VOL. XL VII, NO. 557 



MAY, 1913 



THE 



AMERICAN 

 NATURALIST 



A MONTHLY JOURNAL 

 Devoted to the Advancement of the Biological Sciencei with 

 Special Reference to the Factors of Evolution 



THE SCIENCE PRESS 

 LANCASTER, PA. GARRISON, IT. T. 



NEW YORE : SUB-STATION 84 



