IV CONTENTS 



Page 

 The cyclophorid moUusks of the mainland of America, by Paul Bartsch 



and Joseph P. E. Morrison 142 



Family Cyclophoridae 142 



Subfamily Megalomastominae 142 



Genus Toniocyclus 142 



Subfamily Diplommatininae 148 



Genus Adelopoma 148 



Subfamily Amphicyclotinae 151 



Genus Buckleyia 151 



Genus Lagocyclus 164 



Genus Filocyclus 157 



Genus Calaperostoma 159 



Genus Cyrtotoma 169 



Genus Barbacyclus 175 



Genus Calacyclotus 178 



Genus Mexcyclotus 179 



Genus Megacydolus 181 



Genus Am-phicy dolus 183 



Subfamily Aperostominae 186 



Genus Aperostoma 187 



Subgenus Incidostoma 187 



Subgenus Austrocydotus 195 



Subgenus Neocydotus 203 



Subgenus Cydopomops 219 



Subgenus Aperostoma 221 



Subgenus Cydohidalgoa 268 



Genus Liracydotus 274 



Pseudogeneric term Incerticydus 275 



A list of the mainland cyclophorids -- 279 



Explanation of plates 283 



Index 293 



