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206 



THE GEOLOGICAL HISTORY OF PLANTS. 



of the Cretaceous flora. No composite flowers have be- 

 fore been found in the fossil state, and, as these are among 

 the most complex and specialised forms of florescence, it 

 has been supposed that they belonged only to the recent 

 epoch, where they were the result of a long series of form- 

 ative changes." 



The above presents some interesting new types not 

 heretofore found in the Middle Cretaceous. More espe- 

 cially the occurrence of large flowers of the composite 

 type presents a startling illustration of the early appear- 

 ance of a very elevated and complex form. Great interest 

 also attaches to these Amboy beds, as serving, with those 

 of Aix and Greenland, to show that the margins of the 

 Atlantic were occupied with a flora similar to that occur- 

 ring at the same time in the interior plateau of North 

 America and on the Pacific slope. 



The beds at Aix-la-Chapelle are, however, probably 

 somewhat newer than the Dakota or Amboy beds, and 

 correspond more nearly in age with those of the Creta- 

 ceous coal-field of Vancouver Island, where there is a very 

 rich Upper Cretaceous flora, which I have noticed in de- 

 tail in the *' Transactions of the Royal Society of Cana- 

 da."* In these Upper Cretaceous beds there are fan- 

 palms as far north at least as the latitude of 49°, indicat- 

 ing a very mild climate at this period. This inference is 

 corroborated by the Upper Cretaceous flora of Atane and 

 Patoot in Greenland, as described by Heer. 



The dicotyledonous plants above referred to are trees 

 and shrubs. Of the herbaceous exogens of the period we 

 know less. Obviously their leaves are less likely to find 

 their way into aqueous deposits than the leaves of trees. 

 They are, besides, more perishable, and in densely wooded 

 countries there are comparatively few herbaceous plants. 

 I have examined the beds of mud deposited at the mouth 



♦Vol. ii., 1884. 



