674 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.54. 



bordering the umbilicus are about four times as strong as those on 

 the four anterior cords. The parietal wall bordering the umbilicus 

 is concave and crossed by the axial ribs. Aperture subcircular ; peri- 

 stome rendered sinuous by the spiral sculpture ; parietal wall covered 

 by a thin callus. 



The type (Cat. No. 216838, U.S.N.M), was collected by James Zetek 

 at Punta Paitilla, near Panama City, Panama, in siftings from sand 

 and worm burrows. It measures — greater diameter, 3.8 mm. ; lesser 

 diameter, 3 mm. ; altitude, 1.2 mm. 



DISCOPSIS PANAMENSIS, new species. 



Plate 88, figs. 9, 10, 11. 



Shell lenticular, thin, semitransluscent, bluish-white. Nuclear 

 whorls two, strongly rounded, forming an elevated mucronate 

 apex; succeeding turns one and three- fourths, decidedly depressed, 

 gently rounded. The part following the nuclear turn is ornamented 

 by two strong, spiral cords, one of which is at the periphery and the 

 other halfway between" this and the summit, where it forms a de- 

 cidedly strong angle. Soon after this various other spiral cords 

 make their appearance at intervals, resulting eventually in 10 sub- 

 equal and subequally spaced cords between the suture and the 

 peripheral keel. These cords are rendered nodulose by the somewhat 

 irregularly developed and distributed, decidedly protractedly bent 

 axial riblets which pass undiminished from the summit of the whorls 

 to the periphery. Suture strongly channeled. Periphery rendered 

 angulated by the limiting cords. Base with a very broad funnel- 

 shaped umbilicus, well rounded, the greatest convexity falling on the 

 posterior limit of the anterior third, marked by the irregular axial 

 riblets and numerous very fine closely spaced incised spiral lines 

 which pass equally over the intercostal spaces and ribs. This 

 sculpture passes over the parietal wall into the umbilicus. Aperture 

 very large, pyriform, decidedly oblique; outer lip rendered sinuous 

 by the external sculpture, which is also apparent through the mass 

 of the shell; inner lip evenly curved; parietal wall very narrow, 

 almost crossed by the two ends of the aperture. 



The type (Cat. No. 216839, U.S.M.N.) was collected by Mr. James 

 Zetek at Punta Paitilla, near Panama City, Panama, from sand and 

 worm burrow siftings. The type measures — greater diameter, 2.3 

 nmi. ; lesser diameter, 1.8 mm. ; altitude, 1 mm. 



DISCOPSIS ARGENTEA. new species. 



Plate 88, figs. 1, 2, 3. 



Shell small, discoid, thin, semitranslucent. Nuclear whorls three, 

 smooth, small, forming a quite elevated spire, the axis of which is 

 obliquely tilted to that of the succeeding turns. Postnuclear whorls 



