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ANNALS NEW YORK ACADEMY OF SCIENCES 



Chaniberlin's text book of geology may be consulted, (or tlie more exact 

 and extended exposition of these theories. The present purpose is to in- 

 dicate their applicntion to the pvolution of Innd vertebrates. 



PERMANENCY OF THE OCEAN BASINS 



In the first place, we may note tliat tliey depend as a fundamental 

 basis on the general permanency of the great ocean basins. The conti- 



FiG. 1. — Zoological regions on north polar projection 



The areas within the continental shelf (100-fathom line) are left unshaded. This map 

 represents the true relations of land and water in the northern heinispliere far more 

 correctly than does the usual Mercator projection. The unity of Arctogiva and tlio direct 

 relation is obvious between the various degrees of isolation of the southern continents 

 and of peculiarity of their fauna>. 



nents have been alternately partly overflowed, separated and insular, or 

 raised to their greatest extent and united largely into a single mass. The 

 great ocean basins have in the main been perm;inout. Tliis principle is 



