VOL. XLVIII, NO. 567 



MARCH, 1914 



THE 



AMERICAN 

 NATURALIST 



A MONTHLY JOURNAL 

 Devoted to the Advancement of the Biological Sciences with 

 Special Reference to the Factors of Evolution 



CONTENTS 



I- The Effect of Extent of Distribution on Speciation. Asa C. Chanbleb - 129 



II. Biology of the Thysanoptera. Dr. A. Franklin Shfll - - - - l«l 

 BL Shorter Articles and Correspondence : The Endemic Mammals of the British 



[ V. Notei and Literature: Swingle on Variation in Fi Citrus Hybrids and the 



THE SCIENCE PRESS 

 J*ANGASTER, PA. GARRISON, R. T. 



NEW YORK : SUB-STATION 84 



