MARINE MOLLUSKS — MACGINITIE 65 



In a work such as the present paper, it would be impossible to give 

 complete synonymies for all the species, for in many instances the 

 complete synonymy covers several pages. For example, one species 

 dealt with in this paper has been known under 12 generic and 15 

 specific names, with many combinations of these various generic 

 and specific names. The objective, therefore, has been to include the 

 reference for the original description and, if possible, a recent and 

 accessible American publication ^ that contains an illustration, as 

 well as one of the more recent European publications that contains 

 an illustration. In addition, references in the synonymies may include 

 some of the less well-known synonyms, those containing good dis- 

 cussions or good distribution records, and references to those species 

 placed in synonymy by the present writer. 



Perhaps nowhere in the world do shells consistently exhibit such 

 marked and confusing variations as do the Arctic species. Among 

 the gastropods the genera Buccinum, Boreotrophon , Neptunea, Ber- 

 ingius, and Diaphana and among the pelecypods Musculus, Astarte, 

 and Liocyma are particularly subject to variation. Because of these 

 great variations, species of some of these genera are extremely difficult 

 to identify and in order to resolve these problems it will be necessary 

 to make intensive studies at the specific level. 



The Leptonidae in this country need a complete revision, for many 

 species have not been assigned to the proper genus. A lifetime of 

 work would be inadequate to bring complete order to the taxonomic 

 chaos existing in the Turridae of this country, and the Pyramidellidae 

 and Rissoidae are likewise in need of intensive work. At present the 

 situation in these families is such that in many instances it is impossible 

 to assign a species to a genus. Consequently several species have 

 been referred to "Oenopota" in this paper. 



In many instances the existing knowledge of a species is insufficient 

 to enable one to say whether a specimen represents a variety or 

 merely a form of the species. And in very few instances is existing 

 information sufficient to enable one to refer a specimen to a subspecies 

 in the present explicit meaning of the term. 



The present paper is merely a beginning and no one realizes better 

 than the wi'iter that there are many unresolved problems, but it is 

 hoped that it will point out the need for further study — and it is 

 consoling to know that even the mistakes will contribute toward 

 that goal. 



In order to save space, collection dates usually have been omitted 

 and are included only when they have some special significance, such 

 as in the listing of young stages or of mature eggs or in those instances 



' In recognition of the value of good Illustrations, references to popular and semipopular works have 

 been made freely. 



