THE FLORA OF JAPAN. 137 



On our northwestern coast, in the miocene of Vancouver's 

 Island, among a singular mixture of species referable to Sa- 

 lix, Populus, Quercus, Planera, Diospyros, Salisburia, Mens, 

 Cinnamomum, Personia, or other Proteacea\ ami a Palm 

 (the latter genera decisively indicating a tropical or sub- 

 tropical climate), Mr. Lesquereux has identified one existing 

 species, a tree characteristic of the same region ten or fifteen 

 degrees farther south, namely, the Redwood or Sequoia sem- 

 pervirens. In beds at Somerville referred to the lower or 

 middle pliocene by Mr. Lesquereux, this botanist has recently 

 identified the leaves of Persea Carolinennls, Prunus Carol 7- 

 niana, and Quercus myrtifolia, now inhabiting the warm sea- 

 coast and islands of the southern States. 1 



The pliocene quadrupeds of Nebraska also show that the 

 climate east of the Rocky Mountains at this epoch was much 

 warmer than now. About the upper Missouri and Platte 

 there were then several species of Camel (Procamelus) and 

 allied Ruminantia and a Rhinoceros, besides a Mastodon, 

 an Elephant, some Horses and their allies, not to mention a 

 corresponding number of carnivorous animals. These herbi- 

 vora probably fed in a good degree upon herbage and grasses 

 of still existing species. For herbs and grasses are generally 

 capable of enduring much greater climatic changes, and are 

 therefore likely to be even more ancient, than trees. These 

 animals must have had at least a warm-temperate climate to 

 live in : so that in latitude 40°- 43° they could not have been 

 anywhere near the northern limit of the temperate flora of 

 those days ; indeed the temperate flora, which now in western 

 Europe touches the Arctic Circle, must then have reached 

 equally high latitudes in central or western North America. 

 In other words, the temperate floras of America and Asia 

 must then have been conterminous (with small oceanic sepa- 

 ration), and therefore have commingled, as conterminous 

 floras of similar climate everywhere do. 



At length, as the post-tertiary opened, the glacier epoch 



i These and other data, obligingly communicated by Mr. Lesquenux 

 have been published in the May number of the '< American Journal of 

 Science and Arts," 3 ser., xvii. 



