A MONOGRAPH OF WEST AMERICAN MELANELLID MOL- 



LUSKS. 



By Paul Bartsch, 



Curator, Division of Marine Invertebrates, United States National Museum. 



The present monograph completes the discussion of the West 

 American Mollusks of the superfamily Pyramidelloideae, the Gym- 

 noglossa, of Malacological Manuals. The superfamily consists of the 

 families Pyramidellidae, which has been previously treated/ and the 

 MelanelUdae, here considered. 



All the members of the superfamily are small mollusks, the largest 

 attaining a size but little more than an inch in length. By far the 

 greater number are elongate conic, but there are some which are 

 quite rotund and others that range between these two extremes. In 

 sculpture they vary from smooth to axially ribbed, to spirally striate 

 or lirate, and combinations of these elements. Anatomically the 

 members of this superfamily are differentiated from the other Proso- 

 branchiate mollusks by the absence or extreme depauperation of the 

 radula. 



The' members of the family PyramideUidae are readily distin- 

 guished from those of the Melanellidae by the fact that the nepionic 

 whorls are sinistral and tilted; the axis of the early whorls usually 



• The PyramiJellidae of the Marine Pliocene and Pleistocene Deposits of California, William H. Dall 

 and Paul Bartsch, Mem. Cal. Acad. Sci., vol. 3, 1S03, pp. 269-285. 



SjTiopsis of the Genera, Subgenera, and section of the Family Pyramidellidae, William H. Dall and 

 Paul Bartsch, Proc. Biol. Soc. Wash., vol. 17. 1904, pp. 1-16. 



Notes on Japanese, Indo- Pacific, and American Pyramidellidae, William H. Dall and Paul Bartsch, 

 Proc. U. S. Nat. Mus., vol. 30, pp. 321-369, pis. 17-26, May 9, 1£06. 



The Pyramldellld Mollusks of the Oregonian Faunal Area, William H. Dall and Paul Bartsch, Proc. 

 U. 8. Nat. Mus., vol. 33, pp. 491-534, pi. 44-48, Washington, December, 1907. 



PyramiieUldae of New England and the adjacent Region, Paul Bartsch, Proc. Best. Soc. Nat. Hist, 

 vol. 24, pp. 67-113, pis. 11-14, February, 1909. 



A Monograph of West American Pyramilellfd Mollusks, William H. Dall and Paul Bartsch, Bull, 

 U. S. Nat. Mus. No. 68, pp. I-XII and 1-258, pis. 1-30, Washington, Nov. 10, 1£09. 



More Notes on the Family Pyramidellidae, Paol Bartsch, The Nautilus, vol. 23, 1909, pp. 54-59. 



New species of Shells collected by Mr. John Macoun, at Barclay Sound, Vancouver Islands, British 

 Columbia, William H. Dall and Paul Bartsch, Canada Dept. of Mines, Memoir No. 14-N, 1910. 



Additions to West American Pyramidellid Mollusk Fauna, with descriptions of new species, Paal 

 Bartsch, Proc. U. S. Nat. Mus., vol. 42, May 17, 1912, pp. 261-289, pi. 35-38. 



A Zoogeographic Study based on the Pyramidellid Mollusks of the West Coast of America, Paul Bartsch, 

 Proc. U. S. Nat. Mus., vol. 42, 1912, pp. 297-349. * 



New species of Mollusks from the Atlantic and Pacific Coasts of Canada, William H. Dall and Paul 

 Bartsch, Bull. No. 1, Victoria Memorial Museum, pp. 139-146, Oct. 23, 1913. 



Proceedings U. S. National Museum, Vol. 53-2207. 



295 



