160 PROCEEDINGS OF THE NATIONAL MUSEUM Vol.89 



stricted. Periphery strongly rounded. Base inflated, strongly 

 rounded, marked by the continuation of the axial ribs and by feeble 

 spiral threads, which vary somewhat in number in the different sub- 

 species. Within the umbilicus spiral threads also are present. These 

 are always stronger than those on the rest of the base. The last 

 whorl is slightly solute for about half a turn and is broadly deflected. 

 Aperture broadly ovate; peristome double, the inner moderately 

 exserted and slightly reflected; the outer broadly expanded and 

 reflected, not altogether in one plane but somewhat sinuous and 

 marked on the outside by concentric feeble laminae. The operculum 

 is typically rhytidopomid. The breathing siphon has its beginning a 

 little behind the peristome at the posterior angle and is reflected 

 from there as a slightly tapering tube, which completely plugs the 

 umbilicus; this tube is slightly corrugated. 



This species seems to occupy Habana, Matanzas, and Santa Clara 

 Provinces. It breaks up into several subspecies, which can be dif- 

 ferentiated by the following key and descriptions: 



KEY TO THE SUBSPECIES OF RHYTIDOPOMA CLATHRATUM 



Outer peristome of inner lip slightly fluted candelaense 



Outer peristome of inner lip not fluted. 



Shell slender jumaguaense 



Shell stout clathratum 



RHYTIDOPOMA CLATHRATUM CANDELAENSE. new subspecies 



Pl.\te 11, Figure 2 



This race comes from Loma de Candela and from Loma de Coca. 

 It is distinguished easily from the other two races by having the inner 

 lip of the outer peristome slightly fluted and by having the axial rib- 

 lets much more strongly developed at the summit than in the other 

 two. The spiral sculpture on the umbilicus is also stronger. 



The type, U.S.N.M. No. 355607, comes from Loma de Candela. 

 There are 100 axial riblets on the first of the remaining turns and 120 

 on the rest; it has 3.5 whorls remaining and measures: Length, 9.6 mm. ; 

 greater diameter, 5.3 mm.; lesser diameter, 4.6 mm. 



RHYTIDOPOMA CLATHRATUM JUMAGUAENSE. rew subspecies 



Plate 11, Figure 13 



This subspecies is distinguished easily from the other two by its 

 much slenderer form and by its less expanded outer peristome. 



The type, U.S.N.M. No. 387502, was collected by Bartsch on the 

 sixth mogote from the east at Jumagua near Sagua la Grande, Santa 

 Clara Province. It has 57 axial ribs on the first of the remaining 

 turns and 150 on the last whorl. It has 4.1 whorls remaining and 

 measures: Length, 9.3 mm.; greater diameter, 4.9 mm.; lesser diam- 

 eter, 4.4 mm. 



