352 PROCEEDINGS OF THE NATIONAI^ MUSEUM Vol. S9 



rounded, marked by retractively curved, slender, well elevated, narrow 

 ribs. There is no indication of obsolete spiral threads on spire or base. 

 Suture well constricted. Periphery inflated, strongly rounded. Base 

 short, strongly rounded, narrowly, openly umbilicated, marked by the 

 continuation of the axial ribs and on the parietal wall by feebly 

 developed, slender spiral threads, which are rather few in number, 

 and which are rather distantly spaced. Aperture circular; peristome 

 double, the inner coextensive on the outer lip with the outer, separated 

 from the outer on the inner lip and the parietal wall by an impressed 

 line. On the inner lip and the parietal wall the outer peristome 

 becomes flaringly expanded and attenuated and forms a conspicuous 

 projection at the posterior angle. Operculum typically annularid. 



The typo, U.S.N.M. No. 535645, comes from Tacre, west of Cajo- 

 babo, Oriente Province. It has 4.2 whorls and measures: Length, 

 8.9 mm.; greater diameter, 11.0 mm.; lesser diameter, 8.4 mm. 



The extremely small size and the sharp axial ribs will distinguish 

 this species from all the others. 



Annularex, new^subgenus 



Shell as in Annularella, but with spiral sculpture on the spire. 

 Type: Annularia (Annularex) in.tercisa, new species. 



KEY TO THE SPECIES OF THE SUBGENUS ANNULAREX 



Spiral sculpture of spire strong. 



Outer peristome of inner lip broadly expanded intercisa 



Outer peristome of inner lip not broadly expanded mackinlayi 



Spiral sculpture of spire not strong. 



Spiral threads on umbilical wall strong incerta 



Spiral threads on umbilical wall feeble ramsdeni 



ANNULARIA (ANNULAREX) INTERCISA. new species 



Plate 44, Figures 1-3 



Shell moderately large, depressed-helicoid, flesh colored with a 

 brownish flush; peristome white, with the interior of the aperture 

 pale orange. Nuclear whorls 1.5, small, well rounded, microscopically 

 granulose. The postnuclear whorls are inflated and strongly rounded ; 

 the first turn has 75 very slender, retractively curved axial riblets, the 

 same type of sculpture continuing for another fraction of a whorl; 

 this sculpture is followed by a stage in which there is a differentiation 

 between the stronger, distantly spaced axial ribs and the fine intercal- 

 ated threads, the latter gaining rapidly in strength so that on the last 

 half of the last turn it is difficult to distinguish them from the stronger. 

 In addition to this, the whorls are marked by spiral threads, which 

 are a little stronger than the axial ribs. These are not apparent on 

 the first postnuclear whorl, but on the second 6 are present between 



