CUBAN ANNULARiroAE TORRE AND BARTSCH 153 



are not all of the same strength; that is, some of them are more elevated 

 than others. Some of these ribs develop conspicuous auricles at the 

 summit, which are usually hollow. The spiral sculpture is poorly- 

 developed and is merely indicated by the waviness of the axial 

 riblets in some of the forms, while in others it is more strongly devel- 

 oped, Sutm-e strongly constricted. Periphery well rounded. Base 

 short, inflated, well rounded, narrowly umbilicated, the umbilicus 

 usually hidden by the reflected inner peristome of the parietal wall. 

 The base is marked by the continuation of the axial riblets and spiral 

 thi'eads, which vary in strength and number in the different races. 

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

 the outer broadly expanded, usually more so on the parietal and the 

 inner lip than on the outer, and marked by concentric lines of growth; 

 the inner peristome is slightly exserted. Operculum typically rhy- 

 tidopomid. The breathing siphon begins behind the edge of the post- 

 erior angle of the aperture and is reflected backward into the suture. 



This species ranges over Habana and Matanzas Provinces and 

 breaks up into several races, which the foUowing key and descriptions 

 will help to distinguish: 



KEY TO THE SUBSPECIES OF RHYTIDOPOMA NODULATUM 



Outer peristome fluted on the posterior inner lip palenquense 



Outer peristome not fluted on the posterior inner lip. 



Whorls inflated and strongly rounded nodulatum 



Whorls not inflated or strongly rounded anafense 



KHYTIDOPOMA NODULATUM PALENQUENSE, new subspecies 



Plate 10, Figure 15 



This subspecies centers about Matanzas, El Pan, El Palenque, the 

 Yumuri Valley, etc. It can be distinguished readily from the other 

 two races in that the outer peristome of the inner lip is fluted. 



The type, U.S.N.M. No. 355548, comes from El Palenque. It has 

 46 axial ribs on the first of the remaining turns, 70 on the second, 96 

 on the third, and 112 upon the last. It has a little more than 4 

 whorls remaining and measures: Length, 7.9 mm.; greater diameter, 

 3.8 mm.; lesser diameter, 3.3 mm. 



RHYTIDOPOMA NODULATUM NODULATUM (Poey) 



Plate 10, Figure 12 



1851. Cydostoma nodulatum Poet, Memorias sobre la historia natural de la isla 



de Cuba, vol. 1, pi. 5, figs. 21-23. 



1852. Cydostoma nodulatum Poey, Memorias sobre la historia natural de la isla 



de Cuba, vol. 1, p. 104. 

 1858. Ctenopoma rugulosum Pfeiffer, Monographia pneumonopomorum viven- 



tium, suppl. 1, p. 103, in part. 

 1920. Rhytidopoma nodulatum Henderson and Bartsch, Proc. U. S. Nat. Mus., 



vol. 58, p. 69. 



