204 PROCEEDINGS OF THE NATIONAL MUSEUM Vol.89 



little narrower at the junction of the outer and basal lip, forming a 

 moderately strong auricle at the posterior angle. On the middle of the 

 inner lip the outer peristome is somewhat inbent. The entire surface 

 of the outer peristome is marked by concentric laminae. Operculum ? 

 Siphon at the posterior angle of the aperture directed backward into 

 the suture. 



The type, U.S.N.M. No. 535473, was collected by Torre at Mono 

 Ciego, on the west side of the entrance of the port of Manati, Oriente. 

 It has 3.5 whorls remaining and measures: Length, 10.0 mm.; greater 

 diameter, 5.5 mm. ; lesser diameter, 4.7 mm. 



OPISTHOSIPHON (CUBITASIPHONA) BIOSCAI Torre and Henderson 



Plate 16, Figure 8 



1920. Opisthosiphon {Opisihosiphona) hioscai (Torre and Henderson) Henderson 

 and Bartsch, Proc. U. S. Nat. Mus., vol. 58, p. 67^ nomen nudum. 



1921 Opisthosiphon {Opisihosiphona) hioscai hioscai Torre and Henderson, 

 Proc. U. S. Nat. Mus., vol. 59, p. 256, pi. 40, figs. 4, 6. 



Shell elongate-ovate, flesh colored with a brownish tinge, sometimes 

 pale brown, marked by mterrupted spiral bands of brown, the elements 

 composing these bands being arranged in both axial and spiral series; 

 the interior of the aperture is flesh colored; the peristome is flesh 

 colored with a yellowish tinge. Nuclear whorls 1.5, very small, well 

 rounded, microscopically granulose, with the last portion of the last 

 turn showing the beginning of the axial ribs. Postnuclear whorls well 

 rounded, marked by retractively curved axial ribs, which are rather 

 feebly developed on the early turns, becoming broad, low, and rounded 

 on the succeeding whorls. In the type 72 of these ribs occur upon the 

 first of the remaining turns, 102 upon the second, and 124 upon the 

 last. Some of these ribs at irregular intervals are fused and expanded 

 at the summit into hollow cusps, while others terminate a little short 

 of the summit. Suture moderately constricted. Periphery well 

 rounded. Base moderately long, well rounded, openly umbilicated, 

 marked by the axial ribs and 2 strong, spiral cords on the outside of 

 the umbilicus, and by 2 more strong, spiral cords anterior to these, 

 which are much less conspicuous, while the umbilical wall on the inside 

 is marked by a number of feeble, spiral lines of nodules. The junction 

 of the axial ribs and the spiral threads in the umbilicus causes the 

 axial ribs to become expanded into clawlike elements. Aperture 

 broadly oval; peristome double, the inner slightly exserted and slightly 

 expanded; the outer very broadly expanded on the parietal wall and 

 very broadly reflected over the umbilicus, which it completely hides 

 when viewed squarely; it is reflected over the preceding turn on the 

 parietal wall and is adivate to it. The outer peristome is much 

 narrower on the outer lip, but it is conspicuously expanded at the 



