24 BULLETIN 90, UNITED STATES NATIONAL MUSEUM. 



PLEURODONTE CRUSTA Dall. 



PLate 2, figs. 8, 16. 



Helix (Jeanneretia) crusta Dall, Traus. Wagner Inst, vol. 3, pt. 1, p. 9, 

 pi. 1, figs. 4, 4fl, 46, Qe, Gf, Aug., 1890. 



Tampa silex beds, at Ballast Point, Tampa Bay, Florida, Shep- 

 ard, Newman, Dall, Burns, and Post. U. S. Nat. Mus., No. 111946. 



With this species was also found the following, which from the 

 imperfect specimens at first found was regarded as merely a variety 

 of P. crusta. The latter is the most common of the species found in 

 the silex beds and often occurs most perfectly reproduced in the 

 translucent silex, 



PLEURODONTE CUNCTATOR Dall. 



Plate 4, figs. 8, 9. 



Helix (Jeanneretia) crusta var. cunctator Dall, Trans. Wagner Inst., vol. 

 3, pt. 1, p. 10, Aug., 1890. 



Tampa silex beds at Ballast Point, Tampa Bay ; also on the shores 

 of Old Tampa Bay, an arm of Tampa Bay proper, westward from 

 Hillsborough Bay, Florida, Collected b}^ Shepard, Newman, Dall, 

 and Burns. U. S, Nat. Mus. No. 111950. "^ 



PLEURODONTE DIESPITER Dall. 



Plate 2, figs. 18, 20. 



Helix {Jeanneretia) diespiter Dall, Trans. Wagner Inst., vol. 3, pt. 1, p. 10, 

 pi. 1, figs. 1, la, Aug., 1890. 



Tampa silex beds at Ballast Point, Tampa Bay, Florida. Abun- 

 dant but usually defective. Collected by Dall and Burns. U. S. 

 Nat. Mus. No. 111951. 



There is some doubt as to the generic relationship of this species, 

 but on the whole it seems most closely allied to P. crusta. 



Tribe PROTOGONA. 



Genus POLYGYRA Say. 

 POLYGYRA ADAMNIS Dall. 



Plate 2, figs. 7, 9. 



Helix (Polygyra) aclamnis Dall, Trans Wagner Inst., vol. 3, pt. 1, p. 12, 

 pi. 1, figs. 5, 5a, Aug., 1890. 



Tampa silex beds at Ballast Point, Tampa Bay, Florida. A single 

 specimen collected at Ballast Point by Dall. U. S. Nat. Mus. No. 

 111959. 



This is the earliest Polygyra (of the section Dcedaloch'da Beck) yet 

 reported from the Tertiary of North America. 



