CHAPTER XXVI 



ISLAND COMMUNITIES 



The geographic animal formations of the larger land masses, to- 

 gether with some of their interrelations and an indication of typical 

 mammals, may be summarized as follows: 



Tropical forest (Monkeys) 



Deciduous 



Temperate evergreen forest 

 Transition) 



Tropical savanna 

 (Antelopes) 



Temperate deciduous 

 forest (Gray fox) 



Northern conifers 

 (Fur bearers) 



Temperate parkland 

 (Rodents) 



Scrub 



(Transition) 



Temperate steppe 



(Bison) 



Regions of winter rain 

 (Transition) 



Tundra- 



Mountains 

 (Goats and Sheep) 



Desert 

 (Gazelles and Camels) 



(Reindeer) 



All these have been discussed more or less, although the transition 

 areas have received only incidental attention in chapters devoted to 

 related formations. The communities found on islands do not fit natu- 

 rally into this ecological classification. They are influenced, more than 

 any of the above, by local conditions. Island life particularly depends 

 on distance from the nearest continental land mass and on the length 

 of time since connections existed, if ever, as well as on such ecological 

 factors as climate and soil and the resulting types of vegetation. 



Such special environmental conditions are not at all equally devel- 

 oped on all islands or archipelagoes, which may in fact be arranged 



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