250 UECAFITULATION. [chap. xi. 



imagined difficulty of supplying them with food from the adjoin- 

 ing countries, the whole case is not, I thinlc, 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 ;t 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 tht^ 



* Messrs. Dease and Simpson, in Geograph. Journ., vol. viii. pp. 218 

 ind 220. 



f Cuvier (Ossemens Fossiles, torn. i. p. 151), from Billing's Voyage. 



