2 CRETACEOUS AND TERTIARY FLORA. 



and finds its affinity only in Ludoviopsis geonomazfolia, Sap., of the Eocene 

 of Sezanne. A second, Sterculia modesta, Sap., also of Sezanne, is repre- 

 sented by a beautifully preserved specimen whose identity has been recog- 

 nized by the author. A third, Aralia pungens, is remarkable for its very 

 close relation, perhaps identity, to four species described by Massalongo 

 as Sylphidium from the Eocene of Italy. And still a fourth, Zizyphus Beck- 

 withii, is evidently allied to Z. Harcourtii of Sezanne. These, on seven 

 species only, added to the flora of the Laramie Group, tend to confirm the 

 conclusions which I have admitted on the age of the flora of the great 

 Lignitic, or Laramie, Group. 



3d. A large number of species described from what I called in Volume 

 VII the Green River Group No. 4, which I considered as probably Miocene. 



When that volume was published this flora was known only by a 

 very few species. Since that time a large number of specimens have been 

 procured from the same formation, especially at Florissant, Colorado. The 

 species which they represent are very interesting as indicative of a geolog- 

 ical period older than the ' Miocene, or preceding in age the Carbon and 

 Alaska floras. 



4th. A new contribution to the Miocene Flora from specimens pro- 

 cured from various localities of the Bad Lands of California and Oregon, 

 with mention of new species recently obtained from Alaska, and a note upon 

 a few specimens from the Chalk Bluff of California, a Pliocene formation. 



I.— THE FLORA OF THE DAKOTA GROUP. 



GENERAL REMARKS. 



All that refers to the geology of the Cretaceous Dakota Group — its 

 immediate superposition upon rocks of Permian age; its relation to the 

 strata overlying it in an uninterrupted series of marine deposits up to the 

 base of the Tertiary measures; its thickness, the superficial expanse of its 

 area — has been recorded in the general remarks of Volume VI of these 

 reports. Since that time very little has been added to what was known 

 and published on the subject. 



One fact only should be mentioned now. It is the discovery of numer- 

 ous specimens of Cretaceous plants at the base of the Rocky Mountains in 



