LIST OF CONTRIBUTORS. lit 



Descriptions of twenty-four new species of TJnionida? of the United 



States 191 



Lewis, Dr. F. W. On some New and Singular Intermediate forms of Dia- 



tomaceoe 336 



March. W. T. Notes on the Birds of Jamaica 150, 283 



Poey, F Descriptions des Poissons nouvelles ou peu connues 180 



Stimpson, Dr. Wm. Synopsis of the Marine Invertebrates collected by 



the late Arctic Expedition, under Dr. I. I. Hayes 138 



Tryon, Jr.,0. W. Descriptions of two new species of Fresh Water Mollus- 



ca, from Panama, 146 



Description of a new Exotic Melania 146 



Descriptions of new species of Fresh Water Mollusca, belonging to the 

 Families Amnicolidse, Valvatidse and Limnaeidae ; inhabiting Cali- 

 fornia 147 



Description of anew species of Pleurocera 279 



Description of a new species of Teredo, from New Bedford, Mass 280 



Descriptions of two new species of Mexican Land Shells 281 



Synonymy of the species of Strepornatid:e, a family of Fluviatilc Mollus- 

 ca. inhabiting North America : Parti 306 



Wilson, Dr. T. B. On a Third Kingdom of Organized Beings 113 



Winchell, Alex. Descriptions of Fossils from the Yellow Sandstone lying 



beneath the "Burlington Limestone" at Burlington, Iowa 2 



Wood, Dr. H. C. Descriptions of new Species of North American Pedi- 



palpi 107 



