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analogy with that now existing in the Southern United 
States of North America. But there was a part of it which 
was also allied to eastern Asiatic forms ; and Professor 
Oliver hence endeavored to show that it was more jirohable 
that the plants had migrated by way of Eastern Asia to the 
miocene regions of Europe. Though I am of opinion, and 
though I have endeavoured to prove in my papers on W'e.st 
Indian geology, that Professor Oliver’s hypothesis is scarcely 
the most probable, I am glad that his very able essay will 
still be of great service ; for the data given by him are 
really as much to the point if we assume a migration 
towards the East, a propo.sition which is indeed far more 
tenable on physical grounds, though at first sight appa- 
rently not so, on account of the great depth and width of 
the Atlantic which makes us recoil from the idea of a land 
connection between the .shores of the Atlantic, so lately, 
.speaking geologically, as the period in que-stion, that of the 
upper miocene. This latter argument seems to have weighed 
very strongly with Sir Charles Lyell who, in the 6th edition 
of his Elements of Geology, devotes several pages to a close 
examination of this question. These learned gentlemen 
seem to have overlooked the fact that the European miocene 
flora is extinct, whilst that of North America, Japan, &c., is 
living, and that, as Mr. Hamilton has remarked, it is not 
possible that a migration should take place from a living 
to an extinct flora. 
At first sight this difficulty seems to be removed by the 
researches of Lesquereux and Newbery who have shown 
that the Eocene flora of North America is closely allied to 
that of the Miocene of Europe. But this argument, though 
available for either hj-pothesis, bears much more strongly 
