732 METASPERMAE OF THE MINNESOTA VALLEY. 



form 36.5 per cent, of the extra-continental species; while the 

 Archichlamydeae form 31.9 per cent, of the total species they 

 form 41.0 per cent, of the extra- continental element, and while 

 the Metacblamydeae form 32.3 per cent, of the total flora, they 

 form but 22.5 per cent, of the extra-continental element. This 

 element shows, when compared with the general flora, a fall- 

 ing off in Metachlamydeae and a concurrent increase of Mono- 

 cotyledones and Archichlamydeae. The increase is greatest 

 among the Monocotyledones. 



In the second of the last three tables the distribution by 

 countries of the extra-continental element is indicated. The 

 percentages are fairly exact except in the case of the West 

 Indies. Of this region access has been had only to Grisebach's 

 Flora of the British West Indies. The percentage is probably 

 somewhat too small, but would in any event be likely to be the 

 smallest of the series. It is seen that the extra-continental ele- 

 ment is preponderantly Asiatic, and of the Asiatic group the 

 Manchurian Japanese forms a considerable percentage. Sub- 

 tracting this percentage from the total Asiatic percentage gives 

 54. 2 per cent, as the approximate Siberian element. This divis- 

 ion of the Asiatic element is a proper one and the two groups 

 of extra-continental species thus isolated would be interesting in 

 detailed comparison. Such comparison would, however, be a 

 little removed from the purpose of the chapter. A glance at 

 the table will show several curious facts that may be noted. 

 The Siberian group furnishes a larger percentage of Monocoty- 

 ledones and smaller percentage of Metachlamydeae, compara- 

 tively, than the Japanese-Manchurian. The African element 

 is almost as large as the South American or Australasian, and 

 for the most part consists of the same plants. In all three the 

 preponderant taxonomic group is the Monocotyledones, and of 

 these it is especially the aquatic or marsh forms that are thus 

 widely distributed. In these three distant elements the mono- 

 cotyledonous percentage is somewhat in advance of such gen- 

 eral percentages of the whole extra-continental element. 

 Especially in the most distant element, the Australasian, are 

 the Monocotyledones predominant. Of this element they form 

 66.6 per cent. Of the European element the Monocotyledones 

 form a larger jjercentago than of the Asiatic, while of the 

 Asiatic element the Archichlamydeae and Metachlamydeae form 

 each a larger percentage than of the European. Of the Man- 

 churian-Japanese element the Archichlamydeae and Metach- 

 lamydeae each form a larger percentage than of the Siberian 

 or total Asiatic. 



