NEW MARINE SHELLS FROM PANAMA. 



By Paul Bartsch, 



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



The United States National Museum has for a number of years 

 been receiving moUusks collected by Mr. James Zetek in Panama. 

 Most of these, however, have represented the larger, well-known 

 species. It has been only recently that he has given attention to the 

 securing of minute forms, among which no less than eight new 

 species were discovered: Three Epitorvmms,^ which have already 

 appeared in a paper by Dr. W. H, Dall,^ and the five mollusks 

 described in the present paper. 



In addition to these there are fragments of several other species, 

 which appear to belong to undescribed forms, diagnoses of which 

 will be postponed until better material comes to hand. 



CYLICHNELLA ZETEKI, new species. 



Plate 88, fig. 4. 



Shell small, thin, semitranslucent, bluish-white, or in dead shells 

 cream-yellow. The early whorls always covered by the succeeding 

 turns, so that in adult shells the last turn only is visible. Apex with 

 a shallow umbilicus about one-fifth the diameter of the shell. Sur- 

 face of the shell marked by slender lines of growth and very numer- 

 ous, exceedingly fine, and exceedingly closely spaced spiral striations. 

 In addition to this there are 12 strongly incised spiral grooves, which 

 are subequal and subequally spaced and situated on the anterior two- 

 fifths of the shell, and four incised spiral lines of similar spacing 

 and similar strength situated on the posterior fifth of the shell. 

 Aperture pyriform anteriorly, then forming a slender channel, which 

 is almost of equal width from the anterior two-fifths to the posterior 

 portion ; outer lip thin, extending considerably posterior to the body 

 whorl, strongly rounded at the posterior extremity, slightly con- 

 cave in the middle, then strongly rounded anteriorly; columella 



* Epitonium zeteki, imbex, and thylax. 



2 Notes on the Shells of the Genus Epitonium and its Allies of the Pacific Coast of 

 America, Proc. U. S. Nat. Mus., vol. 53, pp. 486-487, 1917. 



Proceedings U. S. National Museum, Vol. 54— No. 2250. 



571 



