172 PROCEEDINGS OF THE NATIONAL MUSEUM Vol.89 



preceding turn at the parietal wall. The entire outer peristome is 

 marked by numerous slender, concentric lamellae, which are particu- 

 larly emphasized at the posterior angle. Operculum typically opis- 

 thosiphonid. Siphon at the posterior angle of the aperture, reflected 

 backward and toward the suture behind the peristome, connecting 

 with a channel behind the parietal peristome, communicating with 

 the hollow axis of the spire, breathing being accomplished through 

 this by means of the truncated apex when the operculum closes the 

 shell. 



The type, U.S.N.M. No. 535441, and a series of specimens were 

 collected by Bartsch on rocks at Sitio Afuera, at the south end of the 

 Paso de la Escalera, Cubitas Mountains, Camagiiey Province. 



The type has 4.5 whorls remaining and measures: Length, 14.7 

 mm.; greater diameter, 9.3 mm.; lesser diameter, 7.3, mm. It is a 

 medium-sized specimen; in the collection there are larger and smaller 

 individuals. 



OPISTHOSIPHON (BERMUDEZSIPHONA) LAMELLOSUM, new species 



Shell very elongate-ovate, flesh colored, unicolor or banded. 

 Nuclear whorls decollated in all our specimens. Postnuclear whorls 

 inflated, strongly rounded, and marked by retractively slanting, 

 sublamellar axial ribs, which are much more distantly spaced on the 

 early turns than on the last. These ribs form hollow cusps at the 

 summit at more or less regular intervals; they vary materially in 

 strength in the two races here recognized. The spaces separating the 

 axial ribs are microscopic axial threads. Suture strongly constricted. 

 Periphery of the last whorl strongly rounded. Base short, inflated, 

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

 immediately outside of the closed umbilicus by several spiral threads, 

 which render the axial ribs conspicuously scalloped. Aperture 

 broadly oval; peristome double, the inner moderately exserted; the 

 outer broadly expanded, reflected, and auriculated at the posterior 

 angle, and deeply notched on the inner lip, the portion posterior to 

 the notch being reflected into the umbilicus, which it plugs. The 

 outer peristome is marked by fine, concentric lamellae. Operculum 

 typically opistliosiphonid. The siphon is situated at the posterior 

 angle of the aperture behind the peristome; it is reflected into the 

 suture and communicates through a channel behind the parietal 

 wall with the hollow axis and the decollated apex. 



We are recognizing two subspecies, which the following key and 

 descriptions will help to differentiate: 



KEY TO THE SUBSPECIES OF OPISTHOSIPHON (BERMUDEZSIPHONA) LAMELLOSUM 



Shell with interrupted syjiral bands of brown laraellosum 



Shell without interrupted spiral bands of brown lowei 



