FLORAS OF SECOND AEY AND TERTIARY PERIODS. 469 



of numerous plants, many of which belong to existing genera. 

 Amongst these may be mentioned Tulip-trees {Liriodendron), 

 Sassafras (fig. 718), Oaks {Quercus), Beeches (Fagus), Plane- 

 trees {Platanus), Alders {Alnus), Dog- wood (Cornus), Willows 

 (Salix), Poplars (Foptdus), Cypresses (Cupressus), Bald Cy- 

 presses (Taxodium), Magnolias, &c. Besides these, however, 

 there occur other forms which have now entirely disappeared 

 from North America — as, for example, species of Cinnamo- 

 onum and Araucaria. 



-Cretaceous Angiosperms. a, Sassafras Cretaceum ; b, Liriodendron Meekii; 

 c, Leguminosites Marcoiianus ; d, Salix Meekii. (After Dana.) 



The most important plant-remains of the American Cre- 

 taceous rocks have, however, been obtained from a remark- 

 able series of beds known as the " Lignitic Formation," which 

 is largely developed in the Western or Eocky Mountain 

 region, and the precise geological position of which has been 

 a subject of great controversy, and is still unsettled. In the 

 Old World, as is well known, there is a great break between 



