American and English Fossil Floras. 503 



We are now in a position to revert to the Ci'etaceo-Eocene series 

 of America, considering first its floras and then its faunas. It is 

 not possible to attempt much direct comparison between the actual 

 constituents of the floras of Europe and America. Such would be 

 unjustifiable with my present knowledge concerning them, and I 

 must merely point out the salient differences between them. 



I have already remarked that the oldest of the so-called Cretaceous 

 floras of America is composed of varied and perfectly differentiated 

 Anginsperms, in many cases referable, apparently, to existing genera. 

 The oldest Cretaceous flora in Europe containing Dicotyledons, with 

 which I am personally acquainted, is that of Aix-la-Chapelle, and 

 I should certainly hesitate, and I do not think any one else would be 

 bold enough, to attempt to place its leaves in existing genera. 

 With the exception of a few such as Credneria and Protophyllnm, 

 they are, so far as I can recollect, mostly simple ovate or lanceolate 

 leaves with denticulate or serrate margins. The ferns are, with 

 scarcely an exception, completely different to any found in the 

 Dakota series, and, most significant of all, the Coniferaa possess 

 characters, embarrassing to the systematist, which forbid the greater 

 part of them from being placed in the existing genera. I do not 

 hesitate to pronounce it a far more primitive and archaic flora 

 than any yet described from the United States series. Nothing is 

 definitely known as to the age of the Sezanne flora, and those of 

 America seem to have little in common either with it or with 

 that of Gelinden. When we compare the Dakota flora described by 

 Lesquereux, with the flora of the Reading series, at the base of our 

 Eocene, the points of resemblance are as startling as they are 

 unexpected, I find figured in this single work Glyptostrobus gracilis, 

 found by me at Croydon, Gleichenia Kurriana, at Bromley, Sassafras 

 acutilohum, at Newhaven, Bhamnus tenax, Gelastrophyllum ensifolium, 

 Platanus diminutiva, Sassafras ohtusum, Menispermites salinensis, M. 

 ohtiisiloba, Sassafras cretaceum, S. Harkerianum, Liquidambar integri- 

 folium, Ptenostrobus nebrascensis, and the most characteristic of the 

 CarpoUthes, at Eeading. I would not assert that these are all 

 specifically identical, but what I do maintain is that it is an utter 

 impossibility for all the chief types of two imperfectly known floras to 

 resemble each other in this manner in an accidental way — when 

 no 3'ounger Eocene flora bears the remotest resemblance to the 

 Dakota flora ; unless it be that of Mull. I am content for the 

 moment to state the fact without drawing any inference from it. 



After the close of the Reading period the Eocene temperature in 

 England rapidly increased, and became almost tropical during the 

 deposition of the London Clay. There is no further similarity 

 between our fossil floras and those hitherto published from America, 

 until the Middle Bagshot horizon is reached, when we find that of 

 Bournemouth bearing a considerable resemblance to those figured by 

 Lesquereux from the lowest, Laramie, and the other stages of the 

 great Lignitic formation. It is certainly a most singular fact that 

 two floras, each so like the other, should follow at like intervals on 

 both continents and yet be of widely different ages. 



