146 THE JOURNAL OF BOTANY 



BE VIEWS. 



The Pliocene Floras of the Dutch- Prussian Border. Mededeelingen 

 van de Eijksopsporing van Delfstoffen, no. 6. By Clement 

 Eeid, F.R.S., and Eleanor N. Reid, B.Sc. 's-Gravenhage, 

 1915. 



It has long been known that during the earUer part of the 

 Tertiary period the vegetation of Britain included many genera of 

 Flowering plants and Gymnosperms and some Ferns that have 

 since migrated to more southern regions, and are now unknown in 

 Europe ; the inference is that thoughout the greater part of the 

 Tertiary era the climate of Britain was at least as warm as that of 

 the South of France or the Island of Madeira at the present day. 

 Fruits and seeds from the Cromer Forest-bed of Upper Pliocene 

 age, a deposit formed towards the end of the Tertiary period, afford 

 clear evidence of climatic conditions very similar to those of to-day, 

 and point to a gradual lowering of temperature which reached its 

 maximum in the succeeding Glacial period. The occurrence of 

 Arctic and sub-Arctic plants and animals in beds associated with 

 glacial deposits bears testimony to a southern migration from 

 northern Europe ; this was checked by the return of more genial 

 post-glacial conditions and, as the temperature rose, the plants 

 ascended the hills or saved themselves by a return to higher 

 latitudes. No one has contributed to our knowledge of the later 

 stages in the evolution of the British flora as much as Mr. Clement 

 Reid, and he has been very ably assisted by Mrs. Reid in the 

 difficult and laborious task of preparing the material, often in a 

 fragmentary state, for examination, photographing the specimens, 

 and comparing the fruits and seeds with existing types from all 

 parts of the world. The amount of work involved can only be 

 appreciated by those w4io have some acquaintance with the nature 

 of the records and realise the very great difficulty of identifying 

 fruits and seeds in the absence of any thoroughly representative 

 collection of recent forms. 



We now possess a fairly complete sequence of plants, repre- 

 sented chiefly by fruits and seeds, from British localities ranging 

 from the Pliocene beds of Norfolk to the days of the Roman 

 occupation. In 1908 Mr. and Mrs. Reid pubHshed a revised list 

 of plants" from a series of alluvial and estuarine deposits which 

 underlie the boulder clay and stretch for nearly fifty miles along 

 the Norfolk and Suffolk coasts from Sherringham to Pakefield 

 deposited by the Pliocene Rhine, which at that period, "after 

 receiving numerous large tributaries — now separate rivers — seems 

 to have flowed across the present bed of the North Sea. It 

 probably entered the sea somewhere near Cromer." In their 

 concluding remarks the authors summarise the results of their 

 analysis of the flora as follows : " Perhaps the first thing to strike 

 a botanist on examining our list will be how little the flora has 

 altered in the many thousand years that have elapsed and during 



* "On the Pre-Glacial Flora of Britain," Journ. Linn. Soc, vol. 37, p. 20G, 

 1908. 



