THE SUNKEN ISLAND OF ATLANTIS. 17 
has taken place and is derived from the North American Plora 
which since that time has not undergone any essential changes, whilst 
that of Europe, as is actually the case, has experienced vast revolutions. 
That the vegetation of North America has retained since the Tertiary 
period the same character, is proved by several facts, which I shall 
afterwards specify. There can therefore be no doubt that the plants of 
our lignite formations must seek their progenitors, not in our, but 
North American soil. When there are so many corresponding charac- 
teristics, Ave must necessarily assume a community of origin, and it 
would be offending against the economy nature practises to suppose 
that the creative power manifested itself in both Europe and North 
America in exactly the same manner. In short, there is more than one 
reason for thinking tbat the centre from whicb our lignite flora has 
sprung, was far away from Europe, — in the southern parts of the 
United States. 
If these conclusions be correct, tlien there will be no difficulty in 
finding out how the descendants of American Eobinias, Liquidambars, 
Tulip-trees, Hickories, Maples, etc., could reach Europe, and a soil 
favourable to their further extension. Here also there is one alterna- 
tive only. Either these winged or unwinged descendants found their 
way to the western coasts of Europe through the air or sea, or they 
availed themselves of a bridge which at that time existed between the 
two continents, but which the Great Architect of the universe has since 
removed. That plants, especially tlieir seeds, often travel far by the 
agency of wind and waves, and so effect a migration from one continent 
to another, is a well-known fact. We have several cosmopolites swept 
by Uie Gulf-stream from the coast of Mexico to Norway. The great 
range which the Cocoa-nut Palm enjoys is, it will be remembered, 
ascribed to its fruit floating uninjured across the ocean. But if the 
distribution of plants, effected by wind and waves, or the intervention 
of migratory animals, is more closely investigated, it becomes evident 
that the number of species which in this way became cosmopolitan is 
very limited, as plants require constitutions sufficiently tough to bear 
up against the greater or lesser changes which they must necessarily 
undergo. The number of species diffused in this way is a very limited 
one, and can never reach a sufficiently high figure to influence the 
character of the vegetation of a foreign countiy.* The plants imported 
* The vegetation of St. Helena and Ascension being almost entirely derived 
VOL. III. [JANUARY 1, 18G5.] 
