Land Elevations 47 



hot ashes to depths of thirty to sixty meters and that no plants or 

 animals could have survived. 



Oceanic islands have apparently not played an important role in 

 the evolution of land animals from the ocean, but have often 

 furnished habitats which were taken advantage of by animals which 

 could in some way reach them. 



Land Elevation 



Land elevation and the resulting better aeration of ground water 

 may permit littoral animals to migrate inland through the soil 

 (Harms, 1932) . To the writer's knowledge no accurate observa- 

 tions have been made as to what the actual effects of such elevations 

 are. During the great earthquake in Japan in 1923 the shore line 

 at the Biological Station at Misaki rose four feet. Dr. N. Yatsu, 

 the director of the station, states that most of the marine animals 

 which were elevated above their optimum zone soon died and that 

 there was a great decrease in the numbers of littoral animals for 

 several years. A very gradual elevation of a beach might be con- 

 ducive to the assumption of land life by certain littoral animals. 

 The answer to the question waits for evidence. 



