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CONTENTS. 



IX. — On Ilelid- asimsK in California, and the Geographical Distribu- 

 tion of certain West American Land Snails, and previous errors 

 relating thereto, ikc. By Robkht E. ('. Stkarns, 129 



X. — The liife-IIistcn-y of Spirifer Iwris, Hall : — a Paheontological 



study. By Hrnry S. Wtlliams (with plate XIV), 140 



XI. — On the Geology of Richmond County, N. Y. By N. L. Brit- 

 ton (with plates XV and XVI^ - 161 



[Pages 183-192, belonging to No. 6, will be issued with the next number.] 



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