A. Gray—Forest Geography and Archeology. 187 
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 western species are suggestively similar. 
e 
hy 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 any where,—how came California to have them ? 
uch 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 Atlan- 
tic 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 o 
the American continent, one genus to the western side and very 
locally, the rest to a small portion of the eastern border of Asia? 
hy 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 com- 
paratively small area, not only most coniferous trees, but a 
notably larger number of trees altogether than any other part 
of the northern temperate zone? Why should its only and 
near rival be in the antipodes, namely, here in Atlantic North 
America? In other words why should the Pacific and the 
European forests be so poor in comparison, and why the Pacific 
poorest of all in deciduous, yet rich in coniferous trees? 
_ The first step toward an explanation of the superior richness 
in trees of these antipodal regions, is to note some striking sim- 
ilarities of the two, and especially the number of peculiar types 
which they divide between them. The ultimate conclusion 
may at length be ventured, that this richness is normal, and 
that what we really have to explain is the absence of so many 
