CONTENTS. 



PAGE. 



Table op Contents iii 



List of Officers v 



List of Members. Kevised to December 31, 1911 vi 



1. Patrons. 



2. Honorary Members. 



3. Active Members. 



Abstract of History xix 



Record. January 1, to December 31, 1911 xxiii 



Papers Published. January 1, to December 31, 1911 : 



1. Francis E. Nipher. — Nature of the Electric 



Discharge. — Plates I-VI. — Issued February 



8, 1911 1 



2. Charles Henry Thompson. — Four New Plants 



from Mexico. — Plates VII-XII. — Issued 

 April 21, 1911 17 



3. J. Andrew Drushel. — Studies in Glacial 



Geology in Saint Louis and Vicinity. — 

 Plates XIII-XVIL— Issued April 22, 1911 27 



4. Edmund A. Engler. — Figurate Numbers. — Is- 



sued June 23, 1911. 37 



5. Julius Hurter, Sr. — Herpetology of Missouri. 



—Plates XVIIT-XXV.— Issued July 28, 



1911 59 



6. Phil. Rau. — Sexual Selection Experiments in 



the Cecropia Moth. Further Observations 

 on Copulation and Oviposition in Samia 

 Cecropia Linn. — Issued August 9, 1911 .... 275 



7. Title Page. Prefatory Matter and Index of 



Vol. XX. Record January 1, to December 

 31, 1911.— Issued, April 17, 1912. 



List of Authors 321 



General Index 322 



Index to Genera 324 



Classified List of Papers Contained in Volumes XI- 



XX 327 



