130 



TREE ANCESTORS 



especially abundant among the sand dunes that at that time bor- 

 dered the Upper Cretaceous sea in northern Europe (Aix-la-Cha- 

 pelle, Bohemia and Silesia). They were also abundant around the 

 shores of the late Upper Cretaceous sea in the Mississippi valley 

 where one of them has been given the significant Latin name of 

 protofagus, and may actually represent the starting point of the 

 beech line of descent. Dryophyllum also occurs in beds of Upper 

 Cretaceous age in western Greenland, and there are several species 

 recorded from deposits of this age in Montana, Wyoming and 

 Colorado. They have even been recorded from Australia, but 

 these last records are not regarded as authentic. Dryophyllum 

 is even more abundant in the early Eocene than it was in the late 

 Cretaceous. Here in America there are 5 abundant and very 

 characteristic forms in the early Eocene of the Gulf states. There 

 are 3 recorded from Colorado, 1 from Wyoming, 1 from the Yellow- 

 stone Park, CaHfornia and British Columbia. Another is common 

 in the late Eocene of Alaska and Sachalin Island at the opposite 

 ends of the land bridge of which the central planking has since worn 

 away to form Behring straits. In the early Eocene of Europe, 

 which many geologists call the Paleocene, there are abundant 

 leaves of 4 species of Dryophyllum in Belgium, 3 in France and 

 another in Italy. By Oligocene times only 3 doubtful forms are 

 known in France and Italy. It is true that 6 have been recorded 

 from the late Tertiary of Indo-China, but the name Dryophyllum 

 is used for these in the sense that it represents doubtful members 

 of the Fagaceae, and not in a strict botanical sense. 



Dryophyllum 



Quercus 

 oaks 



Pasania 



I 

 Castanopsis 



I 

 Nothofagus 



Castanea 

 chestnuts 



Fagus 

 beeches 



DiAGR.\M Showing the Interrelationships of the Oaks, Chestnuts 

 AND Beeches 



