THE CYCIiOPHORID JjKNT) MOLLUSKS OF AMERIOA 85 



summit of the whorls is appressed to the preceding turn. Periphery 

 well rounded. Base well rounded, openly umbilicated, and provided 

 with a strong keel at the outer limit of the umbilicus. The space be- 

 tween the umbilical keel and the periphery is marked by raised, re- 

 tractively slanting ridges, which join those on the upper portion of 

 the whorl, but here have the reverse slant. They are not quite so 

 strong as those on the upper surface and they weaken in strength 

 toward the umbilical keel. In addition to this, strong incremental 

 lines representing the continuation of the finer axial riblets are present. 

 The umbilical wall is marked by crowded, rather rough axial riblets 

 and incremental lines. Aperture subcircular, slightly angulated at the 

 posterior angle where it is also somewhat protracted ; the outer per- 

 istome is strongly evenly curved; the inner slightly thickened at the 

 umbilical keel. Operculum typically ptychocochlid. 



The specimen figured has 5 whorls and measures : Height, 13.5 mm. ; 

 greater diameter, 21.2 mm. ; lesser diameter, 15.9 mm. It is one of the 

 specimens in the Adams collection at Amherst College, and the label 

 states that it came from Gutters and was donated by Chitty. 



The species centers in Manchester Parish, Jamaica, but it also ex- 

 tends into Clarendon to the east and the eastern part of St. Elizabeth 

 and to the north into St. Ann Parish. 



PTYCHOCOCHLIS GOSSEI, new species 



Plate 13, Figuees 34-36 



Shell rather large, helicoid. The nucleus and early postnuclear 

 turns are almost blood-red; the rest unicolor, chestnut-brown, or 

 banded. In the type there is a white band immediately below the 

 summit and a broad light zone extending from the periphery to the 

 middle of the base, and finer paler lines on the anterior portion of the 

 base, which is also of a paler tint than the upper surface. The nucleus 

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

 whorls are strongly rounded. The first postnuclear whorl is marked 

 by slender, retractively curved axial riblets, which are not quite as 

 wide as the spaces that separate them. These fine riblets continue 

 over the rest of the whorls, becoming a little heavier and decidedly 

 irregular in distribution on the last whorl. On the second postnuclear 

 whorl the beginning of the decidedly oblique, protracted ridges make 

 their appearance. These become intensified as the shell increases in 

 size, and on the penultimate whorl they are about as wide as the spaces 

 that separate them. They do not extend on the anterior fourth of the 

 whorls and on the last half of the last whorl they become much en- 

 feebled. They are never as pronounced as in P. corrugatior (Chitty). 

 On all the whorls, except the last, the suture is well impressed ; on the 

 latter the summit is appressed to the preceding turn. Periphery well 



