194 RARE TREES IN ABBOTSBURY CASTLE GARDENS. 



species in the Kew Herbarium Avith deeply-cut leaves. L. iulipi- 

 fera inhabits the Atlantic declivities of North America from 

 Florida to Canada. 



There is clear proof that a material cooling of the Polar regions 

 commenced towards the early part of the Cretaceous age, when 

 many Dicotyledonous plants were introduced, the remains of Avhich 

 have been found so plentifully in North America and Greenland. 

 These colder conditions caused a migration southward of those 

 plants which were not hardy enough to maintain themselves 

 in their original homes, or had not succumbed to the rigours of 

 the climate. Many plants which once lived within the Polar 

 Circle during the Cretaceous age, are not met with in the oldest 

 beds of the Tertiaries of those regions ; the English and Scotch 

 Eocenes have yielded several, which bear a close relation to the 

 Polar Cretaceous flora. 



