CONTENTS. 



PAGE 



Dedication y 



Preface vii 



Alphabetical List of Species x 



Systematic List of Species xii 



Analytical Key xiv 



Explanation of Map xix 



Map of Distribution of Caucasian forms 1 



Synoptical Table of Classification '2 



Class I. Cephala 3 



Family Limacinea 5 



Colimacea 33 



auriculacea 124 



Lymn^acea 133 



Cyclostomacea 174 



Littoracea 181 



Peristomata 184 



Neritacea 200 



Class II. Acephala 204 



Family Mytilacea 206 



Naiades 211 



Cardiacea 225 



Tables of Distribution 242 



Distribution and Origin of Species 252 



List of Works referred to in the Synonymy 259 



Index 267 



