675 



(lora must necessarily have immigrated across the sea, at least a 

 distance of 450 kilometres - a rauch longer tract than between 

 the Shetland islands and the Færoes (285 km.) 1 . 



The Azores and the Bermudas in certain respects resemble 

 Jan Maven. According lo Wallace's »Island Life« the Azores 

 are also widely separated from othcr islands and countries by vast 

 ocean depths, and distances of some 900 English miles, and are, 

 on the whole, vulcanic too, though of great age. The flora is de- 

 cidedly eastern with a fairly large percentage of endemic species, 

 all of which are, however, related to eastern species. As in the 

 case of the Færoes they lie in the way of the Gulf Stream, bul 

 have notwithstanding, received their piants from the east (Europe, 

 Madeira, the Canaries). Similar depths surround the Bahamas, 

 which are 700 English miles distant from America; they are coral 

 islands, and their flora has immigrated from America. 



A migration, backwards and forwards, across the Skagerak is 

 undoubtedly going on in our own day also; I shall discuss this 

 more ful ly elsewhere 2 . Krakatau may also be mentioned liere, be- 

 cause it has been so thoroughly investigated as regards the immi- 

 gration of its flora. It had been utterly destroyed in 1883, yet 

 3 years after Treub found on it 6 Algæ, 11 ferns, and 15 flowering 

 piants, all told, 26 vascular piants. Ten and a half years Iater 

 Penzig records 62 vascular piants, of which 60 °, o had been trans- 

 ported by the agency of ocean currents, 32% by wind, and 7% 

 by fruit-eating birds (perhaps two have been introduced by man) 3 . 

 True, the distance from the nearest land is not more than 20 km., 

 but some of the piants doubtless travelled a longer distance, about 

 as far as across the English channel. Many curious occurrences 

 of piants can hardly be explained in any other way than by trans- 

 port across vast oceans, e. g. the occurrence of the North American 

 Eriocaulon septangulare on the west coast of Ireland and Scotland, 

 the only Eriocaulacé to be found in Europe, or of the American 

 Rhipsalis Cassyta in Africa, the only genus of cactus which is met 

 with in the old world. 



1 The distances mentioned in this paper are the following; kilometres: 

 Norway — Denmark: 110: Norway — England: 445: Norway the Færoes: 585; 

 Norway— leeland: 970: Denmark— England: 520 (east — western direction: 610); 

 the Færoes — Iceland : 430: Iceland — Greenland: 290. Further, Europe — the 

 Azores: 1400: the continent of Africa — Madeira : 650. 



2 See also Warming: Om Grønlands Vegetation, Meddelelserom Grønland, XII. 



3 Annales du jardin de Buitenzorg, vol. VII, and 2. Sér., vol. III, 1903. 



Hotany of the Færoes. 43 



