DIAGNOSES OF UNDESCRIBED NEW SPECIES OF MOL- 

 LUSKS IN THE COLLECTION OF THE UNITED STATES 

 NATIONAL MUSEUM 



By William Healey Dall 



Honorary Curator of Mollusks, United States National Mui^eum 



In revising portions of the collection of mollusks a number of spe- 

 cies were found which during a previous revision had been recognized 

 as new, and had had a manuscript name inscribed on the label, but 

 which by some chance had escaped publication. Some of these names 

 have found their way into the literature, although undescribed, and 

 it seemed desirable that proper diagnoses should be supplied. To 

 these in this paper have been added a few other new species recently 



received. 



Genus DENTALIUM Linnaeus, 1758 



DENTALIUM NAGOENSE, new species 



Shell slender, translucent white, with circular section, the poste- 

 rior orifice entire; the surface brilliantly polished, without sculpture 

 except faint incremental irregularities; length, 40; diameter at orifice, 

 3; perpendicular to the arch of the curve, 2.6 mm. U. S. Nat. Mus. 

 Cat. No. 333718. 



Dredged in 15 fathoms at Nago, Okinawa, Loochoo (Riukiu) 

 Islands by Langford and Thaanum. 



This at first sight is very close to D. luchuanum Dall, but lacks 

 the posterior longitudinal striation, while the posterior third is less 

 curved and more slender than in that species. 



PENDROMA, new genus 



PENDROMA PERPLEXA, new species 



Shell small, whitish, subturbinate, with nearly four rapidly enlarg- 

 ing, well rounded whorls; nucleus minute, smooth; later whorls 

 axially sculptured with numerous sharp, irregularly spaced, low pli- 

 cations, which cross the early whorls, but on the last whorl become 

 obsolete beyond the periphery; these are crossed by low, simple 

 slender spiral threads with mostly wider interspaces, forming with the 



No. 2668— Proceedings U. S. National Museum. V^ol. 70, Art. 19 



24106—27—1 



