i833-] PROPORTIONATE VEGETATION. 97 



statements which have been given, the extremely desert 

 character of that region will not be disputed. In the 

 European division of the world, we must look back to 

 the tertiary epochs, to find a condition of things among 

 the mammalia, resembling 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 

 accumulated 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 preserved. 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 >forthern 

 Europe and Asia, have lived on the spots where their 

 remams are now found. I do not here speak of the hind 

 of vegetation necessary for their support ; because, las 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 



* 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 tha 

 coast. ' 



t See Humboldt, " Fragmens Asiatjques," p. 386; Barton's "Geography of 

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

 15 the growth of trees in Siberia may be drawn under the parallel of 70*. 



