

PREFACE 



The present volume, mainly concerned with the Family 

 Tornatelliuida?, completes a trilogy treating of the snails of 

 Pacific Islands, chiefly of the Hawaiian Islands; the other 

 volumes deal with the Families Amastridae and Achatmellidas. 



Together with the Partulidas (Volume XX) these are 

 numerically the most important families of the land-snail 

 faunas of the Pacific. They also comprise nearly all of the 

 large laud snails of these faunas. Members of the Super- 

 family Orthurethra, these primitive land snails, dispersed in 

 the Palaeozoic, parallel the Sigmurethra in their adaptations. 

 There are terrestrial and arboreal types, and cylindric, conic, 

 Bulimoid, Achatinoid and Helicoid shell-forms. This re- 

 markable parallelism has caused the Orthurethrous genera to 

 be scattered, in former classifications, among the series of 

 continental families of the Superfamily Sigmurethra, an 

 arrangement which ignored the structural features of the 

 pallial organs. 



Of the 219 species and 44 subspecies or named varieties 

 described in this volume, 93 species and 38 subspecies are 

 here defined for the first time. The type-specimens of 168 of 

 the species and subspecies have been examined by one or 

 (usually) both of the authors; also cotypes, paratypes or 

 specimens from the original lots of many other species. 

 Thirty-seven of the species and subspecies herein described 

 have not been seen by either author. Part of these are nom- 

 inal species, known only by the original descriptions, not 

 subsequently identified by authors or collectors. 



As half the world separated the authors during the prep- 

 aration of the manuscript, it was not always possible to col- 

 laborate upon every point. The first part of the work, up to 

 p. 68, was therefore chiefly by the senior, the succeeding 

 pages, up to p. 113, mainly by the junior author. In the rest 

 of the book the work is mingled in every genus. The Hawai- 



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