478 



DE. MAXWELL T. MaSTEBS OX 



Japan*, Dr. Gray calls special attention to the analogies between 

 the floras of the Eastern United States and that of Japan. From 

 his address to the American Association the following list of 

 Conifers is taken, from among the numerous other plants, showing 

 the analogy of the American and Japanese floras : — 



Atlantic. 



Pacific. 



Japan and N.E. Asia. 



PlNUS. 







resinosa. 





densiflora. 



Strobus. 



monticola. 



excelsa. 



Tsuga. 







canadensis. 



Mertensiana. 



Sieboldii and diversifolia. 



Thuya. 







occidentalis. 



gigantea &c. 



japonica. 



Taxodium. 







distichum. 





heterophyllum. 



Cupkessus (Chamaecyparis). 





thuyoides. 



nutkaensis. 



pisifera and obtusa. 



Taxus. 







canadensis. 



brevifolia. 



cuspidata. 



Torreya. 







taxifolia. 



californica. 



nucifera and grandis. 



Dr. Gray concludes (and he is supported by Oliver and others) 

 that a very peculiar analogy exists between the floras of Tertiary 

 Central Europe and the recent floras of the Eastern American 

 States and Japan. It is supposed that, at some period of the 

 Tertiary epoch, N.E. Asia was united to the north-western part 

 of America, probably along the line now occupied by the Aleutian 

 Islands. Assuming the former existence of land-communication 

 between the three continents in the extreme north, the prevalence 

 of a relatively warm climate, as indicated by the fossil plants 

 found in arctic regions, then it is supposed that on the access of 

 the Glacial Period, plants were driven southwards in various 

 directions, according to local circumstances not as yet fully 

 determined. In this way it is suggested that some plants found 

 a refuge in Asia, some in Eastern, and some in Western Americaf. 

 The presence of northern types in Japan may be accounted for 

 on such a supposition. But, in addition, there is a large propor- 

 tion of species which appear to be endemic in Japan, and of which 

 we have no traces northwards. These are so numerous in the case 



* A ' <fray, Botany of Japan, U.S. Exploring Expedition, p. 433 (1858); 

 also Address to the American Association for the Advancement of Science, 

 Dubuque (1872) Hooker, Flora of N.E. Asm andN.E. America. Gardeners' 

 Chronicle, Aug. 17, 1878, p. 216. 



t Murray, ' Geographical Distribution of Mammals ' (1866), p. 47. 



