THE TERTIARY TO THE MODERN PERIOD. 225 



are Thalictrum minus, L., Thalictrum flavum, L., Ra- 

 nunculus repens, L., Stellaria aquatica, Scop., Corylus 

 avellana, L., TannichelUa pdlustris, L., and Cladium 

 mariscus, Br. With a similar distribution in the Old 

 World, eight species {Bidens tripartita, L., Myosotis 

 ccBspitosa, Schultz, Sumda maritima, Dum., Ceratophyl- 

 lum demersum, L., Sparganium ramosum, Hnds., Pota- 

 mogeton pectinatus, L., Car ex paludosa, Good., and Os- 

 munda regalis, L.) are found also in North America. Of 

 the remainder, ten species {Nuphar luteum, Sm., Meny- 

 antJies trifoliata, L., Siachys pdlustris, L., Rumex mari- 

 timus, L., Rumex acetosella, L., Betula alba, L., Scirpus 

 pauciflorus, Lightf., Taxus baccata, L., and Isoetes la- 

 custris, L.) extend round the north temperate zone, while 

 three {Lycopus europceus, L., Alisma plantago, L., and 

 Phragmites communis, Trin.), having the same distribu- 

 tion in the north, are found also in Australia, and one 

 {Hippuris vulgaris, L.) in the south of South America. 

 The list is completed by Ranunculus aquatilis, L., dis- 

 tributed over all the temperate regions of the globe, and 

 Scirpus lacustris, L., which is found in many tropical 

 regions as well." 



He remarks that these plants, while including species 

 now very widely scattered, present no appreciable change 

 of characters. 



Above this bed are glacial clays, which hold other 

 species indicating an extremely cold climate. They are 

 few in number, only Salix polaris, a thoroughly arctic 

 species, and its ally, S. cinerea, L., and a moss, Hypnum 

 turgescens, Schimp., no longer found in Britain, but an 

 Alpine and arctic species. This bed belongs to the begin- 

 ning of the Glacial period, the deposits of which have as 

 yet afforded no plants in England. But plants occur in 

 post-glacial and upper-glacial beds in different parts of 

 England, to which Carruthers thus refers : 



"The period of great cold, during which arctic ice 

 21 



