part 2] 



PREGLACIAL FLORAS FROM CASTLE EDEN. 



107 



For the three floras the number of species selected were: — Teglian 

 100, Reuverian 133, Pont-de-Grail 17. I decided to compare the 

 percentages of the total number of exotics, and of the number of 

 species belonging to the Chinese-North American association. 

 This association consists of plants now inhabiting Japan, China, 

 Indo- China, the Eastern Himalaya. Assam, Burma, Malaya, 

 Australia, and North America, but not living in Western Europe. 

 The result of the comparison showed that of the selected species 

 the Teglian had 40 per cent, of exotics, the Reuverian 88 per cent., 

 and the Pont-de-Grail flora 94 per cent. Of Chinese-North American 

 •species the Teglian had 16 per cent., the Reuverian 54 per cent., 

 and the Pont-de-Gail flora 64 per cent. There could be no doubt 

 that the Reuverian was much nearer the Pont-de-Grail flora than the 

 Teglian. The Teglian is the age of the Norwich Crag, the Pont- 

 de-Grail is the base of the Pliocene : it seemed certain, therefore, 

 that the Reuverian must be Lower Pliocene, and probabty some 

 way down in it. 



This conclusion was subversive of our former ideas as to the rate 

 at which the character of the West-European flora changed 

 throughout the Pliocene. The change was evidently much slower 

 than we had imagined. I thought it possible, therefore, that the 

 Castle-Eden flora might prove to be older than I had believed at 

 first — a little older than the Teglian. I accordingly extended 

 the comparison to the Cromerian and Castle-Eden floras, selecting 

 the species on the same principles as before. The number of Cro- 

 merian species selected was 135 and of Castle Eden 58. The 



Table showing the Relationships of Five Pliocene 

 Seed-Floras. 



I. 



II. 





III. 



IV. 



V. 



VI. . 



Name of 

 Flora. 



Numb 

 of spec 

 compai 



ies 



•ed. 



Percentage 

 of whole 



flora 

 compared. 



Percentage 



of exotic 



and extinct 



species. 



Percentage 

 of Cliinese- 

 North-Amer- 

 ican species. 



Age, or 

 suggested age 

 of the strata. 



Cromerian 



135 





89 



5 



0-74 



Top ot Pliocene. 



Teglian 



100 





75 



40 



16 



Upper Pliocene 

 (Norwich Crag). 



Castle Eden ... 



58 





55 



64 



31 



Middle Pliocene. 



Reuverian 



133 





46 



88 



54 



Lower Pliocene. 



Pont-de-Gail . 



17 





35 



94 



64 



Base of Pliocene. 



result seemed to indicate very clearly a Middle Pliocene age for 

 the Castle-Eden flora. 



When I reached this conclusion, I wrote to Dr. C. W. Andrews 

 to ask whether, supposing that the elephant-remains and seeds 

 should belong to the same bed. my determination of the age of the 



