THE CYCLOPHORTD LAJsD MOLLUSOKS OF AMERTOA 113 



The species appears confined to the southern coast of St. Elizabeth 

 Parish, Jamaica. It is readily distinguished from the other non- 

 corrugated Poterias by its strong lamellalike axial sculpture. 



POTERIA (POTERIA) PLANA, new species 



Plate 16, Figubes 25-27 



Shell small, helicoid, covered with a pale-brown periotracum. The 

 nucleus consists of a single, moderately elevated, well-rounded, smooth 

 turn. The succeeding turns are marked by slender, retractively curved 

 axial riblets, which are inclined to waviness on the last turn, where in- 

 dications of spiral threads are present. The postnuclear whorls are 

 flattened on the posterior fourth, anterior to the summit. Suture 

 strongly impressed, a little less so on the last whorl. Periphery well 

 rounded and marked by the continuation of the axial sculpture. Base 

 well rounded, openly umbilicated, with an obsolete cord at the periph- 

 ery. The base is marked by a continuation of the axial riblets and 

 indications of obselete spiral threads. The umbilical wall bears 

 slender riblets. Aperture circular, oblique; peristome thin. Oper- 

 culum typically poterid. 



The type, U.S.N.M. No. 535976, was collected by Henderson at 

 Montpelier, St. James Parish, Jamaica. It has 4.9 whorls and meas- 

 ures : Height, 12.5 mm. ; greater diameter, 19.2 mm. ; lesser diameter, 

 14.0 mm. 



The species appears to be rather widely distributed. The specimens 

 before me come from Westmoreland, Hanover, St. James, St. Eliza- 

 beth, and Trelawny Parishes. It resembles most nearly P. (P.) crassa 

 (C. B. Adams), from which the flattening at the summit will readily 

 distinguish it. 



POTERIA (POTERIA) CRASSA (C. B. Adams) 



Plate 16, Figures 16-18 



1851. Cyclostoma crassum C. B. Adams, Ann. Lye. Nat. Hist. New York, vol. 



5, p. 59. 



1852. Cyclotus crassus Pfeiffer, Monographia pneumonopomorum viventium, 



vol. 1, p. 29. 

 1855. Cyclotus (Aperostoma) crassus H. and A. Adams, The genera of recent 



Mollusca, vol. 2, p. 275. 

 1898. Neocyclotus (Plectocyclotus) crassus Kobelt and Mollbndorff, Nachrb. 



deutschen malak. Ges., vol. 29, p. 138, reprint. 



Shell helicoid, small, brownish horn colored. The nucleus con- 

 sists of a single well-rounded, rather elevated, smooth turn. The 

 postnuclear whorls are marked by rather strong, retractively curved 

 axial riblets, which are almost as wide as the spaces that separate 

 them. These riblets become less strong and less regular on the 



