428 Wortman — Studies of Eocene Mammalia in the 



the latitude of Glendive [Montana] warm enough and moist 

 enough to permit these chiefly tropical plants to thrive." 

 Again, in speaking of the genus Cinnamomum, he says : "An 

 almost exclusively tropical genus embracing about fifty species, 

 confined to the Old 'World, but ranging on both sides of the 

 equator. Fossil representatives are abundant in the Tertiaries 

 of Europe, especially in the Eocene, but forms are reported as 

 low as the Cenomanian. The four species of the Laramie thus 

 far described argue a warm climate."- And again, he says of 

 ZizypJnis, a genus related to the Buckthorn: "A widely dis- 

 tributed tropical and subtropical genus containing in the 

 present flora about fifty species. It has been hitherto repre- 

 sented by eight Eocene, one Green River and five Laramie 

 species, none of the last being from the Fort Union strata." 

 He describes three species from the Upper Cretaceous of Mon- 

 tana. In like manner he mentions a number of other types of 

 a tropical or subtropical habit from the Laramie, or Upper 

 Cretaceous beds. Lastly, I may mention the presence of Palms 

 of the genus Sabal, recently described by Hatcher as an abso- 

 lutely conclusive piece of evidence in favor of a Floridian 

 climate during this epoch, as far north as Wyoming and 

 Montana. 



In the Tertiary, a subtropical climate continued in America 

 as far north as central Wyoming, to near the close of the 

 Eocene. This is proved by abundant remains of Palms in the 

 Green Piver shale beds, and by the presence of numerous 

 tropical species of Vertebrates and Invertebrates in the Bridger 

 beds. Before the close of the Eocene, however, the tempera- 

 ture in this latitude underwent a change,, and by the time the 

 Oligocene is reached a strictly temperate climate had appeared. 

 In Europe, similar changes in the climatic conditions through- 

 out the Tertiary, from an almost, if not quite, tropical temper- 

 ature through all the intermediate stages to that of a frigid 

 temperature in Glacial time, are to be met with. 



Viewed from the standpoint of the fossil plants, therefore, 

 the contention that the Northern Hemisphere has passed 

 through all these phases of climate from torrid to frigid, from 

 early in the Mesozoic to the present, is simply incontestable. 

 The evidence is equally conclusive that the cooling-off process 

 was inaugurated at the Pole and gradually extended to the 

 southward. The assumption, moreover, that the higher 

 Angiosperms originated and were evolved in the more southern 

 latitudes, where they so suddenly appear, is illogical and unten- 

 able, not only by reason of the virtual absence of any ancestral 

 forms foreshadowing or leading up to them in the florae of the 

 older epochs, but by the sudden appearance of the same or closely 

 allied types in identically the same manner and, as far as we 



