i83 



THE CHAIN OF LIFE. 



the Cretaceous age was not local merely. In Moravia, in the 

 Hartz, in Belgium and France, even in Greenland, the same 

 great renewing of the face of the earth was in progress. In 

 America it was proceeding on a grand scale, and seems to 

 have set in earlier than in Europe.^ In the Dakota group of the 

 West, one of the lower members of the Cretaceous, and cover- 

 ir' avast area, a rich angiospermous flora has been discovered 

 by Hayden, and described by Lesquereux and Newberry, 

 and beds of coal have been formed from its remains. In 

 Vancouver's Island in British Columbia, Cretaceous coal 

 measures occur, comparable in value and in the excellence of 

 the fuel they afford with those of the true coal formation. 

 Some of the beds of coal are eight feet in thickness, and the 

 shales associated with them abound in leaves of exogenous 

 trees generally similar to those still living in America. In these 

 beds are also found mineralised trunks, which present under 

 the microscope th familiar structures of our oaks, birches, 

 and other modern '^es. Thus all over the northern hemi- 

 sphere the elevation ot the land out of the waters of the great 

 Cretaceous subsidence was signalised by a development of 

 noble and exuberant forest vegetation, of the types still extant. 

 The following list of families found in the Cretaceous, after 

 Saporta, will show the botanist how fully our modern Exogens 

 are represented : — • 



GaMOPETALvE. 



Apocynacem. 

 EricacecR, 

 EbenaceiB. 

 Myrsinece. 



APETALyE. 



Myricace(B. 



Cupuliferce, 



Betulacece. 



SalicacecB. 



MorecB. 



Proteacece. 



Lauracece, 



POLYPETALiE. 



Aj-aliacece. 



Hamameliacece. 



Helleborinece. 



MagnoliacecB. 



Tiliacece. 



Celastracea. 



Anacardiacea. 



Myrtacece. 



^ A poplar is .said to occur in Greenland, in beds held to be Lower 

 Cretaceous. 



