1921] NATURAL SCIENCES OF PHILADELPHIA. 373 



The aperture is broken. Columella concave, truncate at base. 

 iVo callus on the inner lip above. An isolated species. 

 Length 26, diam. 12.7 mm.; 8h whorls remaining. 

 Type and five others, no. 2604 A. N. S. P. 



Cerithium (?) venustum Gabb. Plate XXXII, flg. 4. 



? Cerithium venustum Gabb, Tr. Am. Philos. Soc, xv, 1873, p. 238. 



Sculpture of numerous axial folds, tuberculate at the intersections 

 of three low, equal spiral cords, and a narrower one close below the 

 suture. There are some spiral threads between the cords. There 

 are low, rounded varices on the last six whorls, all being on one side 

 of the shell, one varix on a whorl. 



The type, no. 2598 A. N. S. P., is broken at both ends. No other 

 specimen was found. 



Length 29, diam. 7 mm.; 10^ whorls remaining. 



Gabb questioned the genus. It is perhaps impossible without 

 the aperture to define its relations. 



Clava plebeia (Sowerby) 



Cerithium plebeium Sowerby, Q. J. Geol. Soc, vi, 1849, p. 51, Guppy, xxii, 

 1866, p. 290, pi. 16, fig. 9 (not good). 



An abundant species, perhaps ancestral to the West American 

 C. gemynata (Hinds). 



Clava has been placed between Drillia and Mangilia in Bull. Amer. 

 Pal. V, p. 57. 



Potamides haitensis (Dall) 



Pyrazisinus ? haitensis Dall, Proc. U. S. Nat. Mus. xix, p. 319, pi. 29, fig. 8. 

 A single mutilated specimen. No. 3197 A. N. S. P. 



Potamides prismaticus (Gabb). Plate XXIX, fig. 12. 



Cerithium prismaticum Gabb, Trans. Amer. Philos. Soc, xv, 1873, p. 236. 



Represented by one imperfect shell, no. 2601 A. N. S. P., measur- 

 ing, length 57.3, diam. 28 mm. It is well distinguished by the 

 short, heavy ribs or nodes and the deep, "square-cut groove below 

 the suture". Length of the broken specimen 57.3 mm. 



Potamides suprasulcatus (Gabb) Plate xxix, figs. 10, 11. 



Cerithium suprasulcatum Gabb, Trans. Amer. Philos. Soc, xv. 1873, p. 236. 

 Potamides ormei Maury, Bull. Amer. Pal. v, p. 126. 



The early whorls have three spiral ridges cut into granules by 



longitudinal sulcations (fig. 10). The space between the upper and 



the second spiral ridge is deeper than the other spaces, and on the 



later whorls it becomes a deep, square-cut furrow, defining the su- 



