224 PROCEEDINGS OF THE NATIONAL MUSEUM Vol.89 



basal lip, less so on the inner and parietal wall. Operculum pauci- 

 spiral, with the nucleus almost subcentral, each whorl marked by raised 

 calcareous lamellae as in young Xenopoma, but here the outer surface 

 of the lamellae is not strongly developed and arched over as it is in 

 the other Xcnopomas. 



There are 4 specimens before us, U.S.N. M. No. 493394, received 

 from Dr. C. Ramsden, collected on Mogote de Santa Ana, Oriente 

 Province. The one described and figured has a little over 4 whorls 

 and measures: Length, 10.0 mm.; greater diameter, 7.2 mm.; lesser 

 diameter, 5.2 mm. 



XENOPOMA AGUAYOI, new species 



Plate 19, Figure 7 



.Shell very large, elongate-conic, pale yellow. Nuclear whorls 2, 

 inflated, strongly rounded, microscopically granulose, forming a 

 slender, rather elongated apex. The last portion of the last nuclear 

 turn shows the beginning of the postnuclear sculpture. Postnuclear 

 whorls strongl}?- rounded, marked alternately by decidedly spinose 

 axial lamellae and by finer axial threads between these, the latter vary- 

 ing in number from 4 to 10. The second and third turns have 19 of the 

 strong lamellae, while 22 are present on the fourth, 23 on the fifth, 

 24 on the sixth, and 25 on the last postnuclear whorl. On the first 

 turn the strong spiral sculpture is poorly differentiated. The spines 

 on the lamellae form exceedingly large cusps, which are hollow. 

 These cusps are not well differentiated on the first and second post- 

 nuclear tiu-ns; on the third, 2 strong cusps and indications of lesser 

 ones are present; on the fifth there is a strong median cusp with 2 less 

 strong anterior and one posterior to it; on the sixth whorl there is a 

 strong median cusp with 2 posterior and anterior to it. These become 

 intensified on the first whorl; on the last whorl there are 4 strong cusps 

 and a slender, auriclelike element at the summit, and sometimes a 

 more slender denticle between the one at the summit and the first 

 strong cusp. Between the periphery and the umbilicus two more 

 cusps are present. The umbilical wall also shows some indication of 

 fine spines, although here they are almost obsolete. The last whorl is 

 solute and deflected for about half a turn. Aperture subcircular; 

 peristome double, the inner slightly exserted and reflected; the outer 

 very broadly expanded and of almost the same width all around, 

 marked by concentric laminae. Operculum typically xenopomid. 



The type, U.S.N.M. No. 535541, was collected by Dr. Aguayo at 

 Loma de la Cantera, Miranda, Oriente Province. It is a complete 

 specimen having 9.6 whorls and measuring: Length, 18.2 mm.; greater 

 diameter, 10.1 mm.; lesser diameter, 8.0 mm. 



This species is easily distinguished from all the others by having the 

 peristome broadly expanded on the parietal wall. 



