CONTENTS. 



PART I. 



1. On the Geological position of certain beds which contain 



numerous Fossil Marine Plants of the family Fucoides, 

 near Lewistown, Mifflin county, Pennsylvania. By Rich- 

 ard C. Taylor, Fellow of the Geol. Soc. of London; 

 Associate Fellow of Ingt. Civ. Eng. London ; Member of 

 the Geol. Soc. of Pennsylvania ; of the Acad. Nat. Sci. 

 Philadelphia ; and of the Albany Institute, New York, 5 



2. An Essay on the Gold Region of the United States. By 



James Dickson, F.G.S. London; Hon. Mem. Geol. Soc. 

 Penn., and of various Societies of Europe, . . 16 



3. Some Experiments on a Sulphated Ferruginous Earth from 



Kent county, Delaware, with a view to ascertain its com- 

 mercial value. By Jacob Green, M.D., Professor of 

 Chemistry in Jefferson Medical College, Pennsylvania, 33 



4. Description of a new Trilobite from Nova Scotia. By 



Jacob Green, M.D., &c., 37 



5. On the Structure of the Teeth, in the " Edentata," fossil 



and recent. By Richard Harlan, M.D., &c., . . 40 



6. Critical Notices of various Organic Remains hitherto dis- 



covered in North America, with the description of a new 

 species of Euripterus. By Richard Harlan, M.D., &c., 46 



7. Observations on the Treatise of Mineralogy of Mr C. TJ. 



Shepard, with the Translation of " The Characteristic of 

 the Classes and Orders of Breithaupt." By Andres Del 

 Rio, Professor of Mineralogy in the School of Mines of 

 Mexico, President of the Geol. Soc. of Pennsylvania, &c., 113 



8. On the Conversion of Sulphuret of Silver into Native 



Silver, after the method of Becquerel. By Andres Del 

 Rio, Hon. Mem. GeoL Soc. Penns., &c. &c., . 137 



9. On the Localities in Tennessee, in which the Fossil Re- 



