FOREST GEOGRAPHY AND ARCHAEOLOGY. 221 



continent specifically unchanged, though hardly developed as 

 forest trees on the Pacific side. There are probably, but not 

 certainly, one or two instances on the northern verge of these 

 two forests. There are as many in which eastern and west- 

 ern species are suggestively similar. The Hemlock Spruce of 

 the northern Atlantic States and the Yew of Florida are ex- 

 tremely like corresponding trees of the Pacific forest ; indeed 

 the Yew-trees of all four regions may come to be regarded as 

 forms of one polymorphous species. The White Birch of 

 Europe and that of Canada and New England are in similar 

 case ; and so is the common Chestnut (in America confined 

 to the Atlantic States), which on the other side of the world 

 is also represented in Japan. A link in the other direction is 

 seen in one Spruce-tree (called in Oregon Menzies Spruce) 

 which inhabits northeast Asia, while a peculiar form of it 

 represents the species in the Rocky Mountains. 



But now other and more theoretical questions come to be 

 asked, such as these : — 



Why should our Pacific forest-region, which is rich and in 

 some respects unique in coniferous, be so poor in deciduous 

 trees ? 



Then the two Big Trees, Sequoias, as isolated in character 

 as in location, — being found only in California, and having 

 no near relatives anywhere, — how came California to have 

 them? 



Such relatives as the Sequoias have are also local, peculiar, 

 and chiefly of one species to each genus. Only one of them 

 is American, and that solely eastern, the Taxodium of our 

 Atlantic States and the plateau of Mexico. The others are 

 Japanese and Chinese. 



Why should trees of six related genera, which will all thrive 

 in Europe, be restricted naturally, one to the eastern side of 

 the American continent, one genus to the western side and 

 very locally, the rest to a small portion of the eastern border 

 of Asia? 



Why should coniferous trees most affect and preserve the 

 greatest number of types in these parts of the world ? 



And why should the northeast Asian region have, in a 



