Vlll PREFACE. 



ested will find the evidence upon which both views are based in 

 the descriptive part of this volume. 



In matters of taxonomy the two authors are in almost com- 

 plete agreement. Diverse methods and different material for 

 investigation have caused some difference of view regarding 

 the rank and relationships of the subdivisions and species of 

 Amastra, and the relationships of the Laminellse. Here both 

 views are given, pp. 358-368 (Hyatt) and 137, 324 (Pilsbry). 

 The chief advance over former classifications of Pease, Gulick 

 and others is in the recognition of Heliciform genera derived 

 from Amastra, containing forms which were formerly placed in 

 the Helicoid families Endodontidas or Helicidse. The true re- 

 lationship of Pterodiscus was published by Pilsbry in 1905, 

 without knowing that Hyatt had reached the same result sev- 

 eral years earlier, but had published nothing on the subject. 

 The Heliciform genera Planamastra and Armsia were unknown 

 to Hyatt. 



Only a few incomplete notes relating to the genus Leptachatina 

 were left by H}^att. The account of this intricate group has 

 been prepared by Doctor C. Montague Cooke, of Honolulu, who 

 has studied all of the principal collections of these snails in 

 Europe, America and the Islands. 



The original descriptions of species, or translations of them, 

 have been quoted in nearly all cases, though sometimes dis- 

 pensed with when the original types were before us. This use 

 of an author's own words permits the limitation of additional 

 descriptive matter to the exposition of points originally un- 

 noticed, or inadequately set forth; yet often of the first import- 

 ance in phylogenetics. Such additional matter is given either 

 from the notes of Hyatt, confirmed by the junior author, or 

 from observations by the latter. Views specially Hyatt's are 

 quoted or otherwise distinguished. 



Acknowledgment is due to MRS. J. M. ARMS SHELDON whose 

 liberality has enabled us to illustrate this volume and the one 

 to follow more fully than would otherwise have been possible. 



Our generous friend Doctor C. Montague Cooke has left his 

 large Hawaiian collection in our possession for ten years, and 

 has freely given specimens and information of the first import- 



