FUNDAMENTAL RELATIONS OF ANIMALS 39 



mals and plants which may resemble each other closely, without pay- 

 ing the least regard to their distinct origin, and without even point- 

 ing out the differences they may perceive between specimens from 

 different parts of the world. The perfect identity of animals and plants 

 living in very remote parts of the globe has so often been ascertained, 

 and it is also so well known how closely species may be allied and yet 

 differ in all the essential relations which characterize species, that 

 such loose investigations are no longer justifiable. 



This close resemblance of animals and plants in distant parts of 

 the world is the most interesting subject of investigation with refer- 

 ence to the question of the unity of origin of animals and to that 

 of the influence of physical agents upon organized beings in general. 

 It appears to me, that, as facts now point distinctly to an inde- 

 pendent origin of individuals of the same species in remote regions, 

 or of closely allied species representing one another in distant parts 

 of the world, one of the strongest arguments in favor of the supposi- 

 tion, that physical agents may have had a controlling influence in 

 changing the character of the organic world, is gone for ever. 



The narrowest limits within which certain Vertebrata may be 

 circumscribed is exemplified among Mammalia by some large and 

 remarkable species: the Orang-Outangs upon the Sunda Islands, the 

 Chimpanzee and the Gorilla along the western coast of Africa, several 

 distinct species of Rhinoceros about the Cape of Good Hope, and 

 in Java and Sumatra, the Pinchaque and the common Tapir in South 

 America, and the eastern Tapir in Sumatra, the East Indian and the 

 African Elephant, the Bactrian Camel and the Dromedary, the 

 Llamas, and the different kinds of wild Bulls, wild Goats, and wild 

 sheep, etc.; among birds by the African Ostrich, the two American 

 Rheas, the Emeu {Dromceus) of New Holland, and the Casuary 

 (Casiiarius galeatus) of the Indian Archipelago, and still more by the 

 different species of doves confined to particular islands in the Pacific 

 Ocean; among Reptiles, by the Proteus of the cave of Adelsberg in 

 Carinthia, by the Gopher {Testudo Polyphemus Auct.) of our South- 

 ern States; among fishes, by the Blind Fish (Amblyopsis spelcEUs) of 

 the Mammoth Cave. Examples of closely limited Articulata may not 

 be so striking, yet the Blind Crawfish of the Mammoth Cave and 

 the many parasites found only upon or within certain species of 

 animals are very remarkable in this respect. Among Mollusks I 



