114 BULLETIN 90, UNITED STATES NATIONAL MUSEUM. 



fectly smooth surface except for incremental lines, about 5 whorls, 

 the last near the aperture descending a little, and a smooth flat pad 

 of callus over the umbilical region. The specimen collected has the 

 peristome moderately thickened internally, but has no reflection of 

 the edge or beveled margin as in the smaller species. There is a 

 faint notch at the base of the pillar which has no parallel in the 

 other species. Maximum diameter of shell, 11.5 ; minimum diameter 

 of shell, 9.75; height, 9 mm. 



Tampa silex beds, at Ballast Point, Tampa Bay, Florida. One 

 specimen collected by E. J. Post. U. S. Nat. Mus. No. 166093. 



Family NEEITIDAE. 



Genus NERITA (Linnaeus) Lamarck. 



Nerita (part) Linnaeus, Syst. Nat., ed. 10, 1758, p. 776. 



Nerita Lamaeck, Prodrome, 1799, p. 77. Type, Nerita exuviae Lamarck. 



The name Nerita derives from the ancients and is mentioned (in 

 its Greek form Neritos) by Aristotle. Among eighteenth-century 

 naturalists it was used indiscriminately for Natica^ Nerita^ NeriUna, 

 and other gastropods of similar form, and it M^as not until the time 

 of Lamarck that this very natural group was definitely segregated. 



NERITA TAMPAENSIS Dall. 



Plate 16, fig. 2. 



Nerita tampaensis Dall, Trans. Wagner Inst., vol. 3, pt. 2, p. 421, pi. 17, 

 fig. 3, 1892. 



Tampa silex beds at Ballast Point, Tampa Bay, Florida, and in 

 the overlying limestone at the same place and also at La Penotiere's 

 Hammock, a mile and a half south of Orient Station and 6 miles 

 eastward from Tampa City, on Six-Mile Run; Dall and Burns. 

 U. S. Nat. Mus. No. 165138. 



This is the first species of Nerita which has been described from 

 the Atlantic Tertiary. 



Family FISSURELLIDAE. 



Genus FISSURIDEA Sv/ainson. 



Fissuridea Swainson, Malac, p. 356, 1840. — Pilsbry, in Nautilus, vol. 5, p. 



104. 1892.— Dall, Trans. Wagner Inst., vol. 3, pt. 2, p. 425, 1892. 

 Glyphis Carpenteb, 1856; not of Agassiz, 1840, Pisces. 



FISSURIDEA CHIPOLANA Dall. 



Fissuridea chipolana Dall, Trans. Wagner lust., vol. 3, pt. 2. p. 426, pi. 23, 

 fig. 21, 1892. 

 Oligocene of the Tampa silex beds at Ballast Point; Post. Also 

 in the Chipola marls near the county bridge, Calhoun County, 



