134 BERRY— LOWER EOCENE FLORA OF [April 25, 



rainfall would be effective. Whether or not this would be sufficient 

 to furnish the subtropical conditions that the flora seems to indicate 

 is doubtful. Speculation regarding the Eocene climate of the world 

 as a whole is perhaps out of place, nevertheless it remains true that 

 the sum total of paleontologic evidence indicates that the familiar 

 succession of seasons or of types of vegetation in passing from the 

 luxuriant tropics to the ice-capped poles did not hold good for the 

 Eocene. Paleobotanists have long maintained that the existing cli- 

 mate is essentially a Pleistocene climate of an interglacial character 

 and that for the great bulk of geologic time uniformity and not dif- 

 ferentiation has been the rule rather than the exception. While the 

 older paleobotanists were inclined to overestimate the conditions 

 of torridity, it remains true that from the Lower Cretaceous until 

 toward the close of the Oligocene, not to mention still older floras of 

 more remote botanical affinities, whenever fossil floras are found, 

 from beneath the Equator to within the Arctic circle, they show a 

 degree of uniformity that proves that former climates were secularly 

 unlike these of today and as is obvious this floral evidence would be 

 equally convincing if all the vast number of fossil plants were simply 

 called Phyllites as in Schlotheim's day and no attempt were made to 

 determine their botanical affinity. 



The student of fossil floras is naturally more sanguine and en- 

 thusiastic in predicting former physical conditions than perhaps is 

 warranted by his facts. When however a common Upper Creta- 

 ceous flora can be traced from Texas to Greenland or when we find 

 in the Eocene such unmistakable forms as Artocarpns leaves, Engel- 

 hardtia fruits, and nuts of the Nipa palm associated with forms as 

 characteristic as ferns of the genus Acrostichum all extending almost 

 across the temperate zone in both the eastern and western hemi- 

 spheres it would seem that the burden of proof that climates were 

 not very different from those of today rests with the physicist and 

 not with the paleobotanist. 



It may be noted that all of the Wilcox plants, almost without ex- 

 ception, are plants whose modern representatives inhabit the warmer 

 parts of the earth. There is not a single strictly temperate type in 

 the whole assemblage, the nearest approach to such types being in 

 the genera Jtiglans, Myrica, Magnolia, Cercis, Ilex, Nyssa, and Frax- 



