THE CYCIiO'PHORilD LAIs'D MOLLUSKS OF AMEIRICIA 87 



rounded. Base strongly rounded, openly moderately broadly umbili- 

 cated with a strong keel bounding the outer edge of the umbilicus. 

 The entire surface of the base is marked by irregularly disposed 

 wrinkles and pits. The umbilical keel is rendered rather rough by 

 the incremental lines, which extend strongly and roughly into the 

 umbilicus. Aperture subcircular, rather strongly protracted into an 

 angle at the posterior angle; outer peristome thin, the inner somewhat 

 thickened. Operculum typically ptychocochlid. 



The specimen figured is one of C. B. Adams' original lot, No. 6. 

 This was selected by H. B. Baker ^ as the type of Adams' complex. It 

 has 5 whorls and measures : Height, 14.6 mm. ; greater diameter, 20.8 

 mm. ; lesser diameter, 15.6 mm. No specific locality accompanies this 

 lot. 



The species appears restricted to the north coast of Jamaica in St. 

 Mary and St. Ann Parishes, that is, the stretch between Port Maria 

 and Ocho Kios Bay. 



PTYCHOCOCHLIS GEMMA (Chitty) 



Plate 13, Figures 25-27 



1857. Cyclotus gemma Chitty, Proc. Zool. Soc. London, vol. 25, p. 150. 

 1898. Neocyclotus (Plectocyclotus) gemma Kobelt and Moixendokff, Nachrb. 

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



Shell small, depressed-helicoid, pale horn colored. The nucleus 

 consists of a single well-rounded, smooth turn. The postnuclear 

 whorls are well rounded ; the first is marked by slender, retractively 

 curved axial riblets, which are about as wide as the spaces that sep- 

 arate them. The second postnuclear whorl shows the beginning of 

 oblique wrinkles, which are not quite as wide as the spaces that 

 separate them. On the last whorl these wrinkles assume an irregular 

 distribution, the spaces between them being a little wider than the 

 wrinkles. These rugations do not extend quite to the summit. Suture 

 well impressed in all the turns. Periphery well rounded. Base 

 broadly openly umbilicated, marked by very strong, rough, decidedly 

 oblique, protracted cords, which are wider than the spaces that 

 separate them and are rendered roughened by the axial riblets. The 

 umbilical keel is but feebly expressed, and the umbilical wall is 

 marked by closely spaced axial riblets. Aperture circular, slightly 

 angulated at the posterior angle, oblique ; peristome thin. Operculum 

 typically ptychocochlid. 



The specimen figured is C. B. Adams' unique type in the Amherst 

 College collection, received from Chitty, and is said to have come 

 from Burnt Hill, Westmoreland Parish, Jamaica. It is the only 



6 Nautilus, vol. 48, p. 86, 1935. 



