24 THE NAUTILUS. 



subgenera and sections of the names used as genera and sub- 

 genera in the monograph in question advances our knowledge 

 of the family any more than the raising of a number of sub- 

 genera and sections to generic rank, as Colton believes the writer 

 to have done in his monograph. This rather resembles a game 

 of see-saw ! 



The provisional key of Colton (page 119) is good, and the 

 writer would also be interested to know how useful it may prove 

 to the workers in this family. We would suggest that there is 

 a vast fund of useful information to be acquired from a bio- 

 metric study of both the radula and the genitalia of the Lym- 

 naeas. If we knew the range and the relative amount of varia- 

 tion of these organs we could more intelligently use these criteria 

 for purposes of classification. An abundance of time is needed 

 for this work but the results would compensate for the time ex- 

 pended. The studies which have thus far been made upon this 

 family serve to emphasize the one fact which stands out clearly, 

 the great variability of the shells and organs of the fresh-water 

 pulmonates, a condition in strong contrast with the terrestrial 

 pulmonata where the radula? and genitalia are much more stable 

 in character and hence more satisfactory for purposes of classi- 

 fication. 



PUBLICATIONS RECEIVED. 



AN INDEX TO THE MUSEUM BOLTENIANUM. By Wm. H. Dall. 

 Smithsonian Institution Publication No. 2360. The republica- 

 tion of Bolten's work by Messrs. Sherborn and Sykes (1906) made 

 it accessible to conchologists generally, but its use has been diffi- 

 cult on account of the absence of any index to the great number 

 of names, combined with the unfamiliar nomenclature, which 

 often made even well-known Linnsean species hard to find. Dr. 

 Dall has very appreciably lightened this labor by a full and 

 cross-referenced index. It is prefaced by a historical account 

 of the work, a discussion of its nomenclature, and translations 

 of the Latin Preface and the German Introductions. The Insti- 

 tution desires to give the widest usefulness to this Index, and 

 will supply copies to all who may be interested. H. A. P. 



