248 Geological Society. 



Besides being marked by tbe number of extinct and exotic 

 species which it contains, the Castle-Eden Pliocene is characterized 

 by the absence of aquatic species, and the abundance of those 

 growing on steep banks. From this the Author infers an upland 

 valley, with a gathering-ground standing at least 400 feet, probably 

 much more, above the Middle Pliocene sea-level, in an area now 

 forming part of the North Sea. 



2. ' A Comparative Review of Pliocene Floras, based on the 

 Study of Fossil Seeds.' By Mrs. Eleanor M. Reid, B.Sc, F.L.S., 

 F.G-.S. 



By plotting as a curve the percentages of all exotics, and of 

 Chinese-North American exotics, from the five floras (see last 

 paper), it was found that all lay along a smooth curve, part of 

 Avhich indicated changes in the Pliocene, part in the Miocene. 

 From this curve certain deductions are made : — 



(1) That the study of living and fossil seeds can lead to accurate 

 specific determinations. 



(2) The position of the Pont de Gail and Cromerian being fixed 

 points on the curve, that is, in time (namely, the beginning and end 

 of the Pliocene), then the position in time of the Teglian, as shown 

 by the curve (based on the study of fossil seeds), agrees with the 

 position indicated by palaeontology. Consequently the study of 

 fossil seeds is as accurate a method of determining geological age 

 as palaeontology ; and the age indicated for the Peuverian and 

 Castle-Eden floras is approximately correct. 



(3) The destruction and supplanting of the Chinese-North 

 American exotic flora began about the Middle Miocene, at the time 

 when the great European and Asiatic Alpine ranges attained their 

 maximum uplift ; but it was to these transcontinental barriers that 

 Clement Reid and the Author attributed the extermination of this 

 flora. Therefore the curve gives strong and independent confirma- 

 tion of the truth of their theory, and is in accord with the findings 

 of stratigraphy and palaeontology. 



(4) The curve indicates an incoming flora — the present flora 

 of Western Europe, and in part, of Central and Southern Europe 

 — which first appeared in the Miocene. Of this the aquatic 

 element is now chiefly circumpolar in distribution, whereas the 

 dry-soil element mainly centres in the Himalaya. The latter 

 character may point to a centre of dispersal, but the question ha? 

 not yet been studied. 



(5) The incoming flora only in part survived in Western 

 Europe; the destruction became. greater after the Middle Pliocene; 

 the cause of this is unknown. 



