Introdurlion. xi 



Nearly all the shells described in this paper are represented 

 b}' examples in my own colledlion, and many of them by a large 

 series. Mr. D. D. Baldwin has continually furnished me with 

 valuable assi.stance in the study and arrangement of this genus. 

 Prof. W. T. Brigham and Mr. J. F. G. Stokes, of the Bernice 

 Pauahi Bishop Museum at Honolulu, have very courteously 

 allowed me the use of all material on the subject at their com- 

 mand. The large collecflions of Rev. O. P. Emerson and Mr. 

 D. Thaanum have been carefully examined, as well as many other 

 collections. Mr. C. M. Cooke Jr. has very kindly permitted me 

 to use his careful notes on the type shells at present in the collec- 

 tion of the British Museum. 



In some cases the descriptions have been publi.shed several 

 times, and where the earlier work could not be secured the descrip- 

 tion is taken from a later publication, which is that indicated by 

 the reference. 



Honolulu, January, 1904. 



