VI CONTENTS. 



By John Le Conte. 



On the North American Plants of the genus Tillandsia, with descrip- 

 tions of three new species, ------- 129 



Description of the Siren intermedia, a new species, - - 133 



Observations on the North American Species of the genus Viola, 135 



By Samuel L. Mitchill. 

 Description of a new species of Diodon, ----- £64 



By Messrs. Mitchill, J. A. Smith, and Cooper. 



Discovery of a Fossil Walrus in Virginia. Report on a fossil Skull 

 sent to Dr. Mitchill, by Mr. Cropper, of Accomac County, 

 Virginia, - 271 



By J. Augustine Smith. 



Account of the Dissection of a Proteus of the Lakes ; with remarks 



on the Siren intermedia, ------- 259 



By JonN Torrey. 



Some Account of a Collection of Plants made during a journey to 

 the Rocky Mountains in the summer of 1820, by Edwin P. 

 James, M. D. Assistant Surgeon U. S. Army, - - - 161 



