82 BULLETM 181, UNTPEiD STATES NtATTONAl. MUSEUM 



CYCLOPILSBRYA (CYCLOCAYMANIA) LAEVITESTA (Pilsbry) 



Plate 13, Figures 22-24 



1930. Poferia laevitesta Pilsbey, Proc. Acad. Nat. Sci. Philadelphia, vol. 82, pp. 

 227-228, pi. 16, figs. 18, 18a, 19, 19a. 



Shell small, helicoid, covered with a honey-yellow periostracum. 

 Nuclear whorls 1.4, small, well rounded, smooth. The postnuclear 

 whorls are well rounded, the first marked by very regular, retrac- 

 tively slanting axial riblets, which are not quite so wide as the spaces 

 that separate them. After this the riblets become less regular and 

 more inclined to be lamellose and closely approximated, which render 

 the surface of the spire rather rough but without rugations. Suture 

 moderately constricted. Periphery almost angulated. Base short, 

 well rounded, marked like the spire with indications of fine spiral 

 lirations. A strong keel forms the umbilical angle. The umbilical 

 wall is excavated above this keel. The base also is devoid of ruga- 

 tions. The umbilicus is about one-fourth the diameter of the shell. 

 Aperture decidedly oblique, protracted at the posterior angle into an 

 almost spurlike element. Peristome simple, outer lip thin ; inner lip 

 decidedly thickened. Operculum typically cyclocaymanid. 



The specimen described and figured, Acad. Nat. Sci. Philadelphia 

 No. 150658, is a paratype collected by Charles B. Taylor on Grand 

 Cayman. It has 4.6 whorls and measures: Height, 11.5 mm. ; greater 

 diameter, 16.5 mm. ; lesser diameter, 13.5 mm. 



Genus PTYCHOCOCHLIS Simpson 



1895. Ptychocochlis Simpson, Proc. U. S. Nat. Mus.. vol. 17, p. 431. 



Simpson replaces Platy stoma Klein, several times preoccupied, with 

 the name Ptychocochlis and cites as type Neocyclotus jaTnaicensis 

 Chemnitz, rechristened orthodoxly by Menke in 1830 as Cyclostoma 

 Gorrugatum. The type of Ptychocochlis Simpson is Ptychocochlis 

 corrugata (Mevike)^ Turbo jamaicensis Chemnitz, Conchylien Cabi- 

 net, vol. 11, pp. 277-278, pi. 2'09, figs. 2057, 2058, 1795 (nonbinomial) 

 rechristened in 1830 as Cyclostoma coi^rugatmn Menke, Synopsis 

 methodica molluscorum * * *, p. 39. 



This genus is differentiated from Poteria by having the elevated 

 lamellae of the operculum expanded at the summit to resemble the 

 capital letter T or L inverted, the outer limb of the cross bar being 

 much longer than the inner and touching that of the succeeding 

 whorl, thus forming a complete deck. 



Type: Cyclostoma corrugatum Menke = Ptychocochlis corrugata 

 (Menke). 



The radulae of Ptychocochlis clappij P. martensi (Kobelt), and 

 P. savannensis show the formula 3:3:3:3. The jaw is without a 

 median projection. The verge of P. vendreysi is situated on the 



