VOL. XLVII, NO. 555 



MARCH, 1913 



THE 



AMERICAN 

 NATURALIST 



A MONTHLY JOURNAL 

 Devoted to the Advancement of the Biological Science! with 

 Special Reference to the Factors of Evolntion 



CONTENTS 



Castration in Relation to the Secondary Sexual Characters of Brown Leg- 



Simplification of Mendelian Formula. Professor W. E. Castle 

 Notes and Literature : Some Recent Advances in Vertebrate Paleontology. Pro- 

 fessor Roy L. Moodie 



THE SCIENCE PRESS 

 LANCASTER, PA. GARRISON, H. Y. 



HEW YORK : SUB-STATION 84 



