CONTENTS. 



PAGE. 



Table of Contents Hi 



List of Members. Revised to December 31, 1901: 



1. Patrons v 



2. Active Members v 



History of the Academy (Abstract) xiii 



Record. January 1 to December 31, 1901 xvii 



Papers Published. January 1 to December 31, 1901: 



1. Frank Collins Baker. — A revision of the Limnaeas of 



Northern Illinois. — Plate I. — Issued January 16, 

 1901 1 



2. P. H. Rolfs. — Florida lichens. — Issued March 16, 



1901 25 



3. T. G. Poats. — Isogonic transformation. — Issued May 



16, 1901 41 



4. Francis E. Nipher. — The relation of direct to re- 



versed photographic pictures. — Plates II. -X. — 

 The specific heat of gaseous nebulae in gravitational 

 contraction. — Issued June 7, 1901 51 



5. George Lefevre. — The advance of zoology in the 



nineteenth century. — Issued July 3, 1901 71 



6. Francis E. Nipher. — Physics during the last cen- 



tury. — Issued November 13, 1901... 105 



7. William Trelease. — The progress made in botany 



during the nineteenth century. — Issued November 

 26, 1901 125 



8. Frank Collins Baker. — Some interesting molluscan 



monstrosities. — Plate XI. — Issued November 26, 

 1901 143 



9. Stuart Weller. — Kinderhook faunal studies. III. 



The faunas of beds No. 3 to No. 7 at Burlington, 

 Iowa. — Plates XII.-XX. —Issued December 18, 1901 147 



10. J. Arthur Harris. — Normal and teratological thorns 



of Gleditschia triacanthos, L. — Plates XXI.- 

 XXV. — Issued December 24, 1901 215 



11. Title-page, prefatory matter and index of Vol. 



XI. — Record, January 1 to December 31, 1901. — 



Issued January 12, 1902 



List of Authors 223 



General Index 224 



Index to Genera 225 



