270 THEORY OF A MIOCENE ATLANTIS. [Ch. XV. 



realize the story of the Atlantis spoken of by the Egyptian priests to 

 Plato, we could look back through the whole interval which separates 

 us from the Eocene or Cretaceous periods, we might then indeed 

 freely grant, as geologists, any amount of change that may be re- 

 quired in the position of land and sea. All that is wanting is time 

 for the gradual development of a long series of subterranean move- 

 ments ; that being conceded, there would be no exaggeration in the 

 lines of the poet — 



"Earthquakes have raised to heaven the humble vale, 

 And gulfs the mountain's mighty mass entombed, 

 And where the Atlantic rolls wide continents have bloomed." — Seattle. 



It is the enormous depth and width of the Atlantic which makes us 

 shrink from the hypothesis of a migration of plants, fitted for a sub- 

 tropical climate in the Upper Miocene period, from America to Europe, 

 by a direct course from west to east. Can we not escape from this dif- 

 ficulty by adopting the theory that the forms of vegetation common 

 to Recent America and Miocene Europe first extended from east to 

 west across North America and passed thence by Behring's Straits and 

 the Aleutian Islands to Kamtschatka, and thence by land, placed be- 

 tween the 40th and 60th parallels of latitude where the Kurile Islands 

 and Japan are now situated, and thence to China, from which they 

 made their way across Asia to Europe. 



If that be the case, the breaks in a once continuous province of 

 plants, and the extinction as well as the diminished range of many 

 species, might well have been caused by the mighty revolutions in 

 physical geography which we know to have occurred in various parts 

 of this area in Post-miocene times. 



Professor Oliver, after making a careful analysis of Heer's work, 

 above cited, on the " Tertiary Flora of Switzerland," has given us an 

 able essay on the bearing of the valuable store of facts therein con- 

 tained on the two rival theories above alluded to.* In the first place 

 he has thought it safer to set aside all the cryptogamia, and to discard 

 a certain number of the phfenogamous plants as having been doubt- 

 fully determined by their leaves alone ; but after these deductions 

 there remain about 800 plants referred to 196 genera in the Swiss 

 Miocene flora. It is of course understood that some of these deter- 

 minations are very doubtful in the absence of fruit or flowers, but 

 the positive data which remain are amply sufficient for sound 

 generalizations, and we need not fear that these will be materially 

 shaken by future discoveries. The reasoning is the more to be 

 relied on because in so great a number of genera only twenty-one 

 are extinct, fifteen of these being monocotyledonous and six dico- 

 tyledonous. 



It is admitted that there is an unquestionable analogy between the 



* Nat. Hist. Review, 1862, p. 149. 



