ence and Miscellaneous Articles. 73 



edition of which was published in 1861. Since that period, pur- 

 suing without intermission the study of the Tertiary plants dis- 

 covered in divers countries till then unexplored (for example, the 

 Isle of "Wight, Greenland, &c), he laboured incessantly, adding 

 some general features to the magnificent work to a sketch of which 

 we here limit ourselves. 



Let us first place ourselves in Switzerland, where, as we know, 

 the various freshwater formations belong to the three horizons of 

 the Miocene. The Tertiary flora of Switzerland comprised at 

 least 3000 species of plants. It was consequently much richer 

 and more varied than even that of the most favoured countries of 

 the south of Europe ; and we must go into tropical regions — to 

 Jamaica, for instance, and to Bahia — to see at the present time 

 such an abundance and diversity of forms. Assembled at that 

 time within the little territory of Switzerland, those plants are 

 now disseminated into all parts of the world ; but it is in America, 

 and especially in the southern United States, that most of them 

 are at present found. If, instead of the number of species, we 

 consider the mass of the vegetation, Miocene Switzerland still less 

 resembles the present Europe, and comes nearest to America by its 

 abundance of evergreen oaks, maples, and poplars, by its plane- 

 trees, liquidambars, Robinice, Sequoice, Taxodia, and ternate-leaved 

 pines — to Japan by its Camphorce and Glyptostrobi, and, lastly, to 

 the Atlantic islands by its laurels. It has nevertheless a character 

 peculiar to itself, which is now found nowhere on the surface of 

 the globe — a character expressed at the same time in that singular 

 combination of specific types at present separated by great 

 distances, and by the existence of certain very peculiar species 

 which have become extinct. 



From Switzerland let us pass to Europe, in order to compare 

 the characters of the flora in the various successive Tertiary for- 

 mations. We shall there see striking differences, which impressed 

 a peculiar physiognomy on the vegetation of each period. Thus, 

 in the Eocene flora Indo-Australian types predominate, the 

 American species being but very feebly represented, and the cha- 

 racteristic plants of the temperate zone totally wanting. The 

 Eocene flora was therefore essentially tropical. 



The flora of the Lower Miocene has a subtropical character — 

 though tropical forms are still numerous, and the Indo-Australian 

 types still play an important part. The generality of the species, 

 however, belong at the present time to the subtropical and warm 

 zones ; and, above all, the forms of temperate climates are seen to 

 make their appearance there. Besides, both the subtropical and 

 the temperate forms correspond with American types, and give to 

 the flora an American tint. 



At the period of the Upper Miocene the tropical types have not 

 yet disappeared ; but they are reduced to about 7 per cent, of the 

 total vegetation, while those of the temperate zone rise to 18 per 

 cent. The forms of the subtropical and warm regions still pre- 

 dominate. The American character of the vegetation is expressed 

 still more plainly and evidently. 



Phil. Mag. g. 5. Vol. 7. No. 40. Jan. 1879. G 



