CONTENTS. 



1. Contributions towards a Monography of the Order Pholadacea, 



with Descriptions of New Species 9 



2. Descriptions of Two New Species of Fresh Water Mbllusca, from 



Panama , 12 



3. Description of a New Exotic Melania 13 



4. Descriptions of New Species of Fresh Water Mollusca, belonging to 



the Families Amnicolidse, Valvatidse, and Limnaeidae ; inhabit- 

 ing California 13 



5. Description of a New Species of Pleurocera 17 



6. Description of a New Species of Teredo, from New Bedford, Mass. 17 



7. Descriptions of Two New Species of Mexican Land Shells 18 



8. Synonymy of the Species of Strepomatidse, a Family of Fluviatile 



Mollusca, inhabiting North America. Parti 19 



9. do. do. do. " 2 35 



10. do. do. do. " 3 61 



11. do. do. do. " 4, 73 



12. Additions to Synonymy of Strepomatidse , 91 



Index.., 93 



