| → permitted their former 1859 1860 1861 |
| formerly permitted their 1866 1869 1872 |
|
| → chiefly from the distribution of the fossil Gnathodon), 1859 1860 |
| OMIT 1861 |
|
| → during their long southern migration and re-migration northward, will 1859 1860 1861 |
| moved first southward and afterwards backwards to the north, in unison with the changing climate, they will not 1866 1869 1872 |
|
| → to nearly the same climate, 1859 1860 1861 |
| during their long migrations to any great diversity of temperature, 1866 |
| during their long migrations to any great diversity of temperature; 1869 1872 |
|
| → is especially to be noticed, they will have kept 1859 1860 1861 |
| they will all have migrated 1866 |
| they all migrated 1869 1872 |
|
|
have been due south and north. The Alpine plants, for example, of Scotland, as remarked by Mr. H. C. Watson, and those of the Pyrenees, as remarked by Ramond, are more especially allied to the plants of northern Scandinavia; those of the United States to Labrador; those of the mountains of Siberia to the arctic regions of that country. These views, grounded as they are on the perfectly well-ascertained occurrence of a former Glacial period, seem to me to explain in so satisfactory a manner the present distribution of the Alpine and Arctic productions of Europe and America, that when in other regions we find the same species on distant mountain-summits, we may almost
without other evidence, that a colder climate
→permitted their former
migration across the
intervening
become too warm for their existence. |
|
| If the climate, since the Glacial period, has ever been in any degree warmer than at present (as some geologists in the United States believe to have been the
→chiefly from the distribution of the fossil Gnathodon),
then the arctic and temperate productions will at a very late period have marched a little
north, and subsequently have retreated to their present homes; but I have met with no satisfactory evidence with respect to this intercalated slightly warmer period, since the Glacial period. |
|
|
arctic
→during their long southern migration and re-migration northward, will
have been exposed
→to nearly the same climate,
as
→is especially to be noticed, they will have kept
in a body
their mutual relations will not have been much
in accordance with the principles inculcated in this volume,
will not have been liable to much modification. But with
Alpine productions, left isolated from the moment of the returning warmth,
|
