CONTENTS 



PAOB 



PREFACE v 



LIST OF ILLUSTRATIONS ix 



LAND AND FRESH WATER MOLLUSKS, BY WILLIAM H. DALL* 



General discussion and results i 



Summary of distribution of fresh water species in Alaska 



and adjacent regions i 



Table of distribution of fresh water species according to 



drainage systems now existing 4 



Summary of distribution of land shells of Alaska and ad- 

 jacent regions 7 



Table of distribution of American land shells 8 



Summary of the mollusk fauna of northeastern Asia 9 



Table of distribution of northeast Asiatic land and fresh 



water shells 14 



Conclusions in regard to the Alaskan fauna 15 



Systematic catalogue of land and fresh water mollusks of 



North America north of the forty-ninth parallel 19 



Bibliography 147 



Index to genera and species 157 



HYDROIDS, BY C. C. NUTTING. 



Introduction 175 



Geographic distribution 176 



Systematic discussion 181 



Bibliography 207 



VOLUME INDEX ..,,,..,,,,,,,.,,., ,,,,, 235 



(TB) 



