VI PREFACE. 



ume. Indeed, the main features of this synonymy (excepting so 

 much as had been recognized by earlier naturalists) were original 

 with my colleague, having been worked out before we went over 

 the ground together in Honolulu. While for the accuracy of the 

 synonymy the senior author assumes equal responsibility with 

 Dr. Cooke, it would be unfair to hold the latter responsible for 

 the manner of presentation, or for the treatment of questions left 

 in abeyance for want of time or type material in Honolulu. It 

 was not practicable for my collaborator to go over the work in its 

 final form; and for this reason many statements of fact or opinion 

 throughout the text are made in the first person, especially when 

 based upon material we had not gone over together. The determi- 

 nation of all forms of Achatinella believed to be new to science 

 was also the joint work of both authors, as indicated in the text. 

 Indebtedness to Dr. Cooke for various helpful suggestions rela- 

 tive to Partulina and other genera is acknowledged under the 

 respective species. I may also be permitted to recall the com- 

 radeship which made the months spent in the Islands among 

 the happiest of my life. 



Information used in compiling the maps on pages 183, 277, 

 and 341 was largely supplied by Dr. Cooke and Mr. Spalding. 



Professor Hyatt's MS. descriptive of tree snails was not utilized 

 in the preparation of this volume for the reason that his treat- 

 ment of species could not be reconciled with the views herein 

 expressed. Moreover, it is believed that had Hyatt visited the 

 Islands and seen the actual association of forms, his ideas must 

 have been very materially changed. Professor H} r att's general 

 results in phylogeny and zoogeography, so far as worked out at 

 the time of his death, are given in an appendix ( pp. 370-399), 

 for comparison with the views developed in course of this study. 



In order to keep this volume within reasonable size, an ac- 

 count of the soft anatomy of Achatinelloid snails and an appendix 

 to volume XXI (Amastrida) will form the first part of Vol. 

 XXIII. That volume will also treat of Auriculella, Tornatellina 

 and their allies, and contain a general index of all Achatinelloid 

 snails. 



The color nomenclature follows Ridgway's Color Standards and 

 Nomenclature, except in the first two numbers, which were pre- 

 pared before the publication of that work. 



