>^OTES ON THE NOMENCLATURE OF THE MOLLUSKS OF 

 THE FAMILY TURRITIDAE. 



By William Healey Dall. 



Honorary Curator of MoUusks, United States National Museum. 



In the course of my revision of the West American mollusk fauna, 

 the Turritidae (formerly Pleurotomidae) were reserved until nearly 

 the last, owing to my knowledge of the extremely unsatisfactory con- 

 dition of their nomenclature. 



Owing chiefly to a want of thoroughness and consequent inaccu- 

 racy the recent revisions of the group by Tryon and Cossmann were 

 quite unreliable, though to their labors in bringing material and ref- 

 erences together and so giving a starting point for investigation I am 

 much indebted. Furthermore several recent writers on the group 

 have in my opinion excessively divided it, forming genera, subgenera, 

 and sections on merely specific, or even individual, characters of no 

 physiological or systematic importance. Of the more than 175 

 names of more than specific importance which have been applied 

 to members of this family, probably not more than one third are 

 indicative of characters of sufficient value to warrant a separate nan^e. 



Another difficulty in a satisfactory treatment of the family arises 

 from the fact that these animals often differ among themselves 

 anatomically in ways not expressed in the shell characters; species 

 generically distinct sometimes having extremely similar shells. This 

 has been amply proved in the cases of Leucosyrinx, Irenosyrinx, 

 Steiraxis, ond Aforia for instance. Therefore until much more is 

 known of the anatomy of the species any arrangement must be merely 

 tentative, though it is not unreasonable under the circumstances to 

 put like shells of unknown anatomy in the same systematic group 

 for the present. 



From the recent species we must reason by analogy to determine 

 the proper place of fossils, as no other course is open. It would 

 require several years' work and access to European collections to 

 place, the known species and determine the synonymy of the entire 



Proceedings U- 3- National Museum, Vol. 54— No. 2238. 



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