1908.] 



NATURAL SCIENCES OF PHILADELPHIA. 



143 



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__ Rdtn 



were followed by migrating movements on March 5, 8, 13, 20 and 27. 

 In April the principal movements on the 10th and 25th corresponded 

 to marked increases in temperature, while the great May waves 

 occurred on the 1st and 6th. 



with the proportions of the wave of April 30, which followed the last 

 spell of rainy weather and was the most extensive April movement that 

 our records show\ The ]May waves occurred on the 3d and 7th. 



The correspondence in the migration curves for 1904 and 1905 is 

 remarkable, the movements being about the same in number and 

 extent and nearly the same in time of occurrence. 



