174 PROCEEDINGS OF THE NATIONAL MUSEUM Vol.89 



effect, which, however, is not apparent in the intercostal spaces. The 

 broad spaces between the axial ribs are marked by microscopic axial 

 threads. Suture strongly constricted. Periphery of the last whorl 

 inflated, strongly roimded. Base short, inflated, strongly rounded, 

 and marked by the continuation of the axial ribs, and on the 

 exposed portion of the umbilicus by 3 prominent spiral cords, which 

 render the axial ribs at their junction decidedly scalloped. Aperture 

 broadly oval; peristome double, the ioner rather conspicuously 

 exserted; the outer broadly expanded, slightly auriculate at the 

 posterior angle, and deeply notched on the middle of the inner lip, 

 the portion posterior to the notch being reflected to plug the 

 umbilicus. The outer peristome is marked by numerous, strongly 

 developed, concentric lamellae. Operculum typically opisthosiphonid. 

 The siphon at the posterior angle of the aperture, behind the peristome, 

 is reflected into the suture and communicates -vvith the channel 

 behind the parietal wall, which is connected with the hollow axis 

 and the decollated apex. 



The type, U.S.N. M. No. 387920, has 4 whorls remaining and meas- 

 ures: Length, 13.0 mm,; greater diameter, 8.0 mm.; lesser diameter, 

 6.5 mm. 



A large series of specimens was collected by Bartsch on the north 

 slope of Loma Platero, near Jagiiey, Santa Clara Province. 



OPISTHOSIPHON (BERMUDEZSIPHONA) PROMINULUM, new species 



Plate 12, Figure 2 



Shell very elongate-ovate, moderately thin, pale yellowish brown. 

 Nuclear whorls decollated. Postnuclear whorls somewhat inflated, 

 strongly rounded, and marked by retractively slanting ribs, which 

 are more pronounced and more widely separated on the early turns 

 than on the succeeding whorls. On the last two whorls they become 

 decidedly reduced and they are here but slightly elevated. The 

 spaces between the axial riblets are crossed by microscopic axial 

 threads. Of the axial riblets 82 occur upon the last turn. Some of 

 these axial riblets become expanded at the summit to form hoUow 

 cusps at more or less regular intervals. Suture weU impressed. 

 Periphery of the last whorl inflated, strongly rounded, and marked 

 by the continuation of the weak axial ribs, which extend to the closed 

 umbilicus. The exposed portion of the umbilicus shows 3 spiral 

 cords, which render the axial riblets somewhat scalloped. Base short, 

 well rounded. Aperture broadly oval, peristome double, the inner 

 slightly exserted, the outer broadly expanded, forming an auricle at 

 the posterior angle and being notched on the middle of the inner lip ; 

 the portion posterior to the notch is reflected to plug the umbilicus. 

 On the parietal wall the outer lip extends over and is adnate to the 



