64 BAH1A BLANCA. [CHAP. T, 



that now existing at the Cape of Good Hope. Those tertiary epochs, 

 which we are apt to consider as abounding to an astonishing degree 

 with large animals, because we find the remains of many ages accumu- 

 lated at certain spots, could hardly boast of more large quadrupeds 

 than Southern Africa does at present. If we speculate on the condition 

 of the vegetation during those epochs, we are at least bound so far to 

 consider existing analogies, as not to urge as absolutely necessary a 

 luxuriant vegetation, when we see a state of things so totally different 

 at the Cape of Good Hope. 



We know * that the extreme regions of North America, many degrees 

 beyond the limit where the ground at the depth of a few feet remains 

 perpetually congealed, are covered by forests of large and tall trees. 

 In a like manner, in Siberia, we have woods of birch, fir, aspen, and 

 larch, growing in a latitude t (64), where the mean temperature of the 

 air falls below the freezing point, and where the earth is so completely 

 frozen, that the carcass of an animal embedded in it is perfectly pre- 

 served. With these facts we must grant, as far as quantity alone of 

 vegetation is concerned, that the great quadrupeds of the later tertiary 

 epochs might, in most parts of Northern Europe and Asia, have lived 

 on the spots where their remains are now found. I do not here speak 

 of the kind of vegetation necessary for their support ; because, as there 

 is evidence of physical changes, and as the animals have become 

 extinct, so may we suppose that the species of plants have likewise 

 been changed. 



These remarks, I may be permitted to add, directly bear on the case 

 of the Siberian animals preserved in ice. The firm conviction of the 

 necessity of a vegetation possessing a character of tropical luxuriance, 

 to support such large animals, and the impossibility of reconciling this 

 with the proximity of perpetual congelation, was one chief cause of the 

 several theories of sudden revolutions of climate, and of overwhelming 

 catastrophes, which were invented to account for their entombment. I 

 am far from supposing that the climate has not changed since the 

 period when those animals lived, which now lie buried in the ice. At 

 present I only wish to show, that as far as quantity of food alone is 

 concerned, the ancient rhinoceroses might have roamed over the steppes 

 of central Siberia (the northern parts probably being under water) een 

 in their present condition, as well as the living rhinoceroses and 

 elephants over the Karros of Southern Africa. 



I will now give an account of the habits of some of the more interest- 



* See Zoological Remarks to Capt. Back's Expedition, by Dr. Richardson. 

 He says, "The subsoil north of latitude 56 is perpetually frozen, the thaw 

 on the coast not penetrating above three feet, and at Bear Lake, in latitude 

 64, not more than twenty inches. The frozen substratum does not of itself 

 destroy vegetation, for forests flourish on the surface, at a distance from the 

 coast." 



f See Humboldt, " Fragmens Asiatiques," p. 386; Barton's " Geography of 

 Plants ; " and Malte Brun. In the latter work it is said that the limit of thp 

 growth of trees in Siberia may be drawn under the parallel of 70, 



