226 PROCEEDINGS OF THE NATIONAL MUSEUM Vol.89 



showing the begiimmg of the postnuclear sculpture. Postnuclear 

 whorls strongly rounded, marked by axial lamellae, which bear 

 hollow spines; between these axial lamellae are finer axial tlu-eads. 

 On the first postnuclear whorl the axial sculpture consists of 40 

 slender riblets, while on the succeeding two turns 16 lamellae are 

 present on each; on the fourth whorl there are 18, on the fifth 20, 

 and on the last 24. Two spines are present on the spire of all the turns 

 but the last. On the last an additional spine makes its appearance 

 between the summit and the first strong spine. On the middle of the 

 base there is another spine on the continuation of the lamellae. The 

 last whorl is solute for about a whole turn, and broadly deflected. The 

 inside of the umbilical wall is marked by fine axial threads, continuing 

 the finer sculpture; the coarser lamellae are here much reduced. 

 Aperture subcircular; peristome double, the inner slightly exserted; 

 the outer broadly expanded, slightly digitate, and fluted on the outer 

 lip. Operculum typically xenopomid. 



U.S.N.M. No. 10990 contains 4 specimens from the type locality, 

 Cayo del Rey, Oriente Province, collected by C. Wright. One of 

 these is a perfect specimen, which we have described and figured. It 

 has 8.2 whorls and measures: Length, 14.3 mm.; greater diameter, 

 5.8 mm.; lesser diameter, 5.2 mm. 



This species differs from X. hendersoni and X. spinosissimum by 

 having only three spines on the lamellae of the last whorl. 



XENOPOMA SPINOSISSIMUM, new speciea 



Plate 19, Figure 9 



Shell broadly elongate-conic, pmkish flesh colored with the peri- 

 stome wliite. Nuclear whorls 2, forming a conspicuous apex, the 

 inflated microscopically granulose whorls of wliich form a decidedly 

 mammillated apex. The last portion of the last nuclear turn shows 

 the beginning of the postnuclear sculpture. Postnuclear whorls 

 strongly rounded, marked by slender, raised, spinose axial lameflae, 

 between wliich 6, 8, or even more slender axial threads are present. 

 On the first whorl there are 34 slender axial riblets, on the second 26, 

 on the third 20, on the fourth 22, on the fifth 24, and on the sLxth 26. 

 These lamellae bear two spines on the first, second, and third turns; 

 on the fourth there are 4, on the fifth 5, and on the last 7 between the 

 smnmit and the suture. These spmes are very long, slender, and 

 hollow. Suture strongly constricted. Base short, strongly roimded, 

 marked on the ribs by 2 strong spines and a tliird that is less strong. 

 Witliin the umbilicus there are 5 slender spiral threads. There is 

 httlc difterentiation within the umbilicus between the strong lamellae 

 and the finer sculpture. The last whorl is solute and deflected for a 

 Httle more than half a turn. Aperture subcircular; peristome double, 



