146 PROCEEDINGS OF THE NATIONAL MUSEUM Vol.89 



moderately broadly expanded, slightly reflected, and feebly digitated 

 at the outer margin, marked by concentric lines of growth. The 

 operculum is typically torrellid; it has the center depressed, this 

 depression being responsible for the specific name. The breathing 

 siphon begins immediately behind the peristome at the posterior angle 

 of the aperture and it is reflected as a tapering corrugated tube into 

 the umbilicus, which it completely plugs. 



The species ranges through northeastern Habana and northwestern 

 Matanzas Provinces. We are recognizing three subspecies, which the 

 following key defines: 



KEY TO THE SUBSPECIES OF TORRELLA (TORRELLA) IMMERSA 



Fluting of outer peristome rather strong. 



Axial ribs gathered into series at the summit camaronensis 



Axial ribs not gathered into series at the summit imraersa 



Fluting of outer peristome not strong grillensis 



TORRELLA (TORRELLA) IMMERSA CAMARONENSIS, new subspecies 



Plate 10, Figure 3 



This race comes from various places in the Sierra Camarones, 

 Matanzas Province. It differs from typical T. (T.) immersa immersa 

 in having the axial ribs much more strongly developed at the summit 

 and gathered into series; that is, stronger ribs are separated by narrow 

 spaces occupied by less strongly developed elements. It agrees with 

 T. (T.) immersa immersain having the outer peristome rather strongly 

 fluted, in which respect it differs from T. (T.) immersa grillensis. 



The type, U.S.N.M. No. 535532, comes from Vista Larga farm, 2 

 km. west of La Pena del Leon, Sierra de Camarones. It has 4.4 

 whorls remaming, which bear, respectively, 74 axial ribs on the first 

 whorl, 85 on the second, 110 on the tlm-d, and 112 on the last. It 

 measures: Length, 8.8 mm. ; greater diameter, 4.5 mm. ; lesser diameter, 

 4.0 mm. 



TORRELLA (TORRELLA) IMMERSA IMMERSA ([Gundlach] Pfeiffer) 



Plate 10, Figure 2 



1857. Cyclostoma immersum [Gundlach] Pfeiffer, Malakozool. Blatter, vol. 4, 



p. 42. 



1858. Ctenopoma immersum Pfeiffer, Monographia pneumonopomorum viven- 



tium, suppl. 1, p. 104. 

 1920. Torrella (Torrella) immersa Henderson and Bartsch, Proc. U. S. Nat. Mus., 

 vol. 58, p. 69. 



This subspecies was first described bj^ Gundlach from Loma de Simp- 

 son, which is at the entrance to the Yumuri Valley. We have it also 

 from the Yumuri Valley, Vista Alegre, and from Pan y Palenque, and 



