4 Canadian Record of Science. 



tiary, irrespective of stratigraphical considerations, the 

 subject lost its geological importance. But when a good 

 series has been obtained in any one region of some extent, 

 the case becomes different. Though there is still much 

 imperfection in our knowledge of the Cretaceous and Ter- 

 tiary floras of Canada, I think the work already done is 

 sufficient to enable any competent observer to distinguish 

 by their fossil plants the Lower, Middle, and Upper Cre- 

 taceous, and the latter from the Tertiary ; and, with the 

 aid of the work already done by Lesquereux and Newberry 

 in the United States, to refer approximately to its true 

 geological position any group of plants from beds of un- 

 known age in the west. 



The successive series may be tabulated as on the opposite 

 page, with references for details to the fuller table in my 

 memoir of 1883. 



Though the flora of the Belly River series very closely 

 resembles that of the Lower Laramie, showing that similar 

 plants existed throughout the Senonian and Danian periods 

 in North America, yet it is to be anticipated that specific 

 differences will develop themselves in the progress of dis- 

 covery. In the meantime, it scarcely seems possible to dis- 

 tinguish by fossil plants alone the Lower Laramie beds 

 from those of Belly River ; and, if these are really separated 

 by 1,700 feet of marine strata, as is now believed on strati- 

 graphical grounds, the flora must have been remarkably 

 persistent. The Dun vegan series of Peace River probably 

 corresponds in time with the marine Niobrara and Benton 

 groups farther south and the Mill Creek with the Dakota 

 group. 



PHYSICAL CONDITIONS AND CLIMATE INDICATED BY THE 

 CRETACEOUS FLORAS. 



In the Jurassic and earliest Cretaceous periods the pre- 

 valence, over the whole of the Northern Hemisphere and 

 for a long time, of a monotonous assemblage of Gymno- 

 spermous and Acrogenous plants, implies a uniform and 

 mild climate and facility for intercommunication in the 



