150 PROCEEDINGS OF THE NATIONAL, MUSEUM Vol.89 



Last whorl solute. 



Outer peristome expanded. 



Outer peristome of inner lip very broad. 

 Axial ribs sublamellar. 



Whorls decidedly inflated occidentale 



Whorls not decidedly inflated rugulosum 



Axial ribs not sublamellar wrightianum 



Outer peristome of inner lip not very broad. 



Outer peristome fluted pinense 



Outer peristome not fluted clathratum 



Outer peristome very narrow hespericum 



RHYTIDOPOMA HONESTUM (Poey) 



Shell elongate-conic, white. Nuclear whorls 2, large, strongly- 

 inflated and rounded, microscopically granulose, forming a mammil- 

 lated apex. Postnuclear whorls weU rounded, marked by slender, 

 retractively curved axial ribs, which are expanded into hollow 

 auricles at the summit and which are appressed to the preceding turn. 

 The spiral sculpture is very poorly developed. Suture strongly con- 

 stricted. Periphery well rounded. Base well rounded, marked by 

 the continuation of the axial ribs and usually by strong spiral threads. 

 Aperture broadly oval; peristome double, the inner slightly exserted, 

 the outer moderately expanded, marked by concentric lines of growth, 

 notched on the middle of the inner lip, the part posterior to the notch 

 reflected over the umbilicus, which it covers. Operculum typically 

 rhytidopomid. The breathing siphon is close to the posterior angle 

 of the aperture behind the peristome, which it renders irregular at this 

 point; it is reflected backward into the suture. 



This species appears restricted to Habana Province. We are 

 recognizing three subspecies: 



KEY TO THE SUBSPECIES OF RHYTIDOPOMA HONESTUM 



Axial ribs rather strong itinerans 



Axial ribs weak. 



Axial ribs closely spaced honestum 



Axial ribs not closely spaced nodiferura 



RHYTIDOPOMA HONESTUM ITINERANS, new subspecies 



Plate 10, Figure 10 



This subspecies wc coUected along stone fences near Guanajay. It 

 differs from the other two subspecies in having the axial ribs much 

 more strongly developed. 



The type, U.S.N.M. No. 493413, has 40 axial ribs on the first of the 

 remaining turns and 50 on the last whorl; it has 3.7 whorls remaining 

 and measures: Length, 7.8 mm.; greater diameter, 4.0 mm.; lesser 

 diameter, 3.2 mm. 



