64 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 109 



The Present Study 



The writer undertook the identification of the mollusks from Point 

 Barrow unaware of the great amount of work and complex difficulties 

 involved. The work was scarcely begun before it became evident that 

 the identifications would be far from simple and that library research 

 would be extremely important. The difficulties of identification are 

 due partly to the extreme variability of the Arctic shells, which has 

 resulted in descriptions of numerous forms and varieties as separate 

 species. But perhaps the greatest difiBculty derives from the fact that 

 in all too many instances taxonomists working on western specimens 

 described as new species ones that had previously been described from 

 Europe or Greenland, perhaps assuming that Greenland and the 

 islands north of eastern Canada form an effective geographical barrier 

 in a roughly circular ocean and that the distance in the other direction 

 is too great for migration. Within recent years almost no one in 

 America has worked on Arctic mollusks and the early names have 

 been passed along in the literature without rechecking. Distribution 

 records will be changed considerably when specimens in various 

 collections can be reexamined and when more detailed study can be 

 made at the family or generic level. 



Two other factors contributed toward making the work time con- 

 suming: the inaccessibility of comparative material and of literature. 



1. With the exception of that of the U. S. National Museum, the collections 

 examined by the writer have almost no shells from Arctic waters; and the collection 

 in the U. S. National Museum has relatively few specimens from the European 

 Arctic or even from the Canadian Arctic. (The writer would like to stress the 

 need for an exchange of northern specimens between institutions in this country 

 and European institutions. An exchange of specimens among institutions, not 

 only between different countries but also between institutions within this country, 

 would materially decrease the labors of future workers and, in the event of major 

 disasters, would be good insurance against total loss of specimens of certain 

 species. A picture may be worth a thousand words, but often the best of illustra- 

 tions cannot convey the ideas that a single specimen would impart.) 



2. In order to straighten out some of the taxonomic problems in which many 

 of the species were involved, it was necessary to consult the original descriptions. 

 An attempt was made to read all of the original descriptions but it was not always 

 possible to do so. In several instances the original description is in a copy of a 

 journal or publication available in this country only in the Library of Congress 

 or perhaps one other institution in the East. 



Establishing the exact date of publication was almost mipossible 

 in certain references. In the belief that the reader will be interested 

 in the reason for changes in date or author, explanations for such 

 changes have been included in the text or in footnotes and in some 

 instances explanatory notes have been added in the bibliography. 

 It is hoped that such explanations will save future workers hours 

 of library research. 



