CONTENTS. 



Part 1 — January 1st, 1866. 



1. Description of a New American Species of Helix. By 



Wesley Newcomb, M. D 1 



2. On an Abnormal Specimen of Planorbis bicarinatus. 



By George W. Tryon, Jr 3 



3. Descriptions of New Fresh-Water Shells of the United 



States. By George W. Tryon, Jr 4 



4. Descriptions of New Exotic Fresh-Water Mollusca. 



By George W. Tryon, Jr 8 



5. Description of a New Species of Rissoa. By George W. 



Tryon, Jr 12 



6. Addition to " Catalogue of Helices Inhabiting the West 



Coast of North America, North of Cape St. Lucas." 

 By Wesley Newcomb, M. D 13 



! 7. Monograph of the Family Strepomatidae. (Continued.) 



By George W. Tryon, Jr 14 



8. Note on Helix rufa, DeKay. By E. Michener, M. D 53 



9. Remarks on the Origin and Distribution of the Opercu- 



lated Land Shells which inhabit the Continent of 

 America and the West Indies, with a Catalogue of 

 the American Species. By Thomas Bland 54 



10. Note on the Internal Structure of Megaspira. By Thomas 



Bland 64 



11. Illustrations of Miocene Fossils, with Descriptions of 



New Species. By T. A. Conrad 65 



12. Note on the Genus Gadus, with Descriptions of some 



New Genera and Species of American Fossil Shells. 

 By T. A. Conrad 75 



13. Descriptions of New Species of Australian Fresh-Water 



Shells. By T. A. Conrad 79 



14. Note on Mr. Pease's Species of Polynesian Phanero- 



pneumona. By Geo. W. Tryon, Jr 82 



15. On the Modern Classification of Mollusks. By O. A. L. 



Moreh 83 



16. Reply to Mr. Conrad's Criticism on Mr. Gabb's 'Report 



on the Palsentology of California." By Win. M. Gabb. 87 



EDITOR'S TABLE. 



Reviews 93 



American. — Proceedings of the Academy of Natural Sciences. 

 Foreign. — Journal de Conchy liologie, &c. 



Scientific Intelligence 96 



ILLUSTRATIONS. 



Portrait of Dr. Wesley Newcomb, with Autograph. 

 Three Colored and Two Plain Plates. iii. 



