170 PROCEEDINGS OF THE NATIONAL, MUSEUM Vol.89 



The fact that the outer peristome is erect and forms a strong hood at 

 the posterior angle of the aperture distinguishes this species from all 

 the other Opisthosiphons. 



Animals collected in the Sierra de Meneses opposite Kilometers 

 42 and 43 were described by Bartsch as follows: Pale buff with a 

 smoky tinge and a pinkish area at the base of the dark gray tentacles. 

 There is a median dorsal diffused longitudinal stripe. Sides of the 

 body a little paler than the dorsal part, with the sole of the foot paler 

 than the sides and deeply cleft. The animal at rest suspends itself 

 by a mucous thread. 



OPISTHOSIPHON (BERMUDEZSIPHONA) PALMERI, new species 



Shell elongate-ovate, thin, small. Nuclear whorls decollated in all 

 our specimens. The early postnuclear whorls with strongly raised, 

 lamellar axial ribs, which beyond the second turn become decidedly 

 reduced and which are replaced by ill-defined, low, rounded axial ribs. 

 Some of the axial ribs develop into hollow cusps at the summit, which 

 extend across the well-impressed suture and which touch the preceding 

 whorl. Periphery well rounded. Base moderately long, marked by 

 the continuation of the axial sculpture of the last turn and by a spiral 

 tliread, limiting the outer edge of the umbilicus, which renders the ribs 

 decidedly scalloped. Aperture broadly oval; peristome double, the 

 inner exserted and erect; the outer broadly expanded, sloping at an 

 angle of 45° from the inner peristome, marked by numerous slender, 

 concentric lamellae. On the inner lip the peristome is deeply notched, 

 the portion posterior to the notch being reflected over the umbilicus, 

 which it plugs. Operculum typically opisthosiphonid. The siphon is 

 at the posterior angle of the aperture behind the peristome and it is 

 directed backward into the suture, where it connects through a channel 

 behind the parietal wall with the hollow axis, breathing being accom- 

 plished through the decollated tip. 



This species is distinguished from 0. (B.) cucullatum by its much less 

 erect outer peristome and by the much enfeebled axial sculpture of 

 the later turns. 



We are recognizing two subspecies, which the following key will 

 help to differentiate: 



KEY TO THE SUBSPECIES OF OPISTHOSIPHON (BERMUDEZSIPHONA) PALMERI 



Axial ribs of last whorls well developed palmeri 



Axial ribs of last whorls almost obsolete caraajanense 



OPISTHOSIPHON (BERMUDEZSIPHONA) PALMERI PALMERI, new subspecies 



Plate 12, Figure 3 



This subspecies is known from Guainabo, and Pie Valdes, 

 near Yaguajay, Santa Clara Province. It differs from 0. (B.) 



