254 



ANTIQUITY OF EXISTING CONTINENTS. 



[Ch. XII 



above water, that each, of them is now tenanted by a distinct 

 set of animals and plants. More than this : we find, when we 

 examine the fossil remains of land quadrupeds of Pliocene 

 date proper to each continent, that although they may be of 

 extinct species, they are allied in structure to the living 

 mammalia of the same region. Extinct species of kangaroo 

 for example, and of other marsupials, preceded the livin 

 marsupials on the Australian continent. In like manner 

 species of elephant and rhinoceros, and of catarrhine mon- 

 keys, of forms no longer in existence, inhabited India in 

 Miocene and Pliocene times, before the living representatives 



of the same genera and families were in being ; while, in 



World 



armadillos, and other South American forms belonging to an 

 extinct fauna, flourished in times immediately antecedent to 



same 



mar 



the opposite sides of several continents attests the perma- 

 nence of the great barriers of land, which have, from a 



ration of fish, mollusca, and 

 other aquatic tribes from one sea to the other. But the 

 distinctness of these marine provinces does not go back to 



Miocene 



Mioce 



mollusca and corals of the Atlantic and Pacific Oceans did 

 not then belong to distinct species as they do now. There 

 must have been up to that time a communication through 

 the isthmus of Panama, as is nrovad by the study of the 



marine shells of the West 



If we 



go back still further — to the terrestrial plants and animals 



mixture 



having their nearest living allies in the most distant parts of 

 the globe, that we cannot doubt that the distribution of land 

 and sea bore scarcely any resemblance to that now established. 



5 



permanent 



eolo- 



gical epochs, shift their positions entirely in the course of ages. 



* See Papers by John Carrick Moore, Esq. and Dr. Duncan, referred to in 

 ' Elements of Geology/ 6th edition, 1865, p. 271. 





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