18 



ON THE DISTRIBUTION OF ANIMALS, 



By JAMES EANKIN, Esq., M.A., President. 



The subject of this paper, though one of very great and general interest, has 

 been selected chiefly with a view to elucidate and try how that great question 

 of the Origin of Species may be affected by the facts learnt from a study of 

 the Distribution of the living and also of the extinct species of animals. 



It will hardly be necessary to state that in a short paper like the present 

 it will be impossible to do more than give a rcsumi of some of the leading facts in 

 the distribution of animals, and I therefore have considered that the subject will 

 be best treated by endeavouring to answer two or three great questions bearing, 

 as will be perceived, on the subject of the Origin of Species. 



The first question I propose to consider is, " Whether the facts of the 

 Distribution of animals lead us to believe in the creation of species or groups 

 of animals in centres and subsequent migration therefrom ; or do they lead us to 

 believe in spoi-adic creations, that is, in the same species being created in 

 various parts of the world ?" 



The first thing which will strike any one studying the facts of Distribution 

 is, I think, that the Fauna of each country is more or less peculiar ; and more 

 than this, that the more separated are the countries by natural barriers the more 

 different are their animal productions. 



We also find that wide areas if unbroken by any serious obstacle to migration 

 have many species in common, whereas islands and isolated regions on the main 

 land have a very limited and also usually a very peculiar fauna. To establish the 

 above propositions I need only point to the tropical regions of South America, 

 Africa, and Australia — countries most widely separated by the most impassable 

 of all barriers to land animals, namely, the sea. On these three areas there is 

 not one species of mammal in common, not one species of bird in common. 

 Amongst reptiles also the difference is remarkable : thus the cayman is peculiar 

 to the new world, the crocodile to Africa, and the gavial to India and Australia ; 

 the boa belongs to America and the python to India, the rattlesnake to America 

 and the cerastis to Africa, and the cobra di cajjello to Asia. Amongst fishes, 

 molluscs, and other classes, we find the same rule of limited Distribution hold 

 good, though perhaps in a less degree. Again, looking at islands, we find several 

 remarkable instances of peculiarity of fauna. 



Thus the island of Madagascar alone presents us with the genus lemur, and 

 has, I believe, no species of mammal but the centetes, which is not peculiar to it. 



