180 PROCEEDINGS OF THE NATIONAL MUSEUM Vol.89 



OPISTHOSIPHON (BERMUDEZSIPHONA) OBTECTUM GUAYOSENSE. new subspecies 



Plate 13, Figure 2 



This race comes from the caves near Guayos, in Santa Clara 

 Province. We have also seen it from Las Damas, near Guayos. It 

 differs from the other three subspecies in being much more slender, 

 with the whorls a little less inflated. The ribs are about as strongly 

 developed as those of typical 0. (B.) obtedum obtedum, stronger than in 

 the other two races. The denticulations at the summit also resemble 

 those of typical obtedum. In the type there are 30 ribs on the first 

 of the remaining turns and 104 on the last. 



The type, U.S.N.M. No. 355514, has a little more than 4 whorls 

 remaining and measures: Length, 12.2 mm.; greater diameter, 6.2 

 mm.; lesser diameter, 5.2 mm. 



OPISTHOSIPHON (BERMUDEZSIPHONA) INSULANUM, new species 



Shell subcylindric, rather thin, pale straw colored, with interrupted 

 spiral bands of brown. The early whorls are decollated in all our 

 specimens. Those remaining are very strongly inflated and rounded, 

 and crossed by slightly retractively slanting axial ribs, which are more 

 distantly spaced on the early whorls than on the later, where they are 

 rather closely approximated. These riblets at rather close intervals 

 form slender minute cusps at the summit. The intercostal spaces 

 are marked by microscopic axial threads. Suture strongly constricted. 

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

 and marked by the continuation of the axial ribs and in the exposed 

 portion of the umbilicus by a number of spiral cords, which render 

 the axial ribs feebly nodulose at their junctions. Aperture broadly 

 oval; peristome double, the inner exserted, erect; the outer forming a 

 conspicuous auricle at the posterior angle, narrower on the outer and 

 basal lip, and again expanded on the inner lip, where it is strongly 

 notched; the portion posterior to the notch is bent into and plugs 

 the umbilicus. The outer peristome is marked by slender, concentric 

 lamellae. Operculum typically opisthosiphonid. The siphon situ- 

 ated at the posterior angle of the aperture immediately behind the 

 peristome bends into the suture and connects through a slender 

 channel behind the parietal wall of the outer peristome with the 

 umbilicus, the hollow axis, and the decollated apex. 



The species appears to be confined to the small islands lying 

 off the Santa Clara coast near Caibarien. 



We are recognizing two subspecies, which the following key and 

 descriptions will help to differentiate: 



KEY TO THE SUBSPECIES OF OPISTHOSIPHON (BERMUDEZSIPHONA) INSULANUM 



Suture strongly constricted scopulorum. 



Suture enormously constricted insulanum 



