Cenozoic Floras Around the Northern Pacific 73 



those of the Miocene are in large part restricted to temperate 

 areas. Where the same famiHes fall in both lists, as do the 

 Liliaceae, Juglandaceae, Fagaceae, Lauraceae, Leguminoseae, and 

 Anacardiaceae, they are for the most part represented in the two 

 floras by different genera, which are tropical in the Eocene and 

 temperate in the Miocene. In the lists as here composed, the only 

 genera common to both are Liqtddambar, Platanus, Qiiercus, 

 Stnilax, and Viburnum, all of which are ancient genera of wide 

 distribution since the Cretaceous, ranging at the present time 

 from temperate lowlands to middle altitudes in the tropics. It 

 must be admitted that if all the genera reported from the Mio- 

 cene, especially by the older authors, were included in the list 

 (pp. 68-69), ^^^ resemblance between this list and the Eocene 

 flora would be more marked. Such genera as Anona, Aralia, 

 Cinnamomum, Diospyros, Ficus, Persea, and Sterculia have 

 been regularly recognized in Miocene floras, but usually on evi- 

 dence which is not accepted by the writer. While it is possible 

 that an occasional representative of a tropical genus may have 

 survived as a relict in the Miocene floras of western America, this 

 in no way affects the general conclusion that the members of 

 the older Tertiary forests had in large measure disappeared from 

 the middle latitudes before the beginning of the Miocene. With 

 altered climatic conditions, the northern limits of the ranges of 

 the typical Eocene species shifted southward, and the temperate 

 types of higher altitudes and latitudes moved down to take their 

 places as the forest dominants of Oregon and California. Many 

 of these* have continued to live in western America down to the 

 present time, but subsequent changes in topography and climate 

 have restricted their distribution to the most favored situations. 



* To almost every Tertiary species, a name different from that of its modern 

 equivalent has been applied, but the actual differences as based on leaf characters 

 may not always warrant these specific designations. 



