250 RECAPITULATION. [cHap. x1. 
imagined difficulty of supplying them with food from the adjoin- 
ing countries, the whole case is not, I think, so perplexing as it 
has generally been considered. The plains of Siberia, like those 
of the Pampas, appear to have been formed under the sea, into 
which rivers brought down the bodies of many animals; of the 
‘greater number of these, only the skeletons have been preserved, 
but of others the perfect carcass. Now it is known, that in the 
shallow sea on the arctic coast of America the bottom freezes,* 
and does not thaw in spring so soon as the surface of the land; 
moreover at greater depths, where the bottom of the sea does not 
freeze, the mud a few feet beneath the top layer might remain even 
in summer below 32°, as is the case on the land with the soil at 
the depth of a few feet. At still greater depths, the temperature of 
the mud and water would probably not be low enough to pre- 
serve the flesh ; and hence, carcasses drifted beyond the shallow 
parts near an arctic coast, would have only their skeletons pre- 
served : now in the extreme northern parts of Siberia bones are 
infinitely numerous, so that even islets are said to be almost 
composed of them ;} and those islets lie no less than ten degrees 
of latitude north of the place where Pallas found the frozen 
rhinoceros. On the other hand, a carcass washed by a flood into 
a shallow part of the Arctic Sea, would be preserved for an inde- 
finite period, if it were soon afterwards covered with mud, suffi- 
ciently thick to prevent the heat of the summer-water penetrat- 
ing to it; and if, when the sea-bottom was upraised into land, 
the covering was sufficiently thick to prevent the heat of the 
summer air and sun thawing and corrupting it. 
Recapitulation.—I will recapitulate the principal facts with 
regard to the climate, ice-action, and organic productions of the 
southern hemisphere, transposing the places in imagination to 
Europe, with which we are so much better acquainted. Then, 
near Lisbon, the commonest sea-shells, namely, three species of 
Oliva, a Voluta and Terebra, would have a tropical character. In 
the southern provinces of France, magnificent forests, intwined 
by arborescent grasses and with the trees loaded with parasitical 
plants, would hide the face of the land. The puma and the 
* Messrs. Dease and Simpson, in Geograph. Journ., vol. viii. pp. 218. 
and 220. : 
+ Cuvier (Ossemens Fossiles, tom. i. p. 151), from Billing’s Voyage. 
