and Salix retusa and S. reticulata are not uncommon there, while the Betula nana prefers the peat moors. These plants evidently have descended from those which flourished at a time when the glaciers were retreating, and had formed tarns and small lakes like those of St. Gotthard. Like these the tarns were surrounded by an Alpine flora, the remains of which fell into the mud, and have been preserved to our own days. . . . In the 'Urwelt der Schweiz,' p. 534, &c., I have endeavoured to show that at the Glacial age the Alpine flora very probably occupied the plain land of Switzerland, so far as it was free from glaciers, and that the Alpine plants which we now see insulated on the mountain chains of Northern Switzerland may be the last remains of this ancient flora—the lost children of the Alps surrounded entirely by the inhabitants of the plain. This has now been confirmed by fresh discoveries, and doubtless further investigation will bring to light new facts, which will reveal to us clearly the plants and fauna of the Glacial age. But they hare also in a most surprising manner confirmed another supposition, namely, that which considers our Alpine flora to have had its origin in the far north. Not only all the species which have as yet been found in the glacier mud have their home in the north, but amongst them is found the polar willow, which at the present day is only found in the Arctic zone (in North Lapland and Spitzbergen), but it is entirely wanting in the Alps. So that this species has come from the north into our districts, but here became extinct; while its companions have survived on the Alps up to the present day, and now are separated from their fellow species in the far north by a great extent of country.'
The young Swedish geologist above referred to, Mr. Nathorst afterwards visited Devonshire, in order to examine the Bovey deposits. He was delighted to find the Betula nana in the upper or white beds there. He is, I believe, the son of a Swedish professor, and is a very energetic naturalist; he mentioned that on his Spitzbergen expedition he had been three months without once having on dry clothes, and this had brought on total deafness. In this state he undertook and accomplished the journey to Switzerland and England to investigate these glacial plants.
More information as to the Bovey formations can be obtained in a paper on the lignite formation of Bovey by W. Pengelly, F.R.S., F.G.S., &c, and Professor Heer, printed in the 'Philosophical Transactions for 1863,' to which the reader is referred. At p. 26 (in the separate copies) will be found a note on the plants of the white clay or top beds, and these particulars are repeated, but somewhat more fully, in a note by Professor Heer in his Life of Escher, p. 279. He says, 'The white clay covering the lignite is of a totally different age from it. When the white clay was deposited Betula nana and some species of willow were living there, and their leaves have been preserved in this deposit. But Betula nana at the present day is not to be found in England, though it occurs on the Scotch mountains, and is very common in the Arctic zone. At the age of the glaciers it was also living in the south of Sweden, in Denmark, and on the plain-land of Switzerland, where its remains have been found together with those of other Arctic plants in the deposits of this period. So that there can be no doubt that at that time Devonshire had a colder
