COEKELATION OF EAELY CEBTACEOUS FLORAS. 81 



to trace the development of the vegetable kiugdom upward to the more modern forms," 

 as represented in Western America, and will complete the series of Cretaceous floras 

 extending from the Queen Charlotte Islands beds through the Dakota, Peace Eiver, 

 Nanaimo and Laramie series up to the Eocene period, which has been discovered throirgh 

 the labours of the Geological Survey in Western Canada. I anticipated that we should 

 thus have a good scale for comparison with the Cretaceous floras farther south, already 

 kuoW'U to a considerable extent through the labours of Newberry, Lesquereux and 

 others. 



These anticipations have been more than realized by the magnificent volumes of 

 Fontaine on the Potomac formation of the Eastern United States,' by the discovery by 

 Newberry in 188*7 of the Kootauie Flora in the Great Falls coal-field of Montana,- and by 

 farther discoveries in the Kootanie district itself, to which I propose to direct attention in 

 the present paper. 



Prof. Fontaine's Report now affords excellent terms of comparison for our Kootanie 

 llora ; but Dr. Newberry's paper is in some respects of greater interest, as referring to a 

 region geographically nearer, and in which he has recognized several of the species that 

 had been previously described in Canada, along with others which occur in our more 

 recent collections not yet published. We thus have now before us a very widely distri- 

 buted flora characteristic of the transition from the meagre and peculiar types of the 

 Jurassic to the richer vegetation of the Cretaceous, in which already some species of exo- 

 genous plants appear. It is to be remarked, however, in this connection, that while the 

 Potomac flora of the south-east, like the Mill Creek flora of the Rocky Mountains, includes 

 exogenous plants of primitive types, only gymnosperms and ferns have as yet been found 

 in the Kootanie and Great Falls collections. Such a negative fact cannot be certainly 

 relied on, especially since the collections from these localities, though abundant in 

 individuals are not as yet rich in species. Still so far as this fact goes it would give the 

 impression that the western floras of the Queen Charlotte Islands, Kootanie region and 

 Great Falls coal-field may be somewhat older than that of the Potomac formation. 



I have remarked incidentally in the previous papers on the Cretaceous floras already 

 referred to, on the probable geographical arrangements which accompanied and con- 

 tributed to the distribution at this time of a rich temperate flora from Greenland to the 

 Southern States, and Dr. G. M. Dawson has discussed this subject more fully in his 

 paper on the " Later Physiographical Geology of the Rocky Mountain Region of 

 Canada." ' It would appear from the stratigraphical and pala?outological facts summed 

 x;p in that paper, that in the early Cretaceous a great shallow-water Mediterranean existed 

 in the interior of the American continent, bordered by low and fertile shores, and prob- 

 ably barred across at its northern extremity by low lands extending from Greenland to 

 the nascent ridges of British Columbia, w^hile the Appalachian district formed a land ridge 

 on the east. Around this vast interior basin of warm water, and possibly on islands 

 scattered over it, flourished that vegetation which closed the Jurassic age and inaugurated 

 the reign of Augiospermous plants extending from the middle Cretaceous into the modern. 

 If, as seems in every way probable, the Jurassic age was in America a period of 



' Later Mesozoic Floras, U. S. Geol. Survey, 18S9. 

 - Am. Journal of Science, March, 1891. 



Sec. IV., 1892. 11. 



