PALEOBOTANICAL EVIDENCE 527 



We may now attempt an interpretation of probable temperature con- 

 ditions during Upper Cretaceous time. To begin with Greenland, it 

 of course needs no argument to prove that the climatic conditions there 

 were very different from those obtaining during and since Pleistocene 

 time. The following Atane genera are given with their present-day 

 distribution and climatic requirements: Artocarpus (bread-fruit tree) 

 now confined to the Old World and within 20° of the Equator. Ficu?, 

 a vast tropical genus with a few species ranging into warm temperate 

 regions. Cinnamomum and Laurus, small genera in the cool parts oi 

 the tropics. Pseudocycas, one species of which at least is closely related 

 to the tropical Cycas revoluta. Aralia has about 27 living species in the 

 temperate and warm parts of America and Asia. Panax, a small genus 

 of eastern North America and central and eastern Asia. Pistia, a mono- 

 typic genus very widely distributed in the tropics and subtropics of both 

 hemispheres. Cyathea (tree-ferns) embraces 100 species widely dis- 

 seminated in the tropical and subtropical countries, extending in New 

 Zealand 40° S., but not occurring above the northern tropics. Gleiche- 

 nia, represented in the Atane flora by six species and a profusion of 

 individuals, is confined as now restricted by pteridologists to the tropics 

 and subtropics of the Old World. Widdringtonites, so named from its 

 resemblance to Widdringtonia, a genus of four species now living h\ 

 South Africa and Madagascar. 



There are other genera in the Atane flora whose living representatives 

 have a more or less extensive representation in temperate regions, some 

 of which also have representatives in warm temperate and even in sub- 

 tropical regions. These are Acer, Asplenium, Cassia, Cissites, Diospyros, 

 Hedera, Ilex, Magnolia, Myrsine, Palaurus, Pinus, Pteris, QuercuF, 

 Sapindus, Selaginella, etcetera. 



From the above presentation of facts it seems safe to conclude that the 

 climate of Greenland during Atane time could not have been cooler 

 than warm temperate, and when we consider the presence of bread-fruit 

 trees, figs, cinnamon trees, tree-ferns, etcetera, it might well have been 

 at least subtropical. Heer concluded the Atane flora probably flourished 

 in a climate with a mean annual temperature of 19-20° C. Some 

 students have placed the temperature higher than this, and others ha^'e 

 placed it lower. 



It will be impossible,, indeed perhaps unnecessary, in the space avail- 

 able to make as complete an analysis of the other Upper Cretaceous 

 floras, but a few notable conditions may be pointed out. There i- 

 nothing, so far as I can interpret it, in the floras of eastern Nortl' 



