GO ESSAY ON CLASSIFICATION. 



rivers, or by differences of level above the sea, etc. Tlie 

 details of the geographical distribution of animals exhibit, 

 indeed, too much discrimination to admit for a moment 

 that it could be the result of accident ; that is, the result 

 of the accidental migrations of the animals, or of the acci- 

 dental dispersion of the seeds of plants. The greater the 

 uniformity of structure of these widely distributed organ- 

 ized beings, the less probable does their accidental distri- 

 bution appear. I confess that nothing has ever surprised 

 me so much as to see the perfect identity of the most 

 delicate microscopic structures of animals and plants 

 from the remotest parts of the world. It was this striking 

 identity of structure in the same types, this total inde- 

 pendence of the essential characteristics of animals and 

 plants of their distribution under the most extreme 

 climatic differences known upon our globe, which led me 

 to distrust the belief, then almost universal, that organized 

 beings are influenced by physical causes to a degree which 

 essentially modifies their character. 



SECTION XI. 



COMMUNITY OF STRUCTURE AMONG ANIMALS LIVING IN THE 



SAME REGIONS. 



The most interesting result of the earliest investigations 

 of the fauna of Australia was the discovery of a type of 

 animals, the Marsupialia, prevailing upon this continental 

 island, which are unknown in almost every other part of 

 the world. Every student of Natural History now knows 

 that there are no Quadrumana in New Holland, neither 

 Monkis nor Makis: no Insectivora, neither Shrews nor 

 Moles, nor Hedgehogs ; no true Carnivora, 1 neither Bears, 

 nor Weasels, nor Foxes, nor Viverras, nor Hyoenas, nor 



1 Doubts are entertained respecting the origin of the Dingo, the only 

 beast of prey of New Holland. 



