96 BULLETIN 181, UNITE'D STATES NlATTONlAL MUSEUM 



turn. Postnuclear whorls inflated, strongly rounded; the first is 

 marked by slender, retractively curved axial riblets, which are about 

 half as wide as the spaces that separate them. Axial riblets also 

 cover the rest of the whorls, but beyond the first turn they become 

 less regular and tend more toward the formation of slender lamellae. 

 Beginning with the second postnuclear whorl, oblique ridges make 

 their appearance. These ridges are decidedly protractively curved, 

 and are a little narrower than the spaces that separate them. They 

 are strongest on the early turns and gradually fade and disappear on 

 the middle of the spire, after which they are replaced by irregular, 

 low wrinklings and nodulations, as well as malleations. Suture 

 strongly impressed, except on the last turn, which is appressed to the 

 preceding whorl. Periphery well rounded. Base strongly rounded, 

 openly umbilicated, with a strongly elevated keel marking the outer 

 edge of the umbilicus. This keel is decidedly notched and roughened, 

 and separated from the umbilical wall by a strong groove. On the 

 outside it is also separated by a groove, but here the groove is weaker 

 than that on the umbilical side. The rest of the base is marked by 

 obsolete spiral lines and indications of malleations, as well as strong 

 incremental lines. The umbilical wall is marked by numerous in- 

 cremental lines, which tend toward the formation of riblets. Aper- 

 ture circular, protracted into an angle at the posterior angle; outer 

 lip of the peristome thin; inner, somewhat thickened. Operculum 

 typically ptychocochlid. 



The specimen figured, U.S.N.M, No. 356092, was collected by John 

 B. Henderson at Holly Mount, St. Catherine Parish, Jamaica. It has 

 5 whorls and measures: Height, 19.4 mm.; greater diameter, 28.6 

 mm. ; lesser diameter, 21.0 mm. 



The species has a rather wide distribution through the northern 

 part of the island. It ranges through Trelawny and St. Ann Parishes 

 and the northeastern part of St. Catherine Parish. 



PTYCHOCOCHLIS HENDERSONI, new species 



Plate 15, Figijkes 7-9 



Shell of medium size, depressed-helicoid. The denuded specimen 

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

 The postnuclear whorls are inflated and strongly rounded; the first 

 is marked by slender, feeble axial riblets; the succeeding turns in 

 addition to the axial riblets are marked by protractively curved 

 ridges, which are about as wide as the spaces that separate them and 

 which do not extend on the anterior fourth of the turns. These 

 ridges extend fairly strongly to the very end of the last whorl. 

 Suture strongly impressed on all but the last turn, which is appressed 

 to the preceding whorl. Periphery well rounded. Base broadly 



