH FLORA. 139 



Thus is it supposed that the arctic flora has been driven over all 

 the world, and on the close of the Glacial Epoch the plants 

 situated on what are now tropical plains perished, or else retired 

 up tlie mountains where we now find them, as on Clarence Peak in 

 the island of Fernando Po ; while in the northern hemisphere many 

 retreated back again into arctic regions perhaps accompanied by 

 other plants of the countries they had previously invaded. 



With reference to our own islands, there is reason to believe that 

 the Atlantic type of Watson, or the groups including the Asturian 

 and JVorman or Armorican of Forbes, are very ancient. This is 

 inferred, first, from their fragmentary character ; secondly, from 

 their isolation ; and thirdly, from the fact that boulders have been 

 found stranded on the south coast of England, implying that these 

 islands were severed from the Continent, at least on the west and 

 south-west, during the Glacial Epoch, and that, therefore, these 

 plants owe their origin to a much earlier connexion with the 

 Continent ; for, as already remarked, the nearest continental site 

 of the Asturian plants is to be found in Spain ; while the 

 Armorican doubtless came from Ivormandy. With regard to the 

 Arctic and common English and Scottish types, many of which 

 are to be found in the Arctic regions, they appear to have travelled 

 from the north, or from the Scandinavian regions across the plain 

 of the German Ocean ;* but on the subsequent depression of the 

 land below the sea, and with the elevation of temperature to its 

 present state, the more arctic types would be confined to the tops 

 of our mountains, while the rest would people the plains, and 

 the floras would thus be gradually established in our islands in 

 the conditions in which we now flnd them. 



arc of the terrestrial sphere, which presents the greatest continuity of land. In 

 the first place, Scandinavian genera, and even species, reappear everywhere from 

 Lapland and Iceland to the tops of the Tasmanian Alps, in rapidly diminishing 

 numbers, it is true, but in vigorous development throughout. They abound on 

 the Alps and Pyrenees, pass on to the Caucasus and Himalaya, thence they extend 

 along the KhaTsia Mountains, and those of the peninsulas of India to those of 

 Ceylon and the Malayan Archipelago (Java and Borneo), and after a hiatus of 

 30\ they reappear on the Alps of New iSouth Wales, Victoria and Tasmania, and 

 beyond. Then, again, on those of New Zealand and the Antarctic Islands, many 

 of the species remaining unchanged throughout. It matters not what the 

 vegetation of the bases and flanks of the mountains may be ; the northern species 

 may be associated with Alpine forms of Germanic, Siberian, Oriental, Chinese, 

 American, Malayan, and finally Australian Antarctic types; but whereas these 

 are all more or less local assemblages, the Scandinavian asserts his prerogative of 

 ubiquity from Great Britain to the Antipodes." 



* There appear to have been four well-marked periods at least in the Glacial 

 Epoch : Cl) a period of elevation at the time of Cromer Forest ; (2) one of great 

 depression, so that Great Britain became an archipelago ; then (3) a re-elevation, 

 when the German Ocean was land ; and finally a last depression to its present 

 condition. 



