190 PROCEEDINGS OF THE NATIONAL MUSEUM Vol.89 



This subspecies may be distinguished from 0. (B.) aguilerianum 

 holguinense in having the ribs more distantly spaced and the cusps at 

 the summit much stronger. There appears also to be a lesser tendency 

 to banding. 



The complete specimen, U.S.N.M. No. 535462, has 21 axial ribs on 

 the first turn and 44 on the last. It has 7.3 whorls and measures: 

 Length, 12.3 mm.; greater diameter, 6.0 mm.; lesser diameter, 4.9 mm. 



OPISTHOSIPHON (BERMUDEZSIPHONA) AGUILERIANUM HOLGUINENSE Aguayo 



Plate 14, Figure 11 



1932. Opisthosiphon aguilerianum holguinense Aguayo, Nautilus, vol. 45, p. 93, 

 pi. 6, fig. 1. 



This subspecies comes from Cerro San Juan, Sao Arriba, Holguin, 

 Oriente Province. It differs from the typical race in having the axial 

 ribs more numerous, more closely spaced, and less strongly cusped 

 at the summit. 



The specimen figured, U.S.N.M. No. 535463, has 35 axial ribs on 

 the first of the remaining turns and 57 on the last. It has 4.4 whorls 

 remaining and measures: Length, 11.8 mm.; greater diameter, 6.0 

 mm.; lesser diameter, 5.3 mm. 



OPISTHOSIPHON (BERMUDEZSIPHONA) DETECTUM Torre and Henderson 



Shell smaU, ovate, rather thin, varying in color from pale yellow 

 to pale brown, unicolor, or interruptedly spirally banded. Nuclear 

 whorls decollated in all our specimens. Postnuclear whorls inflated, 

 strongly rounded, and marked by retractively slanting axial riblets, 

 which in the subspecies murinum are rather conspicuously nodulose 

 on the posterior portion of the whorls, much less so in the other races 

 where the nodules are scarcely indicated. The intercostal spaces are 

 marked by microscopic axial hairlines. Most of the axial ribs develop 

 into slender hollow cusps at the summit. These vary in strength in 

 the various races. Suture strongly constricted. Periphery of the 

 last whorl inflated, strongly rounded. Base short, moderately 

 openly umbilicated, strongly rounded, marked by the continuation of 

 the axial ribs and within the umbilicus marked by spiral threads, 

 which are also of varying strength and number in the different races. 

 Aperture broadly oval; peristome double, the inner moderately ex- 

 serted and very slightly reflected ; the outer rather broadly expanded, 

 slightly inbent in the middle of the inner lip in two of the races, adnate 

 to the preceding turn at the parietal wall, and marked by concentric 

 laminae. Operculum typically opisthosiphonid. Siphon at the 

 posterior angle of the aperture behind the peristome directed back- 

 ward into the suture. 



We are recognizing three subspecies, which the following key and 

 descriptions wiU help to characterize : 



