cii. XIV] PALAEOBOTANICAL STANDPOINT 143 



the monotypic genus Stratiotes. Miss Chandler's work on the 

 subject is not yet published, but we may state that a succession 

 of species has been found at different geological horizons which 

 carries the history, with but few interruptions, from the top of 

 the Eocene to the present time. A whole series of extinct forms 

 lies behind the living species. The same is true of other genera 

 though the succession may be less completely known. To name 

 but a few, Dulichmm, Sparganiwn, Potamogeton, Najas, Sam- 

 bucus, Vitis, Magnolia, Rubus, Cotoneaster and Phellodendron are 

 all known to have a long fossil record of species that are now 

 extinct. Given time, the fate of all species is extinction, though 

 exceptionally they survive for long periods. The oldest living 

 species I have myself come across are Vitis lanata and Poly- 

 gonum Convolvulus in the oldest Pliocene (Pont-de-Gail), or 

 possibly Calla palustris in the Bovey Oligocene. 



If now we turn to Age and Area and inquire what evidence it 

 has to offer, we find that it points to survival as the probability, 

 unless extermination be due to "killing out." 



It is possible that we have here a real discrepancy between the 

 two studies, for the evidence of universal extinction of species 

 furnished by the pages of paleobotany is incontrovertible; but 

 Ave should bear that proviso "unless killed out" in mind. For 

 further evidence on the subject we may turn to the history of 

 the Chinese-North-American flora. 



We have seen that all branches of the flora have suffered 

 extermination, either complete extermination, or partial. By a 

 comparison of its old constituents, as seen in the Pliocene 

 deposits of West Europe, with its present constituents, as seen 

 in the Far East and in North America at the present day, Ave 

 may gain some idea how the flora has changed. 



In the first place we discover that not all species have been 

 exterminated, in spite of the great lapse of time, and the immense 

 distances travelled to their present homes. Even if we consider 

 the older deposits, the Reuverian belonging low down in the 

 Lower Pliocene, and the Pont-de-Gail at the base of the Pliocene, 

 we find some species of those remote times still living. As in- 

 stances we may cite Dulichiuni spathaccuiit, Brascnia pdtata, 

 Zelkowa keaki. Magnolia kobus, Liriodendron tulipifera, Stexvartia 

 pseudo-camellia, and Nyssa sylvatica from the large Rcu\-erian 

 flora, and Vitis lanata and Polygonum Convolvulus, as already 

 stated, from the Pont-de-Gail flora. 



But though some species have remained unchanged, it is far 



