NO. 6 PAST CLIMATE OF NORTH POLAR REGION BERRY 1 5 



some Conifer. Why waste time trying to explain the climatic signifi- 

 cance of Paliurns, a mostly extinct genus, when the particular fossil 

 is probably not a Paliurus; or why concern oneself with an Arctic 

 species of Zisyphns when the form in question is probably a Ceano- 

 thusf I ask, can any one prove that the form-genus Pterospermites 

 is genetically related to the existing genus Pterospermmn? or that 

 Elaeodendron is a sound botanical identification ? I think not ! 



On the other hand, the great mass of not only the Kenai but of all 

 the Arctic Tertiary floras are the readily recognizable, normal units of 

 a natural assemblage, which individually leave but slight room for dif- 

 ferences of opinion regarding their identity. If fruits chance to be 

 found in association with the leaves, they are such things as birch or 

 alder cones, never the fruits of the " suspects " above mentioned. 



Of the remaining genera listed in the Kenai flora, all but the follow- 

 ing six are represented in the existing flora of Canada : ^sculns, 

 Diospyros, Ficiis, Liquidambar, Sequoia, and Taxodium. It may be 

 said of these that the ^sciiliis may not be an Msculus, but a Hicoria; 

 that the two species that have been referred to Ficus do not belong 

 in that genus ; and that Sequoin is on the verge of extinction at the 

 present time and its modem range bears little relation to its former 

 range. The case of Sequoia is of especial interest in its bearing on my 

 thesis. Formerly a Holarctic type, it survives today in a most re- 

 stricted area particularly favored by humidity. 



The remaining genera of the Kenai flora appear to be determined 

 with reasonable certainty. Not only are 39 of these represented in 

 the existing flora of Canada, but the following are still represented in 

 the existing flora of Alaska, or adjacent areas in northwestern 

 Canada, or as far north as Labrador and Hudson Bay in eastern 

 Canada: Abies, Acer, Alnus, Alnites, Andromeda, Betida, Carex, 

 Corylus, Equisctum, Fraxinus, Myrica, Osmunda, Phragmites 

 (grass), Picea, Pinus, Popidus, Prunus, Ptcris, Qucrcus, Sagittaria, 

 Salix, Spiraea, Thuifes, and Vaccinium. 



Seventeen of the Kenai species are conifers, and the only types that 

 would seemingly be out of place in a cool temperate climate with 

 well-distributed moisture are Liquidamhar, Paliurus, Taxodium, and 

 Zizyplius. I have already given reasons for discrediting the deter- 

 minations of some of these, and all of them have frequently been 

 found fossil in temperate assemblages. 



The significant feature about these Eocene Arctic floras is that 

 they show a comparable northward swing of not alone their northern 

 limits, but also of their southern limits, which in turn is comparable 

 to the northward advance of the Jackson flora that I have considered 



