CUBAN ANNULARIIDAE — TORRE AND BAKTSCH 377 



SO on the inner lip, and decidedly so at the posterior angle, where it 

 forms a hood, the posterior angle of which touches the preceding 

 whorl. The inner lip at the posterior angle forms a decided shelf, 

 leaving a deep triangular pit at the posterior angle. Operculum 

 typically annularid. 



The type, U.S.N.M. No. 535648, comes from Alto del Cedrito, 

 Monte Libano, Oriente Province. It has 5.3 whorls and measures: 

 Length, 12.9 mm.; greater diameter, 12.5 mm.; lesser diameter, 

 9.5 mm. 



ANNULASIA (ANNULARELLA) NATENSONI, new speciea 



Plate 53, Figures 4-6 



Shell small, turbinate, pale yellow. Nuclear whorls 2, well rounded, 

 smooth, except for the last portion of the last turn, which shows the 

 beginning of the postnuclear sculpture. Postnuclear whorls inflated, 

 strongly rounded, marked by slender axial threads on the first half 

 whorl, after which the axial sculpture becomes differentiated into 

 two types, namely, distantly, rather irregularly spaced, sublamellar 

 ribs, between which occur finer axial threads. Thirty-four of the 

 strong ribs occur on the second whorl and 31 are on the last eight- 

 tenths of the last turn. The finer threads between the lamellar ribs 

 vary in number from 3 to 10. Suture strongly constricted. Pe- 

 riphery of the last whorl inflated, well rounded. Base short, inflated, 

 well rounded, openly umbilicated, marked by the continuation of the 

 axial ribs, which extend prominently into the umbilicus. A feeble 

 spiral thread marks the outer limit of the umbilicus. The umbilical 

 wall itself is free of spiral sculpture. The last whorl is solute for about 

 one-eighth of a turn. Aperture subcircular; peristome double, the 

 inner reflected over the outer on the outer basal and inner lip, forming 

 a shelf at the posterior angle of the aperture; the outer moderately 

 expanded and almost the same width except at the posterior angle, 

 where it forms an auricle. Operculum typically annularid. 



The type, U.S.N.M. No. 535650, was coUected by Natenson at 

 SiUa de Baez west of Baracoa, Oriente Province. It has 4.9 whorls 

 and measures: Length, 7.5 mm.; greater diameter, 7.4 mm.; lesser 

 diameter, 6.2 mm. 



ANNULARIA (ANNULARELLA) INTERSTITIALIS ([Gundlach] Pfeiffer) 



Plate 54, Figures 4-6 



1859. Cyclostorna (Cistula) interstiliale [Gundlach] Pfeiffer, Malakozool. Blatter, 



vol. 6, p. 74. 

 1861. Cistula interstiliale Bland, Ann. Lyceum Nat. Hist. New York, vol. 7, 



p. 27. 

 1920. Tudora {Tudor ellata) inter stitialis Henderson and Bartsch, Proc. U. S. 



Nat. Mus., vol. 58, p. 75. 

 Shell turbinate, thm, semitranslucent, yellowish white, a little 

 darker on the early turns than the last. Nuclear whorls 2, well 



