30 BULLETIN 90, UNITED STATES NATIONAL MUSEUM. 



minishing in width near the junction with the body- whorl across 

 which a thin calhis unites the pillar and outer lips ; pillar and aper- 

 ture without teeth or callosities, a marked chink behind the pillar 

 lip but no umbilical perforation. Height 3.5, maxmium diameter of 

 shell 2 mm. 



Tampa silex beds, Ballast Point, Tampa Bay, Florida, collected 

 by E. J. Post, U. S. Nat. Mus. No. 165017. 



This minute shell was submitted to Doctor Pilsbry, who concluded 

 it should be referred to the genus Pupoides. It is notably smaller 

 than the P. marginatus or P. modicus, perhaps most resembling the 

 latter. The shell of the silex fauna is much thicker and heavier than 

 in either of the recent American species. 



Family UROCOPTIDAE. 



Genus UROCOPTIS Beck. 



UrocopUs Beck, Ind. Moll., p. 83, 1837. 



Cylindrclla Pfeiffkr, Arch. f. Naturg., 1840, p. 41 ; not of Swainson, 1840. 



UROCOPTIS FLORIDANA Dall. 



Plate 1, fig. 4 ; plate 2, fig. 3. 



CylindreUa floridana Dall, Trans. Wagner Inst., vol. 3, pt. 1, p. 13, pi. 1, 

 fig. 6a, Aug., 1890. 



Tampa silex beds at Ballast Point, Tampa Bay, Florida ; Dall and 

 Post. U. S. Nat. Mus. No. 165019. 



The original specimen being somewhat defective, a better one from 

 the Post collection has been figured for the present paper. The 

 species belongs to the section Gongylostoma of Albers. 



Family PLANORBIDAE. 

 Genus PLANORBIS Muller. 



PlanorMs Muller (after Petlver) Verm. Terr., vol. 2, p. 152, 1774, no type 

 selected. — Lamarck, Prodrome, p. 76, 1799 (monotype. Helix cornu- 

 anetis Linnaeus, not in Miiller's original list) ; not of Perry, 1811. 



PlmiorMs MoNTFORT, Conch. Syst, vol. 2, p. 270, 1810 (monotype. Helix 

 corneus Linnaeus). — Dall, Harriman Exp. Rep. Land and fresh water 

 Moll. Alaska, p. 80, 1905. 



PLANORBIS TAMPAENSIS, new species. 



Plate 1, fig. 1. 



Shell of moderate size, with about five rounded whorls, of which 

 the last is only represented by a bit of the margin; the shell being 

 regarded as dextral the upper side shows evenly rounded whorls 

 with a deep suture between them, the spire subsiding in the center 



