186 PROCEEDINGS OF THE NATIONAL MUSEUM Vol.89 



series; these dots may be present on both spu"e and base. Nuclear 

 whorls decollated. Postnuclear whorls mflated, strongly rounded, 

 marked by slightly retractively slanting, sublamellar axial ribs, of 

 which 29 are present on the first whorl and 86 on the last. Almost 

 every other one of these ribs is expanded at the summit into a hollow 

 cusp. The intercostal spaces are wider than the ribs and they are 

 marked by microscopic hairlines. Suture well impressed. Periphery 

 inflated, well rounded. Base moderately long, well rounded, and 

 marked by the continuation of the axial ribs which extend into the 

 umbilicus. The umbilicus is narrowly open and it is marked by a 

 series of concentric spiral threads, which render the axial ribs decid- 

 edly nodulose at their junction. Aperture broadly oval; peristome 

 double, the inner slightly exserted, scarcely reflected; the outer 

 broadly expanded, forming somewhat of an auricle at the posterior 

 angle of the aperture, deeply notched on the inner lip, the portion 

 posterior to the notch expanded as a broad flap, which is reflected 

 over the umbilicus, which it partly conceals. The outer peri- 

 stome is marked by slender concentric lamellae. Operculum typi- 

 cally opisthosiphonid. Siphon situated behind the peristome at the 

 posterior angle of the aperture, dbected into the suture. 



The type, U.S.N.M. No. 535456, comes from Cayo Caguanes, 

 Yaguajay, Santa Clara Province. It has 4.2 whorls remaining and 

 measures: Length, 13.8 mm.; greater diameter, 8.7 mm.; lesser 

 diameter, 6.2 mm. The type is a little larger than additional speci- 

 mens before us from the same locality. 



OPISTHOSIPHON (BERMUDEZSIPHONA) SUBOBTECTUM, new species 



Shell ovate, rather thin, varying in color from pale yellow to brown, 

 unicolor, or with faint interrupted spu'al bands of brown. Nuclear 

 whorls about 2, small, inflated, strongly rounded, forming a slender 

 truncated apex. Postnuclear whorls inflated, strongly rounded, 

 marked by retractively slanting axial ribs, which are only a trifle 

 more distantly spaced on the early turns than on the last. Most of 

 these ribs expand into tiny cusps at the summit. Intercostal spaces 

 marked by microscopic axial hairlines. Suture strongly constricted. 

 Periphery inflated, well rounded. Base short, inflated, strongly 

 rounded and openly umbilicated, marked by the continuation of the 

 axial ribs and by a series of spiral threads within the umbilicus. 

 These threads render the axial riblets wealdy nodulose. Aperture 

 broadly oval, almost subcircular; peristome double, the inner exserted 

 and very slightly expanded; the outer expanded, narrow on the outer 

 and the basal lip, broader at the posterior angle, widest on the inner 

 lip, at the middle of which it is deeply infolded and reflected over the 

 umbilicus. Operculum typically opisthosiphonid. Siphon at the 

 posterior angle of the aperture behind the peristome directed into 

 the suture. 



